HLA Class I Antigen Serves as a Receptor for Human Coronavirus OC43

Human coronaviruses are associated with acute respiratory and enteric disease in man as such their target cells are probably the epithelial cells lining the respiratory and enteric tract. Attachment of virus to specific receptors on the cell surface is a major determinant of virus tropism in pathogenesis (1). Recently, aminopeptidase-N was identified as a cell receptor for the 229e coronavirus (2). Cell receptor(s) for OC43 coronavirus have not been identified. However, it is of pathologic significance that OC43 virus shares DNA sequence homology with the two coronavirus isolates, SK and SD, from the brain of patients with multiple sclerosis (MS) (3). Probing MS and control brain with probes specific for human, murine, porcine and bovine coronavirus by in situ hybridization resulted in the detection of coronavirus RNA in 12 of 22 MS brain samples; five of which were positive with the OC43 probe (4). A study of virus-ligand interactions of OC43 with human rhabdomyosarcoma (RD) cells, which are highly susceptible to virus infection, was undertaken to identify possible cell receptors. The binding of virus collected from the supernatant of infected cells to cell proteins immobilized on nitrocellulose paper was used to screen for virus-ligand interactions. The next step was the identification or development of antibodies to each of the ligands, and to test their ability to blockade receptor activity by culturing infected cells in medium containing the ligand antibodies and measuring the effect on virus yield. The preliminary experiments reported here reveal an interesting observation of strong affinity of OC43 virus for the HLA class I antigen.