Seroprevalence and Genomic Divergence of Circulating Strains of Feline Immunodeficiency Virus among Felidae and Hyaenidae Species

Abstract

Feline immunodeficiency virus (FIV) infects numerous wild and domestic feline species and is closely related to human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV). Species-specific strains of FIV have been described for domestic cat (Felis catus), puma (Puma concolor), lion (Panthera leo), leopard (Panthera pardus), and Pallas' cat (Otocolobus manul). Here, we employ a three-antigen Western blot screening (domestic cat, puma, and lion FIV antigens) and PCR analysis to survey worldwide prevalence, distribution, and genomic differentiation of FIV based on 3,055 specimens from 35 Felidae and 3 Hyaenidae species. Although FIV infects a wide variety of host species, it is confirmed to be endemic in free-ranging populations of nine Felidae and one Hyaenidae species. These include the large African carnivores (lion, leopard, cheetah, and spotted hyena), where FIV is widely distributed in multiple populations; most of the South American felids (puma, jaguar, ocelot, margay, Geoffroy's cat, and tigrina), which maintain a lower FIV-positive level throughout their range; and two Asian species, the Pallas' cat, which has a species-specific strain of FIV, and the leopard cat, which has a domestic cat FIV strain in one population. Phylogenetic analysis of FIV proviral sequence demonstrates that most species for which FIV is endemic harbor monophyletic, genetically distinct species-specific FIV strains, suggesting that FIV transfer between cat species has occurred in the past but is quite infrequent today.

Variability in assays used for detection of lentiviral infection in bobcats (Lynx rufus), pumas (Puma concolor), and ocelots (Leopardus pardalis)

“…We hypothesize that a PLV immunoblot would also be more able to identify PLV-infected pumas than FIV immunoblot. Although we did not screen enough pumas with both types of immunoblots to test this hypothesis, a previous study that demonstrated that immunoblots prepared with species-specific viral antigens were 10% more sensitive than crossspecies viral antigen supports this prediction (Troyer et al, 2005).…”

“…Sixty-three percent of bobcat, 44% of puma, and 0% of ocelot PLV immunoblot positive individuals were PCR positive, indicating that nested PCR with degenerate primers is a poor assay choice for population screening. Previous studies support this conclusion, as even species-specific (nondegenerate) primers can have low sensitivity (Brown et al, 1994;Carpenter et al, 1996;Troyer et al, 2005). Deoxyribonucleic acid PCR may have low sensitivity for detecting lentiviral strains because of low proviral load in blood cells (Blake et al, 2006;Brennan et al, 2006).…”

“…First-round primers were designed from the conserved reverse-transcriptase region of pol. GenBank sequences of FIV (accession M25381 and U11820), PLV (accession U03982), and FIV-Oma (Otocolobus manul; accession U56928) were used to design both the internal and external primers (Troyer et al, 2005). Polymerase chain reactions were performed using 5 ml of DNA (generally corresponding to 100-500 ng of genomic DNA) with 500 mM sodium chloride (KCl); 100 mM Tris-hydrochloride (HCl; pH 8.3); 25 mM magnesium chloride (MgCl 2 ); 0.025 mM (each) of deoxyadenosine triphosphate (dATP), deoxycytidine triphosphate (dCTP), deoxyguanosine triphosphate (dGTP), and deoxythymidine triphosphate (dTTP); 2 mM of each primer, and 1 unit of Taq FIGURE 1.…”

“…Host-specific lentiviruses have been isolated from numerous nondomesticated felids, including three American species: puma (Puma concolor; Carpenter et al, 1996), bobcat (Lynx rufus; Franklin et al, 2007), and ocelot (Leopardus pardalis; Troyer et al, 2005). Unlike domestic cat feline immunodeficiency virus (FIV), which can cause severe immunosuppression and human immunodeficiency virus (HIV)-like symptoms in felids, lentiviruses of wild felids have not historically been associated with significant pathogenicity (VandeWoude and Apetrei, 2006).…”

“…Study of lentivirus in wild African felids and Florida panthers suggests that assays using antigen from puma lentivirus (PLV) are more sensitive and specific than FIVbased assays, including immunoblot, IFA, and ELISA (Osofsky et al, 1996;Van Vuuren et al, 2003;Miller et al, 2006). These assays are likely to vary in sensitivity in wild species because of the substantial genetic variability among the lentiviruses infecting the different species (Troyer et al, 2005). For example, domestic cat FIV, the basis of most commercially available feline lentiviral assays, genetically varies from lion and puma viruses by 25% in its most conserved regions (Brown et al, 1994;Carpenter et al, 1996) and has only 55% amino acid identity to PLV strain 14 in the Gag domain (Langley et al, 1994), the antigenic portion of the virus most often targeted by host antibodies.…”