Effect of Post-Infection Vaccination on Immune Status of Newcastle
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Animal Research International (2021) 18(1): 4020 – 4027 4020 EFFECT OF POST - INFECTION VACCINATION ON IMMUNE STATUS OF NEWCASTLE DISEASE - INFECTED CHICKEN 1 OZIOKO , Ikenna Emmanuel, 2 EZE , Didacus Chukwuemeka , 1 ABONYI , Festus Otaka, 1 NWANKWO , Nwabueze Sunday, 3 EMENNAA , Ekenedilichukwu Paul and 1 NNADI , Pius Ajanwachukwu 1 Department of Animal Health and Production, Faculty of Veterinary Medicine, University of Nigeria, Nsukka , Enugu State, Nigeria. 2 Department of Pathology and Microbiology, Faculty of Veterinary Medicine, University of Nigeria, Nsukka , Enugu State, Nigeria. 3 National Veterinary Research Institute, Vom , Plateau State, Nigeria. Corresponding Author: Ozioko, I. E. Department of Animal Health and Production, Faculty of Veterinary Medicine, University of Nigeria, Nsukka , Enugu State, Nigeria . Email: [email protected] Phone: +234 806355797 0 Received February 26, 2021, Revised March 2 2 , 2001; Accepted April 06 , 2021 ABSTRACT This study investigated the response of chicks infected with velogenic Newcastle disease virus (NDV) to Newcastle disease vaccine - NDV - I 2 . A total of 90 day - old cockerel chicks were used for this study. At three weeks of age, the chicks were randomly separated into two equal groups of 45 chicks designated A and B. After separation, Group A chicks were vaccinated with NDV - I 2 vaccine intraocularly , while Group B chicks were not vaccinated. At six weeks of age, Groups A and B chicks were further randomly separated into sub groups A1, A2, A3 and B1, B2, B3 of 15 chicks each respectively. After separation, chicks in subgroups A2, A3, B2, and B3 were exposed to chicks infected with NDV. Upon manifestation of clinical infections, chicks in subgroups A2 and B2 were revaccinated with NDV - I 2 vaccine , while subgroups A3 and B3 were not vaccinated. Percentage morbidity was 42.86, 64.29, 100 and 92.86 % for subgroups A2, A3, B2 and B3 respectively, while percentage mortality was 14.29, 50, 100 and 71.43 % in subgroups A2, A3, B2 and B3 respectively. This study showed that vaccination of previously vaccinated chicks during Newcastle disease outbreak protects the chicks and reduces both morbidity and mortality significantly . Keywords: Cockerels, Newcastle disease, Vaccination , Revaccination, Geometric mean titre, Morbidity , Mortality INTRODUCTION family Paramyxoviridae , order Mononegavirales (Mayo, 2002 ; Lamb et al. , 2005). Newcastle disease (ND) is an acute and highly Since the emergence of ND in 1926, contagious viral disease that causes severe there has been continuous emergence of new economic lo sses within the poultry industry. The virulent genotypes from global epizootics with disease is caused by Newcastle disease virus year to year changes in genome sequence of (NDV) which is a non - segmented, single - the virus (Diel et al . , 2012; Snoeck et al ., 2013). stranded, negative - sense RNA virus belonging to Newcastle disease is one of the most the genus Orthoavulavirus ( Absalón et al ., economically important viral diseases of poultry 2019) of subfamily Avulavirinae within the ( Bankowski et al. , 1981 ; Alexander, 2000; Lamb and Parks, 2007; Miller et al ., 2010 ). ISSN: 1597 – 3115 ARI 2021 18(1): 4020 – 4027 www.zoo - unn.org Ozioko et al. 4021 Over 250 species of chicks have been reported 200 1 ). These have called for practices such as to be susceptible to NDV as a result of natural emergency vaccination of chicks post or experimental infections. Many more appearance of clinical signs. According to Okwor susceptible species exist but have not yet been et al. (2012), post infection or emergency identified ( Kirkland, 2000 ). An accurate vaccination of chickens against some avian assessment of the distribution of NDV pathogens is commonly practiced in many throughout the world is difficult to achieve due developing countries of Africa and Asia. The to the widespread use of live vaccines. authors also observed that post - exposure or However, studies have concluded that ND is post - infection vaccination can be used in the endemic in many countries of Asia, Africa and management of an outbreak of fowlpox i n the Americas ( Alders et al ., 2001 ; Westbury, chickens. 2001 ) . In Africa and Asia, Newcastle disease is a The aim of this study was to investigate major constraint to both commercial and village the effect of post ND infection vaccination with poultry production (Conan et al ., 2012). NDV - I 2 on the morbidity, mortality and immune Infections with NDV can lead to a broad responses of chicks challenged with range of clinical signs, varying from viscerotropic velogenic strain of ND. asymptomatic enteric infections to systemic infections causing 100 % mortality. Vaccination MATERIALS AND METHODS is required to optimally protect chicks against economically devastating diseases of poultry Experimen tal Animals : A total of 90 white such as ND in endemic regions. To date, a cockerels were sourced at day old from a local number