Early Detection of Avian Oncogenic Viruses from Blood of Apparently Healthy Chickens

Viral neoplasms in commercial poultry are mainly caused by members of two families with Marek’s disease virus (MDV) belonging to Herpesviridae and reticuloendotheliosis virus (REV), avian leukosis virus subgroups A to E and avian leukosis virus subgroup J (ALV-J) belonging to Retroviridae. This study was conducted to know the status of neoplasms caused by avian oncogenic viruses in commercial chickens. 25 blood samples were collected from a broiler breeder flock that appeared healthy but chickens from the flock on necropsy showed visceral tumours. PCR was employed on blood DNAs of these chickens for detection of avian oncogenic viruses which eventually detected the presence of multiple oncogenic virus infection in most birds. MDV specific primers that could differentiate between pathogenic and non-pathogenic serotype-1 virus detected MDV in four blood DNAs. REV could be detected from all the 25 blood DNAs and endogenous ALV was detected in 21 blood DNAs signifying the slow transforming nature of the retroviruses that may take months to perpetuate visible tumours. It was concluded that concurrent presence of multiple oncogenic viruses in the same bird is more common than the presence of single virus. Thus, for early disease control programs, this moderately simple PCR diagnostic technique can be utilized to identify the birds undergoing latent infection with avian oncogenic viruses.