Viruses related to domestic cat FIV occur also in nondomestic felids, indeed FIV strains have been present in the nondomestic cat population for longer than domestic cats [45] . Carpenter et al. (1996) comment that members of at least eighteen of the 37 species in the family Felidae carry an FIV-related virus, as has been shown by the presence in their sera of antibodies which react with FIV antigens. A further twelve species were reported in another study that employed a three-antigen Western blot screening (cat, puma and lion FIV antigens) and a multigene PCR amplification of FIV genes [66] . In South America, 12 [74] . Lentiviruses in eight of these species have been detected in South America [6, 10, 19, 20, 33, 55, 66] .