Cellular receptor interactions of C-cluster human group A coxsackieviruses

1 The Picornaviral Research Unit, School of Biomedical Sciences, Faculty of Health, The University of Newcastle, Level 3, David Maddison Clinical Sciences Building, Royal Newcastle Hospital, Newcastle, New South Wales 2300, Australia 2 Department of Chemistry and Biomedical Sciences, University of Kalmar, SE-382 91 Kalmar, Sweden Correspondence Darren Shafren dshafren{at}mail.newcastle.edu.au The cellular receptor complex of coxsackievirus A21 (CVA21), a C-cluster human enterovirus, is formed by the subtle interaction of individual cellular receptors, decay accelerating factor (DAF) and intercellular adhesion molecule-1 (ICAM-1). In this receptor complex, DAF functions in the membrane sequestration of the virus, while the role of ICAM-1 is as the functional cellular internalization receptor. However, despite the elucidation of the CVA21–cell receptor interactions, there have been few definite investigations into cellular receptor usage of other coxsackie A viruses (CVAs) belonging to the C-cluster. In the present study, radiolabelled virus-binding assays demonstrated that CVA13, -15, -18 and -20, a subset of the human enterovirus C-cluster, bind directly to surface-expressed ICAM-1, but not to surface-expressed DAF. Furthermore, lytic infection of ICAM-1-expressing rhabdomyosarcoma (RD) cells by this C-cluster subset of viruses was inhibited by specific ICAM-1 monoclonal antibody blockade, except for that of CVA20. Despite possessing ICAM-1-binding capabilities, CVA20 employed an as yet unidentified internalization receptor for cell entry and subsequent productive lytic infection of ICAM-1-negative RD cells. In a further example of C-cluster cellular receptor heterogeneity, CVA13 exhibited significant binding to the surface of CHO cells expressing neither DAF nor ICAM-1. Despite a common receptor usage of ICAM-1 by this subset of C-cluster CVAs, the amino acid residues postulated to represent the ICAM-1-receptor footprint were not conserved. GenBank accession numbers for the generated full-length CVA nucleotide sequences are: AF465511 (CVA13); AF465512 (CVA15); AF465513 (CVA18); AF465514 (CVA20) and AF465515 (CVA21).