Fig. 3

Phylogenetic representation of the HTLV-1 genotypes and subgroups. An alignment of complete LTR sequences (774-nt long) from 178 HTLV-1 strains was obtained. The unrooted phylogenetic tree was generated with the neighbor-joining method using the GTR model (gamma = 0.4953). Branch lengths are drawn to scale, with the bar indicating 0.01 nucleotide replacement per site. Numbers on each node indicate the percentage of bootstrap samples (of 1000 replicates). HTLV-1 genotypes (a–g) and subgroups (within HTLV-1a and HTLV-1c) are presented. References strains (presented in the table) are indicated in the tree, except Mel1 and Ethio10 for which the complete LTR sequence is not available