RECEPTOR (CD46) MODULATION AND COMPLEMENT-MEDIATED LYSIS OF UNINFECTED CELLS AFTER CONTACT WITH MEASLES VIRUS-INFECTED CELLS

Recently, it has been observed that the infection of human target cell s with certain measles virus (MV) strains leads to the downregulation of the major MV receptor CD46. Here we report that CD46 downregulation can be rapidly induced in uninfected cells after surface contact with MV particles or MV-infected cells, Receptor modulation is detectable after 30 min of cocultivation of uninfected cells with MV-infected cel ls and is complete after 2 to 4 h, a time after which newly synthesize d MV hemagglutinin (MV-H) cannot be detected in freshly infected targe t cells, This contact-mediated receptor modulation is also induced by recombinant MV-H expressed by vaccinia virus and is inhibitable with a ntibodies against CD46 and MV-H. By titrating the effect with MV Edmon ston strain-infected cells, a significant contact-mediated CD46 modula tion was detectable up to a ratio of 1 infected to 64 uninfected cells , As a result of CD46 downregulation, an increased susceptibility of u ninfected cells for complement-mediated lysis was observed, This pheno menon, however, is MV strain dependent, as observed for the downregula tion of CD46 after MV infection. These data suggest that in acute meas les or following measles vaccination, uninfected cells might also be d estroyed by complement after contacting an MV infected cell.