Epstein Barr Virus (VCA) - IgM ANTIBODIES

Note :

Kindly correlate clinically.VCA IgM titres are elevated during the first 2 months of the disease after which there is reduction in titres of VCA IgM and elevation of VCA IgG and EBNA IgG titre. Hence, it is advised to correlate the result with the clinical history of the patient. If clinically indicated, it is advised to repeat VCA IgG, VCA IgM and NA IgG after 2 to 3 weeks. This will help to confirm the presence of infection, understand its stage and/or rule out serological cross reactivity. False positive EBV VCA IgM results are documented in CMV and other herpesviruses, Parvovirus B19, Toxoplasma gondii, Hepatitis A and HIV infections.
Titres of IgM and IgG antibodies to the viral capsid antigen (VCA) are elevated in the serum of more than 90% of patients at the onset of disease. IgM antibodies to VCA is useful for diagnosis of acute infectious mononucleosis because it is present at elevated titres only during the first two months of the disease. In contrast, IgG antibody to VCA is often used to assess exposure to EBV in the past because it persists for life. IgM VCA antibodies are not demonstrable in the general populations, and thus their presence is virtually diagnostic of acute EBV infection.Antibodies to Early Antigens (EA) are detectable 3 to 4 weeks after the onset of symptoms in patients with Infectious mononucleosis and usually persist for 3 to 6 months. Antibodies to Epstein Barr virus nuclear antigen (EBV-NA) are detectable relatively late (3 to 6 weeks after onset of symptoms) and persist for the lifetime of the patient. The appearance of EBV-NA in a patient with previous VCA-positive and EBV-NA negative is strong evidence of recent EBV infection. The EBV-EA and EBV-NA are also elevated in nasopharyngeal carcinoma, Burkitt's lymphoma and chronic active EBV infection.

Limitations:

Serum specimens drawn early during acute phase of infection may be negative for IgM or IgG class of antibodies.Equivocal results should be followed up with testing of a new serum specimen within 10 to 14 days.Past overt and subclinical infections greatly contribute to high sero-prevalence of various community-related infectious diseases in the general Indian population. Hence, all results must be interpreted in the context of the total clinical history and supplementary findings of other investigative procedures. EBV (VCA) IGM, SERUMEpstein Barr Virus (EBV), classified as human herpes virus type 4, is ubiquitous virus. EBV infection is common, worldwide in distribution and largely subclinical in early childhood. Acute infection in adults results in Infectious Mononucleosis .It has also been aetiologically implicated in Burkitt's lymphoma, Nasopharyngeal carcinoma and lymphoproliferative disorders. Less certain is the aetiologic role of EBV in Rheumatoid arthritis, Hodgkin's disease and its role as a cofactor in AIDS. It is possible that latent and infectious forms of EBV can coexist throughout life in an individual.

Test Utility:

EBV-specific antibody testing is useful in patients with suspected acute EBV infection who lack heterophile antibodies and those with atypical infection. Titres of IgM and IgG antibodies to the viral capsid antigen (VCA) are elevated in the serum of more than 90% of patients at the onset of disease. IgM antibodies to VCA is useful for diagnosis of acute infectious mononucleosis because it is present at elevated titres only during the first two months of the disease. In contrast, IgG antibody to VCA is often used to assess exposure to EBV in the past because it persists for life. IgM VCA antibodies are not demonstrable in the general populations, and thus their presence is virtually diagnostic of acute EBV infection.Antibodies to Early Antigens (EA) are detectable 3 to 4 weeks after the onset of symptoms in patients with Infectious mononucleosis and usually persist for 3 to 6 months. Antibodies to Epstein Barr virus nuclear antigen (EBV-NA) are detectable relatively late (3 to 6 weeks after onset of symptoms) and persist for the lifetime of the patient. The appearance of EBV-NA in a patient with previous VCA-positive and EBV-NA negative is strong evidence of recent EBV infection. The EBV-EA and EBV-NA are also elevated in nasopharyngeal carcinoma, Burkitt's lymphoma and chronic active EBV infection.
Serum specimens drawn early during acute phase of infection may be negative for IgM or IgG class of antibodies.Equivocal results should be followed up with testing of a new serum specimen within 10 to 14 days.Past overt and subclinical infections greatly contribute to high sero-prevalence of various community-related infectious diseases in the general Indian population. Hence, all results must be interpreted in the context of the total clinical history and supplementary findings of other investigative procedures.