Biology of Ebola © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT for SALE OR DISTRIBUTION NOT for SALE OR DISTRIBUTION Disease Can Bring

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALEchapter OR2 DISTRIBUTION NOT FOR SALE OR DISTRIBUTION © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC BiologyNOT FOR SALE OR DISTRIBUTION of EbolaNOT FOR SALE OR DISTRIBUTION

Carolyn© Jones & Bartlett Dehlinger Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

“[A] few weeks into this, I’ve certified the deaths of more patients than in my last © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC two decades. And I’m shocked to the degree to which it has just become part of NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION my daily routine.” —American doctor Joel Selanikio, International Medical Corps, Lunsar, Sierra Leone

n 1976, a deadly© Jones viral outbreak& Bartlett occurred Learning, near LLCthe Ebola River in what ©is Jonesnow & Bartlett Learning, LLC the DemocraticNOT Republic FOR SALE of Congo OR DISTRIBUTION(at the time known as Zaire). NamedNOT for FOR SALE OR DISTRIBUTION Ithe river, Ebola outbreaks have peppered African history ever since, with most occurring sporadically and temporarily—until now. According to the World Health Organization, as of March 22, 2015, the disease has taken an estimated 10,326 © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC livesNOT worldwide. FOR SALE Ebola OR wasDISTRIBUTION previously known as Ebola hemorrhagicNOT FOR fever. SALE While OR DISTRIBUTION the name has shortened, the signs and symptoms of this disease have not. The words of Dr. Selanikio remind us of the emotional toll and psychological stress this Courtesy of Dr. Heidi Soeters/CDC

9781284087789_CH02_Print.indd 23 14/07/15 12:25 AM 24 CHAPTER TWO Biology of Ebola © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION disease can bring. These aspects can easily be obscured when we discuss the cold facts of a miniscule yet lethal virus. While reading this chapter whose focus is on the biology of the Ebola virus, or more accurately, viruses—to be sure, more than one© Jones strain of& EbolaBartlett plagues Learning, the animal LLC kingdom—it is also important© Jones to& reflectBartlett on Learning, LLC theNOT human FOR impact. SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

© Jones & Bartlett■ QUESTIONS Learning, LLC TO CONSIDER© Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Some questions to consider as you read this chapter include: 1. What are the symptoms of Ebola and how is it contracted? 2. What is the classification of Ebola, and how is the classification determined? © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION3. What makes Ebola unique fromNOT its FOR viral SALE relatives OR and DISTRIBUTION what makes it similar? 4. How would you describe the replication cycle of Ebola, and how might details of the replication cycle enable the development of effective antiviral medications to combat Ebola infections? © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC 5.NOT What FOR is the SALE probable OR reservoirDISTRIBUTION organism of Ebola, and haveNOT any other FOR candidates SALE OR DISTRIBUTION emerged since the time of this writing?

9781284087789_CH02_Print.indd 24 14/07/15 12:25 AM 25 Hemorrhagic Viruses © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

Hemorrhagic Viruses © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Hemorrhagic viruses are given their name because they cause viral hemorrhagic fever (VHF), a severe syndrome of the body affecting multiple organ systems with multiple symptoms. Ebola is not the only hemorrhagic virus; there are four families of viruses with© Jones this designation. & Bartlett The Learning, filovirus family, LLC which includes Ebola,© isJones one. Filoviruses & Bartlett are Learning, LLC theNOT focus FOR of this SALE chapter. OR Arenaviruses,DISTRIBUTION bunyaviruses, and flavivirusesNOT FOR are viral SALE families OR DISTRIBUTION with hemorrhagic members as well. Arenaviruses are transmitted to humans by rodents ( TABLE 2.1 ). Bunyaviruses infect rodents, plants, insects, and, to a lesser extent, humans. A well known bunyavirus infecting humans is the hantavirus. Human diseases © Jones & Bartlettcaused by Learning, the flaviviruses LLC include hepatitis C, dengue© Jones fever, & BartlettWest Nile virus,Learning, and yellow LLC NOT FOR SALEfever. ORThey DISTRIBUTION are often transmitted between mammalNOT hosts FOR through SALE aOR mosquito DISTRIBUTION or tick vector. Vectors are organisms that pass infectious agents among different species. The lifecycle of the infectious agent takes place in part within the vector. A few hemorrhagic viruses and their characteristics are described in TABLE 2.2 . The shared symptoms© Jones of & VHFs Bartlett typically Learning, include: LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION • Fever • Muscle aches • Dizziness ©• JonesFatigue & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT• Weakness FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION • Exhaustion

Argentine hemorrhagic fever Junin virus

Bolivian hemorrhagic© Jones fever & BartlettMachupo Learning, virus LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Brazilian hemorrhagic fever Sabiá virus

Chapare hemorrhagic fever Chapare virus

©Lassa Jones fever & Bartlett Learning, LLCLassa virus © Jones & Bartlett Learning, LLC NOTLujo hemorrhagicFOR SALE fever OR DISTRIBUTIONLujo virus NOT FOR SALE OR DISTRIBUTION

Lymphocytic choriomeningitis Lymphocytic choriomeningitis virus (LCMV)

Venezuelan hemorrhagic fever Guanarito virus © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALESource OR: Data DISTRIBUTION from Easton, A. J. & Pringle, C. R. (2011). OrderNOT Mononegavirales FOR SALE. In A. M. OR Q. King, DISTRIBUTION M. J. Adams, E. B. Carstens, & E. J. Lefkowitz, Virus Taxonomy—Ninth Report of the International Committee on Taxonomy of Viruses (pp. 653–657). London, UK: Elsevier/Academic Press.

9781284087789_CH02_Print.indd 25 14/07/15 12:25 AM 26 CHAPTER TWO Biology of Ebola © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

TABLE 2.2 Viral Diseases Causing Hemorrhagic Fevers

Causative© Jones & BartlettSigns Learning, & LLC © Jones & Bartlett Learning, LLC Disease AgentNOT FORFamily SALE ORSymptoms DISTRIBUTIONTransmission TreatmentNOT FORPrevention SALE OR DISTRIBUTION

Yellow fever Yellow Flavivirus Acute phase: Bite from a No antiviral Vaccination fever Headache, Stegomyia medications Avoiding virus fever, muscle aegypti © Jones & Bartlett Learning, LLC © JonesSupportive & Bartlett Learning,mosquito LLC pain mosquito care bites in NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Toxic phase: endemic Severe areas nausea, black vomit, © Jones & Bartlett Learning, LLC jaundice, © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION hemorrhagingNOT FOR SALE OR DISTRIBUTION

Dengue Dengue Flavivirus Sudden Bite from No specific Avoiding fever fever high fever, an infected treatment mosquito virus headache, Stegomyia available bites in © Jones & Bartlettnausea, Learning, LLCaegypti © Jonesendemic & Bartlett Learning, LLC NOT FOR SALE ORvomiting DISTRIBUTIONmosquito NOT FORareas SALE OR DISTRIBUTION

Dengue A Flavivirus Decrease in Bite from No specific Avoiding hemorrhagic different platelets, skin an infected treatment mosquito fever serotype hemorrhaging Stegomyia available bites in © Jones &of Bartlettdengue Learning, LLC aegypti © Jones & Bartlett Learning,endemic LLC NOT FORfever SALE OR DISTRIBUTION mosquitoNOT FOR SALE OR DISTRIBUTIONareas virus with another dengue virus

Ebola/ Ebola and Filovirus Fever, Bite of an No specific Avoiding © Jones &Marburg Bartlett Learning,Marburg LLC headache,© Jonesinfected & Bartlett fruit Learning,treatment LLCdead NOT FORhemorrhagic SALE OR DISTRIBUTIONviruses joint and NOT FORbat SALE OR DISTRIBUTIONavailable animals fevers muscle aches, Blood transfer and bats in sore throat, through cut, outbreak weakness abrasion, areas © Jones & BartlettInternal Learning, LLCor infected © Jones & Bartlett Learning, LLC NOT FOR SALE ORbleeding DISTRIBUTION and animal bite NOT FOR SALE OR DISTRIBUTION hemorrhaging

Lassa fever Lassa Arenavirus Severe fever, Aerosol and Ribavirin Avoiding fever exhaustion, direct contact dead or © Jones &virus Bartlett Learning, LLChemorrhagic with excreta© Jones & Bartlett Learning,infected LLC NOT FOR SALE OR DISTRIBUTIONlesions on from infectedNOT FOR SALE OR DISTRIBUTIONrodents throat rodents Maintaining good home sanitary © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLCconditions NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

9781284087789_CH02_Print.indd 26 14/07/15 12:25 AM 27 Hemorrhagic Viruses © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Infected patients often exhibit signs of bleeding, whether beneath the skin, within internal organs, or from body orifices like the mouth, nostrils, ears, or anus. The term hemorrhagic refers to leakage such as the bleeding described. As VHF progresses, more severe cases result© inJones delirium, & Bartlett shock, seizures, Learning, or coma. LLC The nervous system can© Jonesmal- & Bartlett Learning, LLC function, contributingNOT FORto the SALEaforementioned OR DISTRIBUTION conditions. Common symptoms ofNOT Ebola FOR SALE OR DISTRIBUTION include severe stomach pain, vomiting, and diarrhea.

