Evaluation of reliability and performance of hepatitis B virus-e-antigen assays in tertiary care setting.

Hepatitis B virus-e-antigen (HBeAg) is a viral marker to assess hepatitis B virus (HBV) replication. We have evaluated the reliability of three commonly available HBeAg immunoassays using World Health Organization-International Standard and clinical samples. In addition the performance of enzyme immunoassays (EIAs) was assessed by kinetic binding and reagent exchange experiments. Analytical and diagnostic sensitivity were significantly different among HBeAg assays (P < 0.01). The affinity of capture/detector antibodies varied significantly between EIAs (P < 0.01). Our findings suggest that significant difference in the affinity of capture/detector antibodies to HBeAg may impact the overall performance and the reliability of currently available HBeAg assays in HBV diagnosis and management.

Cost-Effective In-House Neutralization Assay for the Confirmation of HBeAg.

BACKGROUND & AIM: Hepatitis B virus-e-antigen (HBeAg) is an affordable viral marker to assess viral replication kinetics and response to antiviral therapy. In the absence of confirmatory assays, discrepant or false-positive HBeAg results are resolved by screening for other HBV markers. We standardized an in-house HBeAg neutralization assay (HBeAg-NT) to confirm HBeAg in clinical samples. METHODS: The performance and reliability of this assay were evaluated by first WHO International Standard for HBeAg (first WHO-IS HBeAg) from Paul Ehrlich Institute and clinical samples (n = 150) from chronic HBV carriers. Of these, 71 HBeAg-positive sera were used for HBeAg-NT. RESULTS: Concentrations spanning 0.25-10 U of first WHO-IS HBeAg and clinical samples (S/Co ranges from 1.00 to 10.00) were neutralized completely in the HBeAg-NT. CONCLUSIONS: HBeAg-NT is a simple, cost-effective, and reliable direct approach to confirm HBeAg in clinical samples which precludes the need for screening additional HBV markers in low resource settings.

Evaluation of dried blood spots as a feasible alternative to plasma for the detection and quantification of hepatitis c virus in a tropical setting: A pilot study.

Introduction: Confirmatory diagnosis of hepatitis C virus (HCV) infection (HCV RNA detection) is essential before start of the therapy. HCV RNA detection is not available in many parts of India. Shipment of plasma from distant places to referral laboratories may affect HCV RNA titres. Dried blood spots (DBS) provide an easy alternative for transporting samples to centres where HCV RNA testing is done. Aim: Evaluation of DBS as a feasible alternative to plasma for HCV diagnosis. Methods: In this cross-sectional study, 40 consecutive patients' blood samples were collected from patients referred from the Liver Clinic. Whole blood was spotted onto two Whatman 903TM cards. One card was incubated at ≥37°C and other at 4°C for 15 days, after drying. DBS was eluted and run in Abbott RealTime HCV assay. HCV was also quantified using the Abbott ARCHITECT HCV core antigen assay for 29 of the study patients. Results were compared with normal plasma values. Results: The median log HCV RNA value (in log10IU/mL) of plasma was 5.74, with normalised DBS it was 4.92 (≥37°C) and 4.66 (4°C); difference in plasma and DBS median log values was 0.82 (≥37°C) and 1.08 (4°C) logs, respectively. Interclass correlation values were 0.943, P < 0.0001 (≥37°C) and 0.950, P < 0.0001 (4°C), showing high agreement. The median HCV core antigen value (in fmol/L) for plasma was 325.35, whereas it was 4.77 (≥37°C) and 4.64 (4°C) for DBS samples. Conclusions: DBS can be used for sampling patients from distant resource-limited settings as an alternative to plasma for HCV RNA estimation. Larger studies are required to evaluate the feasibility of DBS in the Indian subcontinent, especially for HCV core antigen estimation.