Comparison of serologic assays for detection of antibodies against human herpesvirus 8

Improvement of serologic assays for detection of antibodies against human h erpesvirus 8 (HHV-8) is critical to better understand its epidemiology and biology. We produced the HHV-8 latent (OPF73) and lytic (ORF65, K8.1, and g lycoprotein B) antigens in the Semliki Forest virus system and evaluated th eir performance in immunofluorescence assays (IFAs) and enzyme-linked immun osorbent assays (ELISAs). These assays were compared with other latent anti gen-based assays, including an IFA based on primary effusion lymphoma (PEL) cells and an ELISA based on bacterially expressed ORF73 antigen, as well a s with other lytic antigen-based assays, including an IFA based on induced PEL cells, a commercial ELISA based on purified virions, and ELISAs based o n K8.1- and ORF65-derived oligopeptides. We used a panel of 180 serum speci mens obtained from three groups expected to have high, intermediate, and lo w HHV-8 prevalences. Using three different evaluation methods, we found tha t (i) the performances of the lytic antigen-based ELISAs were almost equiva lent, (ii) the lytic antigen-based assays were more sensitive than the late nt antigen-based assays, and (iii) in general, IFAs were more sensitive tha n ELISAs based on the same open reading frame. We also found that serum spe cimens from healthy individuals contained antibodies cross-reactive with HH V-8 glycoprotein B that can potentially cause false-positive reactions in l ytic PEL-based IFAs. Although this is not a substantial problem in most epi demiologic studies, it may confound the interpretation of data in studies t hat require high assay specificity. Because the K8.1-based IFA provides sen sitivity similar to that of lytic PEL-based IFAs and improved specificity, it can be a useful alternative to the PEL-based IFAs.