Typing Herpesvirus hominis Antibodies and Isolates by Inhibition of the Indirect Hemagglutination Reaction

Inhibition of the indirect hemagglutination reaction (IHA inhibition) was compared to several other methods for type-specific identification of Herpesvirus hominis (HVH) antibodies and isolates. The method appears to have the greatest value for typing antibodies for HVH type 1 and HVH type 2 in human sera; identification of antibody type was relatively simple and results were definitive. The IHA-inhibition test permitted serological diagnosis of HVH type 2 infection in three young adults with meningoencephalitis, thus extending the mounting evidence that nervous system involvement with this virus type is not limited to neonatal infections. II/I indexes of neutralizing or IHA antibody gave an accurate indication of the presence of HVH type 2 antibody in those sera containing type 2 antibody by IHA inhibition, but they indicated the presence of HVH type 2 antibody in one-half or more of the sera shown to contain only HVH type 1 antibody by IHA inhibition. For typing HVH isolates, the IHA-inhibition test gave results identical to those obtained by direct fluorescent-antibody staining using cross-absorbed conjugates, but the IHA-inhibition test was much more cumbersome and time-consuming to perform than was direct fluorescent-antibody staining. A microneutralization technique for virus typing also gave results identical to those obtained with direct fluorescent-antibody staining and IHA inhibition. However, typing HVH isolates by plaque size or the differential effect of incubation temperature was found to be less definitive and accurate.