Taxonomy© Jones & Bartlett of FilovirusesLearning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION The International Committee on Taxonomy of Viruses is responsible for the classification of known viruses. The taxonomy of viruses is based upon their anatomy, or arrangement of physical structures, including the genetic material they carry. © Jones & BartlettViruses thatLearning, possess single-stranded,LLC negative-sense© Jones ribonucleic & Bartlett acid (RNA) Learning, belong LLC to NOT FOR SALEthe order OR DISTRIBUTIONknown as Mononegavirales. The GreekNOT monos FOR refers SALE to the OR single DISTRIBUTION strand of RNA, while the Latin negare indicates the negative polarity of the RNA (see Anatomy of Filoviruses section that follows). The order Mononegavirales contains a total of five families: © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC • Bornaviridae NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION • Nyamaviridae • Rhabdoviridae • Paramyxoviridae ©• JonesFiloviridae & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOTTABLE FOR 2.3SALE provides OR DISTRIBUTION details on the family members of orderNOT MononegaviralesFOR SALE OR. DISTRIBUTION Ebola belongs to the family of viruses known as the Filoviridae, or simply the filoviruses. The family is composed of just three genera: Cuevavirus, Marburgvirus, and Ebolavirus. FIGURE 2.1 shows a phylogenetic tree of order Mononegavirales. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

TABLE 2.3 The Family Members of Order Mononegavirales

Bornaviridae 1 Borna disease virus Sheep, horses, Avian Bornavirus cattle, birds, rodents, sometimes humans © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOTFiloviridae FOR SALE OR3 DISTRIBUTIONEbolavirus Bats,NOT primates, FOR SALE humans OR DISTRIBUTION Marburgvirus Cuevavirus

9781284087789_CH02_Print.indd 27 14/07/15 12:25 AM 28 CHAPTER TWO Biology of Ebola © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION The Family Members of Order Mononegavirales TABLE 2.3 (Continued)

Paramyxoviridae 7 Atlantic salmon Humans, most paramyxovirus vertebrates © Jones & Bartlett Learning, LLC Avian © Jones & Bartlett Learning, LLC metapneumovirus NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Fer-de-lance virus Hendra virus Human respiratory syncytial virus © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOTMeasles FOR virus SALE OR DISTRIBUTION Mumps virus Newcastle disease virus © Jones & Bartlett Learning,Sendai LLC virus © Jones & Bartlett Learning, LLC NOTRhabdoviridae FOR SALE OR11 DISTRIBUTIONRabies virus (RABV) Vertebrates,NOT FOR SALE OR DISTRIBUTION Lettuce necrotic invertebrates, plants yellows virus (LNYV) Bovine ephemeral fever © Jones & Bartlett Learning, LLC virus (BEFV) © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION Infectious NOT FOR SALE OR DISTRIBUTION hematopoietic necrosis virus (IHNV) Potato yellow dwarf © Jones & Bartlett Learning, LLC © Jonesvirus (PYDV) & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOTVesicular FOR SALEstomatitis OR DISTRIBUTION Indiana virus (VSIV)

Source: Data from Easton, A. J. & Pringle, C. R. (2011). Order Mononegavirales. In A. M. Q. King, M. J. Adams, E. B. Carstens, & E. J. Lefkowitz, Virus Taxonomy—Ninth Report of the International Committee on Taxonomy of Viruses© Jones (pp. 653–657). & Bartlett London, UK:Learning, Elsevier/Academic LLC Press. © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

Marburgvirus was the first recognized filovirus, named after Marburg, Germany, © Jones & Bartlettwhere in Learning, 1967 an index LLC case occurred in humans© Jones( FIGURE & 2.2Bartlett). Laboratory Learning, workers LLC NOT FOR SALEhandling OR tissueDISTRIBUTION from green monkeys came downNOT with hemorrhagic FOR SALE fever, OR resultingDISTRIBUTION in 31 cases and seven deaths. As described earlier, in 1976 the first known cases of Ebola hemorrhagic fever were recorded. In addition to the case in Zaire, another outbreak occurred concurrently in © Jones & Bartlett Learning,Sudan. LLC These were the initial strains© Jones of Ebola & recognized,Bartlett Learning, with later outbreaks LLC revealing NOT FOR SALE OR DISTRIBUTIONstill more distinctive species. TheNOT strain FOR causing SALE the OR first DISTRIBUTION ever human outbreak is the same one responsible for the most recent outbreaks in Guinea, Sierra Leone, DRC, and

9781284087789_CH02_Print.indd 28 14/07/15 12:25 AM 29 Hemorrhagic Viruses © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION ORDER FAMILY SUBFAMILY GENUS (if applicable)

Bornaviridae Bornavirus © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FORNyamaviridae SALE OR DISTRIBUTION Nyavirus NOT FOR SALE OR DISTRIBUTION

Cytorhabdovirus Ephemerovirus Lyssavirus Novirhabdovirus © Jones & Bartlett Learning, LLC © JonesNucleorhabdovirus & Bartlett Learning, LLC Rhabdoviridae Perhabdovirus NOT FOR SALE OR DISTRIBUTION NOT SigmavirusFOR SALE OR DISTRIBUTION Sprivivirus Tibrovirus Tupavirus Mononegavirales Vesiculovirus © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Aquaparamyxovirus NOT FOR SALE OR DISTRIBUTION NOT FOR SALE ORAvulavirus DISTRIBUTION Ferlavirus Paramyxoviridae Paramyxovirinae Henipavirus Morbillivirus Respirovirus Rubulavirus © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Metapneumovirus NOT FOR SALE OR DISTRIBUTIONPneumovirinae NOT FOR SALE OR DISTRIBUTION Pneumovirus

Ebolavirus Filoviridae Marburgvirus Cuevavirus © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC ■NOT■ FIGURE FOR SALE2.1 The OR phylogenetic DISTRIBUTION tree of order MononegaviralesNOT shows FOR the five SALE OR DISTRIBUTION member families and the genera each contains. Note the location of Ebolavirus within the tree. Source: Data from Easton, A. J. & Pringle, C. R. (2011). Order Mononegavirales. In A. M. Q. King, M. J. Adams, E. B. Carstens, & E. J. Lefkowitz, Virus Taxonomy—Ninth Report of the International Committee on Taxonomy of Viruses (pp. 653–657). London, UK: Elsevier/Academic Press © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

Liberia, now considered a widespread epidemic. FIGURE 2.3 shows an image of the Ebola virus. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Cuevavirus is the most recent addition to the filovirus family. NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Reported in 2010, the single identified species Lloviu cuevavirus was discovered when colonies of Miniopterus schreibersii (Schreiber’s bats) experienced sudden massive deaths in Portugal, France, and Spain.© Jones This & genus Bartlett is not Learning, known to LLCinfect humans and is named© Jones for & Bartlett Learning, LLC theNOT cave FOR Cueva SALE del Lloviu OR DISTRIBUTION in Asturias, Spain, where infected batNOT car -FOR SALE OR DISTRIBUTION casses were collected for study. In addition to being the most recently discovered filovirus, Cuevavirus is also unique with outbreaks limited to Europe. While the other filoviruses,Marburgvirus and Ebolavi- ■ FIGURE 2.2 A transmission © Jones & Bartlettrus, have Learning, caused infections LLC in Europe and other© regions Jones of & the Bartlett world, Learning,■ LLC electron micrograph showing thus far most of their damage has occurred on the continent of Africa NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTIONmultiple Marburgvirus virions. ( FIGURE 2.4 ). Courtesy of R. Regnery; Dr. Erskin L. Palmer/CDC

