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1987 Characterization of an immunogenic component of type A multocida Hyoik Ryu Iowa State University

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8716813

Ryu, Hyoik

CHARACTERIZATION OF AN IMMUNOGENIC COMPONENT OF TYPE A PASTEURELLA MULTOCIDA

Iowa State University PH.D. 1987

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University Microfilms International

Characterization of an inmunogenic component

of type A Pasteurella multocida

by

Hyoik Ryu

A Dissertation Suhnitted to the

Graduate Faculty in Partial Fulfillment of the

Requirements for the Degree of

DOCTOR OF PHILOSOPHY

Department; Veterinary Microbiology and Preventive Medicine

Major: Veterinary Microbiology

Approved ;

Signature was redacted for privacy. I17 Charge of Major Work

Signature was redacted for privacy. For the Major Department

Signature was redacted for privacy. For the Graduate College

Iowa State University Ames, Iowa

1987 11

TABLE OF CONTENTS

Page

GENERAL INTRODUCTION 1

LITERATURE REVIEW 4

SECTION I. ANALYSIS OF OF PASTEURELLA MULTOCIDA AND SEVERAL GRAM-NEGATIVE BY GAS CHROMATOGRAPHY ON A CAPILLARY COLUMN 33

SUMMARY 34

INTRODUCTION 35

MATERIALS AND METHODS 37

RESULTS 42

DISCUSSION 55

LITERATURE CITED 60

SECTION II. CHARACTERIZATION OF A -PROTEIN COMPLEX OF TYPE A PASTEURELLA MULTOCIDA 63

SUMMARY • 64

INTRODUCTION 66

I-IATERIALS AbD METHODS 68

RESULTS 75

DISCUSSION 86

LITERATURE CITED 91

SECTION III. II-irCNOLOGIC REACTIVITY OF A LIPOPOLYSACCHARIDE- PROTEIN COMPLEX OF TYPE A PASTEURELLA MULTOCIDA IN MICE 94

SUMMARY 95

INTRODUCTION 96 iii

Page

MATERIALS AND METHODS 98

RESULTS 107

DISCUSSION 123

LITERATURE CITED 129

GENERAL SUMMARY 132

LITERATURE CITED 136

ACKNOWLEDGMENTS 148 1

ŒNEEIAL INTRODUCTION

Pasteurella multocida (P. multocida) is a Gram-negative bacterium

capable of infecting most animal species including man. Capsular type A

and scmatic type 3 strains of the microorganism are known to be a major etiological factor of pneumonic of cattle, and econcmic loss to the U.S. cattle industry from the disease exceeds a half billion dollars annually. The scientific and economic importance of £. multocida has led to the development and use of various bacterins for prevention; however, the efficacy of these products has been questioned. In fact, immunization of cattle with Pasteurella bacterins has been demonstrated to be detrimental to the health of the animal. The questionable efficacy and safety of bacterins has led to experimentation with various subcellular fractions of the microorganism in studies of bacterial pathogenesis and in pursuit of a better immunogen.

Lipopolysaccharides (LPS, endotoxin) present in the outer membrane of Gram-negative bacteria have been demonstrated to play important roles in bacterial infection of animals. The £. multocida LPS extracted by conventional methods (phenol-water, phenol-chloroform-petroleum ether or trichloroacetic acid) has been observed to evoke a variety of endotoxic activities in a host including pyrogenicity, depression, diarrhea and death in mice, rabbits and , and lethality for anbryos.

Although LPS extracted by the phenol-water method was poorly immunogenic, many researchers suggested that £. multocida fractions with demonstrated immunogenicity contained the LPS as a part of their constituents. 2

Previously, we have reported that a fraction isolated from a

potassium thiocyanate (KSCN) extract of a P. multocida organism (strain

P-2383; capsular type A and somatic type 3) induced resistance in mice

against a challenge with the homologous bacterium. The fraction, called

P-2383-1, was determined to be a LPS-protein complex since it contained

27% protein and serologically crossreacted with the LPS extracted by the

phenol-water method. However, 2-keto-3-hydroxy-octonate (KDO), which is

an important constituent of Gram-negative bacterial LPS, was not detected

in P-2383-1.

The outer surface of Gram-negative bacteria contains several

distinctive structures including the outêr membrane, capsule, glycocalyx,

fimbriae and flagella. Exopolysaccharides, the outer membrane and the

cell wall may be extremely complex and. variant among bacterial species.

This complexity contributes to a major problan in the extraction and

characterization of individual structural components. Also, different

extraction methods yield variant products; the basic components may be

the same but the nature of complexes can be diverse. This variation

extends to previous experimentation on P. multocida and may account for

the diversity of products reported by individual investigators.

Our previous experimentation on P-2383-1 failed to demonstrate the

presence of KDO in this complex. However, we were convinced that this

was probably due to a limited quantity of this material and an

insensitivity of the assay procedure. This problan is not unique to our experimentation and similar problems have been observed in other

immunogenic fractions of P. multocida such as a free endotoxin, a 3

particulate material and a LPS-protein complex. The potential for LPS to serve in immunogenic capacities such as the protective determinant or as an adjuvant necessitated further characterization of this immunogenic complex.

The objective of this experimentation was to further characterize the chemical composition and biological activities of the LPS-protein complex. Specific aims were; 1) to determine the chemical composition of

P. multocida LPS in comparison with the chemical composition of LPS of several Gram-negative bacterial pathogens, 2) to characterize the LPS- protein complex isolated from the KSCN extract of P. multocida and 3) to examine the immunologic reactivity of the LPS-protein complex in mice.

An alternative format is used for this dissertation. Literature cited in each manuscript is listed at the end of each manuscript while references cited both in the literature review and individual manuscripts are included in "Literature Cited" at the end of the dissertation. 4

LITERATURE REVIEW

Genus Pasteurella multocida

History

A disease process now known as pasteurellosis was reported long

before the isolation of the causative microorganisms. During the 18th

century, large epornitics in poultry were reported throughout European

countries and were first studied in France by Chabert in 1782 (47).

Maillet in 1836 termed the disease fowl in connection with severe

losses of fowl (47).

Renault and Delafond, in the middle of the 19th century, presented

the first experimental evidence of the transmissibility of the disease by

the injection of the infected blood, secretions and tissues into poultry

(52). The presence of a bipolar staining, non-motile organism in the

blood of affected birds was first reported by Rivolta in 1877 and

Perroncito in 1878 (52). Toussaint confirmed these observations in 1879,

was the first to isolate the microorganism from the blood of an affected

chicken, and cultivated it in neutralized urine (47). Pasteur in 1880 grew the bacterium in pure culture in chicken broth and examined the

virulence and immunological properties of the microorganism in chickens

(52). He observed that chickens which recovered frcxn the disease or were

immunized with aged live bacteria, which were found to be avirulent for chickens, were protected against a lethal challenge dose of fresh- cultured, live, virulent microorganisms. However, the immunity could be 5

overwhelmed by a large challenge dose of bacteria.

After isolation of the bacterium from birds, many investigators

found that this organism was a very versatile pathogen capable of

infecting cattle, buffalo, sheep, swine, rabbits, horses, cats, dogs,

rats and mice (83). Moore in 1895 found the organism on the mucous

membrane of the respiratory tract of apparently normal cattle, sheep,

swine, dogs and cats (14). The importance of the bacterium in human

infection was recently recognized in relation to infected animal bites

(38).

The isolation of different strains from multiple animal hosts by

various individuals and at different times resulted in a variety of terms

being suggested to name this microorganism (83). Kitt in 1885 suggested

the term Bacterium bipolar multocidum to name the bipolar organism on the

basis of its infectivity for a variety of hosts. Trevisan in 1887 used

the name "Pasteurella" in honor of Pasteur and listed 3 species: P.

cholerae-gallinarum, P. davainei and P. suilla. Flugge in 1896 related

the organisms to species by names such as Bacillus boviseptica. Bacillus

suiseptica and so on. These classifications represent the early tendency

to form a species name on the basis of the affected host. In following

this procedure in detail, Lignieres listed species names, such as

Pasteurella bovine for wild animal, buffalo and cattle strains, £.

aviaire for avian strains, P. ovine for sheep strains, P. porcine for pig strains, etc. Since all of the strains of the organisms isolated from

the different animals were so similar in their morphology and cultural characteristics, an inclusive name was suggested again as a consequence 6

of the trend to use one name for a variety of strains. The name

Pasteurella septica suggested by Topley and Wilson in 1936 was employed

widely in some European countries. The name Pasteurella multocida

proposed by Rosenbusch and Merchant in 1939 (104) has acquired almost

universal recognition at the present time.

Characteristics

According to Bergey's Manual of Systematic Bacteriology (80), P.

multocida belongs to the family (genera Pasteurella,

Haemophilus and ) of the facultative anaerobic Gram-

negative bacteria. Organisms from infected animal tissues usually appear

as coccobacilli or short rods (1.4 _+ 0.4 by 0.4 + 0.1 um) with non-motile

and bipolar staining properties. Strains isolated from healthy animals

are often pleomorphic with longer bacillary forms and are occasionally

short filaments. With electron microscopic examination of the organism,

Brogden (12) observed small spherical blebs and filamentous appendages on

the surface of the cell. P. multocida can be distinguished from other

Pasteurella species (P. haemolytica, P. gallinarum, P. aerogens, P.

pneumotrophica, P. ureae) by the following characteristics: hemolysis on

blood agar -, growth on MacConkey agar -, growth in lactose -, growth in

mannitol +, indole production +, urease activity - and gas production

from - (80).

Many isolates of P. multocida possess a capsule which usually can be detected by Jasmin's procedure, the Alcian blue method, India ink staining (22), or a negative staining method (12). The amount and 7

chemical nature of the capsule seans to vary greatly from isolate to

isolate. Carter's type A organisms possess the largest capsules that

give the colonies a mucoid appearance (23). The capsule is composed, to

a large extent, of hyaluronic acid (23, 25) that serves as a framework

for the attachment of , proteins and lipids (22). Some

type D P. multocida also possess a hyaluronic acid capsule, but the

amount is quantitatively much less than type A. (23). Carter's type B and

E organisms also possess a capsule but the chemical nature is a glycoprotein rather than hyaluronic acid, an acid-mucopolysaccharide (5,

23).

Typing systans

Methods for grouping and classification of multocida were extensively reviewed by Cornelius in 1929 (33) , Carter in 1967 (22) and

Brogden in 1977 (12). According to the review by Cornelius, early workers tried to establish a serological classification of the bacteria which corresponded to the zoological grouping. Matsuda in 1910 considered that a complement fixation test verified the zoological classification of pig, fowl, rabbit and calf strains. Miesser and Schern in 1910 found no agglutinatory relationship between ovine strains and other animal strains. Fitch and Nelson in 1923 could not demonstrate correspondence between a serological and a zoological grouping. Tanaka in 1926 used complement fixation methods and demonstrated the heterogeneous nature of the zoological groups in this respect. Lai in

1927 found sctne evidence of cross-reactivity among different animal 8

strains by application of a conplanent fixation test.

Cornelius (33) classified 17 of 26 strains into 4 groups by use of

agglutinin-absorption tests and found no relationship between a

serological group and the animal origin of the strains. In 1934, Ochi

examined 72 hemorrhagic septicemia strains isolated from various species

of animals and divided than into 4 groups on the basis of serological,

immunological and pathological properties (12). Like Cornelius, he found

that there was no relationship between his groups and the host of origin.

Rosenbusch and Merchant in 1939 (104) identified 3 serologically

distinctive types among 114 non-hemolytic Pasteurella strains by

agglutinin tests and the ability of the microorganisms to ferment xylose,

arabinose and dulcitol. Little and Lyon in 1944 (72) confirmed the

existence of 3 serologically distinct types within 30 non-hemolytic

Pasteurella strains by passive immunization of mice and agglutination

tests. They found that type specificity, virulence and host origin of

these strains were unrelated. Roberts in 1947 (103) divided P. multocida strains into four groups, I, II, III and IV, on the basis of serum

protection tests in mice.

Carter (18) observed that £. multocida possesses a type specific capsular antigen, presumably in nature. He prepared the capsular antigen from several serologically distinctive strains of P. multocida by 2 methods: (1) Bacteria grown on an were suspended in buffered saline and heated at 56 C for 1 h after centrifugation, the bacterial pellet was discarded and the supernatant fluid was collected, and (2) bacteria grown on an agar plate were treated 9

with 1 M sodium acetate and ethanol followed by subsequent extraction

with phenol and saline. He also iitmunized rabbits and chickens with

0.25% formalized saline-treated bacteria to obtain the type specific

antisera. By the use of the two extracted antigens and type specific

antisera in precipitation tests, he determined that there appeared to be

a type specific polysaccharide antigen consisting of, or associated with,

the capsule. Based on his studies, he identified 3 capsular types, A, B

and C among strains of P. multocida. Later, an additional type D was

demonstrated by Carter and Byrne (24) by the same methods.

Carter (19) applied an indirect hemagglutination test for typing the

bacteria. By the use of his capsular antigen preparations, immune sera

and erythrocytes of human 0 blood type for the test, he found that this

technique yielded highly specific reactions and had advantages over other

typing methods. The type C designation was subsequently dropped because

of difficulties in recognition (19). An additional type E, which was

isolated in Central Africa and closely related to type B strains, was

suggested later (21).

Heddleston et al. (53) introduced a gel-diffusion precipitation test

for serotyping avian isolates of P. multocida. They prepared P.

multocida bacterins from 5 serologically distinctive strains (an

extension of a proposal by Little and Lyon) to immunize chickens for the

preparation of type specific antisera. Typing antigen was obtained from

bacteria suspended in 0.85% NaCl solution containing 0.3% formaldehyde

and heated in a water bath at 100 C for 1 h. The supernatant fluid obtained by centrifugation of the suspension was designated a heat-stable 10

serotyping antigen. They found that the heat-stable antigen of one

reacted only with the homologous serum in gel-diffusion

precipitation tests. On the basis of the experiments, they reported that

at least 5 different could be differentiated by this test.

This serotyping system was further studied (11, 54) and is now composed

of 16 serotypes (12).

Several non-serological typing methods for specific serotypes of P.

multocida strains were suggested for the support of the previous typing

systans. Carter and Annau (23) found that the capsule of type A strains

contains a large amount of hyaluronic acid which endows colonies with a

mucoid appearance. The mucoid appearance of the colony was changed by

treatment with staphylococcal hyaluronidase which depolyraerizes the

hyaluronic acid polymer of the capsule. By use of this method, type A

strains could be identified non-serologically (25). Carter and Suboronto

(26) identified type D strains non-serologically by the use of an

acriflavine reaction that showed a coarse flocculation only with type D

strains in a slide agglutination test.

At present, the most widely used methods for typing P. multocida

organisms are Carter's method for capsular typing and Heddleston's method

for soTiatic typing.

Relationship of serotypes to diseases

There has been difficulty in correlating somatic serotypes of multocida organisms with diseases in animals; however, correlations were

found in Carter's capsular types of the bacterium with geographical 11

distribution, hosts and types of diseases (22). Strains of capsular

types A and D are distributed widely in the world and cause primary and

secondary infections. The clinical syndrome is primarily respiratory disease in a wide range of animal species including cattle, swine, chicken, turkey, cat, dog, rabbit, sheep, mouse and man (20, 22).

Strains of capsular type B cause hemorrhagic septicemia essentially confined to cattle, bison and water buffalo, and geographically distributed in tropical areas (24). Strains of capsular type E cause hemorrhagic septicemia in cattle in Central Africa (21).

The most important serotype of P. multocida in animal diseases in

North America appears to be Carter's capsular type A and Heddleston's somatic type 3. Strains of capsular type A £. multocida are known to cause pneumonic pasteurellosis in cattle .and in chickens and turkeys (14, 22) and economic loss due to the diseases-has been great in animal industries of the United States (14, 22, 52, 82, 83). According to an epidemiological study by Blackburn et al. (11), somatic type 3 was most frequently isolated in the United States accounting for 60% of the cattle and 57% of the chicken and turkey isolates. If isolates containing serotype 3 specificity such as serotypes 3 and 4, 3 and 12, and 3, 4 and 12 were included, more than 96% of the cattle and 80% of the chicken and turkey isolates had serotype 3 specificity. 12

Pneumonie Pasteurellosis in Cattle

Occurrence of pneumonic pasteurellosis

Pneumonic pasteurellosis is a common and serious complication of the

respiratory disease complex of cattle characterized by fever, nasal discharge, coughing and various forms of followed in sane cases by death (1, 21, 132). The economic loss to the U.S. cattle industry from the disease exceeded a half billion dollars annually according to a report from the United States Department of Agriculture (82). Studies on etiology of the disease have indicated that the disease may be the result of the complex interaction or cumulative effect of viruses, bacteria, mycoplasma, chlamydia and environmental factors (7, 28, 39, 105, 106).

However, the most important etiologic agents are currently known to be

Pasteurella haemolytica (P. haemolytica) and P. multocida since these organisms are most consistently and frequently isolated from the lungs of cattle with severe respiratory disease (27, 28, 39, 45, 60, 61, 81).

Although P. multocida is reported to be less involved than P. haemolytica in acute shipping fever pneumonia of feedlot cattle (39, 125, 132), P. multocida has been isolated more frequently than P. haemolytica in the southern part of U.S.A. from cases of pneumonic pasteurellosis (16, 28).

Isolations are most common from weanling calves a few weeks to a few months old and from cases of chronic pneumonia in feedlot and adult cattle (27, 60, 125, 132). 13

Pathogenesis of pneumonic pasteurellosis

Bacterial colonization in the lower respiratory tract of healthy

animals including cattle is a relatively rare event. However, in

individuals suffering from a variety of diseases or environmental stress, colonization occurs frequently (7, 40). Studies on human respiratory diseases indicated that the colonization is the first step in the development of pneumonia (3, 8). The increased colonization of the oropharynx with Gram-negative bacteria has been correlated with changes

in the surface properties and surrounding environments of the epithelial cells lining the upper respiratory tract (9, 116, 117, 129). These changes apparently allow large numbers of bacteria to adhere to the epithelial cells and replicate at a faster rate. Once a large quantity of bacteria are present in the upper respiratory tract, the bacteria can enter the lung by aspiration (62) or as a result of reduced mucociliary clearance (58).

The entrance of bacteria into the lung does not always produce pneumonia since small numbers of Pasteurella organisms introduced into the lung by intratracheal or transthoracic injection were rapidly cleared by the local defense system of the lung (41). This indicates that bacterial colonization of the lung is a prerequisite for production of the disease. It has been suggested that several mechanisms may be involved in the increased bacterial colonization of the lung. The increased rate of bacterial adherence and replication in the upper respiratory tract may result in production of microcolonies which then enter the lung (69). If these microcolonies are enclosed by mucus or 14

bacterial glycocalyx, they will be more difficult to phagocytize than an

individual bacterium and will be resistant to attack by antibiotics and

surfactant including antibodies (34, 36, 69). Viral infections of

phagocytic cells such as alveolar macrophages and may result

in defects of host cellular defense mechanisns. Infected alveolar

macrophages and neutrophils exhibit decreases in their phagocytic

activities such as chanotaxis, ingestion, phagosome-lysosome fusion, lysosome levels and cytokine production (59, 96, 105, 109, 126).

P. multocida can ranain localized in the upper respiratory tract of healthy cattle for a long time but for seme reason, the level or degree of growth is limited and the animal does not exhibit any ill effects (7).

