title: RGD-dependent entry of coxsackievirus A9 into host cells and its bypass after cleavage of VP1 protein by intestinal proteases.
abstract: The recently reported nucleotide sequence of coxsackievirus A9 (CAV-9) showed that unlike other enteroviruses, CAV-9 has an insertion of about 17 amino acids at the C-terminal end of VP1 (K. H. Chang, P. Auvinen, T. Hyypiä, and G. Stanway, J. Gen. Virol. 70:3269-3280, 1989). This sequence includes the RGD (arginine-glycine-aspartic acid) motif which is known to be important in certain protein-protein interactions. We studied the inhibitory effect of RGD-containing peptides in the attachment of CAV-9 to African green monkey kidney cells. A peptide corresponding to the RRGDM sequence derived from the inserted segment of CAV-9 was found to block virus attachment effectively, and the inhibition was dose dependent. Substitution of glutamic acid for the homologous aspartic acid completely abolished the inhibitory effect, indicating great specificity of the action. During replication in the gut, all enteroviruses are exposed to host proteolytic enzymes. Exposure of CAV-9 to purified trypsin or human intestinal fluid resulted in selective cleavage of the VP1 capsid protein. Intact and trypsin-cleaved VP1 proteins gave identical N-terminal sequences, indicating that cleavage of VP1 takes place near the C terminus. Attachment of proteolytically cleaved infectious CAV-9 to green monkey kidney cells was not prevented by RGD-containing peptides, indicating that cleaved CAV-9 is able to bypass RGD-dependent entry. The altered receptor specificity of proteolytically cleaved viruses may have important consequences in the pathogenesis of enteric infections.
authors.affiliation: Enterovirus Laboratory and Molecular Biology Unit, National Public Health Institute, Helsinki, Finland.
authors.forename: M
authors.initials: M
authors.lastname: Roivainen
authors.forename: T
authors.initials: T
authors.lastname: Hyypiä
authors.forename: L
authors.initials: L
authors.lastname: Piirainen
authors.forename: N
authors.initials: N
authors.lastname: Kalkkinen
authors.forename: G
authors.initials: G
authors.lastname: Stanway
authors.forename: T
authors.initials: T
authors.lastname: Hovi
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001667:Binding, Competitive; D002460:Cell Line; D002522:Chlorocebus aethiops; D003384:Coxsackievirus Infections / Q000378:metabolism*; D010450:Endopeptidases / Q000494:pharmacology; D004770:Enterovirus / Q000254:growth & development* / Q000378:metabolism; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000737:chemistry / Q000378:metabolism*; D011971:Receptors, Immunologic / Q000502:physiology*; D018000:Receptors, Peptide; D011991:Receptors, Virus / Q000378:metabolism*; D013329:Structure-Activity Relationship; D014764:Viral Proteins / Q000737:chemistry / Q000378:metabolism*
chemical_list: D009842:Oligopeptides; D011971:Receptors, Immunologic; D018000:Receptors, Peptide; D011991:Receptors, Virus; D014764:Viral Proteins; C051382:arginyl-glycyl-aspartic acid directed cell adhesion receptor; C047981:arginyl-glycyl-aspartic acid; D010450:Endopeptidases