Performing Biokit tests on sera that are initially positive by Focus HSV-2 ELISA could provide a useful strategy to increase the specificity of this HSV-2 serology. The biokitHSV-2 Rapid Test ('Biokit') is a readily accessible alternative to WB for confirmatory testing and can be performed easily on sera within a few minutes. This test is now available as ' biokitHSV-2 Rapid Test' from Biokit USA or as 'SureVue-HSV-2' Rapid Test from Fisher HealthCare, Houston, TX. This test showed high sensitivity and specificity in premarket trials against WB. In 2000, a gG-2-based point of care membrane test, POCkit-HSV-2, was cleared by the US Food and Drug Administration for use with capillary blood and sera. As such, a confirmatory test to improve test specificity is desirable. All of these studies have found that Focus HSV-2 ELISA false positive results are far more likely with sera that have index values in the low positive range (1.1–3.5) than those that have index values above 3.5. A recent study of a low prevalence population suggests that falsely positive tests may not be limited to African populations. However, in select patient groups from several African countries, the Focus HSV-2 ELISA may give falsely positive results when compared with other gG-based tests such as the gG-2 monoclonal antibody inhibition assay or WB. Both groups had relatively high HSV-2 seroprevalence by Western blot (WB) 25% of the pregnant women and 22% of the STD group had antibodies to HSV-2. Specificity of Focus HSV-2 ELISA also was high in these groups: 97 % in pregnant women and 96% in the STD population.

The HerpeSelect HSV-2 gG2 ELISA test (Focus Diagnostics) demonstrated a sensitivity of 96% in a group of pregnant women and 95% in an STD population of men and women. These methods are cost effective, widely available, and are the only commercial methods that accurately differentiate HSV-1 from HSV-2 antibodies. Several enzyme linked immunoassays for HSV-1 and HSV-2 antibodies to the type-specific glycoproteins, gG-1 and gG-2, respectively, are approved by the U.S. As such, serologic detection of past HSV-2 increasingly is being recommended for a variety of immunocompetent and immunosuppressed populations. Over 95% of persons who are HSV-2 seropositive will reactivate and shed HSV-2 from genital sites and 70% of sexual and maternal-fetal transmission occurs from such subclinical shedding. Several studies over the last decade have shown the importance of subclinical HSV-2 reactivation in the epidemiology of HSV-2 infection. Patients, clinicians, and laboratories could benefit from the enhanced specificity of this simple HSV-2 serologic test combination. ConclusionĬonfirmatory Biokit testing of positive Focus HSV-2 ELISA results is fast, easy, and effective in reducing falsely positive HSV-2 antibody results.

Mathematical modeling of the data resulted in expected positive predictive values over 98% for populations with antibody prevalences typical of clinical practices in the US and Europe.

Confirmatory testing increased the specificity markedly among sera with Focus EIA values between 1.1 and 3.5: only 35% of low positive (index values 1.1–3.5) Focus HSV-2 ELISA results confirmed as positive by Biokit and WB compared with 92% of those with index values >3.5. The positive predictive value of the Focus HSV-2 ELISA increased from 80.5% to 95.6% when Biokit testing was performed on sera that were initially positive by Focus HSV-2 ELISA. We tested 782 sera by Focus HSV-2 ELISA, Biokit, and the current gold standard test, Western blot (WB). We evaluated such a strategy for HSV-2 serology by using an easily performed commercial test, biokitHSV-2 rapid test ('Biokit' Biokit USA, Lexington MA) as a confirmatory test for the widely used gG-2 specific serology ('Focus ' HerpeSelect HSV-2 ELISA Focus Diagnostics, Cypress CA). As such, the concern for false positive diagnoses is high confirmatory testing is routine for other viral serologies such as HIV and hepatitis C. HSV-2 is a chronic, life-long viral infection that requires both medical attention and potential alterations in health care strategy. However, even tests with high specificity can have low positive predictive values in low prevalence populations. Commercially available assays to detect antibodies to the herpes simplex virus type 2 (HSV-2)-specific glycoprotein gG-2 have markedly improved serologic diagnosis of HSV-2 infection.

Western blot test for herpes