The mechanisms for colonization of P. multocida in the upper respiratory tract of cattle followed by movement down the trachea into the lung and subsequent production of pneumonia are presently not known. However, characteristics of the P. multocida bacterium in addition to other microbial infections and environmental stress were suggested to be the most important aspect of the pathogenesis (32, 45, 71). 9. multocida is known to produce neuraminidase that breaks down mucus, thus making the mucus less viscous (89). The role of this enzyme in aiding bacteria to reach the lung is not well defined, but, in the gut, it has been shown that Vibrio cholera mutants deficient in this enzyme are less virulent than the parent organian (40). multocida is also known to produce endotoxin (22) that has a wide array of toxic effects in experimental animals. Although the role of P. multocida endotoxin in pneumonic pasteurellosis of cattle has not been studied, many Gram-negative 15

bacterial endotoxins were reported to initiate complément and coagulation

cascades in hosts (63, 85, 91, 110, 115). The result was increased

vascular permeability and coagulation leading to accumulations of

inflammatory cells, edema and both intravascular and extravascular fibrin

in the lung (58, 123). The best studied pathogenic mechanism of P.

multocida infection in cattle is the role of the P. multocida capsule

which allows the bacterium to escape the phagocytic defense mechanism of

the host. Maheswaran and Thies (79) examined the influence of encapsulation on of P. multocida by bovine neutrophils by

using two encapsulated strains, NA77 (capsular type A) and C42 (capsular

type B), and one unencapsulated strain 1173. When they measured the uptake of [^H]thymidine-labeled bacteria in the presence of normal bovine serin, the encapsulated strains inhibited the phagocytic activity of bovine neutrophils while the unencapsulated strain did not. C42

(capsular type B) could be completely phagocytized by the neutrophils in the presence of hyperimmune anti-C42 serum. However, only 3.8% of the

NA77 (capsular type A) bacteria were ingested by the neutrophils in the presence of hyperimmune anti-NA77 serum. When they treated NA77 organisms with bovine testicular hyaluronidase, 90% of the decapsulated organisms were ingested. Therefore, they concluded that the factor associated with MA77 organism which inhibited the phagocytic activity of neutrophils was probably hyaluronic acid which is a major component of the capsule of type A £. multocida. We have previously examined the effect of various type A P. multocida fractions from two encapsulated strains on bovine polymorphonuclear leukocyte (PMN) functions (108). 16

Ingestion of bacteria and halogenation of the ingested bacteria by PMNs

were inhibited in the presence of live cells, heat-killed cells or 2.5%

saline extracted surface material but not in the presence of décapsulated

heat-killed cells. None of the bacterial fractions inhibited oxidative

by PMNs. The PMN inhibitory factor was characterized as a

heat-stable surface material of greater than 300,000 molecular weight.

Treatment of this material with hyaluronidase did not destroy the

inhibitory activity and hyaluronic acid isolated from human umbilical cord did not suppress PMN function. Therefore, it has been suggested

that the capsular hyaluronic acid may not be the inhibitory factor

although the PMN inhibitory factor may be structurally linked to the bacterial hyaluronic acid.

Attanpts to prevent pneumonic pasteurellosis in cattle

The importance of P. multocida in pneumonic pasteurellosis has led to the development and use of various bacterin products for immunization of cattle. Palotay et al. (93) tested several biological preparations in an attempt to prevent respiratory infection in newly weaned beef calves.

Of these products, three agents that significantly reduced mortality were; (1) a commercial hemorrhagic septicemia bacterin, (2) a bivalent bacterin prepared fran P. multocida and P. haemolytica strains, and (3) a formalinized bacterin prepared from chicken embryo-grown P. haemolytica which was isolated from cattle that died from acute pneumonia. However, there was still a 9.38% incidence of disease in the most effectively protected group as compared with a 21.05% morbidity in the control 17

groups.

Hamdy et al. (50) examined the efficacy of 5 different commercial

Pasteurella bacterins in young calves under field conditions. Although

immunized calves showed as much as 500 times greater antibody titer than

the controls, none of these bacterins effectively reduced the incidence

of the disease.

Larson and Schell (70) compared the toxicity of Pasteurella

bacterins with their potential protective value in calves undergoing the

stress of weaning and shipping. Calves given the bacterin developed

significantly higher antibody titers than the controls. However, the

immunized calves developed fever and leukocytosis with neutrophilia,

although these effects were transient and did not clinically alter their

general state of health when compared with the non-vaccinated controls.

Bennett (10) examined the efficacy of commercial Pasteurella

bacterins for yearling feedlot cattle. He found that the mortality rate,

though not statistically significant, was increased in vaccinated calves.

Although P. multocida bacterins have proven efficacy in experimental

animals (17, 29, 57, 133) , these field trials indicated that the use of

bacterins in cattle to prevent pneumonic pasteurellosis did not reduce

the incidence of the disease significantly. In fact, it may be detrimental to the health of the animal. This questionable efficacy and safety of Pasteurella bacterins in cattle has led to examination of various subcellular fractions of the organism for the development of a better immunogen and for the study of their roles in bacterial pathogenesis. 18

Subcellular Fractions of Type A Pasteurella multocida

Capsular antigens

Carter and Annau (23) isolated capsular polysaccharides from the

colonial variants of a P. multocida strain. The agar-grown bacteria were

suspended in distilled water and heated at 56 C for 1 h, followed by

centrifugation at 10,000 rpm. The supernatant fluid obtained by

centrifugation was treated with 95% ethanol containing 0.25% sodium

acetate. The precipitated polysaccharides from the fluorescent variant

were found to induce a high level of protection in mice. Those of the

mucoid variant were not protective. When the surviving mice were

challenged with strains of other serological types, there was no

protection.

Kodama et al. (66) extracted a capsular material from a multocida

strain by treating the organisms at 56 C for 1 h with 2.5% NaCl solution.

This saline extract induced protective immunity in turkeys and chickens.

A precipitate was obtained from the saline extract by treating it with

cetylpyridiniun chloride. This precipitate was not immunogenic. By

continuing studies on the extract, Syuto and Matsumoto (120) demonstrated

electronsicroscopically that treatment of type A P. multocida cells with

2.5% NaCl solution ranoved the capsule of the organism without disrupting the cell membrane. They fractionated the saline extract by gel- filtration on a Sephadex G-200 column and obtained 4 different peaks.

When the immunogenicity of the 4 peaks was evaluated in turkeys, the protective activity was detected only in the first peak. They further 19

purified the protective antigen present in the first peak by absorbing it

onto DEAE-cellulose and eluting with a linear gradient of NaCl solution.

They found that the purified protective antigen had a /protein ratio of 1.5 and formed a single precipitin line with a rabbit antiserum against the original saline extract in gel- diffusion and immunoelectrophoresis. Upon sodiim dodecyl sulfate polyacrylamide gel electrophoresis, the purified antigen showed 4 bands.

By isoelectric focusing analysis, it showed two bands. Each band of the isoelectric focusing analysis was isolated and used to immunize turkeys.

However, neither of the two components, alone or in combination, induced protection in turkeys.

Ganfield et al. (43) tried to purify a protective component(s) from a saline extract of a P. multocida strain. The starting material was obtained frcm the saline (0.85% NaCl containing 0.1% formalin) extract of

2" multocida cells by differential centrifugation at 105,000 x g, and further purified by gel-filtration on Sepharose 2B. Three fractions were obtained after gel-filtration. The first fraction consisted of 10% of the starting material and was immunogenic in mice (80% protection). The second fraction consisted of 75 to 95% of the starting material and doses of 10 to 20 ug induced active iimunity in mice and turkeys. Large doses were found to be lethal. The third fraction was much less effective in inducing a protective immune response. 20

Lipopolysaccharide (LPS) antigens

Rebers et al. (100) examined the serological and immunological

properties of a purified LPS antigen isolated from an encapsulated strain

of P. multocida. A crude LPS obtained by phenol-water extraction contained nucleic acids and capsular polysaccharides as well as LPS. The crude LPS was further purified by treatment with ribonuclease and deoxyribonuclease, followed by centrifugation at 165,000 x g for 3 h.

The purified LPS was fractionated by CsClg density gradient centrifugation at 90,000 x g for 70 h and 3 visible bands were obtained.

The middle band contained most of the LPS. The crude LPS and the middle band (1 to 10 ug) were used to immunize chickens to produce antisera.

Passive administration of antiserum against the crude LPS protected 18% of the chickens. However, passive administration of antiserum against the middle band protected 86% of the chickens. Antisera obtained from the surviving chickens gave a single precipitation line in gel-diffusion with the homologous Heddleston's serotype antigen (12), and no reaction was obtained with any of the other 15 serotype antigens. Therefore, they concluded that P. multocida LPS is an important serological marker in

Heddleston's typing system and antibodies induced against the LPS contribute to the protection of chickens.

Rebers and Heddleston (98) compared the chemical and immunogenic properties of phenol-water extracted LPS (PW-LPS) with free endotoxin isolated from a P. multocida strain. The free endotoxin, which is secreted fran or loosely bound to the surface of £. multocida organism, was obtained by washing the agar-grown bacteria with cold 0.85% NaCl 21

solution containing formalin followed by centrifugation and gel-

filtration on a Sepharose 2B colunn. The free endotoxin induced active

immunity in mice, but the PW-LPS did not. Although the PW-LPS and the

free endotoxin both contained nitrogen, phosphorus, heptose and hexose,

the free endotoxin had more nitrogen. Vigorous mixing of the free

endotoxin or whole cell preparation with 50% phenol at roan temperature

and subsequent dialysis to remove phenol resulted in complete loss of ability to induce active immunity in mice. Since most polysaccharides are stable to phenol and most proteins are irreversibly denatured by it,

it would appear that some form of protein is necessary for the induction of active immunity against P. multocida infection.

Particulate antigens

Heddleston et al. (56) isolated a particulate antigen from two virulent and serologically distinctive strains, X-73 (somatic type 1) and

P-I059 (somatic type 3), of £. multocida. The agar-grown bacteria suspended in formalinized saline solution were incubated for 48 h at 4 C followed by centrifugation for 30 min at 12,000 x g. The supernatant fluid was filtered through a 400-mesh nylon cloth. The filtrate was centrifuged for 2 h at 105,000 x g. A gel-like pellet obtained by the centrifugation was washed and designated a particulate antigen. The particulate antigens of the two strains possessed many of the properties ascribed to endotoxins. It was a high molecular weight, nitrogen- containing, phosphorylated LPS. Injection of 100 to 500 ug of the antigen intravenously into mice, rabbits or chickens produced severe 22

effects on these animals such as depression and diarrhea; death followed.

Almost 100% of the chickens given either intravenous injections of saline suspended particulate antigens in a dose of 2 ug or subcutaneous

injection of the antigens emulsified in mineral oil were protected against a challenge of live homologous organisms Wiich killed 100% of the controls. The same degree of protection was obtained in mice. Good passive protection (90 to 100%) was obtained in mice with rabbit antiserum to the particulate antigen of X-73; however, antiserum to the particulate antigen of P-1059 induced only 0 to 40% protection.

Potassium thiocyanate extracts

Bain (5) used a potassium thiocyanate (KSCN) solution to extract surface materials from a capsular type B P. multocida strain. To a dense suspension of bacteria in normal saline there was added an equal volume of 1 M KSCN solution, followed by incubation at 37 C for 5 h. The bacterial suspension was centrifuged and the supernatant fluid was dialyzed against distilled water. Gaunt et al. (44) prepared a KSCN extract from a serotype 3 P. multocida strain (P-1059) by the method of

Bain (5). The KSCN extract was found to be immunogenic in chickens against a challenge infection of the homologous strain as well as one heterologous strain tested (serotype 1, X-73). Gel-diffusion analysis revealed the presence of two components which were antigenically identical in KSCN extracts of both serotypes. 23

Mukkur (87) immunized mice with the KSCN extract of P. haemolytica

serotype 1. These mice were found to resist a challenge infection of a

type A £. multocida strain, thus demonstrating cross-protection between

the two Pasteurella species. This finding was further supported by the

finding that P. multocida organisms could be killed by incubation with

guinea pig complement and an antiserum directed against the KSCN extract

of P. haemolytica, and vice versa. Mukkur (88) further compared the

immunizing efficiency of his KSCN extract with a formalin-killed P. multocida bacterin prepared from the same organism in mice. All of the

mice immunized with the KSCN extract survived a challenge dose of 1.6 x

10^ cells. All of the mice immunized with the bacterin survived a challenge dose of 15 cells, but the survival rate decreased with

increasing challenge dose. With a challenge dose of 1.5 x 10^ cells, only 10% of the immunized mice survived. When a combination of the KSCN extract and the bacterin were used to immunize mice, the survival rate was no better than that of mice inrounized with the bacterin alone.

Bactericidal titers present in the sera of mice immunized with the extract were ten times higher than those in sera of mice irmiunized with the bacterin. Three times higher titers were present in the sera of mice immunized with the extract compared with those given the bacterin plus the extract. Based on the results, they suspected that immunosuppression might conceivably be due to antigenic competition or partial denaturation of some vital protective antigen(s) as a result of formalin treatment. 24

We have further evaluated immunogenicity and cross-protectivity of

KSCN extracts in mice (107). Mice immunized with KSCN extracts frcxn

several P. multocida strains showed signs of depression for several hours

after immunization but were protected against a challenge with the

virulent homologous bacterium. However, there was no consistent

reciprocal protection between different strains of a serotype indicating

no correlation between serotype and cross-protection of mice. A

component was isolated fron the KSCN extract by centrifugation of the

extract at 87,000 x g for 18 h in a density gradient of 5 to 40%

(wt/vol). A single antigenic component was isolated from the bottom half

of the gradient. Serologic examination and chemical analysis indicated

that this component is a LPS-protein complex. Immunization of mice with

this fraction demonstrated resistance to challenge with the homologous

strain and seme degree of protection against certain heterologous

strains.

Culture filtrate

Srivastava et al. (113) canpared the immunogenicicty of the culture

filtrate, cell walls and cytoplasmic components of a type A P. multocida

strain, and tried to isolate a protective component(s) from the culture

filtrate. The culture filtrate was prepared by centrifugation of bacterial cultures at 10,400 x g for 1 h followed by filtering the supernatant fluid through a 0.45 um membrane filter. The sediment obtained from the previous centrifugation was ruptured in a Ribi cell fractionator followed by centrifugation at 105,000 x g for 1 h. The 25

sediment was designated as cell wall and the supernatant fluid was

filtered through a 0.45 urn membrane filter. The filtrate was designated

as cytoplasm. The cell walls induced more protection in mice than

cytoplasm or culture filtrate. They fractionated the culture filtrate on

a Sephadex G-50 column and obtained 4 fractions. The first fraction was

found to contain a protective material responsible for the protection of

mice and was more immunogenic than cell walls. They indicated that this

material is different from the free endotoxin studied by Heddleston and

Rebers (55) , because it had very low levels of 2-keto-3-deoxy-octonate

and heptose which are principal chemical components of the endotoxin.

Srivastava and Foster (112) continued to study the first fraction

obtained fran column chromatography. They treated it with ether to yield

a "glycolipid-like" material and with phenol to yield a "LPS-like"

material. They found that the ether-treated material was more

protective for mice than the first fraction of the culture filtrate.

However, the phenol-treated material was not immunogenic in mice and was

toxic by rabbit skin tests.

Ribosomal fractions

Baba (4) examined the immunogenicity of a ribosomal fraction isolated from a P. multocida strain. Organisms grown in a liquid medium were harvested and washed by centrifugation. The packed cells were suspended in a Tris-HCl buffer, pH 7.4, followed by rupture in a French press. The ruptured cellular mass was centrifuged at 8,000 x g for 40 min to remove whole cells, cellular debris and cell walls. The 26

supernatant fluid was further purified by differential centrifugation,

zonal electrophoresis and gel-filtration on a Sephadex G-200 column. The

ribosomal fraction exhibited intense protective irrmunogenicity in mice

and turkeys. Sodium deoxycholate treatment of the ribosoraal fraction

resulted in a 13% loss in iirmunological activity and ribonuclease

treatment caused a 60% loss of the activity. Purified ribosomal protein

or ribonucleic acid were not immunogenic in mice.

Phillips and Rimler (94) prepared from P. multocida,

Brucella abortus, Aspergillus fumigatus and chicken liver by gel-

filtrating the chemically-lysed cells in a Sepharose CL-2B column. The

purified ribosomes did not protect chickens against challenge exposure

with a virulent strain of multocida (X-73, serotype 1). However,

substantial numbers of chickens were protected when microbial ribosomes

were fixed to homologous LPS extracted by the phenol-water procedure.

When these immunized chickens were challenged with a heterologous strain

with different serotype (P-1702, serotype 5), there was no protection.

Therefore, they suggested that protection of chickens by ribosomal

vaccine fron P. multocida infection depends on hanologous LPS.

Importance of lipopolysaccharide-protein complex

LPS of many Gram-negative bacteria, called endotoxin, is known to cause a variety of toxic effects in hosts such as pyrogenicity, lethality, Swartzman reaction, bone-marrow necrosis, leukopenia, leukocytosis, hypotension and abortion (63, 75, 85, 115). LPS of P. multocida also exhibited many such toxic effects in hosts (6, 22, 95); 27

however, studies on subcellular fractions of P. multocida indicated that many fractions with danonstrated immunogenicity contained lipopolysacchaides in a LPS-protein complex. The £. multocida fractions containing the LPS-protein complex included a conponent isolated from a

2.5% NaCl extract by Syuto and Matsumoto (120) , a component isolated from a 0.85% NaCl extract by Ganfield et al. (43), LPS-containing materials of

Bain and Knox (6), Rebers et al. (99) and Rebers and Heddleston (98) , a particulate material of Heddleston et al. (56) and a component isolated from a culture filtrate by Srivastava et al. (113) , a conjugated LPS- of Phillips and Rimler (94), and a component isolated from a

KSCN extract by us (107). The chemical nature of these LPS-protein complexes responsible for induction of immunogenicity in hosts has not been determined. However, recent studies on LPS-protein complexes extracted from other Gram-negative bacteria with trichloroacetic acid or butanol indicated that the protein moiety of the complexes may play an important role. The protein moiety, called endotoxin protein or lipid-A associated protein, exhibited several immunostimulatory activities such as induction of mitogenic response of B cells (46, 118), polyclonal activation of murine lymphocytes (119), various stimulatory activities on macrophages and neutrophils (86) , and protection of mice against homologous bacterial infection (64). 28

Immune Responses to Pasteurella multocida Infection

In cattle

In addition to preexisting non-specific resistance and clearance mechanisms, Immunologically-specific resistance mechanians in the respiratory tract of various animal species are important in the control of various infectious agents associated with respiratory diseases (49,

90, 122, 126, 127). However, respiratory immune responses of cattle to

P. multocida infection have not been extensively studied. At present, limited information on the role of bovine immune system in protection against P. multocida infection is available from studies of the systemic immune system. As studies on evaluation of P. multocida bacterin indicated previously, there was no correlation between the increase of serum P. multocida antibody titer and protection of cattle (50, 70).

Maheswaran and Thies (78) developed a whole blood lymphocyte stimulation assay to study cell-mediated immune responses of cattle to P. multocida infection. They observed that peripheral blood lymphocytes from cattle immunized with a pneumonic pasteurellosis strain (type A) exhibited higher stimulation indices when incubated with the antigens of the homologous strain than with the antigens of hemorrhagic septicemia strains (types B and E). These studies may suggest that honorai immunity is not as important as cellular immunity in cattle; however, the systemic immune response of cattle to P. multocida infection may not be the same as the local respiratory immune response. Studies on the respiratory immune system of many animal species have indicated that the respiratory 29

system is relatively ccxnpartmentalized from blood and blood-derived

immune responses, particularly in the upper areas (49, 90, 122, 126).

The respiratory systan itself is canpartmentalized immunologically into

upper, middle and lower areas with apparent functional differences

occurring in each area. Both humoral and cell-mediated immune responses

occurred within the respiratory systan.

In mice

Collins and Vfoolcock at Trudeau Institute conducted extensive studies on the immune responses of mice to multocida infection.

