Infection with Epstein-Barr virus (EBV) results in the development of virus-specific antibodies. The pattern of these antibodies helps to stage the illness . EBV-VCA (IgG) Ab

Epstein-Barr virus (EBV), a member of the human herpesvirus group, has been established as the causal agent of heterophil-positive and heterophil-infectious mononucleosis. The diagnosis of infectious mononucleosis can be made in 80 to 90% of cases by demonstration of heterophil antibodies. In the heterophil-negative cases and for atypical infections, determination of specific antibodies to EBV are useful in establishing the diagnosis. The development of IgM antibodies to the viral capsid antigen (EBV-VCA Ab) can be used for specific diagnosis of a current or recent infection. They arise early in the disease and persist for only 4 to 8 weeks On the other hand, many adults have been exposed to EBV and maintain a low level of IgG in response to this virus. A titer of greater than 1:640 is usually diagnostic Antibodies to the early antigen of EBV (EA-EBV) show two distinct patterns of fluorescence-diffuse staining of both nuclei and cytoplasm (anti-D) and staining of cytoplasmic aggregates (anti-R). Anti-D titers appear 3 to 4 weeks after onset and are present in 70% of EBV-induced mononucleosis. Titers correlate with the severity of clinical illness and disappear after recovery. Anti-R titers appear two weeks to several months after onset and are rarely seen in cases of infectious mononucleosis. They are detectable in atypical cases and remain so for up to two years Antibodies to the nuclear antigen of EBV (EBNA-Ab) appear three to four weeks after onset and persist for life. They are useful in assessing recent infection if patients are VCA-positive, EBNA-negative, and then become EBNA-positive. Reference: Ananthanarayan and Paniker&;s Textbook of Microbiology Tenth edition