The inhibition assay measures the differential abilities of native HSV-1- and HSV-2-infected cell lysates to neutralize patient sample reactivity to recombinant gG2 protein (rgG2), the HSV-2-specific protein used in the HerpeSelect HSV-2 IgG ELISA.2 Separate aliquots of the patient sample are incubated with the 2 lysates, then tested in the HerpeSelect HSV-2 type-specific IgG ELISA. The index value of serum pre-incubated with HSV-2 lysate is then compared to the index value of serum pre-incubated with HSV-1 lysate. The HSV-1 lysate controls for any non-gG2 reactivity present in the serum sample; thus, any inhibition that is detected reflects only the absorption of gG2 reactive antibodies by the native gG2 present in the HSV-2 lysate. An example of how the inhibition value is calculated is shown below:
Index value for serum pre-incubated with HSV-2 lysate = 0.23
Index value for serum pre-incubated with HSV-1 lysate = 2.45
Inhibition = [1 - (0.23/2.45)] x 100 = [1- 0.09] x 100 = 0.91 x 100 = 91%
Inhibition values >60% indicate true HSV-2-specific IgG reactivity.