Genetic characterization of re-emerging Marek’s disease virus in Japanese quails in Tamil Nadu

Abstract

Marek’s disease is an important viral disease of poultry characterized by visceral lymphomas in poultry, although mortality has been significantly reduced by vaccination. However, the recent past has witnessed an emergence of more virulent strains of Marek’s disease virus (MDV) in other avian species like quails, turkeys in addition to commercial poultry in India and other countries. The present study involved molecular detection and characterization of major virulence determinants of MDV from an unvaccinated flock of Japanese quails in Tamil Nadu. The Meq oncogene sequences, with 98.6% identity matrix, revealed various amino acid substitutions and interruptions in the PPPP motifs, suggesting very virulent nature of isolate. However, vIL8 sequences showed 99.87% identity with reference database. This study has provided the first Indian quail-MDV-vIL8 sequence and third quail-MDV-Meq sequence, to be accessioned in GenBank. Phylogenetic analysis of Indian quail isolate revealed Meq sequences clustering with Nigerian MDV isolate, while vIL-8 sequences clustered with the recent Chinese and North Indian MDV isolates.