| In recent years,the outbreak of severe infectious diseases has dramatically threatened public health.As biological agents developed for fighting against various pathogens,vaccines can effectively protect humans from multiple infectious diseases.The subunit vaccines use the immunogenic components of the pathogen as the antigens.which have high antigen purity,low cost,and a relatively simple preparation process.Despite the many advantages,the disadvantages of subunit vaccines are also apparent.Subunit vaccines are poorly immunogenic,and multiple vaccinations are necessary to enhance the immune response.In addition,the adjuvants are also needed to further improve immune protection.With the development of micro-nano technology,using micro-nano materials to enhance the immune response of subunit vaccines has shown unique advantages in the laboratory and preclinical experiments,such as increasing antigen loading,avoiding inactivation of antigens,prolonging the retention time of antigens.However,most existing carriers focus on material design that ignores the connection between the material and the immune system,severely reducing immuneenhancing effects.Therefore,according to the characterization of the immune system,utilizing the advantages of micro-nano materials,the carriers and the immune system can be interconnected,so that the carriers can be designed based on the characterization of the immune system.Based on the overall investigation of the current micro-nano materials used in vaccine carriers and the comprehensive study of the types of vaccines.This dissertation starts with improving the immune protection of subunit vaccines.according to the characterization of antigens and the immune system,designing a series of subunit vaccine carriers based on immune system function regulation.And innate immunity or novel adjuvants are utilized to deliver the subunit vaccines,thereby further enhancing the immune response of subunit vaccines.We prepared an amino-modified amphiphilic polymer(TPCAH)for protein-based subunit vaccine delivery.Using mPEG as the initiator,the compound was prepared by two-step ring opening and one-step addition reaction.And the polymer can selfassemble into nanoparticles in an aqueous solution.Since the amino groups are on the side chain of the polymer,the nanoparticles have a positive charge,which can carry protein antigens through electrostatic interaction.The electrostatic interaction is a physical phenomenon,which will not affect the structure of the antigen and ensure the immunogenicity of the antigen.In addition to providing positive charges,the modified amino groups can also activate the complement system.The activated complement system can further enhance the adaptive immune response,thereby enhancing the immune protection of subunit vaccines.In this work,the loading of the antigens is achieved through the charge difference between the carrier and the antigen.There are no specific requirements for the type,composition and spatial structure of the protein antigen,so this method can be effectively extended to other types of protein antigens.This method is universal and provides a simple and effective solution for the delivery of protein antigens.Based on the above work,we find that the use of innate immunity can effectively enhance the immune response of subunit vaccines.But it is unknown how innate immunity modulates adaptive immunity and enhances subunit vaccine immune responses during immunization.In this work,the microgels were used as carriers to deliver antigens.And the microgels were respectively modified with glucose and mannose to explore the effect of specific binding of receptors and ligands on the uptake efficiency of antigen-presenting cells in innate immunity and the effect of subunit vaccine immune response.As vaccine carriers,the microgels can effectively deliver antigens,ensuring long-term and effective antigen stimulation.The advantages of modified microgels in subunit vaccine carriers were demonstrated by flow cytometry,proving that the mannose-modified microgels enhance the endocytosis through specific binding of ligands to receptors.The results of specific antibody concentrations and spleen lymphocyte types confirmed that the prepared subunit vaccine showed significant immune response enhancement.The modified microgels can effectively regulate immune cells and promote adaptive immunity,significantly enhance the immune protection abilities of subunit vaccines,and provide new research ideas for the design of subunit vaccine carriers.Most existing subunit vaccines can only induce the body to produce specific antibodies,and less attention is paid to cellular immunity that can clear infected cells or abnormal cells.As a component of adaptive immunity,cellular immunity plays an important role in protecting the body from external pathogens and mutated cells.Therefore,a nano-scale MOF was prepared with aluminum ions as the metal center,and antigens were modified on its surface.Subsequently,the subunit vaccine was obtained by absorbing CpG-ODN through electrostatic interaction.The soluble antigen is granulated in the subunit vaccine,which effectively enhances the uptake of antigenpresenting cells and improves the utilization of antigens.The obtained subunit vaccine can prolong the retention time of the antigen in the immune site,thus improving the immune stimulation.Besides,the MOF particles can achieve co-localized delivery of adjuvants while delivering antigens.Cell and animal experiments show that subunit nanovaccine can effectively activate adaptive immunity and produce immune memory.As a vaccine adjuvant,CpG-ODN can further induce the cellular immune response and improve the immune protection of subunit vaccine. |
