MEASLES-VIRUS HEMAGGLUTININ INDUCES DOWN-REGULATION OF GP57-67, A MOLECULE INVOLVED IN VIRUS BINDING

A surface glycoprotein (gp57/67) was previously shown to be involved i n measles virus (MV) binding and characterized in our laboratory. Here , we described down-regulation of cell surface gp57/67 after infection with MV. This effect is specific for MV since cells infected with can ine distemper virus, closely related to MV. did not down-regulate gp57 /67. The decrease in cell surface gp57/67 correlated with expression o f MV glycoproteins and more particularly with the expression of MV hae maggluttinin (MV-H). Indeed, expression of MV-H after infection with a vaccinia virus recombinant coding for MV-H was necessary and sufficie nt to induce down-regulation of 57/67. Kinetics of cell surface expres sion of MV-H and gp57/67 showed that the degree of down-regulation was correlated with the amount of MV-H expressed by infected cells. Exper iments using antibody-prelabelled gp57/67 and indirect immunofluoresce nce microscopy allowed us to follow the fate of gp57/67 and showed tha t down-regulation was occurring by rapid internalization of gp57/67 fr om the cell surface. These results provide additional evidence that th e gp57/67 molecule is closely associated with the pathway of MV infect ion and also reveal a phenomenon which may be related to viral pathoge nesis and persistence.