IDENTIFICATION OF A PUTATIVE RECEPTOR FOR PORCINE REPRODUCTIVE AND RESPIRATORY SYNDROME VIRUS ON PORCINE ALVEOLAR MACROPHAGES

To identify the receptor which may determine the macrophage tropism of porcine reproductive and respiratory syndrome virus (PRRSV), monoclon al antibodies (MAbs) against porcine alveolar macrophages (PAM) were p roduced. Two MAbs (41D3 and 41D5) which completely blocked PRRSV infec tion of PAM were further characterized. It was found that they reduce the attachment of PRRSV to PAM and immunoprecipitate a 210-kDa membran e protein from PAM. This protein was detected on the cell membranes of PAM but not of PRRSV-nonpermissive cells. A colocalization was found between the reactive sites of MAb 41D3 and PRRSV on PAM membranes. All PRRSV-infected cells in tissues of experimentally infected pigs react ed with MAb 41D3. Taken together, all these data suggest that the iden tified 210-kDa membrane protein is a putative receptor for PRRSV on po rcine macrophages.