Diagnostic Methods (continued)

Type-Specific Serologic Tests

Serologic tests detect type-specific and nonspecific antibodies to HSV that develop during the first several weeks to few months following infection and persist indefinitely.

Type-specific serological tests based on antigens specific for HSV-1 (gG1) and HSV-2 (gG2) have been developed and are now commercially available. Serologic type-specific gG-based assays should be specifically requested when serology is performed, because older assays do not accurately distinguish HSV-1 from HSV-2 antibody. Currently, the FDA-cleared gG-based type-specific assays include the laboratory-based assays: HerpeSelect™-1 or HerpeSelect™-2 ELISA IgG and HerpeSelect™ 1 and 2 Immunoblot IgG (manufactured by Focus Technology, Inc, Herndon, VA); and HSV-2 ELISA (Trinity Biotech USA, Berkeley Heights, NJ).

Two other assays, Biokit HSV-2 and SureVue HSV-2 (Biokit HAS, Lexington, MA and Fisher Scientific, Pittsburgh, PA, respectively), are point-of-care tests that provide results for HSV-2 antibodies from capillary blood or serum during a clinic visit.

The sensitivities of these tests for detection of HSV-2 antibody vary from 80% to 98%, and false-negative results may occur, especially early after infection. The specificities of these assays are ≥ 96%; false-positive results can occur, especially in patients with low likelihood of HSV infection. Therefore, repeat or confirmatory testing (e.g., an immunoblot assay if the initial test was an ELISA) may be indicated in some settings.

Because almost all HSV-2 infections are sexually acquired, type-specific HSV-2 antibody indicates anogenital infection. However, the presence of HSV-1 antibody does not distinguish anogenital from orolabial infection.

Type-specific serologic assays might be useful in the following scenarios:

• Recurrent or atypical genital symptoms with negative cultures.
• A clinical diagnosis of genital herpes without laboratory confirmation.
• A sex partner with genital herpes.
• As part of a comprehensive evaluation for STDs among persons with multiple sex partners, HIV infection, and among MSM at increased risk for HIV acquisition.

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