Sensitivity of the Enzygnost anti-EBV/IgG for the determination of the Epstein-Barr virus immune status in pediatric patients

Reliability of the Siemens Enzygnost and Novagnost Epstein-Barr virus assays for routine laboratory diagnosis: agreement with clinical diagnosis and comparison with the Merifluor Epstein-Barr virus immunofluorescence assay

Background

Diagnosis of Epstein–Barr virus (EBV) infection is routinely conducted by clinical laboratories, especially to diagnose infectious mononucleosis. At an estimated general population incidence of 1:200, this represents a potentially significant testing burden. We evaluated the reliability of the Siemens Novagnost® and Enzygnost® EBV microtiter assays measuring VCA IgM and IgG, and EBNA-1 IgG for clinical diagnosis of EBV-related infectious mononucleosis.

Methods

Remnant sera from 537 patients tested for EBV infection were used to compare the Siemens assays to each other and to the Merifluor assay. The Siemens assays are qualitative/semiquantitative, automatable enzyme immunoassays. The Merifluor assays are manual, qualitative indirect immunofluorescent assays. Testing was conducted on the Siemens and Merifluor assays in parallel. All assays were conducted and interpreted according to each manufacturer’s specifications. Agreement of serostatus between each of the three assays was assessed. Discrepant results were resolved using a third method (Mikrogen recomLine).

Results

Final EBV serostatus indicated 2.9% of the population had an acute infection, 89.6% had a past infection, and 7.5% were EBV naive. All three assays demonstrated 100% agreement with acute infection. Agreement with past-infection serostatus was 99.1% for Enzygnost, between 86% and 98.8% for Novagnost, and 98.1% for Merifluor. Seronegative agreement was 100% for Enzygnost, 89.7% for Novagnost, and 92.3% for Merifluor.

Conclusions

The Siemens Enzygnost and Novagnost EBV microtiter assays are suitable for clinical rule-in of acute EBV infection and for identifying EBV-naive individuals. Both assays also adequately identify remote EBV infections. Because these assays can be automated, they can improve speed and efficiency of EBV testing, especially in high-volume laboratories.

Performance of two commercially available automated immunoassays for the determination of Epstein-Barr virus serological status

This study evaluated the performance of two automated Vidas (V) and Liaison (L) immunoassays for Epstein-Barr virus (EBV) serology. The detection of the viral capsid antigen (VCA) IgM, the VCA/early antigen (VCA/EA) IgG, and the Epstein-Barr nuclear antigen (EBNA) IgG was assessed on 526 sera collected for routine EBV testing in immunocompetent subjects. The determination of expected EBV status (186 EBV primary infections, 183 past EBV infections, and 157 EBV-seronegative individuals) was based on results of routine laboratory enzyme immunoassays (EIAs) together with clinical data. The sensitivity and specificity of each individual marker were determined in comparison to the expected EBV status. The agreement between the V and L profiles and the expected EBV status was established through the interpretation of combinations of the different EBV markers. Statistically significant differences between the two tests were found for the specificity of the VCA IgM marker (96.2% for V versus 93.2% for L), the sensitivity of the VCA/EA IgG marker (89% for V versus 94% for L), and the specificity of the EBNA IgG marker (96.5% for V versus 74.2% for L). The results determined for the two assays with respect to overall agreement with the established expected EBV status were not significantly different (89.7% for V versus 88.2% for L), with discrepancies mainly observed in sera referenced as primary infections. These findings demonstrated the similar performances of the Vidas and the Liaison assays for the establishment of an EBV serological status using the VCA, EA, and EBNA markers.

Expanding the spectrum of neurological disease associated with Epstein-Barr virus activity

The purpose of this study was to delineate the spectrum of neurological diseases attributed to Epstein-Barr virus (EBV) activity. The approach was a retrospective study on patients with EBV activity proven by a positive EBV antibody-specific index (AI) and/or cerebrospinal fluid (CSF) PCR. One hundred six children and adults (AI positive = 77, AI + PCR positive = 3, PCR positive = 26) were identified, most with reactivated infections. Twenty-eight showed typical EBV-related diseases (encephalitis, neuritis, meningitis), 19 further infections (HSV encephalitis, neuroborreliosis, HIV infection, bacterial meningitis), nine immune-mediated disorders (multiple sclerosis, optic neuritis), and 50 further diseases not typical for EBV. The highest AI values occurred in patients with encephalitis. No relationship between disease category or AI values and viral loads was found. Additional reanalysis of 1,500 consecutive CSF EBV PCR studies revealed the highest positive rates among patients with further infections (n = 18/227, 7.9%) but lower rates among patients with typical EBV-related disorders (5/395; 1.3%), immune-mediated disorders (n = 2/174; 1.1%) and other conditions (n = 4/704; 0.6%). Intrathecal EBV activity is not restricted to typical EBV-related disorders, unexpectedly frequent in further CNS infections and also present in non-inflammatory conditions. Prospective studies should assess the pathogenic role of EBV in these different diseases.