Molecular tests that can identify early protein markers produced by Epstein Barr Virus (EBV) may have value for diagnosing active infection.
The benefits of this diagnostic approach in patients with mononucleosis and in EBV-infected transplant patients have been evaluated by comparing three different immunoassays.
Scientists at University College Dublin (Ireland) investigate the diagnostic value of anti-early antigen (EA) immunoglobulin G (IgG) testing in the stage-specific differential diagnosis of EBV infection in immunocompetent individuals with atypical antibody responses. Furthermore, they assessed whether anti-EA IgG detection in conjunction with EBV DNA viral load quantification had better predictive value than EBV DNA alone in the diagnosis of EBV-associated disease in immunosuppressed adult liver transplant recipients. During the study period, none of the patients developed post-transplantation lymphoproliferative disorders (PTLD).
Eighty-five serum or plasma samples from 69 individuals were selected from the archived database. The detection of EA IgG in patients'' samples was carried out using three different specific serological assays. The enzyme-linked immunosorbent assay (ELISA) is a microtiter plate assay, which detects and quantifies specific human IgG against EBV p54 EA. The Liaison chemiluminescent immunoassay (CLIA) is a two-step, immunoluminometric sandwich assay using directly coated magnetic particles for the detection of EBV EA IgG against the p54 EA. The recomBlot EBV IgG qualitative immunoblot assay was used as the gold standard. Amplification and quantification of DNA was performed using the Light Cycler EBV Quantification kit (Roche Diagnostics; Mannheim, Germany).
The results showed that the CLIA (DiaSorin; Saluggi, Italy) and immunoblot (Mikrogen; Neuried, Germany) produced more comparable results. However, there was a significant difference between the results of the ELISA (MP Biomedicals; Eschwege, Germany) and the immunoblot EA IgG assays and the results of the CLIA and ELISA assays. Comparisons with the immunoblot results showed that the CLIA is more sensitive (77%) than the ELISA (50%), but that the CLIA is less specific (42%) than the ELISA (100%).
The authors concluded that the automated CLIA was found to be more accurate than the ELISA when using the immunoblot assay as a “gold standard” assay in the detection of EA IgG. There may be a potential role for EA IgG testing, together with EBV viral load, in the prediction of transplant recipients at risk of EBV-associated disease. However, EA IgG does not play a significant role in the differential diagnosis of EBV infection in immunocompetent individuals. The study was published on November 2, 2012, in the journal BioResearch Open Access.