EVALUATION OF THE PLEXUS EPSTEIN-BARR VIRUS MULTI-ANALYTE PANELS FOR DETECTION OF IGG AND IGM CLASS ANTIBODIES TO EBV

Background: Specific laboratory diagnosis of infectious mononucleosis is generally accomplished by serologic detection of IgG- and IgM-class antibodies to a number of EBV protein antigens including early (EA), nuclear (EBNA), and viral capsid (VCA) antigens. Immunofluorescence-based assays (IFA) are considered the gold standard method for serodiagnosis of EBV infection, but enzyme immunoassays are being utilized more frequently because they are easier to perform, amendable to automation, and less subjective to interpretation of results.

 Objective: In this study, we compared FDA-cleared IFA kits with investigational, multiplexed, microwell-plate, microbead-based, fluorescent immunoassay panels (Plexus™ EBV, Focus Diagnostics, Cypress, CA) for detection of antibodies to EBV antigens to determine EBV infection status.

Methods: A total of400 pediatric serum specimens submitted to Children’s Hospital Laboratory for EBV serology as per standard-of-care were studied. These included 250 prospectively and sequentially collected (2007) fresh specimens with unknown EBV serologic status (all-comers) and 150 previously collected (2005-06) and frozen (-20C) specimens with EBV test results indicative of acute EBV infection (acutes). IFA was performed using Merifluor EBV IFA kits (Meridian BioSciences, Cincinnati, OH) for antibodies to VCA IgM, VCA IgG and EBNA. Two separate Plexus EBV panels were used – the IgG panel allowed for detection of antibodies to EA-diffuse, EBNA-1, and VCA-125, while the IgMpanel allowed for detection of antibodies to VCA-125 and heterophile antigen. Fluorescent intensity was measured on a Luminex™ 200 (Luminex Corp, Austin, TX) instrument. Only the results for VCA-IgG, VCA-IgM and EBNA were used for comparison with IFA.

 Results: Overall comparisons of EBV serologic status as determined by IFA vs. Plexus are shown in the table. There was 96% agreement for “susceptible (no infection)” and 97.5% agreement for “acute infection” status between the 2 methods. Agreement for “previous infection” status was ~87%.       

Conclusions: Plexus EBV (1) shows very good correlation with IFA in establishing EBV infection status, (2) should be evaluated further and compared with other assays, and (3) considered for implementation when FDA-cleared.