Genetic  Diversity of the BLV env Gene and gp51 Mutations in Genotypes G4 and G7 Circulating in Dairy Cattle in the Novosibirsk Region (Western Siberia, Russia)

Bovine leukemia virus (BLV) is an oncogenic retrovirus and the etiological agent of enzootic bovine leukosis (EBL), which is spread worldwide. This study presents data on the genetic diversity of BLV in the Novosibirsk region of Russia. ELISA-positive samples were selected from six districts of the Novosibirsk region (Dovolnoye, Barabinsk, Tatarsk, Toguchin, Bolotnoye, and Kochenyovo districts). To assess the diversity of circulating BLV genotypes, samples were collected from settlements and districts that were geographically distant from each other and had no shared pasture lands. In total, 1410 bp fragments encoding the env gene region were obtained from 417 BLV-positive samples. Phylogenetic analysis classified 325 BLV strains (77.9%) as genotype 4 (G4) and 92 strains (22.1%) as genotype 7 (G7). A pairwise identity matrix was constructed for 268 amino acid residues. Pairwise identity of BLV amino acid sequences in the gp51 region ranged from 96.6% to 100% for G4 and from 97.4% to 100% for G7. Multiple alignment of the amino acid sequences identified 74 mutations found in the Russian BLV variants. Through the addition of 417 novel env BLV sequences to GenBank, this study significantly expands the foundational data and knowledge of BLV molecular epidemiology in Russia.