Epstein-Barr virus (early antigen, EA), IgG antibodies
Why this test?
For the diagnosis of recently transferred infectious mononucleosis and its acute period.
For differential diagnosis of diseases with symptoms similar to infectious mononucleosis.
To detect an exacerbation of the infection caused by the Epstein-Barr virus.
For the study of some oncological diseases (Burkitt's lymphoma, nasopharyngeal carcinoma) associated with the Epstein-Barr virus.
In what cases is it prescribed?
With symptoms of infectious mononucleosis (sore throat, enlargement of lymph nodes, spleen and liver, fever, rapid fatigue).
If infectious mononucleosis is suspected in athletes (this disease increases the risk of splenic rupture during physical exertion).
When diagnosing some lymphoproliferative and oncological diseases.
The Epstein-Barr virus belongs to group 4 human herpes viruses. It tends to affect B-lymphocytes and causes an acute disease in humans - infectious mononucleosis. Epstein-Barr virus is also associated with the development of nasopharyngeal carcinoma, Burkitt's lymphoma, Hodgkin's disease, hairy leukoplakia, and B-cell lymphoma.
The virus is spread all over the world. In some countries, up to 95% of the population aged 40 have previously been infected with the Epstein-Barr virus and have antibodies. Infection occurs when the infection is transmitted with saliva. The incidence peaks in early childhood and adolescence.
The virus, entering the bloodstream through the epithelium of the mouth, throat and salivary glands, penetrates B-lymphocytes, stimulating their reproduction. As a result, the tonsils, lymph nodes, and spleen increase. With normal cellular immunity, infected B-lymphocytes and the virus are removed from the blood and the symptoms of the disease gradually disappear. The Epstein-Barr virus, like other herpes viruses, is capable of turning into a latent infection. Its genetic material can be stored in a small number of B-lymphocytes and is capable of asymptomatic reactivation. With defects of cellular immunity, HIV infection, therapy with immunosuppressants, the Epstein-Barr virus can lead to oncological diseases (for example, B-cell lymphoma, nasopharyngeal carcinoma).
In many cases, the primary infection is asymptomatic or with moderate pharyngitis and tonsillitis. The clinical picture of infectious mononucleosis is manifested in 35-50% of infected people.
The incubation period of the disease is 4-6 weeks. In the prodromal period, the infection is manifested by muscle pain, rapid fatigue, and general malaise. Then they are joined by fever, sore throat, enlargement of lymph nodes, spleen and sometimes liver. In some cases, a rash appears on the hands and body. Symptoms persist for 2-4 weeks.
With the beginning of the period of clinical manifestations, atypical mononuclear cells (> 10% of lymphocytes) and indicators of liver dysfunction are detected in the blood.
The main antigens of Epstein-Barr virus, to which antibodies are determined, are viral capsid antigen (VCA), early antigen (EA) and nuclear antigen (EBNA).
Antibodies to early antigens (ant-iEA) appear in the acute period of infection in 70-85% of patients with infectious mononucleosis and disappear after 3-6 months. In 20% of infected people, immunoglobulin data are stored for a long time and must be determined within several years after recovery.
Antibodies to EA include components D (diffuse) and R (restricted), so called depending on the features of immunofluorescent staining of infected cells. The detection of elevated titers of antibodies to antigens EA, EBNA and antiVCA of the IgM class helps to definitively diagnose primary infection with the Epstein-Barr virus with 95 percent accuracy.
The increase of antiEA simultaneously with antiEBNA and antiVCA of IgG class is associated with exacerbation of latent infection. An increase in the titer of antiEA is detected when the virus is reactivated in patients with immunodeficiencies, HIV infection, on the background of taking immunosuppressive drugs, in pregnant women and the elderly. Moderate and high titers of antiEA are determined in patients with Burkitt's lymphoma (due to the R-component) and nasopharyngeal carcinoma (due to the D-component).
The diagnosis of chronic infection caused by the Epstein-Barr virus cannot be based only on an elevated titer of antiEA with negative results of other tests, since antiEA can also be determined in healthy people who have previously contracted infectious mononucleosis. The results of the analysis must be interpreted together with the level of antibodies to EA, EBNA and VCA of the Epstein-Barr virus, as well as PCR indicators and clinical data.