Nucleotide sequence analysis of SA-OMVV, a visna-related ovine lentivirus: phylogenetic history of lentiviruses.

ABSTRACT

The nucleotide sequence analysis of the visna-related South African Ovine Maedi Visna virus (SA-OMVV) demonstrates extensive genetic polymorphism among ovine lentiviruses. Differences between visna virus and SA-OMVV proteins range from 8.5 to 35% mismatched amino acids. Moreover, there is a new open reading frame (orf W) in the central part of the genome. A phylogenetic history calibrated by the divergence and isolation dates of these two ovine lentiviruses shows that radiation of the lentiviridae family is a recent event. Visna virus and SA-OMVV evolved independent of each other for about 42 years. The inferred molecular clock was used to calculate the minimal time elapsed since the divergence of some lentiviruses 93 years for ovine and caprine lentiviruses, 430 years for ungulate and primate lentiviruses, and roughly 200 years for HIV-1, HIV-2, and SIVAGM. BRU, ELI, and MAL HIV-1 isolates diverged in the early 1960s.