EBV nuclear antigen (EBNA) IgG

An antibody that appears months after Epstein-Barr virus infection and stays for life, so a positive result usually points to an infection in the past.

AI-verified against cited sources. Awaiting expert reviewAlso called EBNA, EBNA IgG, EBV NA IgGLOINC 5156-5

What it is

Epstein-Barr virus (EBV) is a very common virus. The CDC says most people are infected at some point, often in childhood and often with no symptoms, and more than 90% of adults carry antibodies from an infection years earlier. EBNA stands for Epstein-Barr nuclear antigen, a protein inside infected cells. After an infection, the body slowly starts making IgG antibodies against it. Labs report the result as negative, equivocal or positive, and many also print a number.

Why it matters

EBNA IgG is read together with VCA IgM and VCA IgG to help tell a first-time EBV infection, such as mono, from an old one. Because EBNA antibodies show up slowly, a positive result usually points to an infection from months or years ago. A result with VCA IgG positive and EBNA IgG negative can fit a recent infection. Negative results on all the EBV antibody tests usually mean you have not been infected before. No single EBV antibody result answers the question alone.

If it’s high

A positive EBNA IgG usually means you were infected with EBV at some point, often years ago. This is very common. It does not mean you have mono now, and it does not mean the virus is active. After the first infection, the virus stays in the body in a dormant state.

Common causes

An EBV infection months or years ago, often in childhood and often without symptoms
Past infectious mononucleosis (mono)

What can help

Ask your clinician how this result fits with your symptoms and your other EBV results
If you were tested because of a recent illness, ask whether the VCA IgM and VCA IgG results change the picture

What can affect your result

Timing: EBNA IgG is usually still negative in the first weeks of a first infection
The lab's kit and cut-offs: results are not interchangeable between manufacturers
An equivocal result may be repeated in 10 to 14 days
Timing: EBNA IgG appears slowly, about 2 to 4 months after symptoms start, so it is usually negative during the first weeks of a first infection.
Labs use different kits and cut-offs. ARUP notes that EBNA values from different manufacturers' methods may not be used interchangeably.

Appears about 2 to 4 months after symptoms start (CDC) and then persists for life.

When to talk to a clinician

An EBNA result on its own is not urgent. Talk with a clinician about a fever, sore throat, swollen glands or tiredness that does not go away. Get urgent care for trouble swallowing or breathing, or sudden severe belly pain, especially on the upper left side. If you cannot breathe well, call 911 or your local emergency number.

Questions you could ask

Which EBV tests should be read together for my situation?
Would repeating the tests later help, since my symptoms started recently?
Does this fit with a past infection, given my other EBV results?
Do I need any follow-up for this result?

Questions people ask

My EBNA IgG is positive. Do I have mono right now?

Usually not. EBNA antibodies appear slowly, about 2 to 4 months after symptoms start, so a positive result usually points to an infection from the past. Your clinician reads it with your symptoms and the VCA IgM and VCA IgG results.

Can EBNA IgG be negative if I was infected before?

Sometimes. Some people with a past or recent infection have VCA IgG without EBNA IgG. Clinicians look at the whole set of EBV tests, and sometimes add other tests, to sort this out.

What does an equivocal result mean?

The number fell between the lab's negative and positive cut-offs. ARUP notes that repeating the test in 10 to 14 days may help.

Show the science and sources

For clinicians and researchers

EBNA IgG (EBNA-1) is measured by immunoassay: Quest reports U/mL with under 18.00 negative, 18.00 to 21.99 equivocal and over 21.99 positive; ARUP (semi-quantitative chemiluminescent immunoassay) reports 17.9 U/mL or less not detected, 18.0 to 21.9 indeterminate (repeat in 10 to 14 days may help) and 22.0 U/mL or more detected; Mayo reports negative or positive by ELISA. Per the CDC, EBNA antibody appears slowly, 2 to 4 months after symptom onset (Quest: about 3 to 4 months), and persists for life; it is absent during the acute phase. The CDC adds that EBNA enzyme immunoassays other than the standard immunofluorescent test may give false-positive results. A pattern of VCA IgG and EBNA IgG without VCA IgM is typical of past infection, and VCA IgM plus VCA IgG without EBNA IgG indicates acute infection (De Paschale and Clerici 2012). Interpretation can still be difficult: VCA IgG can occur without VCA IgM or EBNA IgG in acute or past infection, all three markers can appear together in recent infection or reactivation, and an isolated EBNA-1 IgG profile can raise doubt. Avidity testing, immunoblotting, heterophile antibodies, anti-EA(D) and EBV DNA testing can help. The CDC notes that paired acute and convalescent samples are not useful for separating recent from past infection, because the antibody response is rapid. The magnitude of an EBNA value cannot be correlated to an endpoint titer (ARUP).

LOINC 5156-5 (primary), 31374-2, 30083-0, 7883-2, 22298-4. Specimen: serum.

Sources

Laboratory Testing for Epstein-Barr Virus (EBV), US Centers for Disease Control and Prevention
About Epstein-Barr Virus (EBV), US Centers for Disease Control and Prevention
Epstein-Barr Virus Nuclear Antigen (EBNA) Antibody (IgG) (test code 8564), Quest Diagnostics
Epstein-Barr Virus Antibody to Nuclear Antigen, IgG (test 0050245), ARUP Laboratories
Epstein-Barr Virus Antibody Profile, Serum (test EBVAB), Mayo Clinic Laboratories (via testcatalog.org)
Serological diagnosis of Epstein-Barr virus infection: Problems and solutions, World Journal of Virology (2012)

AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. How we build and check these pages.