Rapid Immunoassay for the Detection of Genital Herpes Infection

Abstract

Objective: We evaluated a new affinity membrane strip test for the diagnosis of herpetic genital infections. Test strip results, which are available by immunoassay in 30 min without the need for special equipment, were compared with the results of viral culture.Methods: Twenty-eight female patients with vulvar lesions thought to be due to genital herpes simplex virus (HSV) infection were tested. The affinity membrane strip was applied to the genital lesion. Dacron swabs were then applied to the lesions and the swab contents cultured for HSV. For the immunoassay, the test strip was immersed in peroxidase-labeled antibodies specific for HSV type 2 (HSV-2), incubated, washed, and developed in the substrate tetramethylbenzidine. Positive reactions appeared as intense blue spots roughly the shape and size of the lesion. Sensitivity and specificity of the test were determined using the results of viral cultures as the standard.Results:The lesions of 8 patients yielded positive strips that correlated with positive cultures. The lesions of 6 patients produced positive strips but the cultures were negative. None of the patients whose lesions yielded negative strips had positive cultures. The lesions of 14 patients produced negative strips and negative cultures. Strips and viral cultures from 10 control patients (no lesions) were negative. Sensitivity and specificity were 100% and 70%, respectively. Positive (PPV) and negative (NPV) predictive values were 57% and 100%, respectively. The accuracy was 78%.Conclusions: The affinity membrane test was extremely sensitive in detecting herpetic genital infection compared with viral culture. The specificity was lower, resulting from false positives based on negative cultures. However, negative cultures may occur in the presence of disease, depending in part on the type of lesion. Thus, specificity may be higher than this preliminary study indicates, and more elaborate search for virus including serologic studies as well as larger groups of patients may be needed to refine this evaluation. With further testing and development, this membrane affinity test for herpes may yield a valuable adjunct to clinical diagnosis of this infection.