Recent Advances in Animal Virology

Not AvailableMarek’s disease (MD) is caused by an oncogenic alphaherpesvirus, a common lymphoproliferative inducing agent usually characterized by mononuclear cellular infiltrates, mostly T-cell lymphomas in various visceral organs and peripheral nerves. The genome is linear and made up of double-stranded DNA molecules of nearly 160–180 kb in size. This was first reported by Dr. József Marek in the year 1907. Various pathotypes exist, and pathotyping is generally done based on the pathology the particular isolate induces in vaccinated and unvaccinated chickens and on their ability to overcome the effects of vaccination. Several avian species including both domesticated and wild birds are susceptible to Marek’s disease, and genetic susceptibility/resistance to MD is well characterized in chickens. The disease is highly contagious, and the transmission occurs mainly by the airborne route. The host responds to MDV infection by mounting both innate and adaptive immune mechanisms. The incidence of Marek’s disease is variable depending upon the pathotype and host susceptibility. Nerve lesions and visceral lymphomas are the prime pathologic changes noticed in MD. In the field, diagnosis is primarily based on the clinical signs and postmortem lesions. Apart from the above methods, virus isolation, identification of various viral markers in tissues, genomic detection assays (PCR, qPCR, nested PCR), and antibody detection (ELISA) aid in diagnosis of MD. Some of the strains used for vaccination are HVT, SB-1, and CVI988. Vaccination against MDV using these strains offers good protection. Despite effective vaccination regime, MD continues to be a threat to the industry due to the evolution of newer pathotypes. Thus, genetic resistance and strict biosecurity measures will be very critical adjuncts to vaccination in controlling the disease.Not Availabl

Not Available

Not AvailableThe present study was conducted to evaluate two Indian native chicken breeds, namely, Aseel and Kadaknath for fertility, hatchability, genetic parameters of juvenile growth traits, and semen quality traits at the onset of sexual maturity. The fertility was similar in Aseel (86.96%) and Kadaknath (85.15%); however, a relatively higher hatchability was observed in Kadaknath (77.94%) than Aseel (70.74%). Heritability estimates of body weights at 4 weeks of age were almost similar in Aseel (0.37) and Kadaknath (0.39), while the estimate of body weight at 6 weeks of age was higher in Aseel (0.42) than Kadaknath (0.31). The heritability estimate of shank length at 6 weeks of age was lower in Aseel (0.16) compared to Kadaknath (0.35). The age at first egg in the flock was comparable in Aseel (148 days) and Kadaknath (150 days). Aseel breed with significantly (P≤0.001) higher body weight, absolute and relative testes weights had significantly higher semen volume (P≤0.05) and sperm motility (P≤0.01) but had lower seminal plasma cholesterol level (P≤0.05) as compared to Kadaknath. It can be concluded that there is a scope for genetic improvement of these two native breeds for juvenile growth traits since heritability estimates of these traits were relatively highNot Availabl

Not Available

Not AvailableInfectious laryngotracheitis (ILT) is one of the highly infectious and contagious diseases of chickens caused by Gallid Herpesvirus 1, a member of the genus Iltovirus. It is an economically important disease in major poultry producing countries, including India. Despite India having large population of poultry birds, very limited information is available on the disease magnitude and molecular epidemiology. We screened 560 tissue samples collected from necropsied cases of tracheitis and conjunctivitis to diagnose ILT by histopathology, immunohistochemistry and polymerase chain reaction. Out of 560 samples, ILT was diagnosed in 90 (16.07%) cases by histopathology; however, polymerase chain reaction detected ILT virus (ILTV) in 128 (22.85%). Immu-nohistochemistry of representative PCR positive tissues (n=30) from trachea, lungs and conjunctiva detected viral antigen in the lining or denuded epithelial cells in 76.66% (23/30) cases. Analysis of age wise occurrence of ILT cases in our study revealed 47.65% in adult birds over 18 weeks of age, 35.15% in grower birds aged between 7 and18 weeks of age, 17.18% in chicks aged less than 6 weeks. Nucleotide sequence of gene encoding viral thymidine kinase revealed involvement of vaccine and virulent strains of ILTV in the investigated cases. Based on our findings and recent publications, we conclude that there is resurgence or re-emergence of ILT in the chicken flocks in different parts of India, indicating a possible biosecurity breach. Further genetic characterization of virus by whole genome sequencing technologies would decipher the genotype circulating in India, and help to design suitable native vaccine candidate(s).Not Availabl

