IDENTIFICATION OF A 40-KDA TO 42-KDA ATTACHMENT POLYPEPTIDE FOR CANINE PARVOVIRUS IN A72 CELLS

The attachment of canine parvovirus (CPV) to different cell lines was quantitated by a fluorescence-activated cell sorter assay. The viral a ttachment was observed to both permissive A72 and nonpermissive ST cel ls but not to nonpermissive MDBK cells. The binding of and infectivity for CPV to A72 cells was reduced upon prior treatment of cells with V ibrio cholerae neuraminidase or lectins, specific for sialic acid. Sim ilarly, treatment of cells with any of several proteases reduced virus binding; however, phospholipase treatment had no effect indicating th at one or more membrane glycoproteins were involved in virus binding. These proteins were characterized with a virus overlay protein blot as say. Virus bound to a protein with a molecular mass of 40 to 42 kDa in membranes prepared from A72 and ST cells and not from MDBK cells. The binding to this polypeptide was specific since increasing amounts of unlabeled virions competitively inhibited binding of radiolabeled viri ons in a dose-dependent manner. A polypeptide of similar molecular mas s was immunoprecipitated from radiolabeled octyl glucoside (OG) extrac t of A72 cells using purified virions, virion-specific antiserum, and protein A. The binding to this polypeptide was decreased but not aboli shed upon prior treatment of the membrane with V. cholerae neuraminida se. CPV preferentially recognized a polypeptide of similar molecular s ize in the OG extract prepared from the biotinylated basolateral surfa ce of polarized MDCK monolayer. Hence, we propose that the 40- to 42-k Da glycoprotein represents a specific attachment molecule for CPV in A 72 cells. (C) 1994 Academic Press, Inc.