FIG. 2.

Rooted phylogenetic tree of PTLV sequences. The tree was generated by the neighbor-joining method based on a 422-bp fragment that corresponds to the LTR (a) and a 522-bp fragment that corresponds to a region of env (b). The HTLV-1 subtype isolate Mel5 was used as an outgroup. The trees were statistically evaluated with a bootstrap analysis with 1,000 bootstraps. Bootstrap values for the major branch points are given as percentages. The different PTLV-1 subtypes are indicated as previously described (7, 10, 14, 15, 16, 21, 25). The strains identified in the chimpanzees and the red colobus monkey of the Taï Forest are highlighted by shaded boxes.