Equine infectious anemia virus gag and pol genes: relatedness to visna and AIDS virus.

Comparison of HTLV-III, the putative AIDS virus, with other related viruses, may help to reveal more about the origin of AIDS in humans. In this study, the nucleotide sequence of the gag and pol genes of an equine infectious anemia virus (EIAV) proviral DNA clone was determined. The sequence was compared with that of HTLV-III and of visna, a pathogenic lentivirus of sheep. The results show that these viruses constitute a family clearly distinct from that of the type C viruses or the BLV-HTLV-I and -II group. Within the family, EIAV, HTLV-III, and visna appear to be equally divergent from a common evolutionary ancestor.