[Expression, purification and immunogenicity of a novel hepatitis E virus-like particle].

Aim: To express and characterize a novel hepatitis E virus (HEV) recombinant protein which contains HEV neutralization epitope(s).
Methods: The gene fragment encoding for amino acid 452-617 of HEV open reading frame 2 protein (pORF2) was inserted into the plasmid pET28a(+). The recombinant plasmid was used to transform the E. coli BL21(DE3) strain. The recombinant protein was expressed by IPTG induction, purified by Ni-NTA chromatography and analyzed by SDS-PAGE, Western blot and electronmicroscopy. Immune responses to the recombinant protein were determined by the immunization of mice.
Results: The expressed HEV recombinant protein was in a naturally-soluble form with a molecular weight of 22,000. The protein assembled into a virus like particle (VLP) with a diameter of approximate 20 nanometers. Moreover, this novel protein was reactive to serum samples obtained from the patients with HEV infection. After the mice were immunized with the protein, they developed anti-HEV antibodies which could neutralize HEV infection in cell culture.
Conclusion: An E. coli-expressed recombinant protein containing 166 amino acid of HEV pORF2 can form VLP with good immunogenicity and antigenicity. This novel HEV VLP is valuable for the development of HEV vaccine and new diagnostic kit.