Kaposi's sarcoma-associated herpesvirus seroprevalence in selected german patients: evaluation by different test systems.

A total of 603 serum samples obtained from 12 different patient and control groups, including potentially cross-reactive sera, were tested for the presence of antibodies against Kaposi's sarcoma-associated herpesvirus (KSHV, HHV-8). The assays used were an inhouse immunofluorescence test (IFT) employing latent KSHV antigens and a prototype enzyme-linked immunosorbent assay (ELISA) coated with recombinant latency-associated KSHV nuclear antigen (LANA, open reading frame 73) and the K8.1 protein. Sera giving discrepant results were additionally tested with two commercial IFTs employing KSHV latent and lytic antigens, respectively. The low KSHV seroprevalence rate found in blood donors (3.0% by in-house IFT, 2.0% by recombinant ELISA) was comparable to that found previously in Western European countries. The highest KSHV seroprevalence rates were found in patients with Kaposi's sarcoma (100% by both assays), followed by HIV-infected men without Kaposi's sarcoma (23.3% by in-house IFT and 17.8% by ELISA) and women (15.7% by in-house IFT and 13.7% by ELISA). Overall correlation between both assays was 91.2%, with the highest rate of discordant results occurring in HIV-infected male subjects. Retesting of the 53 discrepant samples by the commercial IFTs revealed the best, albeit low, correlation between the in-house IFT and the commercial latent antigen IFT and poor correlations between the other assays. Apart from patients with autoimmune antibodies, there was no significant degree of non-specific reactivity in either of the KSHV tests due to antibodies against Epstein-Barr virus and human herpesvirus 6. Despite the lack of a "gold standard" for KSHV antibody detection, the fact that the results obtained overall agreed rather well indicates their suitability for conducting seroepidemiological studies.