A dual recombinant strategy to quantify PreS1 antibody in hepatitis B patients with genotype B or C virus by ELISA.

Elevated levels of anti-preS1 antibodies in patients correlate with faster hepatitis B virus (HBV) clearance, since preS1 is vital for viral entry. However, accurate quantification of preS1 antibodies is hindered by the variation of HBV genotypes. Herein, a quantitative preS1 antibody assay was developed for Chinese patients with predominant HBV genotypes B and C. First, to address genotype diversity, we constructed a dual recombinant protein combining genotype B and C preS1. Second, a mouse-human chimeric antibody with high and comparable affinity for both B and C preS1 is developed as the standard for quantification by screening and cloning. An optimized ELISA kit using these components demonstrated good specificity, accuracy, reproducibility and stability, with a linear range of 10-100 ng/mL. This approach extends the patient coverage in China to over 95%, providing a valuable diagnostic tool. This work demonstrates a proof-of-concept model for developing broad-coverage assays for other multi-genotype viral diseases.