Enhanced Diagnostic Accuracy in Hepatitis B: Human vs. Sheep-Derived Antibodies in HBsAg Confirmatory Testing

Background: HBsAg confirmatory testing is crucial for accurately diagnosing HBV infection and avoiding false positives. We compared the performance of human-derived and sheep-derived anti-HBs reagents in the Elecsys HBsAg confirmatory test (Roche Diagnostics, Germany). Methods: Samples with a HBsAg COI of 0.9 or more underwent confirmatory testing with both reagents. Results showed a high overall agreement rate of 98% between human and sheep reagents. Results: The average confirmation percentage with sheep anti-HBs was significantly lower than with human anti-HBs (6.9% vs. 20.0%, p = 0.002). Additionally, some strongly positive HBsAg samples could not be neutralized. Conclusions: This suggests that the polyclonal antibodies in these reagents have different specificities and affinities for HBsAg epitopes. The findings emphasize the importance of reagent specificity and affinity to ensure accurate HBV diagnosis. Additional HBV markers and clinical context must be considered to confirm the diagnosis.