Quantitative determinations of anti-Kaposi sarcoma-associated herpesvirus antibody levels in men who have sex with men

Infection with Kaposi sarcoma-associated herpesvirus (KSHV; also called human herpesvirus-8) is common among men who have sex with men (MSM). Here, quantitative anti-KSHV antibody levels were measured using luciferase immunoprecipitation systems (LIPS) in an MSM cohort with and without HIV from the NIH Clinical Center. Antibodies were detected using a mixture of 4 KSHV antigens in the MSM cohort and in Kaposi sarcoma (KS) patients. Along with HIV status, these results were compared with K8.1 and ORF73 ELISA, PCR virus detection, and additional LIPS testing. LIPS revealed that 25% (76/307) of the MSM cohort were KSHV seropositive, including 59 HIV+ and 17 HIV− subjects. The anti-KSHV antibody levels detected by LIPS were not statistically different between the KSHV+/HIV+ and KSHV+/HIV− subgroups but were lower than the KS patients (P < 0.0001). ELISA analysis of the MSM cohort detected a 35.5% frequency of KSHV infection and showed agreement with 81% of the samples evaluated by LIPS. Further LIPS testing with v-cyclin, a second ORF73 fragment and ORF38 reconciled some of the differences observed between LIPS and the ELISA immunoassays, and the revised LIPS seroprevalence in the MSM cohort was increased to 31%. Additional quantitative antibody analysis demonstrated statistically lower KSHV antibody levels in MSM compared to KS patients, but no difference was found between KSHV infected with and without HIV coinfection. These findings also suggest that antibodies against v-cyclin and ORF38 are useful for identifying patients with asymptomatic KSHV infection.