Identification of three feline immunodeficiency virus (FIV) env gene subtypes and comparison of the FIV and human immunodeficiency virus type 1 evolutionary patterns

Abstract

Feline immunodeficiency virus (FlI) is a lentivirus associated with AIDS-like illnesses in cats. As such, FIV appears to be a feline analog of human immunodeficiency virus (HIV). A hallmark of HIV infection is the large degree of viral genetic diversity that can develop within an infected individual and the even greater and continually increasing level of diversity among virus isolates from different individuals. Our goal in this study was to determine patterns of FIV genetic diversity by focusing on a 684-nucleotide region encompassing variable regions V3, V4, and V5 of the FIV env gene in order to establish parallels and distinctions between FIV and HIV type 1 (HIV-1). Our data demonstrate that, like HIV-1, FIV can be separated into distinct envelope sequence subtypes (three are described here). Similar to that found for HIV-1, the pairwise sequence divergence within an FIV subtype ranged from 2.5 to 15.0%, whereas that between subtypes ranged from 17.8 to 26.2%. However, the high number of synonymous nucleotide changes among FIV V3 to V5 env sequences may also include a significant number of back mutations and suggests that the evolutionary distances among FIV subtypes are underestimated. Although only a few subtype B viruses were available for examination, the pattern of diversity between the FIV A and B subtypes was found to be significantly distinct; subtype B sequences had proportionally fewer mutations that changed amino acids, compared with silent changes, suggesting a more advanced state of adaptation to the host. No similar distinction was evident for HIV-1 subtypes. The diversity of FIV genomes within individual infected cats was found to be as high as 3.7% yet twofold lower than that within HIV-1-infected people over a comparable region of the env gene. Despite these differences, significant parallels between patterns of FIV evolution and HIV-1 evolution exist, indicating that a wide array of potentially divergent virus challenges need to be considered in FIV vaccine and pathogenesis studies.

S1 gene-based phylogeny of infectious bronchitis virus: An attempt to harmonize virus classification

“…Importantly, however, viral phylogenies based on a single gene (as here) have been previously used to establish viable classification schemes. Notable examples include members of genus Enterovirus (Mirand et al, 2006;Oberste et al, 1999), pestiviruses such as BVDV-1 (Deng et al, 2012;Vilcek et al, 2001) and BVDV-2 (Flores et al, 2002;Jenckel et al, 2014;Weber et al, 2015), circoviruses such as PCV2 (Franzo et al, 2015;Grau-Roma et al, 2008;Segalés et al, 2008), and lentiviruses such as FIV (Marçola et al, 2013;Sodora et al, 1994). In the case of IBV we propose that an effective classification scheme, particularly the designation of lineages and genotypes, should be based on clearly identifiable genetic groups (i.e.…”

Molecular epidemiology of feline immunodeficiency virus in the domestic cat (Felis catus)

“…Five FIV Fca , subtypes, A to E, ( Fig. 1) have been established based on phylogenetic analyses of sequences from the env V3-V5 region (Sodora et al, 1994;Kakinuma et al, 1995;Pecoraro et al, 1996). Recent papers have also used the gag gene to confirm the env clades (Kakinuma et al, 1995;Duarte et al, 2002;Steinrigl and Klein, 2003;Reggeti and Bienzle, 2004;Weaver et al, 2004;Hayward and Rodrigo, 2008).…”

Effect of dual-subtype vaccine against feline immunodeficiency virus infection

“…FIV is a typical lentivirus with ultrastructural morphology, structural protein profile, and reverse transcriptase requirement resembling human and simian immunodeficiency viruses (HIV and SIV). The FIV isolates from domestic cats have been classified into five subtypes, designated A [USA (California) and Europe], B [Japan and USA (except California)], C (Canada), D (Japan) and E (Argentina) by comparing the 684-nucleotide sequences (variable regions V3 through V5) of the FIV env gene (Kakinuma et al, 1995;Pecoraro et al, 1996;Sodora et al, 1994). The hallmark of FIV infection in domestic cats is the immunodeficiency syndrome caused by the severe loss of CD4 + T cells with a concomitant decline in the CD4/CD8 ratio (Ackley et al, 1990;Barlough et al, 1991;Hoffmann-Fezer et al, 1992;Novotney et al, 1990;Torten et al, 1991).…”