9781284087789_CH02_Print.indd 29 14/07/15 12:25 AM 30 CHAPTER TWO Biology of Ebola © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

■■ FIGURE 2.3 A colorized transmission electron micrograph of the Ebola virus. This image was created by CDC microbiologist Cynthia Goldsmith. © Jones & Bartlett Learning,Courtesy LLC of Cynthia Goldsmith/CDC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

■■ FIGURE 2.4 The distribution of reported © Jones & Bartlett Learning, LLC cases© ofJones Marburgvirus & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION (indicatedNOT asFOR MBG) SALE and OR DISTRIBUTION ebolavirus (indicated as EBOZ, EBOIC, and EBOS) on the African continent. © Jones & Bartlett Learning, LLC © Jones &Courtesy Bartlett of CDC Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Anatomy of Filoviruses All viruses share certain anatomical traits. At minimum, viruses possess some form of genetic material enclosed in a protein layer called a capsid. Collectively, the capsid © Jones & Bartlett Learning,and genetic LLC material may be called© Jonesthe nucleocapsid & Bartlett. Some Learning, viruses LLCalso have an addi- NOT FOR SALE OR DISTRIBUTIONtional layer of lipids. These virusesNOT are FOR referred SALE to as OR enveloped, DISTRIBUTION because the lipid layer is termed an envelope . The genetic material of a virus may be deoxyribonucleic acid

9781284087789_CH02_Print.indd 30 14/07/15 12:25 AM 31 Hemorrhagic Viruses © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION (DNA) or RNA in an assortment of forms. DNA viruses exist in either double-stranded or single-stranded genomes. RNA viruses may also be single or double stranded. When a virus contains single-stranded RNA (ssRNA), the genetic material may be deemed positive sense or negative© Jones sense. & With Bartlett negative-sense Learning, RNA, LLC the molecule possesses© a Jonesbase & Bartlett Learning, LLC sequence complementaryNOT FOR to theSALE viral OR messenger DISTRIBUTION RNA (mRNA). In positive-senseNOT RNA FOR SALE OR DISTRIBUTION viruses, the viral genome is identical to its mRNA transcript and thus can undergo direct translation into its protein products. Another way to look at the sense of ssRNA is that it constitutes the polarity of the molecule. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Genetically, filoviruses contain negative-sense, single-stranded RNA. Therefore, NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION during gene expression, a filovirus genome must be transcribed into its complementary mRNA by the enzyme RNA replicase before translation can occur. Filovirus nucleocap- sids are enveloped. © Jones & BartlettFilovirus Learning, virions, orLLC whole viral particles, take on© aJones number & of Bartlettshapes in their Learning, appearance. LLC NOT FOR SALEThis traitOR isDISTRIBUTION known as pleomorphism. FilovirusesNOT may FORbe circular, SALE u-shaped, OR DISTRIBUTION short curli- cues, or long, sometimes branched, filaments. The longestobserved filoviruses reach up to 14,000 nanometers in length and around 80 nanometers in diameter. Each virion consists of a single-stranded RNA molecule, serving as the viral genetic material (or genome) surrounded by a lipid envelope.© JonesFor example, & Bartlett compare Learning, the transmission LLC electron micrograph© (TEM) Jones & Bartlett Learning, LLC images of MarburgvirusNOT FOR(shown SALE previously OR inDISTRIBUTION Figure 2.2) with FIGURES 2.5a andNOT 2.5b FOR. SALE OR DISTRIBUTION Even when observing the same genus, pleomorphism is apparent.

(a) (b)

■■ FIGURE 2.5 (a) This transmission electron micrograph depicts a Marburgvirus © Jones & Bartlettvirion. Learning, This image LLCwas captured in 1968 by F. A.© Murphy,Jones who& Bartlett had grown Learning, the virus in LLC NOT FOR SALEhost OR cell DISTRIBUTION culture. (b) Another transmission electronNOT micrographFOR SALE of MarburgvirusOR DISTRIBUTION taken by F. A. Murphy. Compare this image to Figures 2.2 and 2.5a. Courtesy of Frederick Murphy/CDC

9781284087789_CH02_Print.indd 31 14/07/15 12:25 AM 32 CHAPTER TWO Biology of Ebola © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Transmission of Filoviruses How does someone contract Ebola or any other filovirus? Direct physical contact between© Jones individuals & Bartlett is oneLearning, way, or, LLCin lieu of direct physical contact,© Jones one & individualBartlett Learning, LLC mayNOT pick FOR up theSALE virus OR through DISTRIBUTION contact with the body fluid(s) ofNOT an infected FOR SALE person OR(or DISTRIBUTION animal). There is some experimental evidence that Ebola may be transmitted through small airborne particles, but this has not been directly observed in actual cases. All filovirus outbreaks show the greatest rates of infection occur among patient care- © Jones & Bartlettgivers, followed Learning, by cross-contaminationLLC in patient© Jones care &settings Bartlett such Learning, as hospitals. LLC NOT FOR SALEThe latter OR DISTRIBUTION is known as nosocomial transmissionNOT. Frequently, FOR SALE these OR types DISTRIBUTION of transmissions are the result of reusing contaminated needles or syringes. The manner in which filoviruses like Ebola are transmitted makes patient isolation a critical factor in controlling the spread of infection. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

Characterization of Ebola © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION The Ebolavirus genus has been characterized based on morphological studies using electron microscopy. These observations lend to the development of diagnostic tech- niques. At least five species or strains of theEbolavirus genus are known, four of which © Jones & Bartlett(indicated Learning, here with anLLC asterisk, *) cause disease© in Jones humans: & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION • Bundibugyo ebolavirus (BEBOV)* • Cote d’Ivoire ebolavirus (CIEBOV), also known as Taï Forest Ebola* • Reston ebolavirus (REBOV) © Jones & Bartlett Learning,• Sudan LLC ebolavirus (SEBOV)*© Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION• Zaire ebolavirus (ZEBOV)* NOT FOR SALE OR DISTRIBUTION Thus, the Reston species of Ebola does not result in disease in humans. Studies of the first outbreaks of Ebola in 1976 determined they were caused by the Zaire and Sudan species, respectively, and indeed these two species are named after the locations of their first© Jones appearances & Bartlett in humans. Learning, Both ofLLC these species are highly lethal© Jones to humans, & Bartlett with aLearning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION 90% fatality rate in Zaire cases and 50% fatality rate in Sudan.

Ebola Morphology and Genetics © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALEMorphological OR DISTRIBUTION studies show all Ebola viruses areNOT distinct FOR from SALE their OR closest DISTRIBUTION relatives, the Marburg genus of viruses. Marburg virions obtained through host cell cultures were shorter in length than all Ebola virions. During biosynthesis, Marburgvirus develops inclusion bodies within host cells of unique morphology as compared to © Jones & Bartlett Learning,their LLCEbolavirus cousins. While© Jonesit is difficult & Bartlett to differentiate Learning,Ebolavirus LLC variants NOT FOR SALE OR DISTRIBUTIONfrom one another based on inclusionNOT FOR body SALE morphology, OR DISTRIBUTION only the Zaire ebolavirus

9781284087789_CH02_Print.indd 32 14/07/15 12:25 AM 33 Characterization of Ebola © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

