Feline immunodeficiency virus subtypes A, B and C and intersubtype recombinants in Ontario, Canada

Abstract

Knowledge of the geographical distribution of feline immunodeficiency virus (FIV) subtypes is important for understanding different disease courses and for vaccine design. Intersubtype recombination may develop in areas where more than one subtype is prevalent and has the potential to create new transmittable variants with novel pathogenic properties. In this study, 40 FIV-positive DNA samples were classified by sequence analysis of the LTR–gag region. Phylogenetic analysis indicated that 32 Canadian FIV isolates clustered with previously identified subtypes A, B and C and that subtype A was most frequent in Ontario. Four strains with inconsistent clade assignment were further analysed by sequencing of the env–LTR regions. Comparisons of phylogenetic trees constructed from the two different regions of the genome and analysis of similarities to reference sequences yielded classification of three samples as A/B and one as A/C intersubtype recombinants. Although the A/B recombinant samples were obtained from unrelated cats in geographically disparate regions, a common breakpoint was consistently identified within gag. In addition, there was no evidence of co-infection with parental strains of subtypes A and B as indicated by PCR-based limiting dilution assays, although these assays allowed for the identification of two different recombinant viruses co-existing in one sample. Both sequences contained the same breakpoint. These findings suggested that a new circulating recombinant FIV may be enzootic in Ontario.

Genetic diversity of Brazilian isolates of feline immunodeficiency virus

“…The sequence of the env gene is particularly important since the envelope glycoprotein is the major target for virus neutralization [21,31] and it may be possible to establish potential associations between specific subtypes and the severity of clinical outcomes [30].…”

Phylogenetic Analysis of Feline Immunodeficiency Virus in Feral and Companion Domestic Cats of New Zealand

“…A recent study identified a distinct group of FIV isolates from Texas that possibly represent a new subtype (32). In addition, intersubtype recombination has been detected in natural populations (1,4,23).…”

Evidence for Recombination Between Feline Panleukopenia Virus and Canine Parvovirus Type 2

“…Recombination may modify viral properties and aid adaptation to new host species. This applies also to RNA viruses infecting cats and dogs; for example, group 1 feline and canine coronaviruses [8,21], feline calicivirus [4], feline immunodeficiency virus [2,7,10,29], and canine distemper virus [6]. Recently Shackelton et al [31] found some evidence of natural recombination among porcine, mink, and rodent parvoviruses by analyzing the genetic data deposited in databases, and discussed the possibility that recombination may be important in the natural evolution of parvoviruses, especially in circumstances where parvoviruses cause persistent infections.…”