ELECTROPHORETIC ANALYSIS OF HUMAN HERPESVIRUS-6 POLYPEPTIDES IMMUNOPRECIPITATED FROM INFECTED-CELLS WITH HUMAN SERA

Proteins of human herpesvirus 6 (HHV-6) eliciting human antibody responses were examined in serum from healthy adults and patients with AIDS, chronic fatigue syndrome, Hodgkin's disease, and Sjogren's syndrome. HHV-6 IgG antibody titers measured by immunofluorescence (IF) ranged from 1:10 to 1:1280. Lysates of HHV-6-infected and uninfected cells labeled with [S-35]methionine, [H-3]glucosamine, and I-125 were immunoprecipitated with sera and analyzed electophoretically. Sera with IF titers greater-than-or-equal-to 1:20 immunoprecipitated > [S-35]methionine-labeled HHV-6 polypeptides of approximately 26-180 kDa. At least 10 HHV-6 glycoproteins and 8 HHV-6 polypeptides associated with the surfaces of infected cells were recognized by human sera. The approximate molecular masses of glycoproteins immunoprecipitated by human sera were similar to those immunoprecipitated by monoclonal antibodies. The labeling intensity of HHV-6 protein bands increased with increasing IF titer, and the effect was most prominent for HHV-6 glycopolypeptides. No reactivities with specific HHV-6 polypeptide(s) were characteristic of a given patient group. These findings suggest that HHV-6 glycoproteins are good targets for human antibody responses.