Study On Alum-Pickering Emulsion As Vaccine Adjuvant

Infectious diseases have been one of the major threats to human health in the long term,and vaccination is an effective method to defend it.However,most of adjuvants are unable to effectively activate the cellular immune response.Moreover,the emulsion adjuvant also includes surfactants,and it is difficult to be modified.Therefore,it is important to develop a safe and effective vaccine adjuvant.This research aimed to combine the oil-in-water emulsion with Alum adjuvant to construct a particle-stabilized emulsion(Pickering emulsion),which would increase the contact area and dynamically activate the immune recognition to enhance the immune response.Besides,Alum adjuvant,as inorganic particle adjuvant,has been approved by FDA for clinical application,which has good biocompatibility and stability.The storage stability and immune efficiency of the Pickering emulsion could be enhanced by using Alum as particle stabilizer.In addition,due to the special surface structure of the Pickering emulsion,the antigen could be adsorbed in the gap,and be protected by the particles.The thesis was divided into the following parts.1.Three commercial aluminum adjuvants were investigated.Squalene containing monophosphoryl lipid A(MPLA)was used as the oil phase and alum adjuvant was used as the particle stabilizer to prepare the Pickering emulsion(Alum adjuvant-stabilized Pickering emulsion with MPLA in the oil phase,ALMPE),which could be stored stably at 37? for more than 4 months.The prepared Pickering emulsion possessed uniform size,good dispersibility and biocompatibility.For the OVA prophylactic vaccine,ALMPE effectively activated the titer of specific antibody IgG in serum and promoted the activation and proliferation of IFN-y secreting cells in splenocytes.In therapeutic evaluations,ALMPE loaded with MUC1 and OVA antigens effectively inhibited the tumor growth of B16/MUC1 melanoma and E.G7/OVA,and improved the survival rate of tumor-bearing mice.Loading the recombinant malaria antigen on ALPE-CpG(Alum adjuvant-stabilized Pickering emulsion with CpG in the water phase)simultaneously induced Thl and Th2 type immune responses.For the recombinant malaria vaccine,ALPE-CpG simultaneously induced Thl and Th2 type immune responses,and showed the same immune effect as Freund's adjuvant.2.The boehmite-type aluminium hydroxide nanoparticles were prepared from aluminum isopropoxide by hydrolysis-hydrothermal methods.The boehmite-type aluminium hydroxide nanoparticles were spherical with good dispersity,uniform size distribution and high crystallinity.Pickering emulsion was prepared by using boehmite-type aluminium hydroxide nanoparticles as stabilizer and squalene containing MPLA as oil phase.The effects of preparation conditions on size distribution and stability of Pickering emulsion were investigated,including the concentration of nanoparticles,water phase and dispersion condition.In the immunoassay of OVA model antigen,the Pickering emulsion simultaneously induced the humoral/cellular immune response.In the preliminary heat stability test of hepatitis B vaccine,it also showed a protective effect on the antigen,which provided convenience for the transportation and application of the vaccine in the underdeveloped countries.