# Impact of preS1 Evaluation in the Management of Chronic Hepatitis B Virus Infection

## TL;DR

This study explores the role of preS1 in chronic hepatitis B virus infection and suggests it could be a key target for treatment.

## Contribution

The study identifies conserved antigenic epitopes in preS1 across different HBV genotypes and highlights its potential as a therapeutic target.

## Key findings

- Seven monoclonal antibodies recognized preS1 across HBV genotypes A to D.
- preS1 antigenicity was significantly reduced by an aa45F substitution.
- preS1 expression remained consistent in CHB patients regardless of HBsAg levels or genotype.

## Abstract

Background and Objectives: The measurement of hepatitis B surface antigen (HBsAg) is essential for managing chronic hepatitis B virus infection (CHB). HBsAg consists of three different surface envelope proteins: large, middle, and small HB surface proteins. However, in clinical practice, it is not common to evaluate each of these HB surface proteins separately. Materials and Methods: In this study, we investigated preS1 expression using seven monoclonal antibodies (mAbs) in 68 CHB patients, as well as examining their antigenicity. Results: Although the seven mAbs had been derived from genotype (Gt) C, they could recognize preS1 with Gts A to D. The epitopes were concentrated within the aa33-47 region of preS1, and their antigenicity was significantly reduced by an aa45F substitution. We found that preS1 expression remained consistent regardless of HBsAg levels and different Gts in CHB patients, in contrast to what was observed in SHBs. Conclusions: These results suggest that the antigenic epitope is preserved among different Gts and that the expression pattern of preS1 is altered during CHB, highlighting its vital role in the HBV infection cycle. Our present results suggest preS1 is a promising therapeutic target in CHB.