Human serum antibodies to a major defined epitope of human herpesvirus 8 small viral capsid antigen

The major antibody-reactive epitope of the small viral capsid antigen (sVCA ) of human herpesvirus 8 (HHV-8) was defined by use of overlapping peptides . Strong IgG reactivity was found among similar to 50% of 44 human immunode ficiency virus-positive or -negative patients with Kaposi's sarcoma and 13 subjects who were seropositive by immunofluorescence assay (IFA) for the la tent HHV-8 nuclear antigen. Only 1 of 106 subjects seronegative for both ly ric and latent HHV-8 antigens and 10 of 81 subjects IFA-seropositive only f or the lytic HHV-8 antigen had strong IgG reactivity to this epitope, Among 534 healthy Swedish women, only 1.3% were strongly seropositive. Compariso n of the peptide-based and purified sVCA protein-based ELISAs found 55% sen sitivity and 98% specificity. However, only 1 of 452 serum samples from hea lthy women was positive in both tests. In conclusion, the defined sVCA epit ope was a specific, but not very sensitive, serologic marker of active HHV- 8 infection. Such infection appears to be rare among Swedish women, even wi th sexual risk-taking behavior.