Collins (29) quantitated the growth of P. multocida in both normal mice and mice immunized with a P. multocida bacterin. In normal mice challenged intraperitoneally, the bacteria spread rapidly to the liver and spleen via the blood. Numbers of bacteria recovered from the blood, liver, spleen and peritoneal cavity were quantitated hourly up to 12 h and all rose continuously. In immunized mice, however, the bacteria were rapidly cleared from the blood and nimbers of bacteria in the liver, spleen and peritoneal cavity rose slightly by 6 h post challenge and then gradually decreased. Increased agglutination titers correlated with the degree of protection in the immunized mice. In addition, mice that received 0.2 ml of hyperimmune serum at 1 to 14 days prior to challenge were significantly protected against 100 to 1000 lethal challenge doses.

Although both actively or passively immunized mice effectively limited the growth of bacteria in vivo, peritoneal cells from immunized mice did not exhibit increased bactericidal capacity in vitro as compared to the 30

cells from the control mice.

Woolcock and Collins (130) further evaluated the immune mechanians

in 2» multocida-infected mice. When the bacterin was incorporated into

Freund's complete or incomplete adjuvants, protection with the

incorporated bacterins was always superior to that seen with the non-

incorporated bacterin. Live Mycobacterium bovis, or killed

Corynebacterium parvum immunopotentiated a single dose of the bacterin in

terms of protective immunity against subsequent challenge. Hyper immune

mouse serum, administered intraperitoneally, intramuscularly, or

intravenously 1 to 7 days prior to subcutaneous challenge, was highly

protective to mice. However, mice injected in the thigh with hyperimmune

serum prior to footpad challenge frequently developed a severe

inflammatory response with local swelling within 48 h. Although none of

these mice died, many of their feet developed multiple abscesses

exhibiting a predominantly polymorphonuclear leukocyte response, which

persisted for at least 14 days. A purulent exudate could be expressed

frcm these abscesses with bacterial counts of up to 10^ viable organisms.

Injection of organisms recovered frcm the pus into normal mice revealed

that the bacteria within the abscess were still fully mouse-virulent,

indicating that the long-term survival of the serum-treated mouse was due

to the acquired resistance induced by the local P. multocida infection

and not to the attenuation of the organisms within the footpad.

Collins and Woolcock (31) evaluated the roles of hyperimmune serum

and peritoneal or spleen cells from the immunized mice in protection of mice against P. multocida infection. For evaluation of hyperimmune 31

serum, normal mice were injected intraperitoneally with P. multocida

organisms suspended in 0.2 ml of heat-inactivated normal or hyperirtrnune

mouse serum. After 2 min, mice were killed and the peritoneal cavity was

washed with 2.5 ml of Hanks' balanced salt solution. The washouts were

placed in small plastic tubes and incubated at 37 C in a shaking water

bath. Viable counts of cell-associated and extracellular bacteria were

carried out at frequent intervals over the next 60 rain by means of

differential centrifugation. When the inoculum was suspended in normal

serum, only 1 to 2% of the bacteria were taken up by the cells from the

washout over a 60 min interval. Throughout this time, the extracellular

bacterial population multiplied freely, resulting in a 100-fold increase.

The proportion of the extracellular to cell-associated bacteria remained

constant throughout the test period. On the other hand, mice receiving

hyperimmune serum demonstrated a dramatic shift in the ratio of the

extracellular to cell-associated bacteria present in the culture.

Approximately 90 to 95% of the organisms were taken up by the cells fron

the washout at 60 min. However, there was little evidence of increased

bacterial inactivation over the period and, in fact, the P. multocida

viable counts rose steadly at about the same rate whether immune serum

was present in the system or not. For the active transfer study, mice

were immunized with the bacterin and challenged. Seven days later the

surviving mice were sacrificed to obtain peritoneal and spleen cells.

Suspensions of 1 to 2 x 10® nucleated peritoneal or spleen cells, or a combination of the two were injected intravenously or intraperitoneally

into the normal mice. However, these mice were not protected against 32

lethal effects of the P. multocida challenge.

Based on these results in addition to other successful passive protection studies on multocida infection (5, 22, 65), Collins (30) concluded that immunity to multocida infection is primarily humorally- mediated. Although the final clearance mechanise of P. multocida by the effectively-immunized host is not known, a role for anti-£. multocida antibody is suggested in the inhibition of the rapid spread of the organism to the blood stream and other reticuloendothelial organs. 33

SECTION I. ANALYSIS OF LIPOPOLYSACCHARIDES OF PASTEURELLA MULTOCIDA

AND SEVERAL GRAM-NEGATIVE BACTERIA BY GAS CHROMATOGRAPHY

ON A CAPILLARY COLUMN 34

SUMMARY

Lipopolysaccharides (LPS) of Pasteurella multocida (P. multocida)

and several other Gram-negative bacterial pathogens were analyzed by

methanolysis, trifluoroacetylation and gas chromatography (GC) on a fused-silica capillary column. The GC analysis indicated that LPS

prepared fran a strain of JP. multocida by phenol-water (PW) or trichloroacetic acid (TCA) extraction were quite different in chemical composition. However, LPS prepared from Salmonella enteritidis by the two extraction methods were very similar. PW-LPS extracts from different

Pasteurella strains of a serotype had essentially identical GC patterns.

Endotoxic LPS extracted from 16 different serotypes of P. multocida by PW or by phenol-chloroform-petroleum ether procedures yielded chromatograms indicating similar composition of the fatty acid moieties but minor differences in carbohydrate content. When the chemical composition of endotoxic LPS extracted from several Gram-negative bacteria (£. multocida, Pasteurella haemolytica, somnus, Actinobacillus ligniersii. , Treponema hyodysenteriae, ,

Bacteroides fragilis, Salmonella abortus equi and Salmonella enteritidis) were examined, each bacterial LPS showed a unique GC pattern. The carbohydrate constituents in LPS of various Gram-negative bacteria were quite variable not only in the 0-specific polysaccharide but also in the core polysaccharide. The LPS of closely related bacteria shared more fatty acid constituents with each other than with unrelated bacteria. 35

INTRODUCTION

Pasteurella multocida (P. multocida) is a microorganism capable of

infecting most animal species including man and is responsible for

economically important animal diseases such as fowl cholera and pneumonic

pasteurellosis in cattle (3, 4). The scientific and economic importance

of P. multocida has led to the use of various bacterial fractions in the

development of immunizing agents and for the study of bacterial

pathogenicity. Studies on subcellular fractions of P. multocida have

indicated that many fractions with demonstrated immunogenicity contained

1ipopolysaccharide (LPS) as an important constituent (7, 8, 9, 19, 20,

23).

The P. multocida LPS extracted by conventional methods (phenol-

water, phenol-chloroform-petroleum ether or trichloroacetic acid) has

been observed to evoke a variety of endotoxic activities in a host

including pyrogenicity, depression, diarrhea and death in mice, rabbits

and chickens and lethality for chicken atibryos (1, 4, 18). Since these

endotoxic activities have also been demonstrated in LPS of many Gram-

negative bacteria, it has been generally believed that P. multocida LPS

is structurally similar to other Gram-negative bacterial LPS (1, 21).

However, the chemical relationships between LPS of P. multocida and other

Gram-negative bacteria has not been studied extensively. In addition, the chemical relationships between the endotoxic LPS of P. multocida prepared by different methods-have not been studied. 36

Methods previously utilized for the chanical characterization of £.

multocida LPS wer'e based on detection of fatty acids and colorimetric

assays for 2-keto-3-deoxy-octonate (KDO), glucosamine, L-glycero-D-

mannoheptose (LD-heptose) and neutral sugars that are well-known

components of Gram-negative bacterial LPS (especially Salmonella

species). However, this chanical analysis requires several different

assay systems that are time consuning. Also, the chemical composition of

P. multocida LPS may be variant with composition of bacterial LPS in

extensively studied microorganisms. The fatty acid content of bacterial

LPS should be determined as well for it may be the carbohydrate content.

This is indicated by the studies on synthetic Salmonella lipid A

analogues which indicated that variant composition of fatty acids

exhibited differences in biological activities such as antigenicity,

lethality, pyrogenicity, mitogenicity and canplement activity (12).

Recently, Bryn and Jantzen (3) dempnstrated that analysis of LPS by

methanolysis, trifluoroacetylation and gas chromatography on a capillary column was a highly useful method for determining the chemical composition of bacterial LPS. The objectives of this study were: 1) to analyze the chemical composition of purified P. multocida LPS for future analysis of LPS-containing immunogens of the organism and 2) to examine chemical relationships between the endotoxic LPS of P. multocida prepared by different methods and from different serotypes, and the relationships between P. multocida LPS and LPS frcm other Gram-negative bacterial pathogens. 37

MATERIALS AND METHODS

Cultivation of Bacteria

P. multocida and Pasteurella haemolytica (P. haemolytica) were grown

in Roux bottles containing dextrose starch agar (Difco Laboratories,

Detroit, MI). Salmonella abortus equi (S. abortus equi) was grown in

Roux bottles containing trypticase soy agar (Difco). Actinobacillus

ligniersii (A. ligniersii) was grown in brain-heart infusion broth (BHI;

Difco) with aeration. Haemophilus sotnnus (H. somnus) was grown in Roux

bottles containing BHI, 5% agar (Difco) and 10% sterile bovine serum with

5% COg aeration. After incubation at 37 C for 18 h, the Roux bottle-

grown bacteria were suspended in 0.15 M sterile phosphate buffered saline

solution (PBS, pH 7.2). These bacteria and the broth-grown bacteria were

harvested by centrifugation. Cells were washed three times with PBS by

centrifugation and resuspended in distilled water.

LPS Preparation by Phenol-Water Extraction

Phenol-water extracted LPS (PVf-LPS) of £. multocida (strain P-2383 and P-1062; capsular type A, somatic type 3), P. haemolytica D-80

(biotype A, serotype 1), H. somnus 8025, A. ligniersii and S. abortus equi were prepared according to the method of Westphal and Jann (26) with slight modifications. Briefly, the bacterial suspension in distilled water was heated to 65 C and an equal volume of prewarmed (65 C) 90% 38

phenol was added. This mixture was stirred vigorously, incubated for 15

min at 65 C and centrifuged at 3,000 x g at 4 C. The water phase was

aspirated off, the original volume of distilled water was added to the

remaining phenol phase, and the extraction repeated. The first and

second water phases were combined and dialyzed against daily changes of

distilled water for 4 days. The dialyzed water phase was treated with

ribonuclease and deoxyribonuclease (Sigma Chanical Co., St. Louis, MO)

for 24 h at 37 C and centrifuged at 105,000 x g for 3 h at 4 C. The

pellet was washed once by centrifugation, resuspended in distilled water

and lyophilized.

LPS Preparation by Trichloroacetic Acid (TCA) Extraction

TCA extracted LPS (TCA-LPS) of P. multocida (P-2383) was prepared

according to the method of Staub (24). Briefly, the washed bacteria were

suspended in cold (4 C) distilled water and an equal volume of 0.5 N TCA

was added. After incubation for 3 h at 4 C, the mixture was centrifuged at 3,000 X g for 30 min. The supernatant was removed, warmed to rocm

temperature, neutralized to pH 6.5 with 3 N NaOH, cooled to 0 C in an ice bath, and added to 2 volumes of 100% ethanol (-20 C). The precipitate which formed following overnight incubation at -4 C was sedimented by centrifugation. The supernatant fluid was discarded and the precipitate was dissolved in distilled water to 0.1 the volume of the original bacterial suspension. Microbial debris was removed by centrifugation at

27,000 X g and the supernatant fluid was lyophilized. 39

Other Bacterial LPS

LPS from 16 somatic types of P. multocida prepared by either the PW

procedure (26) or the phenol-chloroform-petroleum ether (PCP) procedure

(6) were kindly provided by Dr. R. B. Rimler, National Animal Disease

Center (NADC), U. S. Department of Agriculture (USDA), Ames, Iowa. A PW-

LPS preparation fron P. haemolytica P-101 (biotype A, serotype 1) was

obtained from Dr. G. H. Frank, NADC, USDA. A Brucella abortus LPS f5 (B.

abortus) was prepared by PW procedure with extraction from the phenol

phase rather than the water phase as previously described (14) and was

supplied by Dr. B. L. Deyoe, NADC, USDA. PW-LPS of Treponema

hyodysenteriae (T. hyodysenteriae), Esherichia coli K235 (E. coli) and

Bacterioides fragilis 9F (B. fragilis) were obtained from Dr. M. J.

Wannemuehler, Veterinary Medical Research Institute, Iowa State

University, Ames, lA. TCA-LPS and PW-LPS of Salmonella enteritidis (S.

enteritidis) were purchased from Sigma Chanical Co.

Standards

Various individual standards vere used for determination of the

retention times as well as internal standards in GC analysis. Rhainnose,

fucose, ribose, galactose, mannose, glucose, glucosamine and KDO were obtained frcxn Sigma. D-glycero-D-mannoheptose (DD-heptose) and L- glycero-D-mannoheptose (LD-heptose) v^re provided by Dr. P. A. Rebers,

NADC, USDA. Unhydroxylated fatty acids from carbon chains 12 to 17 were 40

obtained fron Applied Science (State College, PA) and 3-hydroxy-

dodecanoate (3-0H-12:0), 2-hydroxy-tetradecanoate (2-0H-14;0) and 3-

hydroxy-tetradecanoate (3-0H-14;0) were purchased from Foxboro/Analabs

(North Haven, Conn). A bacterial fatty acid mixture (Cat. No. 4-7080)

was purchased from Supelco (Bellefonte, PA).

Preparation of Samples

Derivatization of the LPS was performed by the method of Bryn and

Jantzen (3) with slight modifications. Briefly, 2 to 5 mg of bacterial

LPS were suspended in one ml of 2 M HCl in methanol (Supelco) in a

teflon-lined screw-capped vial (Supelco) and held at 85 C for 18 h.

Methanolysates were concentrated to dryness at room temperature with

nitrogen gas and trifluoroacetylated by adding 0.2 ml of 50%

trifluoroacetic acid (TFA, gold label; Aldrich Chemical Inc., Milwaukee,

WI) in acetonitrile (HPLC grade; Fisher Scientific, Fair Lawn, NJ) and

heating in a boiling water bath for 2 min. After cooling to room

temperature, the reaction mixture was diluted with acetonitrile to a

final TFA concentration of 10% and injected into the column.

Gas Chromatography (GC) and Peak Identification

The GC analysis was carried out on Hewlett-Packard 402 gas chromatography systan equipped with a flame-ionizing detector that had been modified for the use of a capillary column. Fused-silica capillary 41

columns (GB-1, 25 m x 0.25 mm ID, Foxboro/Analabs, or SPB-1, 30 m x 0.25

ram ID, Supelco) were operated in split mode and with helium carrier gas.

The column tanperature was held for 5 min at 95 C and then programmed to

increase at 4 C per min up to 230 C. Peaks of individual standards and bacterial LPS were recorded with a LKB 2210 recorder (Brarma, Sweden) and retention times were calculated by the distance the individual peak moved from the injection line on the chromatog ram. Sdrrroe the LKB recorder was not equipped with an internal integrator, the quantity of individual constituents could not be determined. 42

RESULTS

Determination of Retention Times of Standard Compounds

As indicated by Bryn and Jantzen (3), most monosaccharide

derivatives are resolved into defined peaks by a capillary column. The

specific GC patterns of standard compounds in this experimentation were

very similar to those reported by Bryn and Jantzen (3). However, it was

necessary to separate the components of LPS with splitter open in

contrast to the procedure of Bryn and Jantzen which was conducted in

splitless mode. Also, they observed the third galactose peak between the

second glucose peak and the second mannose peak, but in our study, it

appeared at the same position as the first glucose peak. Retention times

of the individual standard compounds on the GB-1 column are listed in

Tables 1 and 2: the SPB-1 column gave slightly different retention times,

but the chromatographic sequence was the same as the GB-1 column.

Chanical Composition of P. multocida LPS

Since LPS extracted from enterobacteria is a classical example of bacterial endotoxin, LPS prepared from S. enteritidis was utilized as a standard for comparison with LPS preparations of P. multocida and other bacteria. In contrast to LPS preparations from S. enteritidis (Fig. 1),

LPS prepared from a JP. multocida strain by TCA or PW extraction was quite different in chemical composition (Fig. 2). The PW-LPS of P. multocida 43

Table 1. Gas chromatographic distribution of some commonly occurring LPS

monosaccharides as trifluoroacetylated methylglycosides on a

fused-silica capillary column (GB-1)

Conponent Retention times (min)

Rhamnose 6.1 7.35

Fucose 6.35 6.75 7.8

Ribose 4.9 6.15 6.4

Galactose 10.3 11.15 11.85

Mannose 11.6 12.45

Glucose 11.85 12.0

D-glycero-D-mannoheptose 15.0

L-glycero-D-mannoheptose 15.8

Glucosamine 17.35

2-keto-3-deoxy-octonate 19.85 20.65 44

Table 2. Retention times of common LPS fatty acids as (0-

trifluoroacetylated) methyl esters on a fused-silica capillary

column (GB-1)

Retention time (min)

Chain length Unhydroxylated 2-Hydroxy 3-Hydroxy

C-12 19.25 - 21.95

C-13 22.45

C-14 25.35 27.05 27.45

C-15 28.2

C-16 30.8

C-17 33.4 FIG. 1. Gas chromatograms from a SPB-1 column of two enteritidis LPS

preparations by TCA and PW extractions after methanolysis and

trifluoroacetylation. Conditions of sample preparation and

chromatography are given in the text. Abbreviations: Tyv,

tyverose; Abq, abequose; Rha, rhamnose; Gal, galactose; Man,

mannose; Glc, glucose, DD-Hep, E)-glycero-D-mannoheptose; LD-Hep,

Ei-glycero-D-raannoheptose; GlcN, glucosamine; KDO, 2-keto-3-

deoxy-octonate; 12:0, dodecanoate; 3-OH-12:0, 3-hydroxy-

dodecanoate; 14:0, tetradecanoate; 2-OH-14:0, 2-hydroxy-

tetradecanoate; 3-OH-14:0, 3-hydroxy-tetradecanoate; 16:0,

hexadecanoate; i-16:0, 14-methyl-pentadecenoate; 3-OH-16:0, 3-

hydroxy-hexadecenoate; 17:0, heptadecanoate; 18:0,

octadecanoate; 18:1^, cis-9-octadecenoate 46

Salmonella entorltldls LPS from TCA extraction

Tyv

S Rha

o (O 8 JMJ uLi Salmonella enteritldls LPS from phenol-water extraction 9 I ^

Man i Tyv \ \ Glc 9 Rha CM S| Gal y o (6 ^ LO Hep KDO i \ GlcN A A

I L __L_ I _J I 95 135 175 215 »C 47

Pasteurella muttoclda, strain P-2383 (A,3) LPS from TCA extraction

Gic

GlcN cvi

Pasteurella multoclda, strain P-2383 (A,3) US from phenol-water extraction

Gic

GlcN

Gal KDO

L 95 135 175 215 °C

FIG. 2. Gas chronatograms from a fused-silica capillary column (SPB-1)

of P. multocida LPS prepared by TCA and PW extractions 48

contained many constituents characteristic of other Gram-negative

bacterial LPS including LD-heptose, glucosamine, KDO, tetradecanoate and

3-hydroxy-tetradecanoate. However, TCA-LPS of the organism appeared to

contain more glucose and certain longer chain fatty acids that were

absent in the PW-LPS. LPS extracted from 16 different serotypes

exhibited similar chemical composition with identical fatty acid

constituents regardless of the extraction methods. The differences were

found that LPS extracted from encapsulated P. multocida (serotypes 3, 9

and 13) by the PW procedure contained more polysaccharides than the LPS

extracted from non-encapsulated serotypes by the PCP procedure. Also,

minor variation were found in individual cabohydrate constituents. LPS

of all serotypes contained glucose, galactose, LD-heptose, glucosamine

and KDO. However, sane serotypes contained an additional constituent.

