Bovine Leukemia Virus (BLV) could be subdivided into up to seven groups based on phylogenetic and similarity analyses of sequences from the env gene

Bovine Leukemia Virus (BLV) Could be Subdivided into up to Seven Groups Based on Phylogenetic and Similarity Analyses of Sequences from the env Gene. Rodríguez, S.M., Trono, K., Jones, L.R., Golemba, M., Campos, R. Instituto De Virología - Cicvya - Inta Castelar We sequenced the env gene from 28 BLV field strains from Argentina, and combined these sequences with 45 env sequences representing all the genetic groupings identified previously. These data were analyzed by phylogenetic analysis and similarity comparisons. Phylogenetic analyses showed the existence of five groups of sequences or genotypes. Four genotypes were supported by high bootstraps (89–100) and posterior probabilities (p=1.0), and the fifth one was supported by a high posterior probability (p=1.0) and moderate bootstrap (80–96) values. All these genotypes have one or more counterparts among the groupings identified previously, and thus many groups that were originally named differently correspond actually to the same genotype. Two sequences did not cluster with any other sequence, and were highly divergent when compared to the five groups mentioned above. This indicates that two extra genotypes could exist. The similarity comparisons were highly congruent with the phylogenetic analyses. The mean number of pair wise nucleotide substitutions between sequences from the same genotype was 11.1 (min. 6.5; max. 19), whereas it was 39.6 (min.36.8; max. 47.9) between sequences from different genotypes. Likewise, the mean number of amino acid substitutions in pair wise comparisons at the intra-genotype level was 3.3 (min. 0.4; max. 6.2), whereas it was 9.6 (min. 8.3; max. 13.5) at the inter-genotype level. Our analyses confirmed the existence of geographic clusters (p=6.838E-15, Chi2 test; p=4.583E-12, Fisher’s exact test)