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Phylogeny of lentiviruses. The evolutionary relationships among Pol sequences (∼ 770 amino acids) derived from various mammalian lentiviruses; host species are indicated at the right. Exogenous viruses are depicted in black, with HIV-1, HIV-2, and SIVmac highlighted in red; endogenous viruses are shown in purple. The phylogenetic tree was estimated using maximum likelihood methods (Guindon and Gascuel 2003). The scale bar represents 0.10 amino acid replacements per site.
