Assessment of serologic markers for Epstein-Barr virus

Antibody responses to early antigen (EA) and viral capsid antigen (VCA) were analyzed in 48 proven cases of Epstein-Barr Virus infection and in 48 age- and sex-matched healthy controls to establish optimal cutoff values for diagnosing EBV infection. Predictive values were determined for individual EA and VCA antibody titers and for EA to VCA antibody ratios and the optimal dilution cutoff values for positivity of EA (1:20), VCA (1:640), and EA to VCA (0:031) were selected. When evaluated on a subset of 10 VCA IgM positive cases and 35 negative controls, the three selected cutoff values identified as infections nine of 10, four of 10, and 10 of 10 of the cases and one of 35, none of 35, and one of 35 of the controls, respectively. When evaluated individually on 22 cases of suspected EBV infection who were heterophile antibody-negative and presented with symptoms compatible with EBV infection, an equal number of VCA IgM-positive and negative cases were identified as EBV infections. Overall, the cutoffs EA, VCA, and ratio identified 19 of 22 (86.4%), 14 of 22 (63.6%), and 18 of 22 (81.8%), respectively, and all cases could be identified using combinations of these values. Although these serologic values may be used with some accuracy, until more definitive markers are described a combination of heterophile responses, lymphocyte analysis, clinical symptoms, and serologic cutoff values should be used to assess the role of EBV in patient evaluation.