Rapid detection, culture-amplification and typing of herpes simplex viruses by enzyme immunoassay in clinical samples

Background: The laboratory diagnosis of herpes simplex infection may require rapid (direct) tests, as well as cell cultures, for detection of the virus in clinical samples. The quantity of virus present in clinical samples is variable and this may depend on the period from onset of rash. In addition, not all patients may show obvious symptoms with this infection. The successful culture of herpes simplex virus requires prompt transportation after collection of the specimen as the virus is easily inactived. Hence, rapid and culture tests would enable detection of non-viable and viable viruses.

Study Design: We describe the rapid detection of HSV by EIA directly in various clinical samples using commercially available polyclonal sera. In addition, specimens were inoculated in microwell cell cultures and 4 days post inoculation the culture fluids were tested for HSV and subtyped by a similar EIA (culture amplified EIA).

Results: The direct EIA showed an endpoint detection of 100 TCID₅₀/ml, sensitivity of 92% (all specimen types) and specificity of 100%. The direct EIA sensitivity was 97% in non-genital specimens and 88% in genital specimens. The culture amplified EIA showed a sensitivity of 95% compared to all confirmed HSV positive samples.

Conclusions: The results of the HSV rapid tests were available within 24 h from receipt of specimens. Specimens which were culture negative/direct EIA positive were confirmed by blocking antisera. Culture positive specimens which were direct EIA negative were confirmed by subtyping of the virus.