of lentogenic NDV strains such as B1, F, hatchery. The chicks were not vaccinated LaSota, V4 and I 2 are ex tensively used as live against Newcastle disease at day old as attenuated vaccines for ND control (Rauw et al ., requested. They were brooded under the deep 2009). All live attenuated ND vaccines are litter system with feed and water provided ad known to stimulate both mucosal and systemic libitum as described by Sonaiya and Swan immune responses similar to those of the ( 2004). natural infection. This is because of the ability of th e viruses to replicate within the bird Ethical Issues: All applicable international, irrespective of the site of administration (Senne national, and/or institutional guidelines for the et al. , 2004). Other NDV strains used as popular care and use of animal s were followed (MRC, live vaccines include the Komorov and 2004) . Mukteswar strains, both of which are mesogenic and therefore suitable as booster vaccines Experimental Design : At three weeks of age, following priming with lentogenic isolates the chicks were laid out in a complete (Roohani et al ., 2015). randomized design (CRD) of two equal groups The strain I 2 of NDV is a thermostable of 45 chicks designated A and B. After vaccine which is becoming popular due to its separation, Group A chicks were vaccinated with many advantages such as thermostability, easy NDV - I 2 vaccine by intraocular instillations in the administration by various routes such as eye using a standard dropper according to drinking, eye drop, and mix with food, providing manufacturer’s instruction , while Group B chicks good protection against virulent virus (Miller et were not vaccinated. The various subgroups al ., 2009; Wambura, 2009), efficient ability to were housed separately; feed and water were transmit to non - vaccinated sensitive chicks provided ad libitum . At 6 weeks o f age, groups (Habibi et al ., 2015) and good results in A and B chicks were further replicated thrice reducing serum concentration of acute phase into replicates A1, A2, A3 and B1, B2, B3 of 15 proteins (Firouzi et al ., 2014). chicks each respectively (Figure 1) . After However , there have been reported separation, chicks in subgroups A2, A3, B2 and cases of o ccasional outbreaks of ND even in B3 were exposed to chicks infected with NDV. vaccinated commercial chickens ( Okoye et al ., Animal Research International (2021) 1 8(1): 4020 – 4027 Post - infection vaccination and immune status of Newcastle disease - infected chicken 4022 the infected chicks were used to infect chicks in subgroups A2, A3, B2 and B3. Morbidity and Mortality : Clinical signs and checks were observed for all the birds. Percentage morbidity was calculated by noting the number of chicks that were depressed and listless in a group and dividing by the total number of surviving chicks in the subgroup and multiplied by 100/ day. Percentage mort ality was assessed by noting the total number of dead chicks/day within the study period and this was also expressed in percentage. Collection of Blood Samples : Three millilitres Figure 1: A diagrammatic representation of the of blood each were collected from five chicks in experimental design each of the subgroups. The blood samples were allowed to clot under room temperature and the Upon manifestation of clinical infections, chicks harvested sera were stored at - 20 0 C until used in subgroups A2 and B2 were revaccinated to determine the antibody titres of the chicks on again using the same vaccine, route and days 42, 56, 63 and 70 days of age using the concentration while subgroups A3 and B3 were method s of Beard (1989) and Ruwaan et al . not vaccinated. (2009 ). Eigh t chicks were intramuscularly challenged with 0.2 ml of the virus inoculums. Serology : The sera collected on 42, 56, 63 and Four days post challenge; the infected chicks 70 days of age were used to determine the were used to infect chicks in subgroups A2, A3, antibody titres against ND (Beard, 1989). The B2 and B3 by introducing two each of the geometric mean titre (GMT ) was calculated and intramuscularly infected chicks into their expressed as the reciprocal values of the highest r espective pens. Upon manifestation of clinical dilutions that displayed hemagglutination - infections, chicks in subgroups A2 and B2 were inhibition ( HI ) as described by Villegas and revaccinated again using the same vaccine, Purchase (1989). route and concentration while subgroups A3 and B3 were not revaccinated. Statistical Analysis : Descriptive statistics using percentages were adopted to compare The Vaccine: The EID 50 value of the I 2 vaccine morbidity and mortality rates of chicks in the was determined after inoculation in 10 - day old subgroups , while GMT was used to measure the chicken embryonated eggs (from specific degree of immune responses. antibody negative (SAN) chicks) following OIE/WOAH ( 2012 ) standard. RESULTS Experimental Virus and Challenge: The Clinical Signs : Clinical signs of infection were NDV inoculum used was a velogenic strain of first observed on day six post infection ( PI ) in NDV.