For example, LPS of serotype 2 and 5 contained DD-heptose, but this

compound was not detectable in LPS of other serotypes. In this respect,

LPS from serotypes 2 and 5 appeared to be similar in chonical composition

to P. haemolytica LPS (Fig. 3). However, P. haemolytica LPS contained a

large quantity of dodecanoate which was either not detectable or present

in limited quantity in P. multocida LPS. The PW-LPS from different

strains of a conmon serotype of P. multocida (A, 3; P-1059, P-1062 and P-

2383) gave identical GC patterns. The same was true for P. haemolytica

(A, 1; P-101 and D-80). 49

Ptit»unla muKocldt P2383 (A,3) 3-OH-14;0

14:0 Pasfaursit muKocUa P-1702 (D.6I DD-Hsp QlcN Qlo 16:0 KOO

Past»ur»lÊ hemolytica LD-Hep- 3-OH-14:0— D-80 14:0 OD-Hep QIC 7 12:0 / Qd \ QlcN 3-OH-12:0 16:0 / ^ KDO I ^ • A A • . .1 ^ I *1. i. ki ,Ai ^ .—U WLaa__A__A-A_ 1— 35 25 16 5 mh 215 176 136 96 •C

FIG. 3. Gas chromatograms from a fused-silica capillary column (GB-1) of

LPS preparations from Pasteurella species 50

Chonical Relationship of PW-LPS between P. multocida and Other

Gram-Negative Bacteria

The PW-LPS of Gram-negative bacteria closely related to £. multocida

possessed a chemical composition similar to that of multocida (Fig.

4). The LPS of A. ligniersii, a species of the genus Actinobacillus

within the family Pasteurellaceae, contained the same chemical

constituents as multocida LPS with limited quantitative variations in

glucose and galactose. The LPS of H. somnus, a species of uncertain

affiliation within the genus Haemophilus in the family Pasteurellaceae,

also had similar constituents, but it contained a larger quantity of KDO

than other bacteria within the family. When LPS of bacteria with a

lesser relationship with P. multocida were examined (Figs. 1, 5, 6),

compositional variations were found in both the carbohydrate and fatty

acid moieties. However, the LPS of enteric bacteria (Salmonella species

and coli) did share several typical LPS constituents with £. multocida

LPS such as LD-heptose, KDO and 3-hydroxy-tetradecanoate (Figs. 1, 5, 6).

The LPS of B. abortus also contained 3-hydroxy-tetradecanoate (Fig. 5),

but absence of LD-heptose and predominance of long chain fatty acids made

it uniquely different from other bacterial LPS. The LPS of T.

hyodysenteriae and B. fragilis contained completely distinctive fatty

acid moiety as conpared to LPS of Salmonella species, E. coli and genera of the family Pasteurellaceae (Fig. 6). LPS of both bacteria contained

13-hydroxy-methyl-tetradecanoate and 3-hydroxy-hexadecanoate as main fatty acid constituents rather than tetradecanoate and 3-hydroxy- 51

Haemophilus somus 3-OH-14;0 3-OH-12:0

Lu-Hep

Actlnobacillus llgnleresll

3-OH-14;0

LD Hep

3-OH-12;0

T— —I— —T— I 35 25 15 5 min 215 175 135 95 °C

FIG. 4. Gas chromatograms frcm a fused-silica capillary column (GB-1) of

LPS preparations from H. somnus and A. ligniersii 52

SaJmonetta abortua aqui

QIC 12:0 ^ 14:0 Men Rha 30H 12:0 GlcN Abq 16:0 I LD Hep KDO

-16:0 Brucata abortus ((,)

Man

QIC GlcN KDO

36 26 16 5 mln 216 176 136 86 «C

FIG. 5. Gas chranatograms from a fused-silica capillary column (GB-1) of

LPS preparation from abortus equi and B. abortus (f5) 53

Treponema hyodysenterlae LPS from phenol-water extraction O CO

Î 9 LD-Hep

—-'-wJL

Escherichia coll, K-23S U'S from phenol-water extraction

Glc Rha LD-Hep GlcN Gal KDO

UUl

9 Bacteroldes Iragllls, 9 F CO LPS from phenol-water extraction o 6 0 6 in I i % Rha Gal i Man 7 1 g 0 / M N /GIC GlcN X /bo-Hep LD-Hep 1 % S / V -r I L_ I I 95 135 175 215 °C

FIG. 6. Gas chromatograms from a fused-silica capillary column (SPB-1)

of LPS preparations from T. hyodysenteriae, E. coli {K-235) and

B. fragilis (9F) 54

tetradecanoate (27). B. fragilis LPS contained additional fatty acids such as 3-hydroxy-pentadecanoate, 3-hidroxy-15-methyl-hexadecanoate and

3-hydroxy-heptadecanoate. 55

DISCUSSION

Bacterial LPS is a chemically heterogeneous material which is

present in the outer msnbrane of Gram-negative bacteria and has a variety

of biological activities in a host; these activities may include

toxicity, metabolic alterations or immunological effects (10, 11, 13,

25). LPS isolated fran Salmonella species has been characterized most

extensively and structurally these LPS are composed of three chemically

distinctive regions including 0-specific polysaccharide, core

polysaccharide and lipid A region (10, 11, 13, 25). Common components of

the Salmonella LPS are LD-heptose, KDO and 3-hydroxy-tetradecanoate.

For many years, it was thought that the LPS contains a molecular

component common to all Gram-negative bacteria. Variation in the

structure resided in the polysaccharide moiety, while the remainder of

the structure is the same in all LPS molecules regardless of origins.

Earlier chemical studies on LPS of the family by

Luderitz and coworkers seemed to support this premise (11, 13); recently,

Nowotny and his colleagues questioned the validity of this assumption

based on their experimental evidence (15, 16). They found obvious

differences in the chemical composition, particularly in fatty acid constituents, of LPS prepared from a bacterium by different methods and between LPS from different bacterial species.

The results in this study on chemical analysis of JP. multocida and several Gram-negative bacterial LPS by GC clearly danonstrated the compositional heterogeneity of various LPS preparations in support of the 56

findings of Nowotny and his colleagues (15, 16). Compositional

differences between LPS extracted by PW and TCA procedures from a P.

multocida organisa (Fig. 2) indicated that extraction methods influenced

the chsnical character of LPS. This contrasted with enterobacterial LPS

which seemed to be similar in chemical composition irrespective of the

methods utilized for extraction (Fig. 1). An interesting observation is

the finding that the PCP extraction of the non-encapsulated serotypes of

P. multocida yielded LPS similar to the PW-LPS from the encapsulated

serotypes. This observation may indicate that P. multocida LPS is

basically similar in chemical composition irrespective of the serotype.

The PCP method has been used for extraction of LPS fron non-encapsulated

bacteria since LPS fron these bacteria is more soluble in PCP than in

water (6). This is apparently due to the lack of 0-specific

polysaccharide in non-encapsulated bacteria. This increases

hydrophobicity of LPS of non-encapsulated bacteria as compared with LPS

from encapsulated bacteria. The reason v^y different extraction methods,

PW and TCA procedures, influenced the chemical character of LPS from an

encapsulated £. multocida is difficult to explain. However, this difference may result from the surface character of the encapsulated organism, particularly the mucoid nature of the capsule. The capsule may

influence the effectiveness of TCA in dissociating LPS from the mucoid organism.

The O-specific polysaccharide is reported to exhibit serotype specificity of individual bacteria and to be extremly heterogeneous in chemical composition (10, 11, 13, 15, 25). Studies on Salmonella LPS 57

indicated that the repeating unit of oligosaccharide in the O-specific

polysaccharide is the most important factor for determination of serotype

specificity; individual somatic polysaccharides may exhibit several

serologic specificities (11, 13/ 15). Observations in this study

indicated that the carbohydrate constituents of P. multocida LPS were

very similar between the different serotypes although quantity of the

individual constituents was variable and some serotypes contained an

additional sugar such as DD-heptose. Brogden and Rebers (2) reported

chat LPS isolated from 16 different serotypes of P. multocida did not

crossreact except for LPS of serotypes 2 and 5. Rimler et al. (21)

quantitated carbohydrate composition of £. multocida LPS and found that

LPS of serotypes 2 and 5 were markedly alike in chemical composition;

both contained similar amounts of glucose, galactose, DD-heptose, LD-

heptose and KDO. However, LPS of serotype 1 that was also quite similar

in chemical composition with LPS of serotypes 2 and 5, except for the '

lack of DD-heptose, did not crossreact with LPS of the two serotypes.

This indicates that, in general, LPS of P. multocida contains an 0-

specific polysaccharide unique to the individual serotype and exhibits

primarily one serologic specificity. This contrasts with findings on

Salmonella LPS in which somatic polysaccharides may exhibit several serologic specificities (11, 13, 15).

In contrast to the 0-specific polysaccharide, the constituents (LD- heptose and KDO) of the core polysaccharide have been reported to be common to many Gram-negative bacteria, certainly to all in the family

Enterobacteriaceae (10, 13). However, the results of this study 58

indicated that these conpounds were either absent or present in limited

quantities in some bacterial LPS such as B. abortus and B. fragilis

(Figs. 5, 6). Also, the apparent quantity of these compounds is quite

variable in individual LPS from unrelated bacteria and even related

bacteria within the facultative anaerobic Gram-negative bacteria that

comprise the families Enterobacteriaceae and Pasteurellaceae (Figs. 1, 2,

3, 4 , 6). For example, LPS of salmonella, shigella and escherichia may

contain similar amounts of KDO as previously reported (11, 13); however,

LPS of P. multocida, P. haemolytica and A. ligniersii from the family

Pasteurellaceae contained a lesser quantity of KDO than LPS of H. somnus

from the same family and the family Enterobacteriaceae (Figs. 3, 4).

The fatty acid moiety of LPS, called lipid A, is known to represent

the component of LPS which is responsible for its endotoxic properties

(10, 11, 13, 15, 25). However, compositional differences in lipid A of

various LPS preparations have been reported (12, 15, 16). The results of

this study confirmed the heterogeneity in fatty acid components of

various LPS preparations. Also, the results indicated that LPS of

members of the family Pasteurellaceae (Figs. 3, 4) contained almost

identical fatty acid constituents while they were slightly different from

the LPS of enteric bacteria (Figs. 1, 5, 6). Distinctive differences

were noted in the fatty acid composition of LPS from unrelated bacteria

(Figs. 5, 6). This indicates that the similarities and differences in

the fatty acid composition of various Gram-negative bacterial LPS may depend on relationships between the bacteria. Differences in the

relative endotoxicity of these bacterial LPS can be expected since 59

compositional differences in lipid A of different origin and in synthetic lipid A analogues have been demonstrated to influence biological activities of LPS including endotoxicity (12, 15, 16). 60

LITERATURE CITED

1. Bain, R. V. S., and K. W. Knox. 1961. The antigens of Pasteurella multocida type I. II. Lipopolysaccharides. Immunology 4:122-129.

2. Brogden, K. A., and P. A. Rebers. 1978. Serologic examination of the Westphal-type lipopolysaccharides of Pasteurella multocida. Am. J. Vet. Res. 39:1680-1582.

3. Bryn, K., and E. Jantzen. 1982. Analysis of lipopolysaccharides by methanolysis, trifluoroacetylation, and gas chromatography on a fused-silica capillary column. J. Chromatogr. 240:405-413.

4. Carter, G. R. 1967. Pasteurellosis. p. 321-379. ^ C. A. Brandly and C. Cornelius (ed.). Advances in veterinary science. Academic Press, New York, NY.

5. Collins, F. M. 1977. Mechanians of acquired resistance to Pasteurella multocida infection: a review. Cornell Vet. 67:103-138.

6. Galanos, C., 0. Luderitz, and 0. Vfestphal. 1969. A new method for extraction of R lipopolysaccharides. Eur. J. Biochem. 9:245-249.

7. Ganfield, D. J., P. A. Rebers, and K. L. Heddleston. 1976. Immunogenic and toxic properties of a purified lipopolysaccharide- protein complex from Pasteurella multocida. Infect. Immun. 14:990- 999.

8. Heddleston, K. L., and P. A. Rebers. 1975. Properties of free endotoxin from Pasteurella multocida. Am. J. Vet. Res. 36:573-574.

9. Heddleston, K. L., P. A. Rebers, and A. E. Ritchie. 1966. Immunizing and toxic properties of particulate antigens from two immunogenic types of Pasteurella multocida of avian origin. J. Immunol. 96:124-133.

10. Kabir, S., D. L, Rosenstreich, and S. E. Mergenhagen. 1978. Bacterial endotoxins and cell membranes, p. 59-87. D] J. Jeljaszewicz and T. Wadstrom (eds.). Bacterial toxins and cell membranes. Acadanic Press, New York, NY.

11. Luderitz, 0., K. Jann, and R. Whet, 1968. Somatic and capsular antigens of Gram-negative bacteria, p. 105-228. _In M. Florkin and E. H. Stotz (eds.). Comprehensive biochemistry. Vol. 26A. Elsevier Publishing Co., Amsterdam. 61

12. Luderitz, 0., K. Tanamoto, C. Galanos, and 0. Westphal. 1983. Structural principles of lipopolysaccharides and biological properties of synthetic partial structure, p. 3-17. ^ H. Anderson and F. M. Unger (eds.). Bacterial lipopolysaccharides. American Chanical Society, Washinton, D.C.

13. Luderitz, 0., 0. Vfestphal, A. M. Staub, and H. Nikaido. 1971. Isolation and chemical and immunological characterization of bacterial lipopolysaccharides. p. 145-233. m G. Weinbavm, S. Kadis, and S. J. Ajl (eds.). Microbial toxins. Vol. IV. Academic Press, New York, NY.

14. Moreno, E., M. W. Pitt, G. G. Schurig, and D. T. Herman. 1979. Purification and characterization of smooth and rough lipopolysaccharides from Brucella abortus. J. Bacteriol. 138:361- 369.

15. Nowotny, A. 1971. Chanical and biological heterogeneity of endotoxins, p. 309-329. _ln G. Weinbaun, S. Kadis, and S. J. Ajl (eds.). Microbial toxins. Vol. IV. Academic Press, New York, NY.

16. Nowotny, A., A. Nowotny, and U. H. Behling. 1980. The neglected problem of endotoxin heterogeneity, p. 3-8. ^ M. J. Agawell (ed.). Bacterial endotoxins and host response. Elsevier Publishing Co., Amsterdam.

17. Phillips, M., and R. B. Rimler. 1984. Protection of chickens by ribosomai vaccines from Pasteurella multocida; dependence on homologous 1ipopolysaccharide. Am. J. Vet. Res. 45:1785-1789.

18. Pirosky, I. 1938. Sur les propietes immunsantes antitoxiques et anti-infecteuses de I'antigene glueio-lipidique de Pasteurella aviseptica. C. R. Seances Soc. de Biologie 127:98-100.

19. Rebers, P. A., and K. L. Heddleston. 1974. Immunologic comparison of Westphal-type lipopolysaccharides and free endotoxins from an encapsulated and a non-encapsulated avian strain of Pasteurella multocida. Am. J. Vet. Res. 35:555-560.

20. Rebers, P. A., K. L. Heddleston, and K. R. Rhoades. 1967. Isolation from Pasteurella multocida of a 1ipopolysaccharide antigen with immunizing and toxic properties. J. Bacteriol. 93:7-14.

21. Rimler, R. B., P. A. Rebers, and M. Phillips. 1984. Lipopolysaccharides of the Heddleston serotypes of Pasteurella multocida. Am. J. Vet. Res. 45:759-763.

22. Ryu, H., and M. L. Kaeberle. 1986. Immunogenicity of potassium thiocyanate extract of type A Pasteurella multocida. Vet. Microbiol. 11:373-385. 62

23. Srivastava, K. K., J. W. Foster, D. L. Dawe, J. Brown, and R. B. Davis. 1970. Immunization of mice with components of Pasteurella multocida. Appl. Microbiol. 20:951-956.

24. Staub, A. M. 1965. Bacterial lipido-proteino-polysaccharides, p. 92-93. _In R. L. Whistler (ed.). Methods in carbohydrate chemistry. Vol. V. Acadanic Press, New York, NY.

25. Stephen, J., and R. A. Pietrowski. 1981. Bacterial toxins. American Society for Microbiology, Washington, D.C. 104 pp.

26. Westphal, 0., and K. Jann. 1965. Bacterial lipopolysaccharides. p. 83-91. R. L. Whistler (ed.). Methods in carbohydrate chemistry. Vol. 5. Academic Press, New York, NY.

27. Wollenweber, H. W., E. T. Rietschel, T. Hofstad, A. Weintraub, and A. A. Lindberg. 1980. Nature, type of linkage, quantity, and absolute configulation of (3-hydroxy) fatty acids in lipopolysaccharides frcm Bacterioides fragilis NCTC 9343 and related strains. J. Bacteriol. 144:898-903. 63

SECTION II. CHARACTERIZATION OF A LIPOPOLYSACCHARIDE-PROTEIN COMPLEX OF

TYPE A PASTEURELLA MULTOCIDA 64

SUMI-IARY

A lipopolysaccharide (LPS)-protein conplex isolated from a potassium

thiocyanate extract of a Pasteurella multocida (P. multocida; strain P-

2383, capsular type A and sonatic type 3) was characterized. Chemical

analysis of the complex by gas chromatography on a capillary column

demonstrated that this complex contained most of the chemical

constituents characteristic of LPS extracted by the phenol-water method

from the whole bacterium. However, there apparently was more

carbohydrate than fatty acid in the complex in contrast to LPS in which

fatty acid seemed to be in excess. VJhen toxicity of the complex was

evaluated in 10-day-old chicken embryos, the complex was less toxic (LDg^

= 12.72 ug) than the purified LPS (LD^q = 0.44 ug). The LD^q of the LPS

moiety extracted from the complex was 5.24 ug. Composition of the

complex was analyzed by SDS-PAGE with silver staining and Vfestern

immunoblot. The complex did not migrate through the polyacrylamide gel

unless dissociated with SDS. The complex dissociated with SDS contained

more than 32 different protein and polysaccharide components; at least 18

components reacted with an antiserum against the complex. There was no

significant compositional variation between the complexes from different

strains, but quantitative differences in individual components were

noted. When cross-protectivity of the complex was evaluated in mice,

this complex provided substantial protection not only against the homologous bacterium but also against different P. multocida strains of the same serotype. LPS-protein complexes isolated by the same method 65

from other strains also induced protection against a challenge with P-

2383. 66

INTRODUCTION

Capsular type A and somatic type 3 strains of Pasteurella multocida

(P. multocida) are known to be a major etiological factor of pneumonic

pasteurellosis of cattle (3, 5, 6) and the economic loss to the U.S.

cattle industry from the disease exceeds a half billion dollars annually

(17). The importance of the organism has led to the use of various

bacterins for prevention; however, immunization of cattle with

Pasteurella bacterins has been demonstrated to be detrimental to the

health of the animals in addition to questionable efficacy (9, 10, 15,

21). Therefore, subcellular fractions of the bacterium have been studied

extensively to find an effective immunizing agent.

Lipopolysaccharides (LPS) present in the outer manbrane of Gram-

negative bacteria are known to play important roles in bacterial

pathogenesis since they exhibit many endotoxic activities in a host such

as pyrogenicity, depression, diarrhea, lethality for chicken anbryos, and

death in mice, rabbits and chickens (13, 16, 18, 19, 33). LPS of P.

multocida has also been reported to evoke such endotoxic activities (1,

23, 25). Also, many researchers have suggested that the P. multocida

fractions which possessed itnnunogenicity contained LPS as an important

constituent (8, 11, 12, 22, 25, 26, 30).

