Do we need an ‘in-house’ neutralization assay for confirmation of hepatitis B surface antigen? Answers from a tertiary care hospital in India

Authors


Professor Priya Abraham, Department of Clinical Virology, Christian Medical College, Vellore 632004, India. Email: priyaabraham@cmcvellore.ac.in

Abstract

Background and Aims:  Hepatitis B surface antigen (HBsAg) is an important serological marker for diagnosis of hepatitis B virus (HBV) infection. Commercial kits for detection of HBsAg emphasize confirmation by neutralization assays. In this study, we have standardized an ‘in-house’ neutralization test for HBsAg confirmation.

Methods:  Among 6684 HBsAg-positive samples, 615 were subjected to an ‘in-house’ HBsAg neutralization test (NT). Of these, 91 (100%) high-reactive samples (optical density [OD] 1.000–3.000) and 286 (93%) of 289 low-reactive samples (OD < 1.000) were neutralized, and 235 (100%) grey-zone reactive samples were ‘in-house’ NT negative. Eighty-four samples of varying reactivities that were tested by the ‘in-house’ NT were compared with a commercial NT (AxSYM, Abbott).

Results:  The ‘in-house’ NT showed an excellent agreement (κ = 0.83, P < 0.001) with the commercial confirmatory assay. The sensitivity, specificity, positive and negative predictive values were 90%, 94%, 96% and 87%, respectively.

Conclusion:  The enzyme immunoassay-based ‘in-house’ HBsAg neutralization assay is a feasible alternative to the commercial HBsAg confirmatory assay. This technique is easily adaptable, cost-effective and reliable for the confirmation of HBsAg in a low resource setting, enhancing the overall quality of HBsAg screening.

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