Phylogenetic analysis of Portuguese Feline Immunodeficiency Virus sequences reveals high genetic diversity.

Feline Immunodeficiency Virus (FIV) is a Lentivirus responsible for an immunodeficiency like disease in domestic cats. Based on the genetic diversity of the V3-V5 region of env gene FIV is divided in five phylogenetic subtypes (A, B, C, D and E) with a world-wide distribution. To understand the subtype diversity of FIV in Portugal a serological survey was conducted during 1 year in the Veterinary Faculty Hospital, Lisbon, Portugal to identify seropositive animals. Two viral genomic regions were amplified by a nested PCR, sequenced and the phylogenetic relationships between 24 new Portuguese FIV sequences and other previously published FIV isolates were assessed. The introduction of these sequences induced a subclustering in subtype B including most of the new Portuguese sequences. Moreover, a new cluster emerged, with two highly divergent new sequences that might represent a new subtype. The study of these new FIV isolates showed the presence in Portugal of a unique viral population subclustering within subtype B and of sequences clearly divergent from the five known subtypes, providing a contribution for the understanding of FIV's genetic diversity.