The presence of LPS in the immunogenic fractions of £. multocida has been determined by serologic cross-reactivity of the fractions with the purified LPS (11, 22, 25, 30), endotoxic activities in experimental animals and chicken embryos (8, 11, 12, 25, 26), or detection of 2-keto- 67

3-hydroxy-octonate (KDO) and/or fatty acids by chsnical methods (8/ 12,

22, 26). While these determinations may have suggested the presence of

LPS, they failed to relate basic chemical differences between the immunogenic fractions and the purified LPS.

Previously, we have reported the isolation of an immunogenic fraction fron a potassium thiocyanate (KSCN) extract of P. multocida

(strain P-2383; capsular type A and somatic type 3) by sucrose-density gradient centrifugation (30). This fraction, called P-2383-1, was highly intnunogenic in mice and contained 27% protein and 12% carbohydrate.

Although the fraction crossreacted serologically with LPS extracted from the whole bacterium by Vfestphal's phenol-water procedure, KDO was not detected in P-2383-1 at a protein concentration of 5 mg/ml. The objectives of this study were to determine the endotoxic LPS content in

P-2383-1 and one other LPS-containing immunogen of multocida by gas chromatography on a fused-capillary column, to evaluate P-2383-1 for its toxic activity in chicken embryos, and to discern immunologic relationships between the LPS-protein complexes from different strains of the serotype by compositional analysis in sodinn dodecyl sulfate- polyacrylamide gel electrophoresis (SDS-PAGE) and Western immunoblot. 68

MATERIALS AND METHODS

Organism

Five P. multocida strains (P-2383, E^9238, P-9663, P-9954, P-10027;

capsular type A and somatic type 3) were used in this experimentation.

Culture conditions for growth of P. multocida organisms, preparation of

KSCN extracts and isolation of a LPS-protein complex, P-2383-1, fron a

KSCN extract have been described previously (30).

Isolation of LPS-Protein Complexes

An immunogenic LPS-protein complex, called P-2383-1, was isolated

from a KSCN extract of an encapsulated P. multocida (P-2383; capsular

type A and somatic type 3) by sucrose-density gradient centrifugation

(30). LPS-protein complexes, eqivalent to P-2383-1, isolated from

different strains of the serotype were prepared by the same method and

named P-9238-1, P-9663-1, P-9954-1 and P-10027-1. Another immunogenic

LPS-protein complex, called P-1059-40p, was isolated from a 0.85% NaCl

extract of a non-encapsulated variant (P-1059; capsular type A and

somatic type 3) by gel-filtration as described by Ganfield et al. (8) and

was kindly provided by Dr. R. B. Rimler, National Animal Disease Center

(NADC), the United States Department of Agriculture (USDA), Ames, lA. 69

Fractionation of a LPS-Protein Complex

P-2383-1 was fractionated into LPS and protein moieties by an

extended %stphal's phenol-water procedure described by Sultzer and

Goodman (34). Briefly, P-2383-1 dissolved in 0.32 M NaCl/0.01 M Tris-HCl

buffer was dialyzed against distilled water at 4 C for 2 days and warmed

to 65 C before treatment with equal volume of 90% phenol (65 C). The LPS

moiety (P-2383-1-LPS) was isolated from the water phase while the protein

moiety (P-2383-1-PRO) was collected from the phenol phase by

precipitation with cold ethanol (-20 C). Since P-2383-1-PRO was poorly

soluble in water, it was solubilized by suspending 2 mg (dry weight) in

0.95 ml of distilled water and adding 0.05 ml of 0.1 N NaOH.

Preparation of P. multocida LPS

The phenol-water extracted LPS (PW-LPS) was prepared from strain P-

2383 by the method of Westphal and Jann (36) with slight modifications as described previously (30).

Chemical Analysis

Bacterial fractions were assayed for basic chemical content. Total carbohydrate was determined by the phenol-sulfuric acid procedure (7) using glucose (Sigma Chemical Co., St. Louis, MO) as a standard. Protein content was determined colorimetrically from the reaction of protein with 70

Serva blue G dye (Serva Fine Chemicals Inc., Long Island, NY) using

bovine serum albumin (Sigma) as a standard (24).

Gas Chromatography (GC)

Derivatization of samples for GC analysis was performed by the

method of Bryn and Jantzen (4) with slight modifications. Briefly, 2 to

5 mg of the sample was suspended in one ml of 2 M HCl (Supelco,

Bellefonte, PA) in a teflon-lined screw-capped vial (Supelco) and held at

85 C for 18 h. The methanolysate was concentrated to dryness at rocm

temperature with nitrogen gas and trifluoroacetylated by adding 0.2 ml of

50% trifluoroacetic acid (TFA, gold label; Aldrich Chemical Inc.,

Milwaukee, WI) in acetonitrile (HPLC grade; Fisher Scientific, Fair Lawn,

NJ) and heating in a boiling water bath for 2 min. After cooling to roan

temperature, the reaction mixture was diluted with acetonitrile (HPLC

grade; Fisher Scientific, Fair Lawn, NJ) to a final TFA concentration of

10% and injected into the column. Galactose, glucose and KDO were

purchased from Sigma chemical Co., and LD-heptose was kindly provided by

Dr. P. A. Rebers, NADC, USDA, Ames, lA. These sugars were used for carbohydrate standards and a bacterial fatty acid mixture (Supelco) was

used as a fatty acid standard. The GC analysis was carried out on

Hewlett-Pachard 402 GC system equipped with a flame-ionizing detector that had been modified for the use of a capillary column. A fused-silica capillary column (GB-1, 25 m x 0.25 mm ID, Foxboro/Analabs, North Haven,

Conn) was operated in a split mode and with helium carrier gas. The 71

column tanperature was held for 5 min at 95 C and then programmed to

increase at 4 C per min up to 230 C.

Production of Rabbit Antiserum

Procedures for production of rabbit antiserum to Pasteurella

fractions have been described previously (30). White New Zealand female

rabbits were used for immunization with P-2383-1. The antiserums

obtained fron these rabbits produced a single precipitation line in

crossed-inununoelectrophoresis with the immunizing antigen and 2

precipitation lines were observed in the reaction with whole KSŒ

extract.

Chicken Eïnbryo Lethality

The chicken enbryo lethality test was conducted by the method of

Smith and Thomas (31). Groups of five 10-day-old embryonated eggs were

inoculated with 0.1 ml volumes of 2-fold dilutions of the £. multocida

fractions on the chorioallantoic membrane. The eggs were incubated at 37

C and candled for viability at 24 and 48 h. Fifty percent of lethal dose

(LD50) of the fractions was determined by the method of Reed and Muench

(28) . 72

SDS-PAGE

Discontinuous SDS-PAGE was performed with 10% separating gel and 5%

stacking gel by the method of Laemmli (14) with slight modifications.

Both separating and stacking gels were prepared from a 30% acrylaraide

(Bio-Rad Laboratories, Richnond, CA) stock solution containing 0.8% N,N'-

methylene bis acrylamide (Bio-Rad). The separating gel (100 ml) contained 33.3 ml of the stock solution, 20 ml of 1.5 M Tris-HCl (Sigma),

pH 8.9, 1 ml of 10% SDS, 20 ml of 50% sucrose solution and 25.7 ml of distilled water. Five ul of TEMED (N,N,N',N'-tetramethylethylenediamine,

Bio-Rad) and 8 ul of freshly prepared 10% ammoniim persulfate (Bio-Rad) were added to 10 ml of the degassed separating gel. The stacking gel

(100 ml) contained 16.8 ml of the stock solution, 12.5 ml of 0.5 M Tris-

HCl, pH 6.8, 1 ml of 10% SDS, and 69.7 ml of distilled water. Five ul of

TEMED and 0.1 ml of 10% ammoniim persulfate were added to 10 ml of the degased stacking gel. Sample preparation buffer (100 ml) contained 2 g of SDS, 10 ml of glycerol, 10 ml of 0.04% bromophenol blue, 12.5 ml of

0.5 M tris-HCl, pH 6.8 and 67.5 ml of distilled water. Prior to use for treatment of sample, 0.1 ml of 2-mercaptoethanol was added to 10 ml of the buffer. One-tenth ml of this solution was added to the same volume of an individual sample and the mixture was heated for 4 min in a boiling water bath (95 C). One-tenth mg of proteinase K (PK, Sigma) solubilized in 10 ul of the sample preparation buffer was added to the sample mixture subject to protein digestion and incubated for 1 h at 60 C. Samples were loaded onto the polyacrylamide gels in a volume of 20 to 30 ul and 73

separated for 6 to 7 h at 25 mA per gel (16 an x 11.5 cm x 0.15 an).

After the electrophoresis, the gel was fixed overnight in 25% (vol/vol)

2-propanol-10% (vol/vol) acetic acid solution. Silver staining was conducted with a silver staining kit (Accurate Chemical & Scientific

Corp., Westbury, NY) according to the recommended procedure.

Western Immunoblot

Western immunoblot was performed according to the method of Towbin et al. (35). The polyacrylamide gel subject to immunoblot was washed for

1 h in a blotting buffer solution containing 25 mM Tris-HCl, 192 mM glycine and 20% (vol/vol) methanol (pH 8.3). Separated components in the gel were electroblotted to a nitrocellulose manbrane (Bio-Rad) for 5 h at

21 mA. The membrane was incubated overnight in a Tris-buffered saline solution (TBS; 20mM Tris-HCl, 0.5 M NaCl, pH 7.5) containing 3% bovine serum albumin. The membrane was washed 3 times in TBS containing 0.0005%

(vol/vol) of Tween 20 (TTBS). Rabbit antiserum against P-2383-1 was diluted to 1:100 in TTBS containing 1% gelatin. The membrane was incubated overnight in this antibody solution. The membrane was washed 3 times with TTBS and incubated for 1 h in a TTBS-1% gelation solution containing 1:500 peroxidase-labeled goat anti-rabbit IgG (Sigma). The manbrane was washed twice with TTBS and once with TBS, and incubated in

TBS containing 60 mg HRP color development reagent (Bio-Rad), 20 ml of methanol, 60 ul of 20% (vol/vol) hydrogen peroxide. 74

Mouse Immunization and Challenge

White Swiss mice of one sex, 8 weeks of age, and at least 18 g in weight (Bio-Lab Corp., St. Paul, MN) were utilized for this study. All mice were immunized subcutaneously with 0.1 ml (1 mg/ml protein concentration) of antigen and challenged intraperitoneally 2 weeks later with 0.1 ml of bacterial suspension (100 to 200 CFU). Mice were observed for 1 week after the challenge and deaths recorded. 75

RESULTS

GC Analysis

GC analysis indicated that the constituents of PW-LPS of P.

multocida were galactose, glucose, LD-heptose, glucosamine, KDO, 3-

hydroxy-dodecanoate, tetradecanoate, 3-hydroxy-tetradecanoate and

hexadecanoate (Fig. 1). As illustrated in Fig. 2, both LPS-containing

immunogens, P-1059-40p and P-2383-1, contained most of the chanical

constituents present in PW-LPS of P. multocida except that KDO was

difficult to detect in P-2383-1. However, the differences were observed

in GC patterns of the three preparations indicating quantitative

variations within the shared constituents. P-2383-1 contained a higher

ratio of carbohydrate to fatty acid than P-1059-40p and PW-LPS. The

immunogenic fractions contained considerable amounts of long chain fatty

acids such as hexadecanoate that were present in limited quantity in PtJ-

LPS.

Chanical Analysis

The LPS-protein complexes of several P. multocida strains, equivalent to P-2383-1, contained 5 to 27% carbohydrate and 22 to 38% protein. The LPS moiety of P-2383-1 contained 50% carbohydrate and PW-

LPS contained 24% carbohydrate. 76

Pasteurella multocida, strain P-2383 (A,3) LPS from phenol-water extraction

LO-Hep

QlcN

KDO Lv ->L

35 25 15 5 min 215 175 135 95

1. Gas chromatogram of the phenol-water extracted LPS of P.

multocida (strain P-2383) after methanolysis and

trifluoroacetylation. Conditions of sample prepartion and

chromatography are given in the text. Abbreviations: Gal,

galactose; Glc, glucose; LD-Hep, L-glycero-D-mannoheptose; GlcN,

glucosamine; KDO, 2-keto-3-hydroxy-octonate; 3-0H-12:0, 3-

hydroxy-dodecanoate; 14:0, tetradecanoate; 3-OH-14:0, 3-hydroxy-

•tetradecanoate; 16:0, hexadecanoate 77

PastBureHa muHocldB P-1059.40P

3'OH-14:0 LD'Hep

16:0

3-OH-12;0 oteN

Pasteurala multocida P-2383, P 2383 1 Glc , Qal 3-OH-14:0 1 3-OH-12:0 16:0 LO Hep 14:0 QlcN / KDO

\v' IajijU

I —1— —I— 35 25 15 5 mh 216 175 135 95 °C

FIG. 2. Gas chronatograns of LPS-containing immunogens of P. multocida.

Abbreviations are listed in the legend of Fig. 1 78

Chicken Embryo Lethality

Results of toxicity assays for P-2383-1, its LPS moiety (P-2383-1-

LPS) and PW-LPS in 10-day old chicken embryos are listed at Table 1. The

PW-LPS exhibited the highest toxicity with a LD^Q of 0.44 ug while P-

2383-1 exhibited the lowest toxicity with a LD^Q of 12.72 ug. The LD^Q

of the LPS moiety extracted from P-2383-1 was 5.24 ug.

Compositional Analysis of the LPS-Protein Complexes

The LPS-protein complexes which were not treated with SDS did not migrate through the polyacrylamide gel. The complexes treated with SDS showed visible bands in the polyacrylamide gel at a 0.5 mg/ml protein concentration; however, the protein moiety of P-2383-1 required at least

4 mg/ml protein concentration to show visible bands. The LPS-protein complexes contained at least 32 protein and polysaccharide components with the molecular size ranging from less than 14.3 kilodaltons to greater than 94 kilodaltons (Fig. 3). Most of these components were protein in nature since they were destroyed by proteinase K treatment

(Fig. 4). At least 4 polysaccharide bands of different molecular sizes were identified; however, the predominant band was of smaller molecular size (Fig. 4). Most of these components were shared between the complexes isolated from different strains, but the quantity of individual components was somewhat variable. Analysis by Western immunoblot (Fig.

5) indicated that at least 18 of those components reacted with an 79

Table 1. Lethality for chicken embryos of fractions extracted frcm £.

multocida

Dosage (ug) PW-LPS P-2383-1 P-2383-1-LPS

64 - 6/6^ -

32 - 4/6 -

16 - 4/6 6/6

8 - 3/6 5/6

4 6/6 0/6 2/6

2 6/6 0/6 1/6

1 5/6 - 0/6

0.5 4/6 - -

0.25 1/6 - -

0.125 0/6 - -

^o. of dead/no. tested. 80

94K- 66K- 45K-

36K-

24K-

20.1K- 14.3K- mm# m

FIG. 3. SDS-PAGE profiles of LPS-protein complexes isolated fron P.

multocida strains of capsular type A and sonatic type 3 as

revealed by silver staining. The lanes and fractions were as

follows: 1, molecular weight standard; 2, P-2383-1; 3, P-9238-1

4, P-9663-1; 5, P-9954-1; 6, P-10027-1 81

ni&4m..,',:

FIG. 4. SDS-PAGE profiles of the fractions of P. multocida as revealed

by silver staining. The lanes and fractions were as follows: 1,

PW-LPS; 2, P-2383-1-LPS + PK; 3, P-2383-1-PRO + PK; 4, P-2383-1-

LPS; 5, P-2383-1-PRO; 6, P-2383-1 + PK; 1, P-2383-1; 8, P-9238-

1; 9, P-9663-1; 10, P-9954-1; 11, P-10027-1; 12, molecular

weight standard 82

( > I Vi =v4-. it:;o

•'•hvii ~

K

2 3 4 5 6 7 8 9 10 11

FIG. 5. Western iiraiunoblot of the fractions of P. multocida stained by

peroxidase-labeled goat anti-rabbit IgG. The lanes and

fractions were as follows; 1, PW-LPS; 2, P-2383-1-LPS + PK; 3,

P-2383-1-PRO + PK; 4, P-2383-1-LPS; 5, P-2383-1-PRO; 6, P-2383-1

+ PK; 7, P-2383-1; 8, P-9238-1; 9, P-9663-1; 10, P-9954-1; 11,

P-10027-1 83

antiserum against P-2383-1.

Immunogenicity in Mice

As indicated at Table 2, groups of mice immunized with the LPS- protein complexes were protected against a challenge infection with strain P-2383. Mice inrounized with P-2383-1 were also protected against challenge infections with several P. multocida strains of the serotype that killed 100% of the control mice (Table 3). 84

Table 2. Immunogenicity for mice of LPS-protein complexes of

multocida against challenge exposure with strain P-2383. Each

mouse received 100 to 200 CPU of the bacterium

intraperitoneally

Immunization No. surviving/ no. tested

None 0/5

P-9238-1 4/5

P-9663-1 5/5

P-9954-1 5/5

P-10027-1 5/5 85

Table 3. Immunogenicity for mice of a LPS-protein complex, P-2383-1,

against challenge infections with heterologous P. multocida

strains of capsular type A and somatic type 3

Immunization

Strain challenged Control P-2383-1

P-9238 0/5^ 5/5

P-9663 0/5 5/5

P-9954 0/5 5/5

P-10027 0/5 5/5

^No. surviving/ no. tested. 86

DISCUSSION

We have previously reported that a LPS-protein complex (P-2383-1)

isolated from a KSCN extract of a P. multocida strain (P-2383; capsular

type A and somatic type 3) induced resistance in mice to challenge

infection with the homologous strain (30). P-2383-1 serologically cross-

reacted with PÏ1Î-LPS of the organism, however, KDO was not detected in P-

2383-1 at a protein concentration of 5mg/ml.

Previous experimentation by other workers has demonstrated the

presence of LPS in immunogenic P. multocida fractions as determined by serologic assays (11, 12, 25, 30) , endotoxic activity (8, 11, 12, 25, 26) and chemical methods (8, 12, 22, 26). However, those determinations were quite restrictive in relating LPS as a component of the respective fractions. Serologic reactions involving polysaccharide antigens are widely recognized for cross-reactivity (16, 19). Therefore, cross- reaction between PW-LPS and immunogenic fractions does not necessarily mean the presence of LPS. Toxic activity is a satisfactory indicator of the presence of LPS but does not rule out potential toxic materials other than LPS present in cell wall materials of bacteria (13). Fatty acids are associated with LPS but are common constituents of the bacterial membrane structure (13). Detection of KDO in P. multocida fractions has been used most extensively to determine the presence of LPS; however,

Rimler et al. (29) reported that the amount of KDO in LPS of somatic serotype 3 P. multocida was only approximately 1%. Therefore, detection of KDO in an immunogenic fraction of £. multocida may be difficult if LPS 87

represents only minor component of the fraction.

GC analysis of the P. multocida fractions in this study clearly

indicated the presence of LPS in the two immunogenic fractions (Fig. 2).

