Prophylactic vaccines for hepatitis type E / 中华肝脏病杂志

Over the past few years, hepatitis type E has been increasingly recognized as an underestimated global disease burden. Populations with severe infection-related injuries or deaths include pregnant women, patients with underlying liver disease, and the elderly. Vaccines are the most effective means to prevent hepatitis type E virus (HEV) infection. However, the development of inactivated or attenuated vaccines is not feasible due to the lack of an efficient HEV cell culture system, so researchers have conducted in-depth research on recombinant vaccines. The capsid protein (pORF2), which the virion's open reading frame 2 encodes, contains almost exclusively the HEV neutralization site. Several candidate vaccines based on pORF2 have demonstrated potential for primate protection, with two being well tolerated and highly effective in preventing hepatitis type E in adults. Hecolin® (HEV 239 vaccine), the world's first hepatitis type E vaccine, was approved for marketing in China in 2012.

Screening and identification of human monoclonal antibodies to hepatitis E virus capsid protein / 中国免疫学杂志

Objective:To establish a method for rapidly screening human antibodies recognizing HEV capsids proteins from pe-ripheral blood.The antibodies recognizing HEV capsids proteins were screened from the peripheral blood of vaccinator and the properties of the antibodies were analyzed.Methods:The HEV capsids proteins specific memory B cells in peripheral blood were obtained by flow cytometry sorting.Then antibody variable genes were acquired through single-cell RT-PCR and recombined to express in eukaryocyte.Finally,the properties analysis of recombinant expressed human monoclonal antibodies were carried out.Results:Six hu-manized monoclonal antibodies recognizing HEV capsids proteins were successfully obtained,and most of them had binding activity and neutralizing activity.Conclusion:The sequence of human monoclonal antibodies recognizing HEV capsid proteins is successfully screened and successfully expressed in the eukaryocyte.The properties of the antibodies are identified,which lay the foundation for studying antibody evolution in the human body after vaccination.

Localization of functional domains of HEV ORF1 in cells / 病毒学报

To investigate the expression and localization of various functional domains of ORF1 polyprotein and ORF3 protein of hepatitis E virus in host cells, the coding sequences of the various functional domains (RdRp, HEL, MET, PLP, X) of ORF1 were separately cloned into pcDNA3. 1-GFP vectors for constructing the recombinant plasmids which were verified by enzyme digestion and sequencing. The exact expression of the fusion proteins were detected by Western Blot, and the distribution and localization were observed by the laser scanning confocal microscope(LSCM). In huh7 cells, GFP-RdRp proteins were found mainly in the nuclei, GFP-HEL proteins were distributed vesicularly around the nucleus, GFP-MET proteins were distributed granularly both in the nuclei and the cytoplasm, GFP-PLP proteins had polar distribution around the nucleus, and unknown GFP-X proteins were distributed uniformly both in the nuclei and the cytoplasm. Different localization of these proteins verified the previous data obtained from in vitro studies, providing a support for further research on the biological functions of various proteins coded by HEV genome.

HEV capsid protein interacts with CYP 2A6 and decreases its coumarin 7-hydroxylation activity / 病毒学报

E2 is a recombinant hepatitis E virus capsid protein including its main antigenic determinants but lacking of the particle assembling domain. P239 was the C-terminal extending protein of E2 and could self-assemble to form virus like particles, which might serve as mimicry of virions both structurally and antigenically. We previously used yeast two-hybrid system to screen proteins interacting with E2 based on a human hepatocyte cDNA library. One candidate was identified as the segment (aa388-437) of cytochrome P450 2A6 protein, which is predominantly expressed in liver and important for metabolization. Some studies have demonstrated that hepatitis virus infection may altered cell metabolic clearance of coumrarin which were rapidly matebolised by CYP2A6. In this research, we demonstrated that the protein interaction between HEV capsid proteins and CYP2A6 by pull-down and co-immunoprecipitation. It was also found that their interaction could decrease the CYP2A6 catalytic activity when p239 was incubated within the CYP2A6-transfected Huh7 cells. These results suggested that CYP2A6 might be related to the pathological process when HEV invaded host cells.

Recombinant HEV caspid protein p239 specifically attached on HepG2 cells and blocked the infection of wild-type HEV on liver cells / 病毒学报

By using Western blot and immunofluorescence assays, the recombinant HEV capsid protein p239 was found specifically attached to the HepG2 cell surface and entered to the cytoplasm with the increase of incubation temperature. Pre-mixture of wild-type HEV with p239 blocked the infectivity of the virus on primary cultured human hepatocytes and HepG2 cells, indicating that p239 and HEV competed the same targeting site on these cells. These data provide evidence that p239 has a similar cell surface structure with wild-type HEV.