Binding of equine infectious anemia virus to the equine lentivirus receptor-1 is mediated by complex discontinuous sequences in the viral envelope gp90 protein

Abstract

The identification and characterization of a functional cellular receptor for equine infectious anemia virus (EIAV), designated equine lentivirus receptor-1 (ELR1), a member of the tumour necrosis factor receptor protein family, has been reported previously . Proc Natl Acad Sci U S A, 102 , [9918][9919][9920][9921][9922][9923]. The finding of a single receptor for EIAV is distinct from feline, simian and human immunodeficiency viruses, which typically utilize two co-receptors for infection, but is similar to avian and murine oncoviruses, which use single receptors. This study sought to determine ELR1-binding domains of EIAV gp90. Towards this goal, a GFP-tagged gp90 fusion protein (gp90GFP) expression vector was constructed and a specific cell-cell binding assay was developed to measure EIAV gp90 binding to ELR1. Using these assays, the receptor-binding properties of 41 gp90GFP mutants were evaluated, each with a sequential replacement 11 aa linear epitope peptide from the vesicular stomatitis virus glycoprotein (VSV-G tag), as well as eight mutants containing individual gp90 variable-domain deletions. The results of these studies demonstrated that, in general, gp90 constructs containing substitutions or deletions in the N-terminal third of gp90 retained their receptor-binding activity. In contrast, segment substitutions or deletions in the C-terminal two-thirds of gp90 eliminated receptorbinding activity. Thus, these results reveal for the first time that the ELR1-binding domains of EIAV gp90 are located in the C-terminal two-thirds of EIAV gp90, apparently as a complex of discontinuous determinants. INTRODUCTIONAdsorption and entry of retroviruses into target cells requires the interaction of viral envelope (Env) glycoproteins with specific cellular receptor proteins. Retroviral envelope glycoproteins are synthesized as polyprotein precursors that are cleaved, during transport to the surface of infected cells, into the surface (SU) subunit and transmembrane (TM) subunit. The SU protein is bound at the virion surface through interaction with the TM protein and is responsible for the initial binding to receptor proteins on the target cell surface. Studies of the specificity of functional receptors for various retroviruses have indicated a general pattern of single receptor protein use by oncoviruses (such as murine and avian leukemia viruses) that is in distinct contrast to the dual co-receptor usage observed with the lentiviruses human immunodeficiency virus (HIV), simian immunodeficiency virus (SIV) and feline immunodeficiency virus (FIV) (Eiden et al., 1993;de Parseval et al., 2004;Douglas et al., 1997;Barnard et al., 2006). Whilst the general assumption has been that all lentiviruses may use dual co-receptors for infection of target cells, the recent identification of a single functional receptor for equine infectious anemia virus (EIAV) has revealed an unexpected diversity in lentivirus receptor specificity and interactions .Murine leukemia virus (MuLV) Env SU proteins and their interactions with receptors ...

Identification and characterization of a novel variant of the human P2X7 receptor resulting in gain of function

“…An overlapping PCR strategy and/or fragment swapping with appropriate restriction enzymes were used for mutageneses to create the P2X 7 variants [70]. For overlapping PCR, the two hybrid primers were designed to contain the nucleotide substitution for site-directed mutagenesis of the P2X 7 variants.…”

Residues 140–142, 199–200, 222–223, and 262 in the Surface Glycoprotein of Subgroup A Avian Leukosis Virus Are the Key Sites Determining Tva Receptor Binding Affinity and Infectivity

“…In previous studies on retroviruses, the domain of SU glycoprotein that binds to host cell receptors can be classified into two types: one is concentrated in the highly variable region in SU, as in mouse leukemia virus and ALV-A/B/C/D/E/K ( Battini et al, 1995 ; Federspiel, 2019 ; Chen et al, 2020 ); the other is composed of a complex of discontinuous and multivariate segments of the SU protein, as in human immunodeficiency virus, equine infectious anemia virus, and ALV-J ( Kwong et al, 1998 ; Sun et al, 2008 ; Zhang et al, 2020 ). Previous studies have determined that hr1 and hr2 are the principal binding domains between the viral glycoprotein trimer and the host protein receptor ( Tsichlis et al, 1980 ; Federspiel, 2019 ).…”

Nonsynonymous changes of equine lentivirus receptor-1 (ELR1) gene in amino acids involved in the interaction with equine infectious anemia virus (EIAV)

“…Multiple alternative splicing variants have been reported previously, including a soluble isoform of ELR1 (Lin et al, 2013). Until now, only protein structural information and a few exonic single-nucleotide polymorphisms (SNPs) of horse ELR1 have been reported (www.ensembl.org; Zhang et al, 2005Zhang et al, , 2008Sun et al, 2008). The characterization of TNFRSF14 polymorphisms could shed light on the molecular and functional mechanisms underlying ELR1 and EIAV interaction that may affect virus entrance and subsequent disease progression.…”