The Molecular Characterization of Bovine Leukaemia Virus Isolates from Eastern Europe and Siberia and Its Impact on Phylogeny

Recent studies have shown that bovine leukemia virus (BLV) sequences can be classified into seven distinct genotypes based on full gp51 sequence. This classification was based on available sequence data that mainly represented the BLV population that is circulating in cattle from the US and South America. In order to aid with a global perspective inclusion of data from Eastern Europe is required. In this study we examined 44 BLV isolates from different geographical regions of Poland, Belarus, Ukraine, and Russia. Phylogenetic analysis based on a 444bp fragment of env gene revealed that most of isolates belonged to genotypes 4 and 7. Furthermore, we confirmed the existence of a new genotype, genotype 8, which was highly supported by phylogenetic computations. A significant number of amino acid substitutions were found in the sequences of the studied Eastern European isolates, of which 71% have not been described previously. The substitutions encompassed mainly the C-part of the CD4+ epitope, zinc binding peptide region, CD8+ T cell epitope, and overlapping linear epitope E. These observations highlight the use of sequence data to both elucidate phylogenetic relationships and the potential effect on serological detection of geographically diverse isolates.