Molecular and Pathological Analysis of Oncogenic Virus Induced Multiple Infections in Chickens Reared Under Indian Conditions

• Published in: National Academy science letters 2013-06, Vol.36 (3), p.271-277
• Main Authors: Mitra, Namita, Verma, Ramneek, Singh, Amarjit
• Format: Article
• Language: English
• Subjects: Avian leukosis; Birds; Chickens; History of Science; Humanities and Social Sciences; Infections; Leukosis; Marek's disease; multidisciplinary; Necropsy; Neoplasia; Neoplasms; Pathogenicity; Pathogens; Polymerase chain reaction; Poultry; Research Article; Science; Science (multidisciplinary); Subgroups; Tumor viruses; Vaccination; Vaccines; Viruses
• ISSN: 0250-541X; 2250-1754
• DOI: 10.1007/s40009-013-0130-6

Avian oncogenic viruses viz. Marek’s disease virus serotype-1 (MDV-1), reticuloendotheliosis virus (REV), avian leukosis virus (ALV) subgroups A, B, C, D, E and J can induce neoplastic infections in poultry. In order to identify the prevalence of these viruses in chickens reared under Indian conditions, the present study was conducted on chickens brought for necropsy at the poultry diagnostic laboratory. PCR was employed on 50 DNA samples isolated from chicken neoplasms. Despite vaccination with HVT vaccine strain, MDV-1 was detected in 82 % cases (41/50) of necropsied chickens, consequently referring to the apparent evasion of vaccine protection. REV was detected in 56 % cases (28/50) and ALV in 66 % cases (33/50). Out of 33 samples that were positive for ALV, 24 were detected with ALV subgroup E which is an endogenous virus with little or no pathogenicity including one sample that was positive for both ALV-E and pathogenic ALV-A. However, histopathological analysis detected 41 cases of Marek’s disease, 10 cases of reticuloendotheliosis and one case of lymphoid leukosis (cases inclusive of single and multiple infections). Multiple infection with all the three viruses infecting the same bird at the same time was observed as the most prevalent condition with MDV + REV + ALV combination in 38 % (19/50) samples, whereas MDV + REV and MDV + ALV in 16 % (8/50) samples each and REV + ALV in 2 % (1/50) samples. The difference observed between the proportion of PCR positive and histopathologically positive cases suggested that PCR detected slow transforming retroviral infection as well. Infection of two or more oncoviruses in the same bird was more frequent than the single virus infection and Marek’s disease was the most prevalent oncogenic infection recorded in the poultry birds.