Covalent Conjugation And Immunological Evaluation Of Vaccine Adjuvant With Macromolecular Carriers

Vaccination has made a significant contribution to human health worldwide.However,traditional vaccines that use whole organisms(such as attenuated and inactivated viruses)can cause strong immune responses,but may cause significant adverse reactions such as infections and pathogen mutations.Well-defined synthetic vaccines can avoid these problems,but its immunogenicity is too low and additional adjuvants are needed to enhance its immunogenicity.Adjuvants are substances that are incorporated into vaccines to enhance the immunogenicity of the antigen,but some small molecule adjuvants(such as TLR agonists)are susceptible to adverse reactions due to complex pharmacokinetics in vivo and result in less immunological activity.We envisage that it can be covalently linked to some macromolecular carriers such as proteins,polypeptides,etc.to improve its immunological activity.The main contents of this paper are as follows:Chapter 1:A brief overview of the development of vaccines and adjuvants,and specifically describes the use of TLR agonists as adjuvants.And it also describes the NKT cells and their agonists αalcer,and the problems about aGalcer as vaccine adjuvants.Chapter 2:Studies have shown that covalent conjugation of TLR7 ligand to PEG or protein can increase its immunostimulatory activity.Therefore,we envisage a semi-synthetic nicotine vaccine formed by covalently coupling a TLR4 small molecule agonist with a carrier protein can efficiently trigger an immune response.To this end,we synthesized a three-component covalently coupled vaccine with carrier protein,antigen and adjuvant by protein coupling method of active ester,and evaluated whether the covalently linked adjuvant enhanced the immunological activity of the antigen by mouse experiments and immunoassay results.The experimental test results did not achieve the expected results,and the reasons need further analysis.Chapter 3:Since NKT cells which are activated can rapidly produce a large number of cytokines to regulate immune response,the iNKT agonist αGalcer has been widely studied as a new adjuvant.However,its clinical manifestations are not good.First,the release of almost equal amounts of Thl and Th2 type cytokines after αGalcer activation of NKT greatly impairs the immune effect.Second,αGalcer induces the anergy effect of NKT cells.Therefore we envisaged that covalently coupling αGalcer with some macromolecular carriers such as BSA,MSA,PEG,etc.,selectively triggers the release of Thl or Th2 type cytokines,and avoids or reduces the occurrence of immune potential energy.The effect of covalent attachment to the macromolecular vector on the immunological activity of αGalcer was evaluated by mouse immunoassay and cytokine test.Covalent coupling with macromolecular carriers enhances the immunological activity of αGalcer and triggers a Thl-type immune response to varying degrees.The PEG vector works best.