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

Equine lentivirus receptor-1 (ELR1) has been characterized as the specific functional receptor that mediates equine infectious anemia virus (EIAV) entrance to horse macrophages. This receptor is tumor necrosis factor receptor superfamily member 14 (TNFRSF14). The aim of this study was to investigate the occurrence of allelic variants in the coding sequence of equine TNFRSF14 gene by screening for single-nucleotide polymorphisms (SNPs) in different equine populations. Forty seven horse samples were randomly selected from a reservoir of EIAV-seropositive and seronegative samples collected from different outbreaks and regions of Argentina. DNA samples were scanned via PCR and direct sequencing of exon 3 and exon 5 of TNFRSF14 gene. A total of 21 SNPs were identified, of which 11 were located in coding sequences. Within exon 5, four SNPs caused nonsynonymous substitutions, while two other SNPs caused synonymous substitutions in crucial residues (Ser112 and Thr114) implicated in the interaction with EIAV. Despite some of exon 5 variants occurred exclusively in EIAV-positive or EIAV-negative horses, critical residues for the function of the mature protein were conserved, accounting for selective pressures in favor of preserving the specific function of TNFRSF members and the host immune response. To our knowledge, this is the first report of the existence of allelic variations involving some crucial amino acid residues in horse ELR1. Further, it could be an initial step to test the possible functional relevance and relationship of these variants with EIAV infection and disease progression as well as to develop preventive strategies.