Molecular Characterization of the Env Gene of Bovine Leukemia Virus in Dairy Cattle from Novosibirsk region, Russia

Bovine leukemia virus (BLV) is a retrovirus with oncogenic potential and it is the etiologic agent of enzootic bovine leukemia, widespread throughout the world. The paper presents data on BLV prevalence and diversity in the Novosibirsk region of Russia. PCR diagnos-tics of 200 animals in a large livestock farm and 117 animals from private farms showed prevalence varied from 0 to 79% in private farms and 72% in the large farm. To assess circulating BLV diversity, 232 blood samples positive for the primary immunodiffusion reaction were additionally collected from five large farms. In total, 1000 bps BLV frag-ments encoding the env gene region were obtained for 417 BLV samples. Phylogenetic analysis assigned 325 studied BLV variants to genotype 4, and 92 virus variants to geno-type 7. A pairwise identity matrix was plotted for 270 amino acid residues. Pairwise iden-tity of BLV amino acid sequences with chain start in gp51 varied for genotypes G4 and G7 within 96.6% to 100% and 97.4% to 100%, respectively. Multiple alignment of the studied amino acid sequences identified 54 mutations characteristic of Russian BLV genovariants. This study is a significant addition to knowledge on BLV molecular epidemiology in Russia.