Antibody-dependent, complement-mediated homologous and cross-cytolysis of togavirus-infected cells.

The appearance of viral induced antigen(s) on Sindbis and Semliki Forest (SF) virus-infected chick embryo cells is detected with homologous mouse anti-viral antibody-dependent, complement-mediated cytolysis in a 51Cr release assay. Such antigen(s) is detected within 3 to 4 hr after infection whereas viral cytopathologic effects do not occur until 10 to 12 hr. In addition, significant heterologous cytolysis (anti-Sindbis on SF virus-infected cells, or, anti-SFV on Sindbis-infected cells) could be observed with serum samples tested. These sera were assayed for neutralizing and hemaggluatination-inhibition activities. Heterologous cytolysis cannot be correlated with hemagglutination-inhibition antibody titers nor is cross-neutralizing antibody detected. The possibility is discussed that another previously undefined antigen on infected cell membranes may be involved in heterologous cytolysis.