Expression of Hepatitis B viral surface antigen (Pre S1) in E. coli

Abstract

Hepatitis B is the most common liver diseases, which caused by hepatitis B virus (HBV) infection. There are around 257 million people around the world suffer from severe chronic hepatitis B infection. Therefore, it is necessary to develop a vaccine to prevent viral infection. PreS1 is one of the HBV envelope proteins that have been proved to be an effective vaccine. Accordingly, Viral DNA was purified from patients’ serums and amplified by PCR using specific primers. Amplicons of 324 bp bands of PreS1 was observed on gel electrophoresis. The PreS1 was cloned into pTXB21 plasmid to form the recombinant plasmid pTXB1_PreS1 and transformed into DH5α E. coli. Screening of transformants was done using Colony PCR and Sequencing. Alignment of 26 polypeptide sequences showed conservation of this region. The pTXB1_PreS1 was retransformed into T7 Express Competent E. coli and screened using colony PCR. The PreS1 was expressed as a recombinant protein fused to an intein tag with a molecular weight of ~ 39.5 kD. The PreS1 protein was purified by a single affinity chromatography step and after cleaved from intein tag by Dithiothreitol the obtained protein had a molecular weight of ~ 11.5 kD. Only one protein band was observed on the SDS-page gel. The PreS1 protein was successfully cloned and expressed in E. coli, which can be used as a vaccine against HBV.