MULTIPLE ISOFORMS OF CD46 (MEMBRANE COFACTOR PROTEIN) SERVE AS RECEPTORS FOR MEASLES-VIRUS

Measles virus (MV) causes a productive infection in humans and certain simian hosts. Rodent cells such as Chinese hamster ovary (CHO) and mu rine cell lines normally resist MV infection. Human CD46, or membrane cofactor protein, a complement regulatory protein, recently has been r eported as the cellular receptor for MV. Multiple isoforms of the CD46 protein exist; four of these isoforms are commonly expressed on human cells. Expression of each of the four isoforms in CHO cells followed by exposure to MV led to the appearance of viral proteins within the c ells and on the cell surface as detected by immunofluorescence. Syncyt ium formation also was observed in the cultures. CHO cells expressing any of the four isoforms and exposed to MV formed infectious centers w hen plated on Vero cell monolayers, indicating that the cells can tran smit virus to uninfected cells. The murine fell line MC57 expressing t he BC1 isoform of CD46 also stained positively for MV antigens and was positive in the infectious center assay after exposure to MV. Treatme nt of CD46-expressing cells with antibody to human CD46 inhibited MV b inding in a dose-dependent manner. These observations indicate that an y of the four primary isoforms of CD46 are able to serve as a receptor for MV.