Identification of very virulent marek’s disease virus strains in India by sequence analysis of 132 bp repeats of BamH-HI region

Abstract

The present study was aimed to screen the poultry samples for MDV (Marek’s disease virus) from Directorate of Poultry Research poultry farms (DPRF) and commercial poultry farms (CPF) in and around Hyderabad. The MDV was diagnosed with polymerase chain reaction using primers targeting for 132 bp repeats of BamHI-H region. The product of 302 bp and 434 bp were amplified in DPRF and CPF samples. Analysis of sequenced nucleotide data showed that the difference exist due to the presence of one or two repeats of 132 bp repeats in BamH-HI region. The homology was observed between all Indian and other published strains for 132 bp repeats of BamH-HI region. The percent of identity of DPR-2 (CPF) was 96.7 and 100% with DPR-3 (DPRF) and MDV-Anand4 isolate, respectively. The phylogenetic analysis of 132 bp repeats of BamH-HI Region of MDV revealed that the DPR-3(DPRF), DPR-2(CPF) and other Indian strains were clustered with very virulent plus pathogenic strain (584A), very virulent strains (595 and Md5)and virulent to moderate pathogenic strains, respectively. The present study seems the first report for the identification of single 132 bp repeats of MDV strains in India. This virulence may be due to the continuous adaptation of virus in poultry birds of different age groups and breeds maintained in DPR poultry farms. Therefore, there is a need to develop a new strategy and vaccines for birds against new highly virulent strains of the virus.