The presence of typical constituents of the bacterial LPS was

demonstrated in the chromatograms of the immunogenic fractions. Also,

these chrcmatograms clearly showed compositional differences between the

two fractions, which previously have been considered to be similar materials since they contained the same protein and carbohydrate content

(8, 30). This indicates that this GC procedure is not only useful for detection of LPS in bacterial fractions but also useful for direct comparison of chemical composition of various fractions. The differences in ratio of polysaccharide to fatty acid between the immunogenic fractions and PW-LPS may be explained by the unique nature of cell wall structure of Grant-negative bacteria. The cell wall is a multilayered structure including cytoplaanic membrane, a thin rigid layer of peptidoglycan and outer manbrane (13, 16). LPS exists in the outer leaflet of the double-tracked outer membrane and the fatty acid moiety of

LPS, lipid A, is responsible for the toxicity. Approximately 50% of the

LPS is held non-covalently in the membrane and often forms blebs that can be easily detached frcm the membrane in exponentially growing bacteria and by mild physical and chanical treatments. Therefore, it is possible that different extraction methods used for the preparation of the bacterial fractions may influence the chemical composition of LPS in the products. The exact mechanism of individual reagents used for extraction of bacterial fractions is not known. However, a chaotrophic reagent. 88

KSCN, may extract a part of LPS present in the outer membrane such as LPS

blebs or cleave off sane fatty acids fron lipid A, while phenol-water

treatment may extract the whole LPS and even the inner leaflet of the

outer membrane, or some fatty acids frcm the cytoplasmic monbrane. It is

also possible that the purification process utilized in the preparation

of the bacterial fractions may have influenced the chemical composition

of the final products. The PV^LPS was prepared from bacteria washed

several times by centrifugation and could have resulted in a loss of the

surface materials of P. multocida. P-2383-1 was isolated frati unwashed

bacteria and should have resulted in retention of most of the cell

surface materials. While P-2383-1 obviously contains LPS, there is in

addition an abundance of proteins and other polysaccharides. Therefore,

the relative amount of LPS in these two preparations was distinctively

different.

The fatty acid content and composition of lipid A is known to

influence toxicity of LPS (19, 20). The quantity and type of fatty acids

present in various £. multocida fractions was variant. This may account

for the differing toxicity of these materials in chicken anbryos. P-

2383-1 was less toxic than PW-LPS. The LPS moiety of P-2383-1 (P-2383-1-

LPS) was more toxic than P-2383-1 but less toxic than PW-LPS. These

results were expected since only a part of P-2383-1 is LPS and P-2383-1-

LPS contained more carbohydrate than fatty acid in comparison with Ptf-LPS

(Figs. 1, 2). The variability in relative fatty acid content in these respective LPS-containing fractions probably is responsible for differing toxicity. 89

P-2383-1 was previously reported to be a single antigenic component

of the KSCN extract that contained at 25 different antigenic components

as determined by crossed-immunoelectrophoretic techniques with and an

antiserum pool prepared from rabbits immunized with whole cell lysate,

ribosomal-protein complex and KSCN extract of strain P-2383 (30). The

purpose of SDS-PAGE and Western immunoblot analysis was to find a

molecular component responsible for induction of immunogenicity in mice,

however, the results of this study were somewhat disappointing. P-2383-1 was previously determined to be a single macromolecule (30) v^ose large size was indicated by the inability of P-2383-1 to migrate through the polyacrylamide gel. However, silver staining of the gel of P. multocida fractions (Figs. 3, 4) indicates that P-2383-1 appeared to be a molecular complex that is composed of more than 32 different protein and polysaccharide components. Analysis by Vtestern immunoblot (Fig. 5) indicated that at least 18 different components from P-2383-1 reacted with an antiserum against P-2383-1 that showed a single precipitation line with P-2383-1 and two lines with the KSCN extract.

The protective antigen is probably one of the proteins associated with P-2383-1. While P-2383-1-LPS reacted with the antiserum against P-

2383-1, it did not induce immunity that protected mice from challenge with P. multocida (see Section III). Alternatively, the LPS may lack immunogenicity, a property that is well recognized (27). Phenol-water extracted protein from P-2383-1 was also demonstrated to lack immunogenicity (see Section III). However, phenol-water treatment may have altered some of proteins present in P-2383-1. This assumption would 90

be supported by the fact that about 8 times greater protein concentration

was required for the protein moiety than for the LPS-protein complex to

show visible bands in SDS-PAGE and Vfestern immunoblot. Also, a major

protein band approximately 24 kilodaltons in molecular size apparently

was altered since the intensity of the band was quite different between

P-2383-1-PRO and the original complex (Fig. 5).

The results of the mouse protection study indicated that P-2383-1 induces substantial cross-protection against different strains of P. multocida of the same serotype (Table 3). Also, mice immunized with the

LPS-protein complexes isolated from different strains were protected against P-2383 (Table 2). This might be expected since the LPS-protein complexes from different strains were found to contain common antigenic components when examined by SDS-PAGE and Wfestern immunoblot (Figs. 3, 4,

5). Therefore, the LPS-protein complex isolated from a KSCW extract of a single strain of P. multocida can potentially provide cross-protective immunogenicity at least within strains of capsular type A and somatic type 3 that have been most frequently isolated from the cases of bovine pneumonic pasteurellosis in the United States (3). 91

LITERATURE CITED

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2. Bennett, B. W. 1982. Efficacy of Pasteurella bacterins for yearling feedlot cattle. Bovine Practice 3:26-30.

3. Blackburn, B. 0., K. L. Heddleston, and C. J. Pfow. 1975. Pasteurella multocida serotyping results (1971-1973). Avian Dis. 19:353-356.

4. Bryn, K., and E. Jantzen. 1982. Analysis of lipopolysaccharides by methanolysis, trifluoroacetylation, and gas chranatography on a fused-silica capillary column. J. Chromatogr. 240:405-413.

5. Carter, G. R. 1967. Pasteurellosis: Pasteurella multocida and Pasteurella haemolytica. p. 321-379. ^ C. A. Brandly and C. Cornelius (eds.). Advances in veterinary science. Vol. II. Academic Press, New York, NY.

6. Collier, J. R. 1968. Pasteurellae in bovine respiratory disease. J. Am. Vet. Med. Assoc. 152:824-828.

7. Dubois, M., K. A. Gilles, J. K. Hamilton, P. A. Rebers, and R. Shiith. 1956. Colorimetric method for determination of sugars and related compounds. Anal. Chan. 28:350-356.

8. Ganfield, D. J., P. A. Rebers, and K. L. Heddleston. 1976. Immunogenic and toxic properties of a purified lipopolysaccharide- protein complex from Pasteurella multocida. Infect. Immun. 14:990- 999.

9. Hamdy, A. H., N. B. King, and A. I. Trapp. 1965. Attempted immunization of cattle against shipping fever: a field trial. Am. J. Vet. Res. 26:897-902.

10. Harris, W. F. 1973. Are the licensed bovine bacterins effective? Should the formula be changed? J. Am. Vet. Med. Assoc. 163:841-844.

11. Heddleston, K. L., and P. A. Rebers. 1975. Properties of free endotoxin from Pasteurella multocida. Am. J. Vet. Res. 36:573-574.

12. Heddleston, K. L., P. A. Rebers, and A. E. Ritchie. 1966. Immunizing and toxic properties of particulate antigens from two immunogenic types of Pasteurella multocida of avian origin. J. Immunol. 96:124-133. 92

13. Kabir, S., D. L. Rosenstreich, and S. E. Mergenhagen. 1978. Bacterial endotoxins and cell membranes, p. 59-87. J. Jeljaszewicz and T. Wadstrom (eds.). Bacterial toxins and cell membranes. Academic Press, New York, NY.

14. Lasimli, U. K. 1970. Cleavage of structural proteins during the assembly of the head of T4. Nature 227:680-685.

15. Larson, K. A., and K. R. Schell. 1969. Toxicity and immunogenicity of shipping fever vaccines in calves. J. Am. Vet. Med. Assoc. 155:495-499.

16. Luderitz, 0., K. Jann, and R Whet. 1968. Somatic and capsular antigens of Gram-negative bacteria, p. 105-228. In M. Florkin and E. H. Stotz (eds.). Comprehensive biochemistry. Vol. 26A. Elsevier Publishing Co., Amsterdam.

17. McMillan, C. W. 1983. Working together, sharing knowledge, p. 64- 79. In R. W. Loan (ed.). Bovine respiratory disease. Texas A & M University Press, College station, TX.

18. Morrison, D. C. 1983. Bacterial endotoxins and pathogenesis. Rev. Infect. Dis. 5, Suppl. 4:s733-s747.

19. Nowotny, A. 1971. Chemical and biological heterogeneity of endotoxins, p. 309-329. G. Weinbaun, S. Kadis ad S. J. Ajl (eds.). Microbial toxins. Academic Press, New York, NY.

20. Nowotny, A., A. Nowotny, and U. H. Behling. 1980. The neglected problem of endotoxin heterogeneity, p. 3-8. _In M. J. Agawell (ed.). Microbial endotoxins and host responses. Elsevier Science Publishers, Amsterdam.

21. Palotay, S. L., S. Young, S. A. Lovelace, and J. H. Newhall. 1963. Bovine respiratory infections. II. Field trial using bacterial vaccine products as a means of prophylaxis. Am. J. Vet. Res. 24:1137-1142.

22. Phillips, M., and R. B. Rimler. 1984. Protection of chickens by ribosomal vaccines fron Pasteurella multocida; dependence on homologous 1ipopolysaccharide^ ÂnT J. Vet. Res. 45:1785-1789.

23. Pirosky, I. 1938. Sur les propietes immunsantes antitoxiques et anti-infecteuses de I'antigene glueio-lipidique de Pasteurella aviseptica. C. R. Seances Soc. de Biologie 127:98-100.

24. Read, S. M., and D'. H. Northcote. 1981. Minimization of variation in the response to different proteins of the Cocmasie blue G dye- binding assay for protein. Anal. Biochem. 116:53-64. 93

25. Rebers, P. A., and K. L. Heddleston. 1974. Immunologic comparison of Westphal-type lipopolysaccharides and free endotoxins fran an encapsulated and a non-encapsulated avian strain of Pasteurella multocida. Am. J. Vet. Res, 35:555-560.

26. Rebers, P. A., K. L. Heddleston, and K. R. Rhoades. 1967. Isolation from Pasteurella multocida of a lipopolysaccharide antigen with imnunizing and toxic properties. J, Bacteriol. 93:7-14.

27. Rebers, P. A., M. Phillips, R. Rimler, and R. A. Boykins. 1980. Immunizing properties of Vfestphal lipopolysaccharide from an avian strain of Pasteurella multocida. Am. J. Vet. Res. 41:1650-1654.

28. Reed, L. J., and H. Muench. 1938. A simple method of estimating fifty percent endpoints. Am. J. Hyg. 27:493-497.

29. Rimler, R. B., P. A. Rebers, and M. Phillips. 1984. Lipopolysaccharides of the Heddleston serotypes of Pasteurella multocida. Am. J. Vet. Res. 45:759-763.

30. Ryu, H., and M. L. Kaeberle. 1986. Immunogenicity of potassium thiocyanate extract of type A Pasteurella multocida. Vet. Microbiol. 11:373-385.

31. Sknith, R. T., and L. Thomas. 1956. The lethal effect of endotoxins on chick embryo. J. Exp. Med. 104:217-231.

32. Srivastava, K. K., J. W. Foster, D. L. Dawe, J. Brown, and R. B. Davis. 1970. Immunization.of mice with components of Pasteurella multocida. Appl. Microbiol. 20:951-956.

33. Stephen, J., and R. A. Pietrowski. 1981. Bacterial toxins. American Society for Microbiology, Washington, DC. 104 pp.

34. Sultzer, B. M., and G. W. Goodman. 1976. Endotoxin protein: a B cell mitogen and polyclonal activator of C3H/HeJ lymphocytes. J. Exp. Med. 144:821-827.

35. Towbin, H., T. Staehelin, and J. Gordon. 1979. Electrophoretic transfer of protein from polyacrylamide gels to nitrocellulose sheets; procedure and some applications. Proc. Natl. Acad. Sci. USA 96:4350-4354.

36. Westphal, 0., and K. Jann. 1965. Bacterial lipopolysaccharides: extraction with phenol-water and further applications of the procedure, p. 83-91. _In R. L. Whistler (ed.). Methods in carbohydrate chemistry, vol. 5. Academic Press, New York, NY. 94

SECTION III. IMMUNOLOGIC REACTIVITY OF A LIPOPOLYSACCHARIDE-PROTEIN

COMPLEX OF TYPE A PASTEURELLA MULTOCIDA IN MICE 95

SUMMARY

Immunologic reactivity of a lipopolysaccharide (LPS)-protein complex

isolated from a potassium thiocyanate extract of a Pasteurella multocida

strain (£. multocida; capsular type A and somatic type 3) was evaluated

in mice. When the LPS-protein complex was fractionated into LPS and

protein moieties by phenol-water treatment, both components lacked

immunogenicity. The protein moiety was extremely blastogenic for mouse B cells while the original complex had a limited activity. Although hyperimmune serum against the LPS-protein complex protected mice against challenge thereby indicating a role for humoral immunity, the LPS-protein complex of P. multocida was also found to induce cell-mediated immunity.

The LPS-protein complex induced a blastogenic response only by the T cells from mice inmunized with the same complex while T cells fron other mice were not reactive to the complex. This complex also induced a delayed type hypersensitivity reaction in the hind footpads of mice inmunized with the complex while non-inmunized control mice did not react to the complex. When mice immunized with the complex were challenged with a facultative intracellular parasite. Salmonella enteritidis, growth of the bacterium was suppressed as compared to multiplication of the bacteria in control mice. 96

INTRODUCTION

Pasteurella multocida (P. multocida) is a Granv-negative

microorganism responsible for economically important diseases in animals

such as fowl cholera and pneumonic pasteurellosis of cattle (5, 7). The

scientific and economic importance of P. multocida has led to the use of

various bacterins for prevention; however, the efficacy of these products

has been questioned (3, 13, 18, 22). In fact, immunization of cattle

with Pasteurella bacterins has been demonstrated to be detrimental to the

health of the animals (3, 18). The questionable efficacy and safety of

bacterins has led to experimentation with various subcellular fractions

of the organism in studies of bacterial pathogenesis and in pursuit of a

better immunogen.

Lipopolysaccharides (LPS, endotoxin) of many Gram-negative bacteria

have been demonstrated to play important roles in bacterial infection of

animals (16, 29). LPS of P. multocida has been observed to evoke a

variety of endotoxic activities in experimental animals (2, 5, 7). Also,

many of the £. multocida fractions with demonstrated immunogenicity

contained LPS as one of their constituents (11, 14, 15, 24, 25, 26, 27).

At present, immunity against P. multocida infection induced by the

various LPS-containing fractions is not clearly understood. The chemical

nature of these fractions responsible for the immunogenicity and the type of immunity induced by the fractions is presently unknown. 97

We have been investigating the immunogenic activity of a LPS-protein complex isolated from a potassium thiocyanate (KSCN) extract of type A P. multocida. The objectives of this study were to find the chemical nature of the complex responsible for induction of immunogenicity and to determine the type of immunity induced by the complex in mice. 98

MATERIALS AND METHODS

Organism

P. multocida strain P-2383 (capsular type A and somatic type 3) was

used throughout this experimentation. Culture conditions for growth of

the organism, preparation of a KSCN extract and isolation of a LPS-

protein complex (P-2383-1) from the KSCN extract have been described

previously (26).

Fractionation of LPS-Protein Complex

The LPS-protein complex was fractionated into LPS and protein moieties by an extended Wèstphal's phenol-water procedure described by

Sultzer and Goodman (30). Briefly, P-2383-1 dissolved in 0.32 M

NaCl/0.01 M tris-HCl buffer was dialyzed against distilled water at 4 C before treatment with hot phenol (65 C). The LPS moiety (P-2383-1-LPS) was obtained from the water phase while the protein moiety (P-2383-1-PRO) was collected from the phenol phase by precipitation with cold ethanol

(-20 C). Since P-2383-1-PRO was poorly soluble in water, it was solubilized by suspending 2 mg (dry weight) in 0.95 ml of distilled water and adding 0.05 ml of 0.1 N NaOH. 99

Preparation of multocida LPS

The phenol-water extracted LPS (PW-LPS) was prepared from strain P-

2383 by the method of Wtestphal and Jann (32) with slight modification as

described previously (26).

Chemical Analysis

P. multocida fractions were analyzed for basic chemical content.

Total carbohydrate was determined by the phenol-sulfuric acid procedure

(10) using glucose (Sigma Chemical Co., St. Louis, MO) as a standard.

Protein content was determined colorimetrically from the reaction of

protein with Serva blue G dye (Serva Fine Chemicals, Inc., Long Island,

NY), using bovine serum albumin (Sigma) as a standard (23).

Immunization and Challenge of Mice

White Swiss mice of one sex, 8 weeks of age, and at least 20 g in

weight (Bio-Lab Corp., St. Paul, MN) were used throughout this

experimentation. Concentration of £. multocida fractions used for

immunization were; P-2383-1 and P-2383-1-PRO (1.0 mg/ml protein

concentration) and P-2383-1-LPS (0.5 mg/ml carbohydrate concentration).

Mice were immunized by the subcutaneous route with 0.1 ml of £. multocida

fractions for the active protection studies, lymphocyte blastogenesis assay, induction of delayed-type hypersensitivity and effect on growth of 100

Salmonella enteritidis (S. enteritidis). To produce hyperimmune serum,

the immunized mice received a booster injection of 0.1 ml of antigen by

the same route 2 weeks after the primary immunization. Serum was

collected 1 week later and 0.2 ml of the serum was injected

intraperitoneally into normal mice for the passive protection studies.

The mice were challenged with 0.1 ml of virulent JP. multocida suspension

intraperitoneally 2 weeks after active immunization or 24 h after passive

immunization.

Isolation and Separation of Spleen Cells

Any one day between 2 to 3 weeks after immunization, mice from each group were utilized for collection of serum and isolation of spleen cells. The mouse was bled first from the ophthalmic venous plexus and then killed. The spleen was removed aseptically and infused with 1 ml of

RPMI 1640 medium (Gibco Laboratories, Grand Island, NY) containing 2 mM

L-glutamine and 25 mM N-2-hydroxyethylpiperazine-N'-ethanesulfonic acid supplemented with (Sigma; 100 units/ml) and streptomycin

(Sigma; 0.1 mg/ml) and 10% fetal calf serum (FCS; Hazleton Research

Products, Denver, PA). The spleen was minced through a 60-raesh stainless steel screen and the screen was rinsed with 3 ml of medium. The spleen cell suspension was transferred to a screw cap tube and the debris allowed to settle for 10 min. The supernatant was transferred to another tube and the cells washed twice with medium by centrifugation at 400 x g for 5 min. The pellet was resuspended in 2.5 ml of a filter-sterilized 101

red cell lysing solution containing 0.645 M NH^Cl, 0.01 M KHCO^ and 0.1

mM disodium ethylenediamine tetraacetate (EDTA; Sigma). After incubation

for 10 min in an ice bath with occasional shaking, the suspension was

centrifuged through a layer of PCS. The supernatant was discarded and

the pellet was washed twice by centrifugation. The spleen cells were

counted and standardized to 10^ cells per ml in a phosphate buffered

saline solution (PBS; pH. 7.2) containing 5% PCS. T and B lymphocytes

from the spleen cell suspension were separated by a panning procedure

(34) using a sterile petri dish (100 x 20 mm, 1005 Optilux: Falcon,

Oxnard, CA) and rabbit anti-mouse immunoglobulins (Igs) obtained from Dr.

M. J. Wannemuehler, Veterinary Medical Research Institute, Iowa State

University, Ames, Iowa. Briefly, the Igs were diluted in 10 ml of 0.05 M

Trizma hydrochloride solution (Sigma), pH 9.5, and sterilized through a

0.2 um membrane filter (Gelman Sciences Inc., Ann Arbor, MI). The final concentration of the Igs was adjusted to 10 ug per ml and 10 ml of the solution was poured into the plate. After a 40 min incubation at room temperature, the solution was decanted and the plate was washed 4 times with 10 ml of PBS and once with 5 ml of PBS containing 1% PCS. Por direct binding, 3 ml of the standardized spleen cell suspension was poured into each Ig-coated plate with care taken to avoid bubbles. The plate was incubated on a level surface at 4 C for 70 min with unattached cells redistributed by swirling the plate at the 40 min mark. The nonadherent (Ig") cells were removed by swirling and decanting the supernatant. Plates were'gently washed 5 times in 10 ml of PBS containing 1% PCS. To recover the bound (Ig"*") cells, 5 ml PBS containing 102

5% FCS was added and the entire surface of the plate was flushed by the

use of a pipet. The Ig~ cells were considered as T cells and Ig"*" cells

were considered as B cells. Purity of the pan-purified T and B cells was

determined by a fluorescence microscopy using fluorescein-conjugated goat

anti-mouse Igs (Cooper Biomedical, Westchesters, PA).

