Over 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 disease. Therefore, the isolation of viral DNA by polymerase chain reaction is not very effective. To determine whether the Epstein-Barr virus infection is active or if a person has had it in the past, antibodies are determined using ELISA (enzyme-linked immunosorbent assay).
What is this virus?
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 ill.
This virus belongs to the herpes virus family. Most often, it causes a disease such as infectious mononucleosis. But it can also be the cause of malignant lymphomas, nasopharyngeal carcinoma (malignant neoplasms of the nasopharynx), chronic fatigue syndrome.
Its peculiarity is that for a long time it is able to be in the body in a "sleeping state", namely in B-lymphocytes. Further, depending on the level of the immune response, several outcomes of the disease are possible. Firstly, the virus can continue to be in lymphocytes until the end of a person’s life, without causing any symptoms. Secondly, self-elimination is possible, that is, removal of the virus from the body. Thirdly, the virus can exit 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 uncontrollably divide, which leads to the development of a tumor process.
Clinical manifestations of diseases caused by this virus
Infectious mononucleosis, as the most common manifestation of infection with this virus, is transmitted from the carrier or patient to a healthy person by airborne droplets. With this pathology, the virus infects lymphoid tissue and cells of the immune system - B-lymphocytes.
The duration of the incubation period is four to six weeks. Clinically, a viral infection is manifested by inflammation of the tonsils, an increase in the 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, rapid breathing, palpitations. 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, you must urgently consult a doctor to determine the level of antibodies using enzyme-linked immunosorbent assay.
What antibodies can be determined using ELISA?
First, 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 in the blood, the following groups of antibodies are determined:
- antibodies to capsid antigen - can be of the class IgM and IgG - antibodies of the type anti-VCA IgM, anti-VCA IgG;
- antibodies to a nuclear antigen - only IgG class - anti-EBV antibodies IgG-EBNA (ven. protein);
- 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 a comprehensive diagnosis and identification of different combinations of antibodies allows you to determine the phase of the infectious process. An isolated determination of one of them, for example, an anti-EBV IgG-EBNA assay (poison protein), has no diagnostic value.
IFA Benefits
Determination of anti-EBV IgG-EBNA 56 (venom. Protein.) Using enzyme-linked immunosorbent assay 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 use the given examination method to determine exactly 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 to reduce the risk of an erroneous result due to the human factor;
- minimum error and high accuracy of the result.
Now the enzyme-linked immunosorbent assay is widely used not only for the diagnosis of the Epstein-Barr virus. If earlier it took several days to sow some pathogens, now you can get the result within a few hours after passing the analysis.
Antibodies against nuclear antigen
EBNA antigens are called nuclear antigens because they are located in the nuclei of cells infected with the virus. They are determined in the cells of malignant lymphomas, nasopharyngeal carcinoma.
Anti-EBV IgG-EBNA (poison. Protein.) Appear later than all. Their highest level is determined in the recovery period (4 months - a year after infection). This group of antibodies can persist for a long time after the disease, even for life.
What are the various combinations of antibodies?
When the anti-EBV IgG-EBNA analysis in the blood is negative, but anti-VCA IgM is present, these data indicate the presence of an active phase of infection. Primary infection is also indicated by elevated anti-VCA IgG titers one month after infection if antinuclear antibodies are not available.
When antibodies against the virus capsid and anti-EBV IgG-EBNA (poison protein) are detected immediately, it is highly likely that the current infection is present in the body.
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 long after the illness, and the virus can reactivate without any symptoms.
Why is this examination necessary?
Determination of the level of anti-EBV IgG-EBNA (poison protein) in the blood using enzyme-linked immunosorbent assay 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 course of lymphomas, nasopharyngeal carcinoma and other oncological diseases that the virus causes.
What conclusions can be drawn upon obtaining the results?
If anti-EBV IgG-EBNA (poison protein) is elevated, this may indicate the presence of the following conditions:
- recovery after infectious mononucleosis;
- Epstein-Barr, a past viral infection;
- chronic course of this infection;
- tumor process caused by this virus.
A negative ELISA result is determined due to the following reasons:
- lack of virus infection;
- the onset or height of infectious mononucleosis, when these antibodies have not yet been synthesized;
- long-passed infectious mononucleosis;
- immunodeficiency state of the body, in which the production of protective antibodies is disrupted.
Need to pay attention!
If the result of decoding anti-EBV IgG-EBNA (poison white) is doubtful, you need to pass the analysis again after a few weeks.
There is no general norm for the level of these antibodies. Each diagnostic center has its own values. However, if the titer of anti-EBV IgG-EBNA (poison. Protein.) ≥ 600 IU / ml, this is most likely indicative of a previous infection process.
If the analysis is carried out for pregnant women, it is first necessary to exclude the presence of diseases similar in symptoms to infectious mononucleosis: toxoplasmosis, cytomegalovirus, human immunodeficiency virus.
As noted earlier, for the correct diagnosis of a viral infection, it is necessary to simultaneously determine the levels of all antibodies that are produced in this disease.