Epstein-Barr virus (capsid antigen, VCA), IgM antibodies
Why this test?
For the diagnosis of infectious mononucleosis and assessment of the stage of infection.
For differential diagnosis of herpes infections.
For differential diagnosis of tonsillitis.
To detect reactivation of the Epstein-Barr virus during organ and tissue transplantation.
In what cases is it prescribed?
In case of clinical (hepatosplenomegaly, tonsillopharyngitis, swelling of the maxillary and cervical lymph nodes) and laboratory (atypical lymphocytes in peripheral blood) signs of infectious mononucleosis.
In case of questionable results of the ELISA test, as well as for results conforming.
With HIV infection.
During immunosuppressive therapy after organ or bone marrow transplantation.
Epstein-Barr virus is a widespread virus of the Herpesviridae family that reproduces mainly in B-lymphocytes, but can also infect T-lymphocytes and epithelial cells. The way of transmission is airborne. Peak incidence - 15-25 years. The first contact with the Epstein-Barr virus occurs, as a rule, in childhood (up to 10 years), which leads to the development of a latent asymptomatic or mildly symptomatic infection.
Infection in adults leads to the development of infectious mononucleosis, which in most patients is accompanied by fever, intoxication, as well as damage to lymph nodes (lymphadenopathy), palatine and pharyngeal tonsils. The liver and spleen are often enlarged, petechiae appear on the mucous membrane of the upper palate. In some cases, infectious mononucleosis is complicated by hepatitis, pneumonia, hemolytic anemia, thrombocytopenia, aplastic anemia, rupture of the spleen, as well as cardiac (myocarditis) and neurological disorders (Guillaume-Barré syndrome, encephalitis, meningitis). In rare cases, a chronic active infection develops, in which the symptoms of the disease persist for more than 6 months after the initial infection with the Epstein-Barr virus, and there are also histological signs of damage to internal organs (pneumonitis, hepatitis, hypoplasia of the bone marrow, uveitis) and antigens or DNA are detected virus in tissues. In addition, very high titers of virus-specific antibodies are often found in this condition. Conversely, with chronic fatigue syndrome, the titer of antibodies to the Epstein-Barr virus or other viruses is only slightly elevated.
The Epstein-Barr virus infects more than 90% of the healthy population and is stored in small amounts in memory B cells. Accordingly, about 90% of adults are virus carriers. The virus is stored in B-lymphocytes and epithelial cells throughout life and when immunity is reduced (for example, with HIV infection or immunosuppressive therapy) it can contribute to the development of lymphoproliferative diseases, nasopharyngeal carcinoma or - most often - infectious mononucleosis.
Determination of IgM and IgG antibodies to individual proteins allows more accurate determination of the phase of the course of the infection, given the high frequency of virus persistence. Immunoblotting to determine IgM and IgG antibodies to individual proteins provides additional information about the phase of the infection. The detection of VSA 125 protein indicates the early phase of the infection. VSA 19 appears during the peak of the infection and at the end of the acute process. The late phase of the infection is indicated by the detection of the highly specific marker VSA 22, which is detected alone or together with EBNA-1 (P79). The latter protein is present for a long time in persons who have contracted an infection, and is a convincing indicator of a previous infection. The frequent presence of IgM-P45 and IgM-p79 during an active process, IgM-p43 and IgG-p27 correlates with the severity of the infection, and the detection of IgM-p65, IgM-p33 - with the presence of hepato- and splenomegaly.
This study has a high specificity (98%) and sensitivity (95%) of the method, allows to determine antibodies to individual antigens of the virus, the full spectrum of detected clinically significant antigens, to confirm the results of screening, to carry out differential diagnosis between acute and past infection.