■■ FIGURE 2.6 The generalized © Jones & Bartlett Learning, LLC © Jonesanatomy & Bartlett of all Ebola Learning, viruses LLC NOT FOR SALE OR DISTRIBUTION NOT FORincludes SALE a single-stranded OR DISTRIBUTION RNA genome, one or more RNA replicase enzymes, a lipid envelope, and glycoprotein © Jones & Bartlett Learning, LLC © Jones & Bartlett projections.Learning, LLC © ttsz/iStockphoto NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

species of Ebola formed inclusion bodies composed of filoviral matrix proteins and nucleoproteins. The association between these proteins continued into the assembly stage of the ZEBOV© Jones lifecycle, & Bartlettalso unique Learning, to this species. LLC © Jones & Bartlett Learning, LLC All Ebola speciesNOT are FOR composed SALE of OR an ssRNA DISTRIBUTION genome and one or more RNA replicaseNOT FOR SALE OR DISTRIBUTION enzymes surrounded by a lipid envelope studded with glycoproteins ( FIGURE 2.6 ). The Ebola nucleocapsid is intertwined with the viral proteins NP, VP35, VP30, and L. Glycoprotein (GP) spikes are embedded on the Ebola envelope, while the space in © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC between the nucleocapsid and envelope are occupied by the viral proteins VP40 and NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION VP24. There are a total of seven genes in the 19-kilobase Ebola genome, listed in 3′ to 5′ order as follows: 3′-leader-NP-VP35-VP40-GP/sGP-VP30-VP24-L-trailer-5′ © Jones & BartlettGenome Learning, sequencing LLC studies conducted by Broad© Jones Institute & Bartlett and Harvard Learning, University LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION researchers in fall 2014 revealed a number of variations in Ebolavirus sequences among a sample of Sierra Leone patients. During the first month of the outbreak in Sierra Leone, 78 patients provided blood samples allowing for a total of 99 genome sequences. For some patients,© multipleJones &samples Bartlett were Learning, taken over LLCa span of time in order to observe© Jones & Bartlett Learning, LLC any changes thatNOT may FORoccur SALEduring ORthe courseDISTRIBUTION of disease progression. A total NOTof 395 FOR SALE OR DISTRIBUTION mutations were discovered among the sequencing data, indicating rapid change in the viral population. Of these, more than 340 are unique to the current widespread epidemic and 50 are exclusive to the West Africa outbreaks. © JonesThe sequencing & Bartlett data Learning, prove the ongoing LLC widespread epidemic© isJones genetically & Bartlett distinct Learning, LLC fromNOT the FOR first SALE Ebola ORoutbreaks DISTRIBUTION in 1976, indicative of mutations NOTaccumulating FOR SALE over time. OR DISTRIBUTION The data also suggest there was a single infection—a common ancestor infecting one person—dating back to 1976. Therefore, although today’s strain of Ebola is not genetically identical to the 1976 version, it is likely a direct descendant. Genome sequencing has © Jones & Bartlettrevealed Learning, current Ebolavirus LLC populations diverged© from Jones the original & Bartlett population Learning, sometime LLC NOT FOR SALEwithin OR the DISTRIBUTION last decade. Furthermore, the researchersNOT were FOR able SALEto determine OR DISTRIBUTION the virus was spread from Guinea to Sierra Leone by 12 people, all of whom attended the same funeral.

9781284087789_CH02_Print.indd 33 14/07/15 12:25 AM 34 CHAPTER TWO Biology of Ebola © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Ebola Natural History An understanding of Ebola ecology may aid researchers in determining the animal origin of© the Jones disease & (discussedBartlett Learning,in detail in the LLC paragraphs that follow). ©Based Jones on outbreak & Bartlett his- Learning, LLC tory,NOT Ebola FOR is SALEthought OR to have DISTRIBUTION the ecological niche of rainforest ecosystems,NOT FOR particularly SALE OR DISTRIBUTION in the western and central regions of Africa. Transmissions during the past 17 outbreaks (1996–2007) have occurred between humans and nonhuman primates, antelopes known as duikers, and, possibly, bats. This is based on RNA sequence data of Zaire ebolavirus in- © Jones & Bartlettfections inLearning, human and LLC serological analysis of mammalian© Jones reservoirs & Bartlett, or animal Learning, of origin, LLC NOT FOR SALEfor the OR ZEBOV-specific DISTRIBUTION immunoglobulin G (IgG)NOT antibody. FOR Interestingly, SALE OR anDISTRIBUTION infographic published by the Centers for Disease Control and Prevention (CDC) outlining the ecology of Ebola displays bats as the primary reservoirs of Ebola ( FIGURE 2.7 ). They are the primary candidates at present, as discussed further in this chapter. © Jones & Bartlett Learning,A LLC2004 University of Kansas© study Jones by &Peterson, Bartlett Bauer, Learning, and Mills LLC comparing the NOT FOR SALE OR DISTRIBUTIONphylogeny and ecological niche characteristicsNOT FOR SALE of the ORfilovirus DISTRIBUTION family proposed relationships among the Ebola species. Zaire ebolavirus and Cote d’Ivoire ebolavirus appear most closely related, with Sudan ebolavirus being most distantly related to all other species, followed by Reston ebolavirus. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE■ ■ORFIGURE DISTRIBUTION 2.7 A recent infographic produced NOTby the FORCDC shows SALE bats OR as DISTRIBUTIONthe reservoir of Ebola viruses. Courtesy of CDC

9781284087789_CH02_Print.indd 34 14/07/15 12:25 AM 35 Characterization of Ebola © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Zaire ebolavirus Zaire ebolavirus was the first Ebola species discovered, and it also represents the source FIGURE 2.8 of the most recent© Jones widespread & Bartlett epidemic. Learning, LLC displays a map of West© Africa Jones & Bartlett Learning, LLC indicating the distributionNOT FOR of casesSALE within OR DISTRIBUTIONthe countries of Guinea, Sierra Leone, Liberia,NOT FOR SALE OR DISTRIBUTION and Côte d’Ivoire. This information was provided by the World Health Organization (WHO) and is current up to October 10, 2014. Epidemiologists utilize maps such as this one to observe trends in the spread of infection. Treatment strategies can also be influenced by these© Jones distribution & Bartlett maps. Learning,Note the locations LLC of hospitals, laboratories,© Jones transit & centers Bartlett for Learning, LLC patients,NOT FOR and WHO-designatedSALE OR DISTRIBUTION Ebola Treatment Units (ETUs). TheNOT opening FOR image SALE of this OR DISTRIBUTION chapter depicts the view from inside one ETU looking out through the entrance.

© Jones & Bartlett Learning, LLCSENEGAL © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION KOUNDARA MALI GUINEA GUINEA-BISSAU MALI LABE KOUBIA SIGUIRI GACUAL DINGUIRAYE TOUGUE © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC

BOKE DALABA NOTKINDIA FOR PISALETA OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION KOUROUSSA DABOLA MANDIANA FRIA MAMOU BOFFA FARANAH DUBREKA KANKAN © Jones &CONAKRY Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NORTHERN NOT FOR SALE OR DISTRIBUTIONKOINADUGU NOT FOR SALE OR DISTRIBUTION KISSIDOUGO

KEROUANE BOMBALI KAMBIA BEYLA EASTERN PORT GUECKEOOU LOKO TONKOLILI KONC N’ZEREKORE SIERRA © Jones & Bartlett Learning, LLC LEONE © Jones & BartlettMACENTA Learning, LLC WESTERN SO KENEMA LOFA LOLA NOT FOR SALE OR DISTRIBUTIONAREA MOYAMBA NOT FOR SALE OR DISTRIBUTION SOUTHERN CÔTE D’IVOIRE BONTHE GBARPOLU YOMOU

PUVEHUN

All cases NIMBA 1 – 10 © Jones & BartlettGRAND CAPE Learning, LLC BONG © Jones & Bartlett Learning, LLC 11 – 100 MOUNT 101 – 200 NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

201 – 300 MONTSERRADO GRAND 301 – 600 BASSA LIBERIA RIVERCESS GRAND GEDEH SINOE No cases reported © Jones & Bartlett Learning, LLC © Jones &RJVER Bartlett Learning, LLC NO LONGER ACTIVE - No cases in GEE NOT FORprevious 21 SALEdays OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION ACTIVE - New cases in MARY LAND previous 21 days GRAND NEWLY INFECTED - New cases in KRU previous 7 days (in previously uninfected areas) © WHO 2014, All rights reserved

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC ■■ FIGURE 2.8 The distribution of Ebola infections within West Africa as of October 10, NOT FOR SALE2014, OR asDISTRIBUTION reported by the World Health Organization.NOT FOR SALE OR DISTRIBUTION © World Health Organization 2014. All rights reserved

