Vol. 9, Issue 6, Part D (2024)

Neoplastic diseases of poultry caused by viruses are of greater economic importance. These viruses include Marek’s disease virus (MDV), avian leukosis virus (ALV) containing subtypes A to J and the reticuloendotheliosis virus (REV). The aim of the present study was to investigate the natural co-infection of Marek’s disease virus (MDV) and avian leukosis virus in the backyard poultry. A backyard poultry farm consisting of 2000 Aseel cross birds was reared as intensive system of management at Madurai district of Tamil Nadu. There was mortality of 0.5 to 1 percent at 11th weeks of age and the mortality was increased up to 4 to 5 percent at 12th weeks of age. The infected flock showed the clinical signs of dullness, depression and stunted growth. Post mortem examination revealed that enlarged liver with various sized white foci on the surface, enlarged spleen and thickening of proventriculs. Samples i.e. liver, spleen and feather follicles were collected for histopathology and molecular diagnosis. Histopathology of liver revealed multifocal, random dense coalescing infiltration of pleomorphic population of lymphoid cells. Polymerase chain reaction (PCR) test demonstrated that the amplification of Marek’s disease virus serotype 1 meq gene (583 bp) from liver, spleen and feather follicle samples and env gene (295-326 bp) of avian leukosis virus subtypes A to E from liver and spleen samples. However, the samples were negative for avian leukosis virus subtype J. In conclusion, the study has demonstrated that natural co-infection of two ongogenic viruses (Marek’s disease virus and Avian leukosis virus) in Aseel cross chicken by the examination of gross and histopathological lesions and confirmatory molecular detection.