Typing of herpes simplex virus with type-specific human immunoglobulin M in an indirect immunofluorescence assay

Sera from nine individuals with suspected primary herpes simplex virus type 1 (HSV-1) or type 2 (HSV-2) infection were screened to identify those containing HSV type-specific immunoglobulin M (IgM). Selected sera were then utilized in an IgM-specific indirect immunofluorescent-antibody HSV-typing assay (patent pending). To evaluate the procedure, 29 HSV isolates were grown in cultures of continuous human amnion cells, fixed, and used as substrates for indirect immunofluorescence. Determination of virus type was based on intensity of fluorescence of the substrate with HSV-1- and HSV-2-specific antisera after staining with fluorescein-conjugated anti-human IgM. Typing of the isolates by restriction endonuclease digestion showed that of 29, 18 were HSV-2 and 11 were HSV-1. Results by IgM-specific indirect immunofluorescent-antibody assay were identical to those by restriction endonuclease digestion for 27 of the isolates; 2 isolates failed to replicate adequately in the test cells. The IgM-specific indirect immunofluorescent-antibody procedure appears to be a simple, rapid, and accurate technique which could be of use to clinical virology laboratories.