9781284087789_CH02_Print.indd 35 14/07/15 12:25 AM 36 CHAPTER TWO Biology of Ebola © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION The Zaire strain of Ebola is historically the most virulent. Zaire ebolavirus has resulted in 17 separate outbreaks since the initial outbreak in 1976. Multiple outbreaks have taken place in Zaire (now DRC) and Gabon, with additional outbreaks in South Africa and twice in© Russia. Jones The & latestBartlett outbreak Learning, has spread LLC infections into Sierra Leone, © Jones Guinea, & and Bartlett Liberia Learning, LLC asNOT well. FOR West AfricanSALE countriesOR DISTRIBUTION experience repeated outbreaks thatNOT seem FORto indicate SALE a con OR- DISTRIBUTION nection to ecology for this species, whereas infections in South Africa and Russia were caused by exposure to healthcare workers and laboratory researchers, respectively. The widespread nature of the most recent outbreaks has reached epidemic proportions. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Sudan ebolavirus The second species of Ebola recognized, Sudan ebolavirus was first seen in the country of Sudan in 1976, not long after ZEBOV made its appearance in Zaire. Compared to © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Zaire ebolavirus, SEBOV is less fatal, yet more fatal compared to Bundibugyo ebolavirus. NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION A total of eight outbreaks of Sudan ebolavirus have taken place since 1976, with all but one occurring in either Sudan or Uganda. The lone exception was an isolated infection of a laboratory worker in England, which happened in 1976. This patient survived. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC CoteNOT FOR d’Ivoire SALE ebolavirusOR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Also known as Taï forest virus, Cote d’Ivoire ebolavirus was not observed until 1994 in Côte d’Ivoire (Ivory Coast). The lone human case was a scientist who performed an © Jones & Bartlettautopsy onLearning, a wild chimpanzee LLC in the Taï forest region© Jones of Côte & Bartlettd’Ivoire and Learning, soon became LLC NOT FOR SALEill. The OR patient DISTRIBUTION was treated in Switzerland and survivedNOT FOR the infection. SALE OR DISTRIBUTION

Reston ebolavirus This species is perhaps the most enigmatic in terms of its origin, as it represents the only © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTIONEbola species initially observed outsideNOT FOR of the SALE African OR continent. DISTRIBUTION Reston ebolavirus was found in 1989 when captive macaques came down with hemorrhagic fever. The macaques originated from a breeding facility in Luzon, Philippines, but resided in Reston, Virginia, lending this species of Ebola its name. It is the only Ebola species that has yet to infect humans.© Jones After & sevenBartlett separate Learning, contamination LLC events, there have been© Jones13 instances & Bartlett of expo- Learning, LLC sureNOT in FORhumans. SALE One ORlaboratory DISTRIBUTION worker who handled the infectedNOT macaques FOR postmortem SALE OR DISTRIBUTION developed Ebola antibodies, but none of the exposed individuals ever showed any signs of disease. All cases took place in the United States, Italy, or the Philippines. The question remains whether REBOV emerged in the similar ecological conditions of the Philippines © Jones & Bartlett(i.e., tropical Learning, rainforests) LLC or if this species migrated© fromJones somewhere & Bartlett else. Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Bundibugyo ebolavirus The most recently discovered species is Bundibugyo ebolavirus. Isolated from a © Jones & Bartlett Learning,2007–2008 LLC outbreak in the Bundibugyo© Jones district& Bartlett of western Learning, Uganda, LLC BEBOV is the NOT FOR SALE OR DISTRIBUTIONleast fatal within the genus withNOT a mortality FOR SALE rate of OR34%. DISTRIBUTION Despite this, BEBOV results in twice the rate of bleeding manifestations in patients compared to other strains

9781284087789_CH02_Print.indd 36 7/16/15 5:54 PM 37 Characterization of Ebola © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION of Ebola. Only one other outbreak of Bundibugyo ebolavirus has taken place. In 2012, 36 individuals became infected with BEBOV in DRC. Although this occurred concurrently with an outbreak of Sudan© Jones ebolavirus & Bartlett in Uganda, Learning, there is noLLC epidemio- © Jones & Bartlett Learning, LLC logical evidence NOTlinking FOR the twoSALE events. OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

Paleovirology of Mononegavirales During© Jones the course& Bartlett of more Learning, than 3 billion LLC years of evolution of life© Jones & Bartlett Learning, LLC onNOT this FOR planet, SALE species OR have DISTRIBUTION accumulated snippets of viral genesNOT FOR SALE OR DISTRIBUTION within their genomes. Think of them as footprints implanted into the host cell DNA, left behind by viral invaders of long ago. Observation of these viral remnants offers insight into the ancient relationships between © Jones & Bartlettviruses and Learning, their hosts. LLC One collaborative study ©among Jones researchers & Bartlett at theLearning, LLC NOT FOR SALEInstitute OR forDISTRIBUTION Advanced Study at the Simons CenterNOT for FOR Systems SALE Biology OR DISTRIBUTION(Princeton, New Jersey); the Fox Chase Cancer Center, Institute for Cancer Research (Philadelphia, Pennsylvania); and the University of California, Irvine determined ssRNA viruses of the order Mononegavirales have deposited artifacts of their past presence in 19 verte- © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC brate species (Belyi,NOT Levine, FOR &SALE Skalka, OR 2010). DISTRIBUTION Within the order, the families FiloviridaeNOT FOR SALE OR DISTRIBUTION and Bornaviridae are almost exclusively represented in these 19 species at nearly 80 separate genome locations. The earliest integration event is estimated at approximately 40 million years ago. This tells us that members of order Mononegavirales have been infecting© Jones vertebrate & Bartlett species Learning, for at least LLC that long. Based on sequence© Jones data, the & integratedBartlett Learning, LLC viralNOT artifacts FOR SALEare linked OR to DISTRIBUTION genetic coding for matrix proteins, glycoproteins,NOT FOR viralSALE nucle- OR DISTRIBUTION ocapsids, and RNA replicase. These are the very genes expressed in the fi lovirus lifecycle (discussed later). Why would vertebrate genomes hold onto relics of viral RNA? Based on the principles of natural selection, it is a reasonable conclusion that they must pro- © Jones & Bartlettvide some Learning, biological benefiLLC t. Perhaps their presence© Jones somehow & Bartlett infl uences Learning, their relative LLC NOT FOR SALEvirulence OR DISTRIBUTIONupon an infected host in present time,NOT or even FOR whether SALE a speciesOR DISTRIBUTION is resistant or susceptible to infection. If there does prove to be a correlation between the presence of endogenous Mononegavirales sequences and virulence, this would give the virus an advantage, too. A species resistant to infection would serve the critical function of acting as the viral reservoir,© Jones thus allowing & Bartlett the persistence Learning, of LLCthe virus. © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Research Classiﬁ cation The CDC (2009) classifi es Ebola viruses as Biosafety Level 4 (BSL-4) infectious agents,© Jones a class & Bartlett of “dangerous Learning, and LLCexotic agents that pose ©a highJones individual & Bartlett risk Learning, LLC ofNOT aerosol-transmitted FOR SALE OR laboratoryDISTRIBUTION infections and life-threateningNOT FORdisease SALE that OR is DISTRIBUTION frequently fatal, for which there are no vaccines or treatments, or a related agent with unknown risk of transmission” (p. 45). There are a total of four safety levels in as- cending order, placing Ebola among infectious agents with the highest amount of risk © Jones & Bartlettposed to Learning, researchers LLChandling this genus of viruses.© Jones Hemorrhagic & Bartlett viruses Learning, like Ebola LLC NOT FOR SALEare investigated OR DISTRIBUTION by the Viral Special PathogensNOT Branch FOR of SALE the CDC OR ( DISTRIBUTIONFIGURE 2.9 ). Their handling requires the most stringent protocols to prevent contamination.

