Suresh, PJohnson Rajeswar, JSukumar, KHarikrishnan, TJSrinivasan, PTANUVAS2020-03-122020-03-122020-01http://krishikosh.egranth.ac.in/handle/1/5810145281TNV_IJAR_2020_54(1)83-89This study was undertaken to characterize the oncogenicity associated vIL8 (viral interleukin-8) gene at molecular level for three serotype 1 Marek’s Disease Virus (MDV) field isolates recovered from vaccinated poultry flocks. The prime aim was to generate nucleotide sequence data for important oncogenicity associated vIL8 gene of MDV1 which is very much lacking in India. Eighty six blood samples were collected from 15 commercial layer and broiler breeder farms. Isolation was done in duck embryo fibroblasts (DEF) and vIL8 gene was amplified by Polymerization Chain Reaction (PCR) and sequenced. The isolates were shown to have a homology of 99.8-100 per cent within themselves and 94.6-95.1 per cent with various isolates of China and 96.6 – 99.5 per cent with other isolates of USA for vIL8 gene. Alignment analysis of the nucleotide sequences had shown nucleotide mutations at three different positions and displayed perfect regularity. Phylogenetic analysis of vIL8 sequence of three isolates and other six reference strains showed that the analyzed nine MDVs could be distinctly separated into two clusters. The study revealed that the field isolates of serotype 1 MDVs circulating in vaccinated flocks had been shown to have consistent mutations in different positions in vIL8 gene.enVeterinary ScienceArticle