Interaction of cytomegalovirus immune complexes with host cells.

After adsorption to host cells of a mixture of cytomegalovirus (CMV) and immunoglobulin G (IgG)-anti CMV, at least 99% of the surviving fraction consisted of infectious virus-antibody complexes which could be neutralized by anti-human IgG antibody. The virus-antibody complexes penetrated into cells and were uncoated more slowly than native virus. When the virus-antibody complexes were treated with anti-human IgG antibody before adsorption was allowed to take place, anti-human IgG antibody immune complexes were adsorbed to host cells less readily and uncoated less efficiently than were untreated complexes. Furthermore, after adsorption, anti-human IgG antibody-IgG-CMV complexes were further retarded in their penetration and uncoating. These observations suggest that neutralization of CMV by IgG-anti-CMV resulted from interference with the normal mechanisms of penetration and uncoating. Anti-human IgG antibody enhanced the degree of neutralization by augmenting the inhibitory effect of antibody on these stages of virus-host interaction and also reduced adsorption of the complex.