Preliminary Study Of Influenza Universal Vaccine Based On HA2Protein

Either pandemic influenza or seasonal influenza can pose a great threat to human health, and it was proved by the novel A (H1N1) influenza pandemic in2009again. Vaccination is the most effective way of controlling and preventing influenza. Due to high mutation rate, the vaccine strain must be changed frequently to match with the circulating virus. However, the limitation of the current predictive method can not accurately match the vaccine candidate with epidemic strain, decreasing the effectiveness of vaccine. Thus, universal vaccine, which can protect human from multiple influenza variants infection, becomes a hot area of the influenza vaccine development. In present study, core antigen of Hepatitis B (HBc) which can form the virus like particle (VLP) was employed to be fusion-expressed with the linear conserved region (LCR) locating at HA2protein76-130amino acids of influenza A virus to form chemic VLP. We expect that influenza universal vaccine developed in the present study could provide potent cross-protection against multiple subtypes of influenza A virus.Aims of the project1. Express LCR fragment from influenza A virus used HBc VLP platform and form a novel VLP vaccine.2. Immunological evaluate of this VLP vaccine and evaluate its cross protection efficacy using animal experiment. Contents of the project1. Chose LCR gene fragment of HA2from A/Hubei/1/2010(H5N1), inserted to N-terminal of HBcAg gene, express to a fused protein in Prokaryotic expression system and self-assemble to a VLP.2. The mice novel was immunized with VLP vaccine LCR-HBc and the immunological responses of LCR-HBc vaccine was evaluated by determining the level of HA-specific antibody, cellular immunity. Furthermore, the cross protection efficacy was evaluated via virus challenge experiment use mouse adapted PR8strain.Results of the subject1. LCR-HBc can be efficiently expressed in E.coli after codon optimization and properly assembled to form chemic VLP.2. The expressed product with6xHis tag was purified by Ni-NTA affinity chromatography after degeneration dissolved and the purity was more than85%.3. Though immunological evaluation in mice, we can observe significantly increase of HA-specific antibody level after the boost, compared with the control groups. For the cellular immunity, LCR-HBc can stimulate the mouse lymphocytes to produce IFN-y. Additionally, two effective epitopes for stimulating IFN-gamma was identified:LNKKMEDGFL and DKVRLQLRDN.4. LCR-HBc group showed the lighter symptoms, lower virus load in mice lung (P<0.01) and higher survived rate than two control groups.The findings generated from the present study suggested that the LCR-HBc fusion gene can be effectively expressed in E.coli system and properly self-assemble to VLP. Mice experiment showed that LCR-HBc can elicit high level of humoral immunity as well as cellular immunity, suggesting potent cross-protection against different subtypes of influenza A virus. Thus, our work could pave the way for further development of universal vaccine in the future.