Identification of porcine alveolar macrophage glycoproteins involved in infection of porcine respiratory and reproductive syndrome virus

The aim of this study was to identify the receptor(s) for PRRSV on porcine alveolar macrophages (PAMs) by producing monoclonal antibodies (MAbs) against these cells. Hybridoma supernatants were selected for their ability to block PRRSV infection. Four MAbs, 1-8D2, 9.4C7, 9.9F2, and 3-3H2 inhibited infection and recognised cell surface, PAM-specific antigens as shown by immunofluorescence and immunoperoxidase monolayer assay. These MAbs were then used to identify cellular proteins involved in PRRSV infection by radioimmunoprecipitation assays (RIPAs). MAbs 1-8D2 and 9.9F2 each recognised a 150 kDa-polypeptide doublet, while MAbs 9.4C7 and 3-3H2 both recognised a 220 kDa-polypeptide. Glycosidase treatment demonstrated all these polypeptides to be N-glycosylated. Thus, multiple glycoproteins appear to be involved in infection of PAMs by PRRSV.