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.