Preliminary seroepidemiological studies carried out on clinical cases suggested that FIV infection is widespread in the domestic cat population of Argentina [65] . The genetic diversity of FIV isolates from Argentine domestic cats has been well characterized [47, 75] . FIV isolates were isolated from peripheral blood mononuclear cells of four domestic cats. Phylogenetic analysis revealed that one isolate clustered with subtype B and the others formed subtype E [47] , prototype sequence for this group (Figure 2) .