Evolution of feline immunodeficiency virus in Felidae: implications for human health and wildlife ecology.

Genetic analyses of feline immunodeficiency viruses provide significant insights on the worldwide distribution and evolutionary history of this emerging pathogen. Large-scale screening of over 3000 samples from all species of Felidae indicates that at least some individuals from most species possess antibodies that cross react to FIV. Phylogenetic analyses of genetic variation in the pol-RT gene demonstrate that FIV lineages are species-specific and suggest that there has been a prolonged period of viral-host co-evolution. The clinical effects of FIV specific to species other than domestic cat are controversial. Comparative genomic analyses of all full-length FIV genomes confirmed that FIV is host specific. Recently sequenced lion subtype E is marginally more similar to Pallas cat FIV though env is more similar to that of domestic cat FIV, indicating a possible recombination between two divergent strains in the wild. Here we review global patterns of FIV seroprevalence and endemnicity, assess genetic differences within and between species-specific FIV strains, and interpret these with patterns of felid speciation to propose an ancestral origin of FIV in Africa followed by interspecies transmission and global dissemination to Eurasia and the Americas. Continued comparative genomic analyses of full-length FIV from all seropositive animals, along with whole genome sequence of host species, will greatly advance our understanding of the role of recombination, selection and adaptation in retroviral emergence.