Optimization and Application of Quantitative In-House ELISA for Diagnosis of HBsAg and its Correlation with Commercial ELISA and Molecular Kits

Background: Several studies have indicated the role of quantitative hepatitis B surface antigen (HBsAg) evaluation in managing and prognosis of hepatitis B virus (HBV) infection. Thus, quantitative evaluation of HBsAg using cost-effective assays can be an important approach to managing HBV patients. Objectives: This study aimed to set up and apply an in-house quantitative enzyme-linked immunosorbent assay (ELISA) to evaluate HBsAg in research and diagnosis. Methods: New Zealand white rabbits were immunized with HBsAg. Sera were collected 28 days after immunization, and polyclonal HBsAb (antibody to hepatitis B surface antigen) were purified and evaluated. Then, the in-house quantitative ELISA was optimized. Finally, the functional characteristics of the assay were evaluated using 200 plasma samples compared to commercial ELISA and quantitative TaqMan real-time PCR. Results: The assay has a limit of detection (LOD) of 0.5 ng/mL with a specificity and sensitivity of 94% and 97%, respectively. The assay's highest coefficient of variation (CV) values for intra- and inter-assays were 7.23% and 8.59%, respectively. The correlation of the developed assay with commercial ELISA was 0.987 (P-value = 0.024). The correlations of the developed assay and commercial ELISA with quantitative TaqMan real-time PCR were 0.739 and 0.658, respectively (P-value = 0.017). Conclusions: The developed assay has a suitable sensitivity and specificity. It is also reproducible and well-correlated with commercial assays. Most importantly, it is cost-effective and, thus, can be used for detecting and quantifying HBsAg in research and diagnosis.