Not Available

Not AvailableSepticemia in chicken is one of the main causes of death and leads to significant financial losses for the poultry farmers. There is very scarce information available in India on its pathology in chicken. Many bacterial pathogens are known to cause septicemia, either as primary agents or secondary agents, in association with other bacteria or viruses. The present study was conducted to explore the pathology in various organs of septicemic chickens. A total of 443 chicken carcasses with septicemic conditions from 71 different flocks were included in this study. The necropsy revealed 18.74%, 20.32%, and 60.95% of birds with mild, moderate and severe gross lesions respectively. Polyserositis with lesions such as hepatomegaly, splenomegaly and necrosis in the liver as well as generalized congestion were reported more frequently. On histopathological investigation, the more severe lesions were detected in the following organs: in decreasing order, the heart (66.20%), liver (64.79%), lungs (60.56%) and spleen (57.75%). Various microscopic lesions characteristic of septicemia have been reported, earlier ranging from acute inflammatory reactions such as vascular changes to chronic lesions such as granulomatous inflammation and fibrosis. Here, we made a first attempt to score gross and histopathological changes of septicemia in chicken and identified, described and documented the most common and distinctive septicemic lesions in different organs. This study was limited to 71 flocks of chicken suspected of septicemia due to limited logistics and time constraints. Hence detailed longitudinal study involving different types of birds with large sample size is required to elucidate the pathology of septicemia in chickens and to learn more about associated pathogens.Not Availabl

Not Available

Not AvailableGallibacterium anatis is a Gram-negative bacterium of the Pasteurellaceae family that resides normally in the respiratory and reproductive tracts in poultry. It is a major cause of oophoritis, salpingitis, and peritonitis, decreases egg production and mortality in hens thereby severely affecting animal welfare and overall productivity by poultry industries across Europe, Asia, America, and Africa. In addition, it has the ability to infect wider host range including domesticated and free-ranging avian hosts as well as mammalian hosts such as cattle, pigs and human. Evaluating the common virulence factors including outer membrane vesicles, fimbriae, capsule, metalloproteases, biofilm formation, hemagglutinin, and determining novel factors such as the RTX–like toxin GtxA, elongation factor-Tu, and clustered regularly interspaced short palindromic repeats (CRISPR) has pathobiological, diagnostic, prophylactic, and therapeutic significance. Treating this bacterial pathogen with traditional antimicrobial drugs is discouraged owing to the emergence of widespread multidrug resistance, whereas the efficacy of preventing this disease by classical vaccines is limited due to its antigenic diversity. It will be necessary to acquire in-depth knowledge on important virulence factors, pathogenesis and, concerns of rising antibiotic resistance, improvised treatment regimes, and novel vaccine candidates to effectively tackle this pathogen. This review substantially describes the etio-epidemiological aspects of G. anatis infection in poultry, and updates the recent development in understanding the pathogenesis, organism evolution and therapeutic and prophylactic approaches to counter G. anatis infection for safeguarding the welfare and health of poultry.Not Availabl

Not Available

Not AvailableBacterial septicemia causes huge economic losses in the poultry industry and there is no systematic research available in India on the connection of various pathogens associated with septicemia. The present molecular epidemiological study was conducted to investigate the association of different bacterial and immunosuppressive viral pathogens in septicemia suspected chickens. A total of 443 chicken carcasses with septicemic conditions from 71 different flocks were included in this study. Heart blood swabs were subjected to bacterial culture for Salmonella spp., Pasteurella multocida, Escherichia coli, and Gallibacterium anatis. Of these 51 flocks tested for E. coli, 49 (96.1%) flocks were found positive. Among flocks tested for Salmonella spp., 2 flocks were found positive. All tested flocks were found negative for G. anatis and P. multocida as well as air sac swabs tested negative for Mycoplasma spp. Bacterial cultural examination revealed that majority of septicemic chickens were found to be infected with E. coli and these E. coli isolates showed the highest resistance to vancomycin (60%), followed by erythromycin (50%) and cefotaxime (38%) and maximum sensitivity to cefotaxime and clavulanic acid combinations (81.5%), followed by chloramphenicol (69.6%) and ertapenem (67.2%). Among the 5 avian pathogenic E. coli (APEC) virulence genes were detected in 36 flocks and highest frequency of iss (100%), followed by ompT or iutA (97.2%), hly (61.1%) and iroN (47.2%) genes. On polymerase chain reaction (PCR) screening, 10.5, 4.5, 52.2, 19.4, 9.0, 4.5, 20.1 and 19.4% of the flocks were positive for G. anatis, Ornithobacterium rhinotracheale, APEC, Salmonella spp., Mycoplasma gallisepticum, Mycoplasma synoviae, chicken infectious anemia virus and Marek's disease virus, respectively. To our knowledge, the present study is first on the etiology of septicemia in chicken flocks in India. The present study infers that the majority of septicemic deaths in broiler chickens less than 8 weeks have been connected with APEC and majority of E. coli isolates are multidrug resistance, suggesting the need for surveillance and intervention to curb the inadvertent use of antibiotics. Although, incidence of G. anatis association with septicemia was reported, still requires a rigorous epidemiological study to determine the actual prevalence. However, more detailed studies encompassing vast geographical area with large sample size and long duration of the studies are necessary to provide a clear picture of the interaction of different pathogens causing septicemia in chicken.Not Availabl