Evaluation of immunoassays for detection of antibodies to human herpesvirus 7.

An enzyme immunoassay (EIA), an immunoblot assay (IB), and an indirect immunofluorescence assay were developed for detection of human herpesvirus 7 (HHV-7) antibodies in human serum. Cross-absorption studies with EIA or IFA using HHV-7 and human herpesvirus 6 (HHV-6) antigens indicated that most human sera contain cross-reactive HHV-6 and HHV-7 antibodies and that the degree of cross-reactivity varies between individual serum specimens. Inhibition of homologous antibody activity by absorption with heterologous virus ranged from 0 to 57% by EIA. However, for every sample tested, absorption with homologous virus removed more activity than did heterologous virus. An 89-kDa protein was identified as an HHV-7-specific serologic marker by IB. Activity to this protein was not removed by absorption with HHV-6 antigen. Of the three assays, the EIA was the most sensitive (94%), while the IB was the most specific (94%). Approximately 80% of specimens collected from German adults and children older than 2 years were positive for HHV-7 antibodies by these assays.