What this test measures
HSV-1 type-specific IgG is the immunoglobulin-G antibody against glycoprotein G1 (gG1) of herpes simplex virus type 1. It distinguishes HSV-1 from HSV-2 infection — a critical distinction because HSV-1 is mostly oral (cold sores) while HSV-2 is mostly genital, though either can affect either site.
IgG appears 2–6 weeks after primary infection and persists for life. The type-specific assay uses recombinant gG1 to avoid the cross-reactivity that plagued older combined HSV IgG assays.
Why it matters
HSV-1 is extremely common — over 80% of Indian adults are HSV-1 positive, mostly from childhood oral exposure. Most infections are mild or asymptomatic (occasional cold sores). However, HSV-1 increasingly causes first-episode genital herpes (especially in younger adults), and rarely causes serious disease (HSV encephalitis, neonatal herpes).
HSV-1 IgG is used in: pregnancy workup (especially in seronegative women whose partners are HSV-1 positive — risk of primary infection in pregnancy), recurrent oral ulcer evaluation, atypical genital lesions, and pre-transplant evaluation. A positive IgG indicates lifelong infection and risk of recurrence.
How to prepare
No fasting required. Mention pregnancy status, recurrent ulcers, partner status, or any active lesions.
Markers & reference ranges
Reference ranges below are typical adult values. Your lab's reported range may differ slightly based on the assay platform and patient demographics — always read your report against the range printed on it.
| Marker | Normal range | If low | If high |
|---|---|---|---|
| Anti-HSV-1 IgG (Type-Specific) (Index / Reactive-Non-reactive)[1][2] | Reactive in past HSV-1 infection (most adults) | Non-reactive — no past HSV-1 exposure. Susceptible to primary HSV-1 infection. Less common in adults but more common in younger people. | Reactive — past or established HSV-1 infection. The virus persists in nerve ganglia for life; recurrence can occur. Asymptomatic viral shedding can transmit HSV-1 to close contacts. |
HSV-1 vs HSV-2 IgG — clinical context
| Pattern | Most common site | Implication |
|---|---|---|
| HSV-1 IgG+, HSV-2 IgG− | Oral (cold sores), some genital | Common — most adults; partner discussion if genital lesions |
| HSV-2 IgG+, HSV-1 IgG− | Genital | Sexually transmitted; partner counselling |
| Both positive | Mixed | Both infections present |
| Both negative | None | Susceptible — primary infection risk |
Frequently asked questions
Most adults have HSV-1 IgG — why test?
To confirm whether recurrent oral or genital ulcers are due to HSV-1, to inform pregnancy management (especially in seronegative women), and for discordant-couple counselling.
Can HSV-1 cause genital herpes?
Yes — increasingly so, particularly in younger adults. HSV-1 genital herpes tends to have milder, less frequent recurrences than HSV-2 genital herpes.
How long does HSV-1 IgG stay positive?
For life. The virus and antibody persist permanently.
Can I get HSV-1 from kissing someone with cold sores?
Yes — HSV-1 spreads through direct contact with active lesions. Avoid kissing during outbreaks. Asymptomatic shedding can also transmit, though less efficiently.
Is HSV-1 dangerous?
Most HSV-1 infections are mild. Serious complications (HSV encephalitis, neonatal herpes, eye involvement) are rare and need prompt treatment.
I am pregnant and HSV-1 negative. Should I worry?
You are susceptible to primary HSV-1 infection. If your partner is HSV-1 positive, discuss preventive measures during pregnancy with your obstetrician — primary HSV-1 acquired in late pregnancy can transmit to the baby.
Can HSV-1 be cured?
No. Antivirals (aciclovir, valaciclovir) shorten outbreaks and reduce shedding but do not eliminate latent virus.
Related Infectious Disease tests
Tests commonly ordered alongside HERPES SIMPLEX VIRUS I (HSV)-IGG, or that help interpret an unexpected result.
Sources & references
- CDC — Genital Herpes · accessed 2026-05-30T00:00:00.000Z
- NIH MedlinePlus — Herpes Test · accessed 2026-05-30T00:00:00.000Z
- NCBI StatPearls — Herpes Simplex Virus · accessed 2026-05-30T00:00:00.000Z
- IDSA — HSV Guidance · accessed 2026-05-30T00:00:00.000Z
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