Identification of a putative cell receptor for human cytomegalovirus

Proteins from a variety of cell types were separated using SDS-PAGE, transferred to nitrocellulose filters, and probed with intact human cytomegalovirus (HCMV). Virus bound to cell proteins was detected directly using 125I-labeled HCMV or indirectly using an immunologic assay with a secondary antibody labeled with 125I. Using this approach proteins of molecular weights 32 and 34 kDa were identified that would bind HCMV and were present on T4+ and T8+ lymphocytes, a B lymphoblastoid cell line, and human diploid fibroblasts. Binding of labeled virus to cells could be blocked by the addition of unlabeled homologous virus. Treatment of virus with NP40 to remove the virus envelope blocked binding to cellular proteins. Both the 32- and 34-kDa proteins could be copurified with cellular membranes. HCMV bound equally well to T4+ and T8+ cells as well as to either replicating (PHA or interleukin-2 stimulated) or resting lymphocytes. Interestingly, there appeared to be a single binding site for HCMV on human fibroblasts (34 kDa). The results support the idea that there is a receptor for HCMV present on the surface of human lymphocytes and fibroblasts.