Mitogens

Phytohemagglutinin (PHA, 20 ug/ml; Burroughs Welcome, Triangle Park,

NC), concanavalin A (Con A, 25 ug/ml; Miles Laboratories, Elkhart, IN),

PW-LPS of P. multocida (20 ug/ml, dry weight), P-2383-1 (100 ug/ml,

protein concentration), P-2383-l-protein (100 ug/ml, protein concentration) and P-2383-1-LPS (40 ug/ml, carbohydrate concentration) were used as mitogens.

Lymphocyte Blastogenesis Assay

Mitogenic responses of the spleen cells and pan-purified T and B lymphocytes were determined in a 96 well tissue culture plate (Costar,

Cambridge, MA). Two hundred ul of the standardized cells (2 x 10^) and

25 ul of mitogen or medium were added to each well in triplicate sets.

After incubation at 37 C in a humidified CO^ incubator for 48 h, 1 uCi of

[ H]-thymidine (Amersham Corp., Arlington Heights, IL) was added to each well. After an additional 16 h incubation the cells were harvested on a multiple well harvester (Flow Laboratories, Inc., Rockville, MD) and 103

collected on filter pads. The pads were dried, placed in vials

containing scintillation fluid and counted in a liquid scintillation

counter.

Enzyme-Linked Immunosorbent Assay (ELISA)

One-tenth ml of P-2383-1-PRO (0.25 ug/ml protein concentration) and

P-2383-1-LPS (0.5 ug/ml carbohydrate concentration) diluted in a buffer

containing 15 mM sodiun carbonate and 35 mM sodium bicarbonate (pH 9.6)

was added to each,well of a flat bottom microplate (Immulon 1; Dynatech

Laboratories, Inc., Alexandria, VA). The plate was incubated at 37 C for

24 h and stored at 4 C in a humidified chamber prior to use. The

antigen-coated plate was rinsed 5 times with a cold washing solution containing 0.5 M NaCl, 0.5% Tween 80, 12 mM sodium phosphate monobasic

and 5 mM sodium phosphate dibasic (pH 7.2). One-tenth ml of serial 1:3 dilutions of mouse serum was added to all the wells starting from a 1:20 dilution and the plate was incubated for 2 h at roan temperature. The plate was washed again and 0.1 ml of peroxidase conjugated goat anti- mouse IgG and IgM (Pel-Freez Biologicals, Rogers, AR) was added to each well. After incubation for 2 h, the plate was washed again and 0.05 ml of a substrate solution (Kirkegaard & Perry Laboratories, inc.,

Gaithersburg, MD) containing hydrogen peroxide and 2.2'-azinodi-(3- ethylbenzthiazoline sulfonic acid) was added to each well. After incubation for 10 min, the enzyme reaction was stopped by adding 0.1 ml of 0.5% hydrofluoric acid and the absorption at 405 nm was determined 104

with an ELISA reader (Litton Bionetics, Charleston, SC).

Delayed-Type Hypersensitivity Reaction (DTH)

DTH of mice against P. multocida fractions was tested by the footpad

swelling technique described by Gray and Jennings (12). Groups of mice

were immunized with P. multocida fractions as indicated previously. Two

weeks after immunization, 0.03 ml of P. multocida fraction (the same

concentration used for immunization) was injected into a hind footpad of

one leg using a 27 gauge needle. The same volume of 0.32 M MaCl/0.01 M

tris-HCl buffer (Sigma) was introduced to a hind footpad of the other leg

as a control. The mouse footpads were observed at 2, 4, 6, 8 and 18 h

and the swelling was measured at 1, 2, 3, 4, 5 and 6 days with a dial gauge caliper (Fisher Scientific Inc., Itasca, IL). The footpads for

histological examinations were excised, fixed in 10% formalin, decalcified with EDTA and paraffin sections were stained with hematoxylin and eosin.

Effect on Growth of S. enteritidis in Spleen

A enteritidis strain used in this experimentation was obtained from the National Veterinary Services Laboratory, Ames, Iowa. The serological cross-reactivity of the organism with P. multocida was examined by a slide agglutination test with antisera against whole cells and P-2383-1 of P. multocida. No serological cross-reaction was observed 105

between the two organisms. The organism was passed five times through

mice with reisolation frcrn the spleen and the final isolate was grown for

4 h at 37 C in yolk material from 6-day old anbryonated chicken eggs.

The culture was divided into aliquots and stored at -70 C. For the

preparation of bacterial culture, the infected yolk material was thawed,

inoculated on a 5% bovine blood agar plate and incubated for 24 h at 37

C. One colony was transferred to 30 ml of trypticase soy broth (TSB;

Becton Dickinson and Co., Cockeysville, MD) and incubated for 18 h at 37

C. One-tenth ml of the culture was transferred to 5 ml TSB and incubated another 4 h. Mice were injected with approximately 1.5 x 10^ colony

forming units (CPU) of the bacteria (spectrophotometrically adjusted and plate counted) by the intraperitoneal route. To obtain a growth curve of

S. enteritidis in the spleen of normal mice, groups of mice were sacrified at 1, 3, 5, 7 and 10 days after infection with the bacteria.

The spleens were aseptically ranoved and placed in homogenizer tubes containing 5 ml of PBS. They were dispersed with a teflon pestle, serially diluted and plated on a well-dried MacConkey agar plate in duplicate. Colony counts were conducted after incubation at 37 C for 18 h.

To determine the effect of a LPS-protein complex of £. multocida (P-

2383-1) and fractions of the complex on growth of enteritidis, groups of either 3 or 5 mice were treated as follows; Day 0, primary immunization subcutaneously or no treatment; Day 14, secondary immunization by the footpad route or no treatment; Day 21, challenge 106

infection with enteritidis intraperitoneally; Days 22 or 26, determination of CFU per spleen. 107

RESULTS

Chemical Analysis

The carbohydrate and protein content of P-2383-1 and its phenol-

water extracted fractions are listed in Table 1. P-2383-1 contained 12%

carbohydrate and 27% protein, P-2383-1-LPS contained 50% and 7%, and P-

2383-1-PRO contained less than 2% and 100% respectively.

Immunogenicity

The non-fractionated LPS-protein complex {P-2383-1) induced substantial protection in mice against a challenge with strain P-2383; however, fractions (P-2383-1-LPS, P-2383-1-PRO) obtained from the complex and a mixture of the two fractions failed to provide substantial protection (Table 2). The protein moiety (P-2383-1-PRO) mixed with 20% alixninum hydroxide induced a degree of protection, but the surviving mice were clinically ill and has not completely recovered 10 days after the challenge, the last day of observation.

Blastogenesis Assay of Mouse Spleen Cells

Spleens from mice immunized with P-2383-1 were hyperplastic and yielded approximately 180 million cells while spleens from the control mice and mice immunized with other antigens were normal in size and 108

Table 1. Chemical analysis of a LPS-protein complex of P. multocida (P-

2383-1) and fractions of the complex

Antigens Carbohydrate (%) Protein (%)

P-2383-1 12 27

P-2383-1-LPS 50 7

P-2383-1-PRO < 2 100 109

Table 2. Immunogenicity for mice of a LPS-protein complex of P.

multocida (P-2383-1) and its fractions against challenge

exposure with strain P-2383. Each mouse received 100 to 200

CFU

Immunization No. surviving/ No. tested

Control 0/10

P-2383-1 11/11

P-2383-1-PRO 0/5

P-2383-1-PRO + 20% Aluminum hydroxide 4/10^

P-2383-1-LPS 0/5

P-2383-1-PRO + P-2383-1-LPS 0/5

\he surviving mice were clinically ill up to 10 days. 110

yielded approximately 120 million cells. The recovery of T and B cells

by the panning procedure was approximately 35% each of the total spleen

cells. Membrane fluorescence indicated that at least 97% of the cells in

the T and B cell preparations were homogeneous. The optimal mitogenic

concentrations of P. multocida fractions were determined and used in

blastogenesis assays except for P-2383-1-PRO. The protein content of P-

2383-1-PRO was adjusted to equivalence with that of P-2383-1 since a

higher concentration was extremely blastogenic to B cells. As indicated

in Table 3, the mitogenic responses of non-separated spleen cells to P.

multocida fractions were not different between the control mice and mice

immunized with P-2383-1. P-2383-1 induced an extremely significant

mitogenic response by T cells isolated from the mice immunized with P-

2383-1 while other £. multocida fractions did not (Table 4). The LPS- containing fractions of P. multocida were found to induce non-specific blastogenic responses of B cells (Table 5). Although the protein content of P-2383-1-PRO was the same as P-2383-1, P-2383-1-PRO induced a much greater blastogenic response of B cells than the original canplex (Table

5).

Antibody Titer and Passive Protection

Antibody titers of sera obtained from the mice used for the blastogenesis assay are listed in Table 6. The sera from the mice immunized with P-2383-1 had the highest antibody titers to both ELISA antigens. The sera from the mice immunized and boosted with P-2383-1-PRO Ill

Table 3. Blastogenic responses of spleen cells isolated from mice

immunized with a LPS-protein complex antigen of P. multocida

(P-2383-1) or non-immunized control mice

Iirmunizing preparation

Mitogen Control P-2383-1

None 448 + 55^ 377 + 19

Phytohemagglutinin 27,675 + 5,756 19,240 + 4,910

Concanavalin A 32,475 + 6,624 18,534 + 772

P-2383 PW-LPS 9,273 + 136 7,710 + 549

P-2383-1 7,550 + 1,148 9,728 +1,383

P-2383-1-PRO 21,322 + 3,257 15,217 + 4,595

P-2383-1-LPS 5,016 + 1,845 6,458 + 403

^Counts per minute. Mean + SD (n = 3). 112

Table 4. Blastogenic responses of pan-purified T (Ig~) cells from mice

immunized with a LPS-protein complex antigen of P. multocida

(P-2383-1) or fractions of the complex

Immunizing Preparation

Mitogen Control P-2383-1 P-2383-1-PRO P-2383-1-LPS

None 1.2 + 0.5^ 1.4 + 0.2 1.2 + 0.3 1.4 + 0.4

PHA 65.5 + 7.8 73.1 + 18,2 63.8 + 16.4 76.4 + 6.7

Con A 90.8 + 7.7 73.6 + 11.0 66.4 + 19.8 76.6 + 14.5

PW-LPS 4.9 + 0.4 4.5 + 0.4 4.7 + 1.7 4.1 + 0.6

*** P-2383-1 5.1 + 0.2 20.1 + 7.5 4.9 + 2.0 3.6 + 0.8

P-2383-1--PRO 5.3 + 0.4 5.8 + 1.5 8.1 + 3.4 6.8 + 2.9

P-2383-1-•LPS 2.3 + 0.1 2.7 + 0.7 2.8 + 0.4 3.4 + 0.5

^x 10^ counts per minute, mean SD (n = 6).

p < 0.005; level of statistical significance as compared to the control (Student's T-test). 113

Table 5. Blastogenic responses of pan-purified B (Ig*) cells from mice

immunized with a LPS-protein complex antigen of P. multocida

(P-2383-1) or fractions of the complex

Immunizing Preparation

Mitogen Control P-2383-1 P-2383-1-PRO P-2383-1-LPS

None 1.0 + 0.1^ 0.9 + 0.2 1.0 + 0.2 1.0 + 0.1

PHA 3.7 + 0.2 2.3 + 1.2 3.0 + 0.8 3.8 + 0.6

Con A 2.1 + 0.2 1.5 + 1.0 1.5 + 0.4 3.0 + 0.9

PW-LPS 35.9 + 4.7 41.4 + 11.5 46.8 + 11.9 63.5 + 6.1***

P-2383-1 30.0 + 6.1 30.4 + 9.0 21.4 + 6.4 28.0 + 8.4

P-2383-1-•PRO 68.0 + 8.0 69.3 + 11.5 79.1 + 21.3 87.2 + 17.9

P-2383-1-•LPS 13.8 + 2.3 14.8 + 4.5 15.5 + 5.3 23.5 + 3.7***

\ 10^ counts per minute, mean SD (n = 5).

p < 0.005; level of statistical significance as compared to the control (Student's T-test). 114

Table 6. Antibody titers in ELISA of the sera obtained from mice used

for lymphocyte blastogenesis assays

ELISA Antigen

Antiserum^ P-2383-1-PRO P-2383-1-LPS

Control 1:60^ 1:60

P-2383-1 1:14,580 1:14,580

P-2383-1-PRO 1:1,620 1:180

P-2383-1-LPS 1:4,860 1:4,860

^Serum obtained from mice immunized with different antigens.

^Average antibody titer (n = 6). 115

has a mean antibody titer of 1:4,860 to the same antigen. The sera from

the mice immunized and boosted with P-2383-1-LPS had a mean antibody

titer of 1:43,740 to the protein antigen (Table 7). Only the serum from

the mice immunized and boosted with P-2383-1 protected mice against £.

multocida infection although serum from mice immunized and boosted with

P-2383-1-LPS had an equivalent antibody titer (Table 7).

Induction of DTH

Only mice immunized with P-2383-1 developed DTH when the same antigen was introduced into the hind footpad. Injection of P-2383-1 as well as other antigens into footpads of normal mice or mice immunized with other antigens induced a tanporary swelling (up to 2.8 irm) at 24 h and the footpads returned to normal size (2.2 mm) by 48 h. The injection of P-2383-1 into footpads of the mice immunized with P-2383-1 induced a swelling that was visible at 18 h after the injection, reached peak swelling (up to 4.7 nm thick) at 48 h, and then slowly subsided returning to normal thickness by 7 to 10 days (Fig. 1).

Histological examination of footpad tissue revealed cellular infiltration characteristic of the typical DTH response in mice. At 24 h, there were focally-intense cellular infiltrates composed primarily neutrophils, but occasionally macrophages (Fig. 2-A). Increased numbers of mononuclear cells had diffusely infiltrated into the footpads at 48 h and the ratio of neutrophils to mononuclear cells in the lesion was approximately 50:50 (Fig. 2-B). At 72 h, cellular infiltration was 116

Table 7. Resistance of mice against challenge infection with P.

multocida strain P-2383 following intraperitoneal

administration of mouse antiserum

ELISA Antigen Challenge Infection

Antiserum® P-2383-1-PRO P-2383-1-LPS 98 c.f.u. 980 c.f.u.

Negative control 1:60^ 1:60 0/5^

P-2383-1 1:43,740 1:14,580 5/5 5/5

P-2383-1-LPS 1:43,740 1:4,860 0/5

^Serum obtained fron mice immunized with different antigen.

^Antibody titer.

^No. of mice surviving/ no. of mice tested. 117

2.5

5 2.0

1.5

1.0

5 0.5

Day

FIG. 1. Footpad enlargement of mice immunized with P-2383-1 following administration of the same antigen was introduced into the

footpad 2 weeks post-immunization (n = 10) 118

W J i

PIG. 2. Photographs showing histopathologic changes in the footpads of

mice immunized with P-2383-1. Tissues were obtained at various

times following introduction of P-2383-1 into the footpad at 2

weeks post-immunization: A, 24 h; B, 48 h; C, 72 h; D, 6 days 119

predominantly composed of mononuclear cells, large foamy macrophages and

lymphocytes (Fig. 2-C). At day 6, few neutrophils were present but

mononuclear cells were still in residence (Fig. 2-D)

Growth of S. enteritidis in the Spleen

A growth curve of enteritidis in the spleen of normal mice was

determined. The initial accumulation of the bacteria in the spleen at

day 1 was slighly less than the inoculum, but thereafter the organisms

grew logarithmically up to day 5 (Fig. 3). By 7 to 10 days, there was no

further dramatic increase in the number of bacteria; however, hyperplasia

of the spleen was noted. At day 14, multifocal necrosis in the spleen

was observed although the mice were clinically healthy. Day 5 (log phase growth) was chosen to evaluate the iinmunizing effect of the LPS-protein complex, P-2383-1, on growth of S. enteritidis in spleen. There was no difference at day 22 (one day after the challenge) in bacterial counts in spleens of the control mice and mice immunized with P-2383-1 while highly significant differences were observed at day 26 (Tables 8 and 9).

Inoculation of P-2383-1 into footpads of normal mice also induced a degree of immunity indicated by suppression of bacterial growth in the spleen (Table 9). Fractions of P-2383-1 failed to induce suppression equivalent to P-2383-1. 120

Days

FIG. 3. Growth of enteritidis in the spleen of normal mice. Each

mouse received 1.7 x 10^ CFU of the bacterium intraperitoneally

(n = 5) 121

Table 8. Growth of S. enteritidis in the spleens of mice iimunized with

P-2383-1 or non-imnunized control mice. Each mouse received

1.7 X lO'^ CFU of the bacterium intraperitoneally at day 21

CFU^

Primary Secondary

immunization^ immunization*^ Day 22 (n = 5) Day 26 (n = 5)

None None 8.2+2.6 x 10^ 1.3 ^ 0.6 x 10®

P-2383-1 P-2383-1 7.3 + 1.6 x 10^ 2.7 + 1.4 x 10***

Values indicate CFU per spleen, mean +_ SD.

^Mice were immunized subcutaneously at day 0.

^Mice were immunized via footpad at day 14.

p < 0.005; level of statistical significance as compared to the non-immunized control (Student's T-test). 122

Table 9. Growth of S.' enteritidis in spleens of non-immunized control

mice and mice iitmunized with P-2383-1 or fractions of P-2383-1.

Each mouse received 1.5 x 10^ CFU of the bacterium

intraperitoneally at day 21

Primary Secondary

immunization^ immunization^ CFU°

None None (n = 5) 6.4 + 2.1 X 10^

None P-2383-1 (n =: 5) 1.4 + 0.7 X

None P-2383-1-LPS (n = 5) 4.5 + 1.1 X 10^

None P-2383-1-PRO (n = 5) 5.9 + 2.3 X 10^

P-2383.-1 None (n = 5) 2.7 + 1.8 X 104***

P-2383--1 P-2383-1 (n = 5) 1.8 + 0.9 X 104***

P-2383--1-LPS P-2383-1-LPS (n = 3) 2.0 + 0.4 X

P-2383--l-PRO P-2383-1-PRO (n = 3) 2.6 + 1.1 X

^Mice were immunized subcutaneously at day 0.

^Mice were immunized via footpad at day 14.

"Values indicate CFU per spleen, mean SD.

p < 0.005; level of statistical significance as compared to the non-immunized control (Student's T-test). 123

DISCUSSION

We have previously reported that a LPS-protein conplex isolated from

a KSCN extract of a P. multocida strain (P-2383; capsular type A and

somatic type 3) induced resistance in mice to challenge with the

homologous strain (26). Clinical signs in these mice following challenge

infection suggested that the purified LPS-protein complex, P-2383-1,

would be a better immunogen than the original KSCN extract (26). In this

study, the immunogenic reactivity of P-2383-1 was further characterized

by fractionating it into LPS (P-2383-1-LPS) and protein (P-2383-1-PRO)

moieties by phenol-water treatment.

