Nucleotide sequences of Australian isolates of the feline immunodeficiency virus: comparison with other feline lentiviruses.

Proviral DNA from four Australian isolates of feline immunodeficiency virus (FIV) was amplified by PCR and the nucleotide sequence determined for two conserved regions within gag (p15/p24) and pol (RT) genes. Comparison with the nucleotide and deduced amino acid sequence of two previously described U.S. isolates from California (Petaluma and PPR), and a third from Maryland (MD) as well as the Japanese isolate TM2, revealed a close similarity between the Australian and Californian isolates with 95-97% nucleotide and 96-99% amino acid homologies. By contrast, the Maryland and Japanese isolates were more distantly related with only 84-87% nucleotide and 90-94% amino acid homology with either the Australian or Californian isolates. The relationship of the Australian FIV isolates to other domestic isolates as well as eight lentiviral isolates from wild felidae (panthers) published previously, was investigated further by constructing a phylogenetic tree based on the pol sequence. This revealed two subgroups of FIV, an Australian/Californian group and a less tightly clustered Maryland/Japanese group. These results suggest that the genomic variability of FIV is reflected by more than simply geographic distance. Furthermore, the relative genetic homogeneity found between Australian isolates suggest a shorter period of evolution of the virus in Australia than in North America.