Characterisation and phylogenetic analysis of repetitive DNA sequences in the BamH1-H region of Marek’s disease virus from turkeys: Implications on viral pathogenicity and vaccine efficacy

Marek’s disease virus (MDV) is a highly pathogenic alphaherpesvirus that causes paralysis and lymphoproliferative disease in birds, posing a significant threat to the poultry industry. Though initially described in chicken, the infection is now common in other species of poultry including turkeys and quails. This study investigated MDV infection in turkeys by screening 57 tissue samples. Out of these, 26 samples tested positive. The primary focus of the study was to characterise the 132 bp tandem repeats within the BamH1-H region of the MDV genome, the number of which has been previously correlated with the virulence of MDV. Each MDV-positive sample was found to contain two copies of the 132 bp repeats. Among the positive samples, two representative samples were sequenced and further analysis revealed high per cent similarity among each other. A phylogenetic analysis was conducted, providing insights into the evolutionary relationships of the field isolates. The findings of this study might contribute to a deeper understanding of MDV and in assisting future epidemiological studies and vaccine development strategies. Keywords: Marek’s disease, 132 bp repeats, molecular characterisation, phylogenetic analysis