Figure 5.

HIV-2 origins. The phylogenetic relationships of representative SIVsmm and HIV-2 strains are shown for a region of the viral gag gene (SIVmac239 coordinates 1191–1921). SIVsmm and SIVmac are shown in black; the eight groups of HIV-2, each of which represents an independent cross-species transmission, are shown in different colors. The phylogenetic tree was estimated using maximum likelihood methods (Guindon and Gascuel 2003). The scale bar represents 0.05 nucleotide substitutions per site.