A SENSITIVE AND SPECIFIC LATERAL-FLOW BASED RAPID POINT-OF-CARE

Introduction: Herpes simplex virus (HSV) is a frequent human pathogen, causing a wide range of diseases. There are two well characterized serotypes. HSV-1 commonly causes infections in the oropharynx. HSV-2 is most closely associated with infections of the genital tract, and can cause disease in neonates after vertical transmission from an infected mother. In previous studies as many as 85% of active cases of primary genital herpes were caused by HSV-2. In addition, the preponderance of recurrent cases of genital herpes are caused by HSV-2. A rapid, easy to use, HSV-2 specific point-of-care assay could provide an effective alternative to traditional laboratory-based methods and facilitate reporting of a result and counseling of the patient in a single visit. The HerpeSelect Express device utilizes colloidal gold conjugated antihuman IgG and native gG-2 antigen in a visually read immunochromatograhic format to detect HSV-2 specific IgG antibodies in serum or whole blood.

Methods: A total of 976 (575 from sexually active adults, 401 from pregnant women) capillary whole blood samples were tested with the newly developed HerpeSelect® ExpressTM IgG test. Results were compared to the HerpeSelect®2 ELISA (ELISA) and HerpeSelect®1 and 2 Immunoblot IgG (Immunoblot). In addition, sera positive for other viruses were selected for cross-reactivity testing. The HerpeSelect Express test is performed by adding sample and a specific buffer to the device. The test and control lines form and can be read within 15 minutes. The test is considered valid if the control line appears.

Results: For the sexually active adult population, the sensitivity of the HerpeSelect Express IgG test was 97.5% (237/243) and the specificity was 98.5% (322/327) compared with ELISA. For pregnant women, the sensitivity of the HerpeSelect Express IgG test was 94.2% (114/121) and the specificity was 96.4% (266/276) when compared to ELISA. Overall cross-reactivity was 4.2% (9/213). For the HerpeSelect Express IgG test, concordance of results between whole blood and serum was 99%.

Conclusion: The HerpeSelect Express IgG test demonstrated excellent sensitivity, specificity and concordance with the HerpeSelect 2 ELISA and HerpeSelect 1 and 2 Immunoblot IgG. This new test can be used in many point-of-care settings*, which can facilitate treatment and counseling.

* The product is FDA cleared and currently categorized as moderately complex. Focus is seeking CLIA waiver.