Herpes Simplex Virus 1 and 2 (IgG), with Reflex to HSV-2 Inhibition

Casandra

Casandra Test Code QD97046Version 1 (DRAFT)

Performing Lab

Lab Quest DiagnosticsLab Test ID 17169

Herpes Simplex Virus 1 and 2 (IgG), with Reflex to HSV-2 Inhibition

Clinical Use

Use

Detection of type‑specific IgG antibodies to herpes simplex viruses types 1 and 2 is useful in evaluating prior or recent infection. Reflex confirmatory testing for HSV‑2 IgG inhibition is performed when initial HSV‑2 IgG screen yields a low positive (index 1.10–6.00) to reduce false‑positive results and improve specificity of serologic diagnosis. This test does not substitute for direct detection of HSV (e.g., NAAT or viral culture) in active lesions.

Special Instructions

Testing is performed initially with an FDA‑cleared HSV‑2 IgG assay (Diasorin Liaison XL). Reflex to HSV‑2 IgG Inhibition immunoassay (HerpeSelect inhibition assay) is triggered when index results fall between 1.10 and 6.00. Inhibition >60% indicates confirmed HSV‑2 IgG positivity; <60% indicates negative. Inhibition may be indeterminate if repeat testing yields negative or equivocal results. Western blot confirmatory testing is available through University of Washington; reflex inhibition assay is only performed at Quest. Reflex path must be followed as per internal workflow.

Limitations

Negative serology does not exclude recent infection due to window period of antibody development (seroconversion may occur up to 6 months post‑exposure). A small percentage (0.2%) of HSV‑2 isolates lack glycoprotein G and may induce false‑negative results. Low positive HSV‑2 IgG indices (1.10–6.00) may reflect false positives, thus reflex to inhibition is required. Inhibition may fail to yield interpretable result if baseline IgG is unmeasurable; counseling and repeat testing 2–3 weeks later may be necessary. Serologic testing not recommended for routine screening in asymptomatic individuals due to false positive risk; direct viral detection preferred for lesions.

Test Details