Emergence of CD134 cysteine-rich domain 2 (CRD2)-independent strains of feline immunodeficiency virus (FIV) is associated with disease progression in naturally infected cats

Abstract

BackgroundFeline immunodeficiency virus (FIV) infection is mediated by sequential interactions with CD134 and CXCR4. Field strains of virus vary in their dependence on cysteine-rich domain 2 (CRD2) of CD134 for infection.FindingsHere, we analyse the receptor usage of viral variants in the blood of 39 naturally infected cats, revealing that CRD2-dependent viral variants dominate in early infection, evolving towards CRD2-independence with disease progression.ConclusionsThese findings are consistent with a shift in CRD2 of CD134 usage with disease progression.Electronic supplementary materialThe online version of this article (doi:10.1186/s12977-014-0095-7) contains supplementary material, which is available to authorized users.

Central and peripheral reservoirs of feline immunodeficiency virus in cats: a review

“…These findings agreed with evidence for FIV Env-CD134 binding patterns changing over time in individually infected animals, which may ultimately influence viral cell surface affinity due to nucleotide base changes in env and reflect isolates sensitive to circulating anti-CD134 autoantibodies [44][45][46]. Recent studies further [47]. Variants characterized as Env recombinant viruses have also been described [48].…”

Neutralising antibody response in domestic cats immunised with a commercial feline immunodeficiency virus (FIV) vaccine

“…Phylogenetic analysis of full length env sequences revealed that cat SV1 was infected with a recombinant clade A/B isolate of FIV, the major parent being related to the Clade A isolate GL8. Furthermore, the receptor utilisation phenotype of the SV1 Env variants resembled that of GL8, characteristic of the phenotype displayed by “early” isolates circulating during the acute phase of infection and requiring the CRD2 domain of CD134 for infection [44,45] . Hence it is likely that the Env variants isolated from SV1 had been transmitted recently, raising the question: were the immune responses induced by FIV vaccination insufficient to protect cat SV1 against infection with a recombinant virus displaying the “acute” phenotype?…”

Something old, something new

“…59 Accordingly, viral phenotyping might assist in the clinical staging of individual cats diagnosed with FiV infection.…”