Different antibody response to a neutralizing epitope of human cytomegalovirus glycoprotein B among seropositive individuals.

The amino-terminal portion of human cytomegalovirus glycoprotein B (HCMV-gB) was expressed as a fusion protein to analyze the neutralizing epitope recognized by human monoclonal antibody C23 and the humoral immune response to this epitope. The linear neutralizing epitope was further localized to the peptide within 17 amino acids (position 68-84) which were conserved between two HCMV laboratory strains. Ten out of 17 HCMV-seropositive human sera contained the antibody against this epitope. Although seven sera were negative for reacting with the fusion protein, the viruses isolated from the same patients retained the epitope. The immunogenicity of the epitope and the possible application of C23 human monoclonal antibody for passive immunization against HCMV infections are discussed.