Infections
EBV blot
Confirmatory immunoblot for antibodies against the Epstein-Barr virus; helps make sense of an unclear pattern of results.
Everything about this testWhat it measures
The Epstein-Barr virus (EBV) causes mononucleosis (glandular fever) and then stays in the body for life. Separate antibody tests (VCA IgM, VCA IgG and EBNA IgG) each measure the response against one part of the virus. In an immunoblot, separate proteins of the virus are placed on a strip, so it becomes visible which proteins the antibodies in your blood react to. This makes it easier to assess whether it is a first infection or an infection from long ago: antibodies against the nuclear protein EBNA only develop months after the first infection. As a confirmation test, the blot mainly says something if the pattern of those separate tests is unclear or contradictory.
- Confirmation of a recent first infection with the Epstein-Barr virus (mononucleosis)
- Confirmation of an infection from long ago, with an unclear pattern of results
Positive
Antibodies against one or more proteins of the Epstein-Barr virus were found. Which pattern of proteins lights up determines the meaning. If the antibodies react mainly to proteins of the virus coat and not to the nuclear protein EBNA, this fits a first infection in the last few months, as in mononucleosis. If there are also antibodies against EBNA, it is an infection from some time ago. Almost all adults have these antibodies; a positive result therefore says little on its own about the cause of symptoms.
Negative
No antibodies against proteins of the Epstein-Barr virus were found. You have then probably never had the infection, which is uncommon in adults. Very early in a first infection the antibodies may still be absent; if there is a clear suspicion, the test is then repeated after a few weeks or the virus is looked for with a PCR.
If your result is abnormal
The result is assessed together with VCA IgM, VCA IgG and EBNA IgG. If the pattern fits a recent first infection, the illness usually clears up on its own and the GP watches for rare complications such as an inflamed liver or an enlarged spleen. If the picture stays unclear, the test can be repeated after a few weeks or a PCR follows. Mononucleosis is not notifiable.
Reliability
The blot is meant as confirmation when the standard EBV tests show an unclear pattern, for example a single positive VCA IgM without a fitting clinical picture. According to the test guide of UMC Utrecht, VCA IgM, VCA IgG and EBNA IgG are always assessed together; a rapid test for so-called heterophile antibodies is less sensitive and less specific than these EBV-specific tests. As a stand-alone first test the blot has little value, because almost everyone has antibodies. The result says nothing about the amount of virus in the body; that requires a PCR.
Limitations
- Almost all adults have antibodies against EBV; a positive result therefore does not automatically distinguish between a recent and an old infection.
- Very early in a first infection, antibodies may still be absent.
- With reduced immunity, the antibody pattern can be abnormal and hard to interpret.
- The result says nothing about the amount of virus or about it becoming active again; that requires a PCR.
How common is this
Infection with the Epstein-Barr virus is very common in the Netherlands: half of the population over 5 years old has had the infection, and most adults had it before the age of twenty, usually without noticing. In teenagers and young adults the infection more often causes symptoms, such as a sore throat, fever, swollen glands and tiredness that can last 2 to 3 months.
Who is this useful for
Meant as confirmation with an unclear or contradictory pattern of the standard EBV tests, usually with symptoms that fit mononucleosis. In people without symptoms or with long-lasting tiredness without a recent illness, the result changes little: almost everyone has antibodies, and these then say nothing about the cause of the symptoms.
Downsides and risks
- A positive result occurs in almost everyone; still, long-lasting symptoms can wrongly be attributed to it, so that another cause is found later.
Sources
Always discuss an abnormal result with your GP. If a result is strongly abnormal, we try to reach you as soon as possible. Read your result yourself as well and contact your GP if in doubt. A test does not make a diagnosis. Read more about risks and results