9781284087789_CH02_Print.indd 37 14/07/15 12:25 AM 38 CHAPTER TWO Biology of Ebola © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

■■ FIGURE 2.9 In this image from the Centers for Disease © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning,Control and LLC Prevention, a NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTIONmicrobiologist looks out from a Biosafety Level 4 (BSL-4) laboratory. Courtesy of James Gathany/CDC

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Viruses are obligate parasites: They require a host for their survival. However, we refer NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION to them as parasites in a loose sense, because they are not technically alive at all. As a matter of course, they are acellular (not made of cell[s]) and thus violate the cell theory of biology, which states: © Jones & Bartlett Learning,1. All LLC organisms are composed ©of atJones least one & Bartlett cell. Learning, LLC NOT FOR SALE OR DISTRIBUTION2. All cells come from preexistingNOT cells. FOR SALE OR DISTRIBUTION 3. The cell is the smallest form of life. In order to replicate, viruses must associate with a host cell. Generally, a virus pene- trates the host cell with its genetic material, which may be DNA or RNA (either sin- © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC gleNOT or doubleFOR SALE stranded), OR andDISTRIBUTION takes advantage of gene expressionNOT mechanisms FOR SALE present OR DISTRIBUTION within. A gene in the most basic sense provides information to create a protein; think of it as a recipe. When a gene is expressed, the cell is “cooking” the recipe. Gene expression involves two steps: transcription and translation. Transcription creates a © Jones & Bartlettmessenger Learning, RNA molecule LLC from a DNA, or sometimes© Jones RNA, &template. Bartlett Translation Learning, turns LLC NOT FOR SALEthe mRNA OR DISTRIBUTION molecule into a protein product. TheseNOT two FOR steps SALE comprise OR what DISTRIBUTION is referred to as the central dogma of molecular biology ( FIGURE 2.10 ). By hijacking the host cell, it unwittingly creates copies of the virus, resulting in its own death as the newly formed virions burst through in their escape, onward to infect new host cells and © Jones & Bartlett Learning,repeat LLC the whole process. © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTIONViruses have a number of replicativeNOT FOR strategies SALE that OR depend DISTRIBUTION primarily on the type of genetic information they carry. As viruses rely on host cell machinery to complete their

9781284087789_CH02_Print.indd 38 14/07/15 12:25 AM 39 The Replication Cycle of Filoviruses © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

DNA

Replication © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FORTranscription SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION mRNA

Translation © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Ribosome ■■ FIGURE 2.10 The central dogma of NOT FOR SALE OR DISTRIBUTION molecular biologyNOT describes FOR SALE the flow OR DISTRIBUTION of genetic information from DNA to messenger RNA during transcription, then from messenger RNA to a © Jones & Bartlett Learning,Polypeptide LLC © polypeptideJones & Bartlett(or protein) Learning, product LLC NOT FOR SALE OR DISTRIBUTION NOTduring FOR translation. SALE OR DISTRIBUTION

replication cycles, their mode of replication is dependent upon the presence of or, as we shall see in the case© Jones of filoviruses, & Bartlett the lack Learning, of necessary LLC enzymes integral to carrying© Jones out & Bartlett Learning, LLC expression of theNOT viral genome.FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

Attachment and Entry into Host Cell

Electron© Jones microscopy & Bartlett studies Learning, of different LLC Ebola species revealed the© virus Jones enters & Bartletthost cells Learning, LLC FIGURE 2.11 viaNOT endocytosis. FOR SALE Endocytosis OR DISTRIBUTION is the engulfment of a substance intoNOT a cell FOR ( SALE OR). DISTRIBUTION The endocytosis is cell-receptor mediated, which requires the virus to attach to the host cell membrane via receptors on its surface. Specifically, the virus exhibits glycoproteins that enable binding. The host cell membrane begins to invaginate, creating a cavity that eventually © Jones & Bartlettpinches offLearning, to enclose LLCthe virus in a vesicle. The virus© Jones has now & entered Bartlett the Learning,host cell. From LLC NOT FOR SALEthis point, OR DISTRIBUTIONthe viral membrane fuses with the vesicleNOT membrane, FOR SALE releasing OR the DISTRIBUTION viral genome into the host cell’s cytoplasm (liquid interior).

© Jones & Bartlett Learning, LLC ©■ Jones■ FIGURE & Bartlett2.11 This modelLearning, LLC NOT FOR SALE OR DISTRIBUTION NOTdemonstrates FOR SALE the OR process DISTRIBUTION of endocytosis. The large white cell is surrounding the smaller red substance with its membrane. Ultimately, the red substance will © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC become completely engulfed and NOT FOR SALE OR DISTRIBUTION NOT FOR SALE pinchOR DISTRIBUTION off into the white cell. © Knorre/Shutterstock

9781284087789_CH02_Print.indd 39 14/07/15 12:25 AM 40 CHAPTER TWO Biology of Ebola © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Research has shown that Ebolavirus preferentially targets cells of the immune system, including macrophages and dendritic cells. Once these cells are infected, they release glycoproteins synthesized by the infecting virions. The secreted glycoproteins (sGPs)© Jones mimic & Bartlettthe behavior Learning, of the viral LLC glycoproteins embedded© Joneson their & envelopes. Bartlett Learning, LLC InNOT this FORway, Ebolavirus SALE OR confuses DISTRIBUTION the immune system into essentiallyNOT FORdisarming SALE itself. OR DISTRIBUTION Dendritic cells normally undergo what is known as maturation during times of infection, during which they release cytokines to promote an adaptive immune response and also trigger the activation of helper T-cells that fight pathogen invasions. Ebola is © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC capable of deregulating dendritic cells and preventing maturation and the associated NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION adaptive immune response. Furthermore, infected macrophages overexpress and release cytokines, which promote an inflammatory response. As this proceeds unchecked, the cytokine storm causes the associated symptoms of VHF such as fever, aches, and leakage © Jones & Bartlett Learning,of blood LLC into tissues. © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Negative-Sense RNA Replication Filovirus host cells do not normally undergo RNA replication, because their genomes are composed© Jones of & DNA. Bartlett The RNA Learning, replicase LLCenzyme needed for the virus© toJones complete & Bartlett its repli- Learning, LLC cationNOT cycleFOR is SALE lacking. OR Negative-sense DISTRIBUTION ssRNA viruses such as EbolavirusNOT FOR circumvent SALE this OR DISTRIBUTION roadblock by carrying one or more copies of the RNA replicase enzyme with them. Upon entering a host cell, the virion piggybacks with the RNA replicase enzyme(s), which then commences making positive-sense strands using the negative-sense strand as a © Jones & Bartletttemplate. Learning, These positive-sense LLC strands act as complementary© Jones & BartlettmRNA copies Learning, of the viral LLC NOT FOR SALEgenome. OR The DISTRIBUTION genetic information carried within NOTthe positive FOR strandsSALE canOR nowDISTRIBUTION be used as templates to synthesize more RNA replicase enzymes as well as other viral proteins necessary for reproduction. Indeed, the synthesized positive strands serve as intermediates in the creation of new negative-sense ssRNA offspring ( FIGURE 2.12 ). It is believed the © Jones & Bartlett Learning,individual LLC genes of the viral genome© Jones are transcribed & Bartlett in Learning,sequential order LLC by the action NOT FOR SALE OR DISTRIBUTIONof RNA replicase recognizing startNOT and FOR stop regionsSALE ORflanking DISTRIBUTION each gene. FIGURE 2.13 summarizes these steps of the filovirus lifecycle. As noted,this lifecycle is common to negative-sense ssRNA and double-stranded RNA viruses. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC ReleaseNOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Once new progeny are produced in the host cell, they move toward the host cell membrane. In Zaire ebolavirus, the matrix protein VP40 appears to play a critical role in © Jones & Bartlettinteracting Learning, with the LLChost cell membrane beneath© Jones its surface, & Bartlett allowing Learning, viral exit LLCby NOT FOR SALEbudding OR ( DISTRIBUTIONFIGURES 2.14a and 2.14b ). The virionsNOT become FOR SALEenveloped OR in DISTRIBUTION a lipid membrane of their own and are now ready to infect neighboring cells of the host organism. VP40 is experimentally linked to at least two host cell endosomal sorting complexes required for transport (ESCRT). In the broadest sense, ESCRTs are involved in any © Jones & Bartlett Learning,activity LLC that requires remodeling© of Jones the cell &membrane. Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTIONThe tumor susceptibility geneNOT 101 FOR protein SALE is encoded OR DISTRIBUTION by the human gene TSG101 and is part of the ESCRT-I complex. This particular ESCRT aids in the regulation

9781284087789_CH02_Print.indd 40 14/07/15 12:25 AM 41 The Replication Cycle of Filoviruses © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

© Jones & Bartlett Learning, LLC © Jones■■ FIGURE& Bartlett 2.12 Learning, This scanning LLC NOT FOR SALE OR DISTRIBUTION NOT FORelectron SALE micrograph OR DISTRIBUTION (SEM) from the National Institute of Allergy and Infectious Diseases (NIAID) shows a multitude of newly replicated Ebolavirus virions © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC within a cultured VERO E6 cell. NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTIONVERO E6 is a cell line derived from kidney epithelial cells of green monkeys. The image is magnified 50,000×. © Jones & Bartlett Learning, LLC Courtesy of National© Jones Institute of Allergy and& Infectious Bartlett Diseases (NIAID)/CDC Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

(–) strand and ds strand RNA viral chromosomes cannot act as mRNA. Their chromosomes enter the host cell with a molecule of © Jones & Bartlett RNALearning, replicase. LLC © Jones & Bartlett Learning, LLC NOT FORRNA SALE replicase OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION (–) (+) strand RNA makes more replicase and other viral proteins. The RNA replicase (+) © Jones & Bartlettmakes a (+)Learning,(–) LLC © Jones(+) & Bartlett Learning, LLC NOT FOR SALEstrand OR mRNA. DISTRIBUTION NOT FOR SALE OR DISTRIBUTION (+)

(–) (+) (+) strand RNA also acts as a template for replicase to produce © Jones & Bartlett Learning, LLC more© (–) Jonesstrand chromosomes & Bartlett (or Learning, LLC NOT FOR SALE OR DISTRIBUTION ds chromosomesNOT FOR in the SALE case of ORds DISTRIBUTION RNA viruses).

