The Study For Preparation Of Aptamer And Polyclonal Antibody Aimed To Fima Pili Protein Of Salmonella Typhimurium

Salmonella enterica serovar Typhimurium(S.typhimurium)is a kind of enteropathogenic bacteria that can cause gastroenteritis,typhoid and dysentery by infecting humanity or animals.A large amount of cases created by S.typhimurium are found all over the world,and the pathogen poses a great threat to the healthy life of human beings due to its very high level of incidence and mortality rate especial in poverty-stricken areas.Pili are some kinds of filamentous appendages attached on bacterium,and they have significant roles in initial adhesion,forming biofilms and even signal transmission in the process of infecting organism.Pilin is very important for achieving physiological functions of pili,for the pili is constituted by pilins.As the main constituent units of bacterial pili,pilin are important to achieve initial adherence,biofilm development and signal transmission in the progress of infecting or forming biofilm for pathogenic bacteria.Aptamer is a kind of oligonucleotide fragment that can bind to target specifically,and it's very promising to be used in treating bacterial or biofilm infection by targeted drug delivery,therefore,an aptamer targeted to Fim A pili protein of S.typhimurium was selected to lay a foundation for targeted drug delivery beaed on aptamer.In addition,a polyclonal antibody was made to make preparations for studying the molecular mechanism of the pili affects biofilm formation.(1)Fim A protein is a main structure of type? pili of S.typhimurium,and it is of great importance to realize capabilities of pili.After a recombinant plasmid p ET-28a-fim A was conducted to express the recombinant protein,the purified with the concentration was 1.594 mg/m L,and can be used in following experiments.(2)Aptamer is a kind of oligonucleotide with high affinity and specificity to targets selected by systematic evolution of ligands by exponential enrichment(SELEX).In this section,an aptamer specifically targeted to Fim A protein of S.typhimurium was selected,that has high affinity(29.8±7.88 n M)and specificity to Fim A protein.(3)A polyclonal antibody targeted to Fim A protein was made also by injecting mice.Indirect enzyme-linked immunosorbent assay(ELISA)indicated that the antiserum titers reached to 1:64000 or 1:32000.In addition,western blot proved that the specificity of polyclonal antibody was good in this experiment.