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

Casandra

Casandra Test Code QD25343Version 1 (DRAFT)

Performing Lab

Lab Quest DiagnosticsLab Test ID 17170CPT Codes 86695, 86696

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

Clinical Use

Use

This test employs a two-step serologic approach: an FDA‑cleared HSV‑2 IgG assay on the Diasorin Liaison XL platform, reflexing to an HSV‑2 IgG inhibition immunoassay for specimens with index values between 1.10 and 6.00 to reduce false positives in low-positive screens. It is used to detect HSV‑2 type‑specific IgG antibodies, though serologic testing is not the preferred diagnostic method for genital herpes—NAAT or culture of lesions is preferred; serology may be useful in recurrent atypical genital symptoms negative by PCR, clinical diagnosis without lab confirmation, or for partners at higher risk or with history of genital herpes. A negative result does not definitively rule out infection, particularly in early infection stages or rare glycoprotein G deficient isolates. (Reflex confirmatory testing improves specificity.)

Special Instructions

Reflex testing is automatic when the HSV‑2 IgG index is between 1.10 and 6.00. If the inhibition assay cannot determine a result due to low baseline IgG, repeat sampling in 2–3 weeks is recommended.

Limitations

False positives are common at lower index values; confirmatory inhibition testing is recommended for screen positives in the 1.10–6.00 range. A negative result does not exclude recent infection due to variable seroconversion times—some individuals seroconvert as late as 6 months post‑infection. A small percentage of HSV‑2 isolates lack glycoprotein G and may yield false‑negative results. Inhibition assay may be indeterminate if baseline IgG is absent on confirmatory testing, particularly for low‑index samples.

Test Details