■■ FIGURE 2.13 The replication cycle of negative-sense, single-stranded RNA viruses requires transcription of positive-sense strands before translation can occur. The © Jones & Bartlettpositive-sense Learning, strands LLC act as mRNA transcript© templates, Jones & which Bartlett are translated Learning, into LLC NOT FOR SALEgene OR products. DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

Note: ds stands for double-stranded.

9781284087789_CH02_Print.indd 41 14/07/15 12:25 AM 42 CHAPTER TWO Biology of Ebola © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

(a) (b)

■©■ JonesFIGURE & 2.14 Bartlett (a) This Learning, scanning electron LLC micrograph (SEM) has© beenJones digitally & Bartlett Learning, LLC NOTcolorized FOR SALEto differentiate OR DISTRIBUTION Ebola virions (in red) budding from theNOT surface FOR of aSALE VERO OR DISTRIBUTION cell (in blue). This SEM was produced under high levels of magnification by the National Institute of Allergy and Infectious Diseases (NIAID). (b) This SEM is an up- close version of Figure 2.14a. The Ebola virions are still displayed in red; however, in this image the VERO cell is now a taupe coloration. © Jones & BartlettCourtesy of Learning, National Institute of Allergy and LLC Infectious Diseases (NIAID)/CDC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

of the vesicular trafficking process. In essence, it behaves as a gatekeeper and facil- itates the escort of materials in and out of the cell through cargo-carrying vesicles. © Jones & Bartlett Learning,The humanLLC gene NEDD4 encodes© Jones the other & Bartlettprotein associated Learning, with LLC ZEBOV’s VP40. NOT FOR SALE OR DISTRIBUTIONKnown as the E3 ubiquitin ligaseNOT NEDD4 FOR protein, SALE itOR releases DISTRIBUTION ubiquitin proteins that appear to aid in viral budding. As mentioned earlier, a separate protein product is also released from certain Ebola-infected cells. The Zaire ebolavirus genome contains the GP gene which encodes a short,© Jones nonstructural & Bartlett glycoprotein Learning, known LLC as sGP that is never incorporated© Jones into & the Bartlett freshly Learning, LLC assembledNOT FOR ZEBOV SALE virions. OR DISTRIBUTIONFurther investigation of the mechanismsNOT involved FOR in SALE release OR of DISTRIBUTION Ebola virions into their host organism is integral to the development of antiviral treatments.

Ebola is a zoonotic disease, meaning it can be spread from animals to humans. One © Jones & Bartlett Learning,unknown LLC in our understanding of© EbolaJones is &the Bartlett animal origin, Learning, or reservoir, LLC of transmis- NOT FOR SALE OR DISTRIBUTIONsion. How exactly the virus firstNOT made FOR contact SALE with OR Homo DISTRIBUTION sapiens is still a mystery; however, particulars of Ebolavirus outbreaks have revealed distinct clues.

9781284087789_CH02_Print.indd 42 14/07/15 12:25 AM 43 Ebola Reservoirs © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION It Is What It Isn’t First, index cases of Ebola are relatively rare compared to other viruses. Furthermore, the index cases of filoviruses© Jones tend & Bartlett to be isolated Learning, rather than LLC occurring in multiples ©at Jonesonce. & Bartlett Learning, LLC While some moreNOT common FOR viral SALE infections OR DISTRIBUTION are transmitted through insect vectors,NOT it isFOR SALE OR DISTRIBUTION not likely for a member of the arthropods to harbor and pass on Ebola. If that were so, we would expect more index cases simply because human contact with insects is so frequent. In addition, phylogenetic analyses of the filovirus family show a positive correlation to© geographic Jones & region,Bartlett meaning Learning, each viralLLC strain is strongly associated© Jones with &a particularBartlett Learning, LLC location.NOT FOR This SALE observation OR DISTRIBUTIONsuggests a degree of stability for the EbolaNOT reservoir. FOR SALE It is likely OR DISTRIBUTION the reservoir maintains permanent residence or else we would expect there to be a wider geographic distribution of each strain. Building on this logic, if a reservoir is firmly rooted in its habitat, then there is an increased probability of resistance or immunity to © Jones & Bartlettthe virus Learning, and therefore LLC low death rates of the reservoir© Jones species. & Bartlett As infected Learning, nonhuman LLC NOT FOR SALEprimates OR exhibitDISTRIBUTION high mortality rates, they are generallyNOT FOR not consideredSALE OR prime DISTRIBUTION reservoir candidates. Experimental studies have attempted infecting various species with Ebola. A sum- mary of their results is presented in TABLE 2.4 . Species that suffer high rates of death © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC are probably not aNOT reservoir, FOR because SALE a OR reservoir DISTRIBUTION needs to survive in order to continuouslyNOT FOR SALE OR DISTRIBUTION introduce the disease to new individuals.

The Leading Hypothesis © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC OneNOT of FORthe primary SALE suspects OR DISTRIBUTION is the fruit bat. Often, disease reservoirsNOT are FOR species SALE hunted OR DISTRIBUTION by humans as food sources, and fruit bats are commonly hunted in Africa. Bolstering

Experimental Ebola Infections of Various © Jones & BartlettTABLE Learning, 2.4 LLC © Jones & Bartlett Learning, LLC Organisms NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Organism Inoculation Resulting in Infection?

Plants Zaire ebolavirus No

Arthropods © Jones &Zaire Bartlett ebolavirus, Learning, Reston LLC Very little © Jones & Bartlett Learning, LLC NOT FORebolavirus SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

Reptiles Zaire ebolavirus Single infection; low levels of further circulation within © Jones & Bartlett Learning, LLC the population© Jones & Bartlett Learning, LLC NOTRodents FOR SALE OR DISTRIBUTIONZaire ebolavirus Yes NOT FOR SALE OR DISTRIBUTION

Bats Zaire ebolavirus Yes; many do not become ill, no deaths

© Jones & BartlettNonhuman Learning, Primates LLC Zaire ebolavirus © Jones Yes;& Bartlett highly lethal Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Source: Swanepoel R, Leman PA, Burt FJ, Zachariades NA, Braack LEO, Ksiazek TG, Experimental inoculation of plants and animals with Ebola virus. Emerg Infect Dis. 1996; 2:321–5.

