Antigenic analysis of two chimeric hepatitis B core particles presenting the preS1 neutralizing epitopes

Objective To construct full-length hepatitis B core particles presenting preS1 aa 21-47 epitope and truncated core particles presenting preS1 aa 37-45 epitope on their surface and compare their antigenicity.Methods PreS1 aa21-47 epitope and aa 37-45 epitope were inserted respectively into full-length hepatitis B core (aa 1-183) and truncated HBcAg(aa 1-144),between the 78th (Asp) and 79th (Pro).The genes synthesized after the codon optimization were ligated to the pET43.1 a vector with the same cohesive terminal (NdeI and XhoI) and expressed in the E.coli expression system.The morphology of the proteins of interest were observed by electron microscope and characterized by ELISA and Western Blotting.Results The morphology of the virus-like particles were confirmed by electron microscope.H2 were solid particles with a diameter of (31.61 ± 1.27) nm,while H3 were hollow particles with a diameter of (28.46 ± 1.16) nm.Statistical analysis showed that H2 is larger than H3 in the diameter (P ＜ 0.01).The antigenicity of the inserted epitopes and carrier protein were identified by ELISA and Western Blotting.Conclusion Chimeric hepatitis B core particles presenting the preS1 neutralizing epitopes on their surface have been expressed,purified and identified,which lays the foundation for its application in vaccine research. Key words: Hepatitis B virus;  Epitopes;  Viral core proteins;  Virus-like particle