Study On Lipid Modification And Secretion Of A New Polysaccharide Conjugate Vaccine

Shigella spp.is a kind of short bacterium,which belongs to gram-negative bacterium.It is a pathogenic bacteria in human and primate animal,and is the most common pathogen in bacillary dysentery.Human beings are susceptible to Shigella.It needs less bacteria to make people sick.It is prevalent in developing countries.Incidence rate in China is second only to pneumonia and tuberculosis,and poses a major threat to the global health system.At present,researchers have developed a new polysaccharide conjugate vaccine for the prevention of Shigella.Although the vaccine has a preventive effect,it often has some shortco mings,such as poor immunogenicity,the need to add adjuvants to the immune system in order to effectively play its role,and the preparation process is also complicated and has many disadvantages.Therefore,the further improvement and optimization of the new polysaccharide conjugated vaccine has become a hot spot.Through the above two aspects of the new polysaccharide combined vaccine transformation,in order to make it become a more economic and efficient vaccine,so that it has a broader application prospects.In this study,the new polysaccharide conjugate vaccine was modified and optimized from two aspects:? In order to improve its immunogenicity and reduce the addition of adjuvants,bacterial lipoproteins,which play an important role in the process of immune response,were added to the polysaccharide binding vaccine.In the immune system,lipoproteins can not only trigger the innate immune system of the host,but also cause the adaptive immune response,which can be used as one of the effective components of vaccines.The lipoproteins were purified by introducing the lipopolysaccharide region into the constructed polysaccharide binding vaccine vector and transferring it into Shigella to make it lipopolysaccharide.Mice were selected as model animals and immunized three times by subcutaneous injection.The antibody titer was detected by ELISA,and IgG antibody could be produced in mice;the bactericidal experiment in vitro showed that the antibody could combine with the bacteria to form antigen antibody complex,so as to activate complement pathway to kill bacteria;finally,for the detection of protection,the mice immunized for three times were tested for virus attack,which had high protection effect.? The purpose of this study is to simplify the extraction and purification of recombinant protein of polysaccharide binding vaccine,and to make the target protein in glycosylation system of polysaccharide binding vaccine secreted directly in extracellular medium by using vector protein YebF which can directly cause protein secretion and expression.This process is not only more convenient and efficient to reduce the production time and cost,but also to avoid the destruction of protein in the process of cell breakage.