9781284087789_CH02_Print.indd 43 14/07/15 12:25 AM 44 CHAPTER TWO Biology of Ebola © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION this hypothesis is the recent discovery of Ebola nucleic acid sequences residing in DNA samples derived from at least three fruit bat species. This is indicative of prior contact, because Ebola viruses have the potential to leave behind bits of RNA in its hosts (see the section© Jones Paleovirology & Bartlett of MononegaviralesLearning, LLC, earlier in this chapter).© Furthermore,Jones & Bartlett experi- Learning, LLC mentalNOT FOR studies SALE have shownOR DISTRIBUTION bats are capable of surviving Ebola infection.NOT FOR SALE OR DISTRIBUTION Typically, a reservoir is identified when an outbreak of disease is observed in a particular wildlife population. Indeed, previous Ebola outbreaks were observed in tandem with outbreaks in other species. Scientists from the Robert Koch Institute © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC and the Wild Chimpanzee Foundation recently monitored wildlife communities NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION surrounding southeastern Guinea, where the outbreak likely originated in humans ( FIGURE 2.15 ). While they have not seen any signs of decline in any local populations of bats or other species, such as chimpanzees and antelopes, they did find a © Jones & Bartlett Learning,suspicious LLC clue in the village of© Meliandou. Jones & JustBartlett 50 meters Learning, from where LLC patient zero, FIGURE 2.16 NOT FOR SALE OR DISTRIBUTIONa young boy, lived, a burnt out NOTtree stands FOR (SALE OR DISTRIBUTION). Villagers told the Robert Koch researchers this tree once contained a population of insectivorous Angolan free‐tailed bats (Mops condylurus), which local children would play with, as well as capture and barbeque ( FIGURE 2.17 ). © JonesCould the & Bartletttransmission Learning, of Ebola LLC to the 2-year-old patient ©zero Jones have &taken Bartlett place Learning, LLC inNOT this FORtree? SALEFruit bats OR are DISTRIBUTION not found in Meliandou, suggestingNOT other FOR potential SALE can OR- DISTRIBUTION didates for transmission are nonexistent. Additionally, out of 169 fruit bats captured in surrounding areas and tested for Ebola by the research team, none carried the virus. Lastly, the first individuals to contract Ebola in Meliandou were children and © Jones & Bartlettwomen, Learning,increasing the LLC likelihood that hunting© and Jones contact & Bartlettwith infected Learning, bushmeat LLC, NOT FOR SALEusually OR carried DISTRIBUTION out by men of the village, was notNOT how FOR transmission SALE OR occurred. DISTRIBUTION All of these indicators combined pointed away from fruit bats. The researchers went on to consider the smaller, insect-eating Mops condylurus described by villagers. Previ- ous studies have found Ebola antibodies in this species, which may be evidence of © Jones & Bartlett Learning,infection. LLC FIGURE 2.18 shows ©a Jonesmap of &Gabon Bartlett and DRC,Learning, two countries LLC southeast NOT FOR SALE OR DISTRIBUTIONof Guinea, where this discoveryNOT was FORmade. SALE Furthermore, OR DISTRIBUTION sampling the remains of the tree revealed DNA fragments of the Angolan free-tailed bats, confirming villager

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC 0.06 NOT FORCarnivore SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Chimpanzee 0.05 Duiker Primate 0.04 Other mammals Humans © Jones & Bartlett0.03 Learning, LLC © Jones & Bartlett Learning, LLC

NOT FOR SALESigns/km OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION 0.02 FIGURE 2.15 Densities of various 0.01 ■■ species observed in southeast © Jones & Bartlett Learning,0.00 LLC © Jones & BartlettGuinea, Learning, comparing LLC 2010–2011 NOT FOR SALE OR DISTRIBUTION 2010/11 NOT2014 FOR SALEwith 2014. OR DISTRIBUTION Year Robert Koch Institute and the Wild Chimpanzee Foundation. http://embomolmed .embopress.org/content/early/2014/12/29/emmm.201404792.figures-only

9781284087789_CH02_Print.indd 44 14/07/15 12:25 AM 45 Ebola Reservoirs © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

(a) Meliandou (b) Guéckédou Guéckédou Kagbadou Guinea Kéléma Massif du © Jones Ziama& Bartlett Learning,Index LLC house © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTIONHollow tree (burned) NOT FOR SALE OR DISTRIBUTION Liberia Hollow tree (inhabited) Women’s washing place Bat capture sites Outline village Anthropological investigation Road/ Paths Bat capture sites Fôret classée © JonesBiomonitoring & Bartlettsites Learning,de Diécké LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

■■ FIGURE 2.16 These maps show: (a) the location of Meliandou, Guinea, in relation to investigative sites within West Africa, and (b) the relative placement of patient zero’s © Jones & Bartletthome Learning, (“index house”) LLC and the burnt out tree suspected© Jones of & harboring Bartlett Angolan Learning, free- LLC NOT FOR SALEtailed OR batsDISTRIBUTION within the village of Meliandou. NOT FOR SALE OR DISTRIBUTION Robert Koch Institute and the Wild Chimpanzee Foundation. http://embomolmed.embopress.org/content/early/2014/12/29/emmm.201404792.figures-only

(a)© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

(b) (c) (d) © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

■■ FIGURE 2.17 (a) The village of Meliandou, Guinea. (b–d) The burnt out tree that may have housed Angolan free-tailed bats. (d) A stick near the opening of the tree, which © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC may have been left there by village children who once played close by. NOTRobert FORKoch Institute andSALE the Wild Chimpanzee OR Foundation. DISTRIBUTION http://embomolmed.embopress.org/content/early/2014/12/29/emmm.201404792.figures-onlyNOT FOR SALE OR DISTRIBUTION

accounts. The first Ebola patient in this epidemic may have played with an infected © Jones & Bartlettbat or accidentally Learning, ingested LLC the droppings of an© infected Jones bat. & Bartlett However, Learning, this cannot LLCbe NOT FOR SALEdefinitively OR DISTRIBUTION proven without further investigation.NOT It isFOR important SALE to OR note DISTRIBUTION the insectivorous bat hypothesis is still just that.

9781284087789_CH02_Print.indd 45 14/07/15 12:25 AM 46 CHAPTER TWO Biology of Ebola © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION OGOOUE-IVINDO/MBOMO

Casinycteris argynnis Libreville Eidolon helvum © Jones & Bartlett Learning,GABON REPUBLIC LLC © Jones & Bartlett Learning, LLC Epomops franqueti MOYEN-OGOOUENOT FOR SALE OR DISTRIBUTIONOF CONGO 1235 NOT FOR SALE OR DISTRIBUTION 4% ZEBOV IgG Hypsignathus monstrosus 0.3% MARV IgG Megaloglossus woermanni Microchiroptera* 272 Brazzaville © Jones & Bartlett Learning, LLC HAUT-OGOOUE© Jones & BartlettMicropteropus Learning, pusillus LLC 4% ZEBOV IgG Myonycteris torquata NOT FOR SALE1.9% MARVOR DISTRIBUTION IgG NOT FOR SALE OR DISTRIBUTION NYANGA Rousettus aegyptiacus *Including Mops condylurus 440 and Hipposideros gigas 5% ZEBOV IgG 2.2% MARV IgG © Jones & Bartlett Learning, LLC 200 © Jones & Bartlett Learning, LLC 5% ZEBOV IgG NOT FOR SALE OR DISTRIBUTION 1.7% MARV IgG NOT FOR SALE OR DISTRIBUTION

■ FIGURE 2.18 A map of Democratic Republic of Congo and Gabon, two countries southwest of Guinea, which shows a sampling of bat populations across the region. © JonesThe pie charts& Bartlett indicate Learning, the relative LLC proportions of fi lovirus antibodies© Jones observed & Bartlett in Learning, LLC bat specimens, where MARV represents Marburgvirus and ZEBOV represents Zaire NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION ebolavirus. Mops condylurus (Angolan free-tailed bat) is represented in grey within the Microchiroptera lineage. Large serological survey showing cocirculation of Ebola and Marburg viruses in Gabonese bat populations, and a high seroprevalence of both viruses in Rousettus aegyptiacus. Xavier Pourrut, Marc Souris, Jonathan S Towner, Pierre E Rollin, Stuart T Nichol, Jean-Paul Gonzalez and Eric Leroy, BMC Infectious Diseases 2009, 9:159 doi:10.1186/1471-2334-9-159. © 2009 Pourrut et al.; licensee BioMed Central Ltd. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Courtesy of Dr. Heidi Soeters/CDC

1.© JonesHow might & Bartlettthe infection Learning, mechanisms LLC displayed by Ebola virions© affect Jones the &progression Bartlett Learning, LLC of symptoms in viral hemorrhagic fever? NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION 2. What is the relationship between the magnitude of the current widespread epidemic and the conditions present in affected countries, and how might these correlations offer suggestions for improvement in response efforts and/or prevention of future outbreaks? © Jones & Bartlett3. How Learning,can understanding LLC the evolution of order© Mononegavirales Jones & Bartlett and its Learning, member family LLC NOT FOR SALE Filoviridae OR DISTRIBUTION aid in the development of treatmentsNOT and/or FOR vaccines? SALE OR Or DISTRIBUTIONunderstanding Ebola genomics?

9781284087789_CH02_Print.indd 46 14/07/15 12:25 AM