[Cloning and sequence analysis of cDNA encoding porcine alphav subunit for FMDV receptor]

Receptors play a crucial role in determining the pathogenesis and tissue tropism of virus. Foot-and-mouth disease virus (FMDV) has been showed to use four integrins, alphavbeta1, alphavbeta3, alphavbeta6 and alphavbeta8 as receptors to initiate infection. In this study, the porcine integrin alphav gene was cloned by RT-PCR from the lung tissue of healed pig infected experimently with FMDV, and compared its nucleotide and deduced amino acid sequence with the av gene of other animals. The 3141bp cDNA of bovine integrin alphav encodes a polypeptide of 1046 amino acids consisting of a 30-residue putative signal peptide, a 955-residue ectodomain, a 29-residue transmembrane domain, and a 32-residue cytoplasmic domain. The ectodomain contains 11 potential N-linked glycosylation sites (NXT/NXS), 2 calcium binding domains (DX[D/N] XDGXXD) and 18 cysteine residues. The nucleotide sequence similarities of integrin alphav between pig and cattle, human, rheses monkey, house mouse, chicken, dog are 93.3%, 91.5%, 91.4%, 85.6%, 73.2% and 89.9% respectively; and the amino acid sequence similarities are 96.3%, 94.6%, 94.1%, 90.8%, 81.6% and 93.8%, respectively. The alphav gene of cattle and pig exhibited the highest sequence homology. It is possible that host tropism of FMDV may related to divergence in receptors among different species.