Phylogenetic relationship of Bulgarian HIV-1 subtype B polymerase sequences.

<p>The 691-bp alignment was composed of 104 Bulgarian HIV-1 B strains and 45 subtype B reference sequences from the Los Alamos HIV database. Antiretroviral resistance-associated mutations were stripped from the alignment. The tree was rooted by using an HIV-1 subtype A1 strain as the outgroup. Tree topology was inferred using maximum likelihood analysis implemented in MEGA5. Support for each node was determined using 1,000 bootstrap replications with only values ≥70 shown. Scale bar indicates the number of nucleotide substitutions per site. Nearly identical tree topologies were also obtained with Bayesian analysis. Bulgarian sequences are shown using green branches and taxon names.