This study indicated that PW-LPS of £. multocida, P-2383-1 and its

LPS moiety P-2383-1-LPS can induce non-specific blastogenic responses of

mouse B cells (Table 5). This confirmed previous observations that LPS

of Gram-n^ative bacteria is a potent mitogen for mouse B cells (21, 30,

31). The results also indicated that P-2383-1-PRO, at the same protein concentration as P-2383-1, was extremely blastogenic for B cells while

the original complex had more limited mitogenic activity. Similar results have been observed in the studies on classical endotoxin proteins

(or lipid A-associated proteins) that have been fractionated from butanol or trichloroacetic acid-extracted LPS of Escherichia coli and Salmonella typhosa by the phenol-water procedure (21, 30, 31). In addition, both P-

2383-1-PRO and endotoxin proteins were poorly soluble in water, but readily soluble in diluted alkali or phenol (30). Also, they were composed of several distinctive components with molecular weights from 8 124

to 40 kilodaltons (31, see Section II) and known to represent major

proteins found on the outer cell manbrane (31). This would indicate that

the protein component of P-2383-1 may have similar characteristics to the

endotoxin protein of enterobacteria. The mechanism of blastogenic

response of B cells to the endotoxin protein is not clear; however, the

endotoxin protein has been reported to exhibit various immunostimulatory

activities (21, 31). These activities included activation of B cells,

macrophages, neutrophils and mast cells, non-specific resistance to a

bacterial infection in mice, and induction of interferon both in vitro

and in vivo.

In contrast to classical endotoxin protein of enterobacteria, P-

2383-1-PRO was inconsistent in its immunologic activity. This protein material lacked immunogenicity in mice as determined by challenge infection (Table 2) and failed to induce DTH responses and non-specific resistance to S. enteritidis infection (Table 9). This would indicate that the protein component is not the same material as endotoxin protein of enterobacteria although both exhibit similar chemical and physical characteristics. It is possible that phenol-water treatment of the LPS- protein carpiex may denature the protein or alter the antigenic determinant(s) of the complex associated with immunogenicity. Analysis of the complex and its fractions by SDS-PAGE and Western immunoblot indicated that the complex contained more and stronger protein bands than its protein component even at 8 times less protein concentration than the protein component (see Section II). In addition, a major protein band approximately 24 kilodaltons in size present in the complex was 125

apparently altered since several weak bands were found rather than the

single band. However, there is clear evidence that immunogenic

specificity of the LPS-protein complex is associated with the protein

moiety. Since P-2383-1-PRO mixed with 20% aluminum hydroxide provided a

degree of protection (Table 2), this material apparently requires an

adjuvant. The reason for lack of immunizing activity of this material

may be due to the absence of LPS that is known to be a potent adjuvant

(16, 21). Adjuvant activity of the LPS is indicated by the finding that

a high titer of antibody was induced against the protein moiety when P-

2383-1-LPS was used for immunization (Table 6).

The results of our experimentation on immune mechanisms involved in

protection of mice against £. multocida infection indicate that the LPS- protein complex of £. multocida can induce both humoral and cell-mediated

irrmunity in mice. Protection of mice against challenge by passive transfer of immune serum against P-2383-1 would support the induction of humoral immunity (Table 7). However, specificity of antibody is of great importance. Antiserum against P-2383-1 provided protection while antiserum against P-2383-1-LPS did not although both antisera had a similar antibody titer. Protection of mice against P. multocida infection by passive immunization has also been danonstrated by other workers (5, 6, 8, 15, 33). Since the bacteria were seldom found in parts of the body of the passively immunized mice other than the site of inoculation (6, 8), Collins and Woolcock suggested that the primary role of antibody is inhibition of the rapid spread of the organism to the blood stream and other reticuloendothelial organs. 126

Evidence for induction of cell-mediated immunity by P-2383-1 was

found in observations of the blastogenic response of T cells to P-2383-1,

DTH and inhibition of growth of S. enteritidis in the immunized mice.

The mitogenic response of the pan-purified T cells from mice immunized

with P-2383-1 (Table 4) indicated that T cells were sensitized to this

antigen although the subpopulation of responding T cells is not known.

DTH reactions in the footpads of mice immunized with P-2383-1 is further

evidence of cell-mediated ittmunity. The size and duration of swelling

and histological changes in the footpad were very similar to the DTH

reaction induced by Mycobacterium tuberculosis-purified protein

derivative (12, 17). Since mice can suppress growth of the facultative

intracellular parasites including Listeria monocytogenes (L.

monocytogenes), Brucella abortus and enteritidis by cell-mediated

mechanisms, the suppressive effect of P-2383-1 on growth of

enteritidis, which has no serologic relationship with P-2383-1, would

also support the induction of cell-mediated immunity by the LPS-protein

coTiplex of P. multocida (Tables 8 and 9). However, these findings contradict the explanation of Collins and Woolcock on immune mechanisms of mice against P. multocida infection. They found that transfer of peritoneal or spleen cells from immune mice to normal mice 1 h before challenge did not provide protection and the cellular response of the passively immunized mice to the P. multocida organisms was predominantly polymorphonuclear in nature. Based on these findings, they suggested that immunity to P. multocida infection in mice is primarily humoral in nature. However, they also found that hyperimmune serum did not 127

influence in vitro bactericidal activity of peritoneal cells from normal

and immune mice. Also, the inoculated bacteria multiplied for a long

period of time (14 days) at the site of infection in mice that received

hyperimmune serum without losing virulence. Recent studies on acquired

resistance to L. monocytogenes in mice by Campbell and her colleagues may

explain contradictory observations on immune mechanisms involved in

protection of mice against P. multocida infection. For many years, the

acquired resistance in mice to a facultative intracellular bacterium such

as L. monocytogenes was thought to be a systemic activation of

mononuclear phagocyte bactericidal activity (19, 20). However,

Czuprynski et al. (9) suggested that the increased mobilization of

neutrophils and mononuclear phagocytes into the site of infection is of

prime importance in resistance to listeriosis. They came to this conclusion since they could demonstrate no difference in bactericidal

activities of the phagocytic cells from normal and immune mice. Also,

the immune mice were able to recruit rapidly a large number of the

phagocytic cells at the site of infection. Similar results have been

found for other facultative intracellular parasites such as S. enteritidis and Brucella abortus (P. A. Campbell, Saninar, Annu. Meet.

Am. Soc. Microbiol. 1986, Session 80). However, the ability of the immune mice to accumulate neutrophils and monocytes at the site of infection was credited to release of lymphokines by T cells. This would indicate a role for the cell-mediated immunity. Like the facultative intracellular parasites, P. multocida may be eliminated by neutrophils and macrophages if large numbers of these cells were present at the site 128

of infection. However, mice may not recruit these phagocytic cells at

the site of P. multocida infection without induction of cell-mediated

immunity (1). The induction of cell-mediated immunity, i.e., production

of lymphokines by T cells, may require significant time and appropriate

antigenic stimulation. Antibody against the organism may provide these

requirements by inhibiting the spread of the organism rapidly throughout

the body while certain surface materials, such as the LPS-protein complex, detached from the bacteria may serve as a stimulatory agent for later development of cell-mediated immunity. 129

LITERATURE CITED

1. Adelman, N. E., M. E. Hammond/ S. Cohen, and H. F. Dvorak. 1979. Lymphokines as inflammatory mediators, p. 13-58. _In S. Cohen, E. Pick, and J. J. Oppenheim (eds.). Biology of the lymphokines. Academic Press, New York, NY.

2. Bain, R. V. S., and K. W. Knox. 1961. The antigens of Pasteurella multocida type I. II. Lipopolysaccharides. Immunology 4:122-129.

3. Bennett, B. W. 1982. Efficacy of Pasteurella bacterins for yearling feedlot cattle. Bovine Practice 3:26-30.

4. Blackburn, B. 0., K. L. Heddleston, and C. J. Pfow. 1975. Pasteurella multocida serotyping results (1971-1973). Avian Dis. 19:353-356.

5. Carter, G. R. 1967. Pasteurellosis; Pasteurella multocida and Pasteurella haemolytica. p. 321-379. _IB C. A. Brandly and C. Cornelius (eds.). Advances in veterinary science. Vol. II. Academic Press, New York, NY.

6. Collins, F. M. 1973. Growth of Pasteurella multocida in vaccinated and normal mice. Infect. Immun. 8:868-875.

7. Collins, F. M. 1977. Mechanisms of acquired resistance to Pasteurella multocida infection: a review. Cornell Vet. 67:103-138.

8. Collins, F. M., and J. B. Woolcock. 1976. Immune responses to Pasteurella multocida in the mouse. J. Reticuloendothelial Society 19:311-321.

9. Czuprynski, C. J., P. E. Henson, and P. A. Campbell. 1984. Killing of Listeria monocytogenes by inflammatory neutrophils and mononuclear phagocytes from immune and non-immune mice. J. Leukocyte Biol. 35:193-208.

10. Dubois, M., K. A. Gilles, J. K. Hamilton, P. A. Rebers, and R. Smith. 1956. Colorimetric method for determination of sugars and related compounds. Anal. Chem. 28:350-356.

11. Ganfield, D. J., P. A. Rebers, and K. L. Heddleston. 1976. Immunogenic and toxic properties of a purified lipopolysaccharide- protein complex from Pasteurella multocida. Infect. Immun. 14:990- 999.

12. Gray, D. F., and P. A. Jennings. 1955. Allergy in experimental mouse tuberculosis. Am. Rev. Tuberc. Pulmonary Dis. 72:171-195. 130

13. Hamdy, A. H., N. B. King, and A. I. Trapp. 1965. Attempted immunization of cattle against shipping fever: a field trial. Am. J. Vet. Res. 26:897-902.

14. Heddleston, K. L,, and P. A. Rebers. 1975. Properties of free endotoxin from Pasteurella multocida. Am. J. Vet. Res. 36:573-574.

15. Heddleston, K. L., P. A. Rebers, and A. E. Ritchie. 1966. Immunizing and toxic properties of particulate antigens frcm two iimunogenic types of Pasteurella multocida of avan origin. J. Immunol. 96:124-133.

16. Kabir, S., D. L. Rosenstreich, and S. E. Mergenhagen. 1978. Bacterial endotoxins and cell membranes, p. 59-87. _In J. Jeljaszewicz and T. Wadstrom (eds.). Bacterial toxins and cell membranes. Academic Press, New York, NY.

17. Kong, Y. M., D. C. Savage, and L. N. L. Kong. 1966. Delayed dermal hypersensitivity in mice to spherule and mycelial extracts of Coccidioides iinmitis. J. Bacterid. 91:876-883.

18. Larson, K. A., and K. R. Schell. 1969. Toxicity and immunogenicity of shipping fever vaccines in calves. J. Am. Vet. Med. Assoc. 155:495-499.

19. Mackaness, G. B. 1962. Cellular resistance to infection. J. Exp. Med. 116:381-406.

20. Mackaness, G. B. 1964. The immunologic basis of acquired cellular resistance. J. Exp. Med. 120:105-120.

21. Morrison, D. C. 1983. Bacterial endotoxins and pathogenesis. Rev. Infect. Dis. 5, Suppl. 4:s733-s747.

22. Palotay, S. L., S. Young, S. A. Lovelace, and J. H. Newhall. 1963. Bovine respiratory infections. II. Field trial using bacterial vaccine products as a means of prophylaxis. Am. J. Vet. Res. 24:1137-1142.

23. Read, S. M., and D. H. Northcote. 1981. Minimization of variation in the response to different proteins of the Cocxnasie blue G dye- binding assay for protein. Anal. Biochem. 116:53-64.

24. Rebers, P. A., and K. L. Heddleston. 1974. Immunologic comparison of Westphal-type lipopolysaccharides and free endotoxins from an encapsulated and a non-encapsulated avian strain of Pasteurella multocida. Am. J. Vet. Res. 35:555-560. 131

25. Rebers, P. A., K. L. Heddleston, and K. R. Rhoades. 1967. Isolation from Pasteurella multocida of a 1ipopolysaccharide antigen with immunizing and toxic properties. J. Bacterid. 93:7-14.

26. H., and M. L. Kaeberle. 1986. Immunogenicity of potassium thiocyanate extract of type A Pasteurella multocida. Vet. Microbiol. 11:373-385.

27. Srivastava, K. K., J. W. Foster, D. L. Dawe, J. Brown, and R. B. Davis. 1970. Immunization of mice with components of Pasteurella multocida. ^pl. Microbiol. 20:951-956.

28. Staub, A. M. 1965. Bacterial lipido-proteino-polysaccharides extraction with trichloroacetic acid. p. 92-93. J[n R. L. Whistler (ed.). Methods in carbohydrate chemistry. Vol. 5. Academic Press, New York, NY.

29. Stephen, J., and R. A. Pietrowski. 1981. Bacterial toxins. American Society for Microbiology, Washington, DC. 104 pp.

30. Sultzer, B. M., and G. W. Goodman. 1976. Endotoxin protein: a B cell mitogen and polyclonal activator of C3H/HeJ lymphocytes. J. Exp. Med. 144:821-827.

31. Sultzer, B. M., G. W. Goodman, and T. K. Eisenstein. 1980. Endotoxin protein as an immunostimulatant. p. 61-65. D. Schlessinger (ed.). Microbiology. American Society for Microbiology, Washington, DC.

32. Westphal, 0., and K. Jann. 1965. Bacterial 1ipopolysaccharides: extraction with phenol-water and further applications of the procedure, p. 83-91. ^ R. L. Whistler (ed.). Methods in carbohydrate chemistry. Vol. 5. Academic Press, New York, NY.

33. Woolcock, J. B., and F. M. Collins. 1976. Immune mechanism in Pasteurella multocida-infected mice. Infect. Immun. 13:949-958.

34. %socki, L. J., and V. L. Sato. 1978. "Panning" for lymphocytes: a method for cell selection. Proc. Natl. Acad. Sci. USA 75:2844-2848. 132

GENERAL SUMMARY

The experimentation reported in this dissertation includes three

subjects; 1) determination of the chemical composition of Pasteurella

multocida (P. multocida) lipopolysaccharides (LPS) in comparison with the

chemical composition of LPS of several Gram-negative bacterial pathogens;

2) characterization of a LPS-protein complex isolated from a potassium

thiocyanate (KSCN) of P. multocida organism; 3) examination of the

immunologic reactivity of the LPS-protein complex in mice.

Chanical composition of LPS of £. multocida and several other Gram-

negative bacterial pathogens were analyzed by methanolysis,

trifluoroacetylation and gas chromatography (GC) on a fused-silica

capillary column. The GC analysis indicated that LPS prepared frcm a

strain of £. multocida by phenol-water (PW) or trichloroacetic acid (TCA)

extraction w^re quite different in chemical composition. However, LPS

prepared from Salmonella enteritidis by the two extraction methods were

very similar. PW-LPS extracts from different Pasteurella strains of a serotype had essentially identical GC patterns. Endotoxic LPS extracted from 16 different serotypes of multocida by PW or by phenol- chloroform- petroleum ether procedures yielded chromatograms indicating similar composition of the fatty acid moieties but minor differences in carbohydrate content. When the chemical composition of endotoxic LPS extracted from several Gram-negative bacteria (P. multocida, Pasteurella haemolytica, Haemophilus somnus, Actinobacillus ligniersii. Brucella abortus, Treponema hyodysenteriae, Escherichia coli, Bacteroides 133

fragilis, Salmonella abortus equi and Salmonella enteritidis) were

examined y each bacterial LPS showed a unique GC pattern. The

carbohydrate constituents in LPS of various Gram-negative bacteria were

quite variable not only in the 0-specific polysaccharide but also in the

core polysaccharide. The LPS of closely related bacteria shared more

fatty acid constituents with each other than with unrelated bacteria.

When the chemical composition of the LPS-protein complex isolated

from the KSCN of a P. multocida (strain P-2383, capsular type A and

somatic type 3) was analyzed by GC, this complex was found to contain

most of chemical constituents characteristic of LPS extracted by the PW

method from the whole bacterium. However, there apparently was more

carbohydrate than fatty acid in the complex in contrast to LPS in which

fatty acid seemed to be in excess. When toxicity of the complex was

evaluated in 10-day-old chicken embryos, the complex was less toxic (LD^g

= 12.72 ug) than the purified LPS (LD^Q = 0.44 ug). The LD^Q of the LPS moiety extracted from the complex was 5.24 ug. Composition of the coTiplex was analyzed by SDS-PAGE with silver staining and Vfestern

immunoblot. The complex did not migrate through the polyacrylamide gel unless dissociated with SDS. The complex dissociated with SDS contained more than 32 different protein and polysaccharide components; at least 18 components reacted with an antiserum against the catiplex. There was no significant compositional variation between the complexes from different strains, but quantitative differences in individual components were noted. When cross-protectivity of the complex was evaluated in mice, this complex provided substantial protection not only against the 134

homologous bacterium but also against different P. multocida strains of

the same serotype. LPS-protein complexes isolated by the same method

from other strains also induced protection against a challenge with P-

2383.

Immunologic reactivity of the complex was evaluated in mice by

fractionating the complex into LPS and protein moieties by PW treatment.

Both PW extracted components lacked immunogenicity in mice. The protein

moiety was extremely blastogenic for mouse B cells while the original

complex had limited activity. Although hyperimmune serum against the

LPS-protein complex protected mice against challenge thereby indicating a

role for humoral immunity, the LPS-protein conplex of P. multocida was

also found to induce cell-mediated immunity. The LPS-protein complex

induced a blastogenic response by T cells from mice immunized with the same complex while T cells from other mice were not reactive to the complex. This complex also induced a delayed type hypersensitivity reaction in the hind footpads of mice immunized with the complex while nonimmunized control mice did not react. When mice immunized with the complex were challenged with a facultative intracellular parasite,

Salmonella enteritidis, growth of the bacterium was suppressed as compared to multiplication of the bacteria in control mice.

For many years, immunity to multocida infection in animals has been thought to be primarily humoral in nature. This conclusion was based on findings frcxn experimental infections with P. multocida in laboratory animals including relatively successful protection by passive immunization, correlation between serum antibody titer and degree of 135

protection, and failure of protection by active transfer of sensitized

cells. However, the increased serum antibody titer in cattle immunized

with P. multocida bacterins has been demonstrated to have no relationship

with protection of the animal against the disease. This inconsistencies

may be explained by the differences in animals (cattle versus

experimental animals such as mice), between systemic and local

respiratory immune system, or by the nature of antigen including

specificity of the antigen and presence of competitive antigens or

deterimental factors.

The possibility exists that another type of immunity, i.e., cell-

mediated immunity, is more important in prevention of the disease in

cattle. This study on characterization of the LPS-protein complex

indicated that the complex induced not only honorai but also cell-

mediated immunity. Also, the complex contained LPS which is known to

exhibit a variety of immunostimulatory activities in a host including

adjuvanticity. In addition, the complex isolated a strain of £. multocida was found to induce cross-protection against different strains of capsular type A and somatic type 3 which has been most frequently

isolated from the cases of bovine pneumonic pasteurellosis in North

America. There is now a need to examine the ûtimunogenicity of this complex as a potential immunizing agent against £. multocida infection in cattle. 136

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ACKNOWLEDGMENTS

I wish to express my sincere appreciation to individuals who

willingly gave assistance and advice in the conduct of this

experimentation and in the preparation of this dissertation.

I am especially grateful to Dr. M. L. Kaeberle, my major professor,

for his advice and patience in the conduct of this experimentation and

the preparation of this dissertation.

I wish to thank Drs. T. T. Kramer, D. C. Beitz, J. J. Andrews and J.

A. Roth for serving on the graduate comnittee.

I also wish to express my appreciation to Messrs. E. C. Johnson, Y.

W. Chiang, and Mrs. S. Basnyat for their technical assistance. I also

acknowledge the valuable assistance provided by my Korean friends, Drs.

C. J. Kim and P. D. Ryu.

Finally, I wish to express my great appreciation to my wife,

Myungwon, and children, Tina and Albert, for their understanding and

patience throughout the course of my graduate study.

This research was supported by the State of Iowa Livestock Advisory

Council project 400-23-80.