Comprehensive analysis of Marek’s disease virus in Turkeys: Kerala, India

Abstract

The increasing prevalence of Marek's disease (MD) in turkeys poses a significant threat to the poultry industry, necessitating efficient and reliable methods for identifying virulent strains. This study focuses on evaluating molecular techniques as a practical alternative to traditional pathotyping assays, which are often time-consuming and labour-intensive. By analysing critical genetic markers such as meq, vIL-8, pp38 and the 132 bp repeats in the BamH1-H region of MDV genome, the research aims to accurately determine the pathotypes of Marek's disease virus (MDV) responsible for recent outbreaks in turkeys in Kerala. A total of 129 clinical samples were screened using polymerase chain reaction (PCR), out of which 27 tissue specimens tested positive for MDV. Pathotype marker genes were identified in all positive samples, and they revealed mutations characteristic of v and vv pathotypes, but not of the vv+ pathotype. Additionally, double 132 bp repeats were identified, a feature known to be characteristic of pathogenic strains. These findings suggest that the outbreak may be caused by v or vv pathotypes, with no indication that the virus has evolved into the more virulent vv+ pathotype. It also explores the genetic diversity of MDV through phylogenetic analysis, providing insights into the virus's evolution and adaptation. The study forms the first report on molecular characterisation and phylogenetic analysis of MDV in turkeys in India.