It remains to be demonstrated that FIV-related viruses cause severe disease in species other than the domestic cat [6, 38] . The apparent absence of clinical signs in pumas and lions may reflect a longer period of coevolution between virus and host in these species, whereas in the domestic cat, the virus and host have not yet had time to reach a similar state of nonpathogenic coexistence [6, 7, 57] . However, it is by no means certain that FIV does not cause disease in non-domestic cats. Not long ago, reports have shown immune depletion associated with FIV infection in lions and pumas [56, 57] and another recent study reported evidence of immune suppression in the Pallas' cat (Otocolobus manul), including histopatological changes [8] . In addition, interspecies transmission (although is rare) may occur [22, 67] . For example, a leopard cat (Felis bengalensis) was found to be infected with a domestic cat virus [42] and FIV infecting one puma was more characteristic of domestic cat FIV rather than puma FIV [10] .