More than 90% of the population is infected with the Epstein-Barr virus. The vast majority are carriers of the virus, that is, the virus does not cause them any diseases. Therefore, the isolation of the DNA of the virus using the polymerase chain reaction is not very effective. To determine whether a Epstein-Barr virus infection is active or a person has had it in the past, antibodies are determined using an ELISA (enzyme-linked immunosorbent assay) method.
What is this virus like?
The spread of the Epstein-Barr virus is extremely high, especially in the countries of the African continent. This territory is characterized by infection of more than 95% of the population. Most often, small children and adolescents are sick.
This virus belongs to the family of herpes viruses. Most often it causes a disease such as infectious mononucleosis. But it can also be the cause of malignant lymphomas, nasopharyngeal carcinoma (nasopharyngeal malignancy), chronic fatigue syndrome.
Its peculiarity is that it is able for a long time to be in the body in a sleeping state, namely in B-lymphocytes. Further, depending on the level of the immune response, several outcomes are possible. First, the virus can continue to be found in lymphocytes until the end of a person’s life, without causing any symptoms. Secondly, self-elimination is possible, that is, the removal of the virus from the body. Thirdly, the virus can escape from the lymphocyte into the bloodstream, which causes an active immune response and severe symptoms. Most often they proceed as an infectious mononucleosis. And the most unfavorable option is the one in which B-lymphocytes suddenly begin to divide uncontrollably, which leads to the development of a tumor process.
Clinical manifestations of diseases caused by this virus
Infectious mononucleosis, as the most frequent manifestation of infection with this virus, is transmitted from a carrier or patient to a healthy person by airborne droplets. With this pathology, the virus infects the lymphoid tissue and the cells of the immune system – B-lymphocytes.
The duration of the incubation period is four to six weeks. A viral infection is clinically manifested by inflammation of the tonsils, an enlarged liver and spleen, an increase in almost all groups of lymph nodes, high fever, and a rash on the body.
The patient’s condition is extremely serious. The temperature rises to high numbers, characterized by high sweating, increased breathing, heartbeat. The patient is worried about extreme fatigue and lethargy, he cannot even get out of bed.
The duration of the active phase of the disease averages one to one and a half months.
There is no specific treatment. It is necessary to observe strict bed rest due to the high probability of rupture of the spleen, drink plenty of fluids.
In the presence of these symptoms, an urgent need to consult a doctor to determine the level of antibodies using enzyme immunoassay.
What antibodies can be detected by ELISA?
Firstly, all antibodies in the body can be divided into two classes: IgM, which indicate the presence of an acute infection in the body, and IgG, which characterize a past or chronic infection.
When infected with a microorganism from the herpes virus family, the following groups of antibodies are detected in the blood:
- antibodies to the capsid antigen – can be of the class IgM and IgG – antibodies of the form of anti-VCA IgM, anti-VCA IgG;
- antibodies to nuclear antigen – only class IgG – antibodies anti-EBV IgG-EBNA (poison. bel);
- antibodies to membrane antigen (MA).
Important in the diagnosis of this infection is the need to determine the presence of all antigens together. Since only complex diagnostics and detection of different combinations of antibodies allow determining the phase of the infectious process. An isolated definition of one of them, for example, an analysis for anti-EBV IgG-EBNA (poison. Bel.), Has no diagnostic value.
Advantages of ELISA
Determination of anti-EBV IgG-EBNA 56 (poison. Bel.) Using an enzyme immunoassay method has several advantages:
- high sensitivity – the ability to determine the presence of antibodies even with their minimum amount in the blood;
- high specificity – the ability to determine with the help of this method of examination precisely those antibodies that are necessary;
- speed of obtaining results, which allows you to make a diagnosis in the first days after infection;
- a high level of manufacturability, which helps reduce the risk of getting an erroneous result due to the human factor;
- minimum error and high accuracy of the result.
Now the method of enzyme immunoassay is widespread, not only in the diagnosis of Epstein-Barr virus. If earlier, in order to sow some pathogens, it took several days, now you can get the result within a few hours after the analysis.
Antibodies produced against nuclear antigen
EBNA antigens are called nuclear because they are found in the nuclei of cells infected with a virus. They are detected in the cells of malignant lymphomas, nasopharyngeal carcinoma.
Anti-EBV IgG-EBNA (poison. White) appear after all. Their highest level is determined during the recovery period (after 4 months – a year after infection). This group of antibodies can persist for a long time after the disease, even for a lifetime.
What do different combinations of antibodies indicate?
When the anti-EBV IgG-EBNA assay in the blood is negative, but anti-VCA IgM is present, these data indicate the presence of an active phase of infection. Elevated titers of anti-VCA IgG also show a primary infection one month after infection, unless anti-nuclear antibodies are present.
If antibodies are immediately detected against the capsid of the virus and anti-EBV IgG-EBNA (poison. Bel.), It is very likely that the body has a current infection.
But at the same time, a simultaneous increase in the level of these antibodies in the blood is not always evidence of an active viral infection. After all, IgG antibodies are detected for a long time after the disease, and the virus can be reactivated without any symptoms.
What is this survey for?
Determining the level of anti-EBV IgG-EBNA (poison. White) in the blood using enzyme immunoassay is necessary in the following situations:
- to confirm the diagnosis of infectious mononucleosis;
- in order to distinguish between infectious mononucleosis and diseases that have similar symptoms;
- for the diagnosis of exacerbation of chronic viral infection;
- to monitor the progress of lymphomas, nasopharyngeal carcinomas, and other cancers that the virus causes.
What conclusions can be made when getting the results?
If anti-EBV IgG-EBNA (poison. Bel.) Is elevated, this may indicate the presence of the following conditions:
- recovery from infectious mononucleosis;
- a past Epstein-Barr viral infection;
- chronic course of the infection;
- tumor process caused by this virus.
A negative ELISA result is determined for the following reasons:
- no virus infection;
- the beginning or the height of infectious mononucleosis, when these antibodies have not yet been synthesized;
- long-transmitted infectious mononucleosis;
- immunodeficiency state of the body, which disrupts the production of protective antibodies.
Need to pay attention!
If the result of decoding anti-EBV IgG-EBNA (poison. Bel.) Is doubtful, you need to pass the analysis again in a few weeks.
There is no general rule for the level of these antibodies. Each diagnostic center has its own values. However, if the titer of anti-EBV IgG-EBNA (poison. White) ≥ 600 U / ml, this is most likely indicative of an infectious process carried over in the past.
If the analysis is performed for pregnant women, it is necessary first of all to exclude the presence of diseases similar in symptoms to infectious mononucleosis: toxoplasmosis, cytomegalovirus, human immunodeficiency virus.
As noted earlier, in order to correctly diagnose a viral infection, it is necessary to simultaneously determine the levels of all antibodies that are produced in a given disease.