Study Of Peptides Mimetic To The Type 5 Capsular Polysaccharide Of Staphylococcus Aureus From Matitis In Dairy Cows

Subclinical mastitis is one of the major diseases of economic loss in dairy farming. More than 80% of the cows surfed mastitis are caused by staphylococcus aureus. Staphylococcus aureus in the milk threat consumer health. Clinical cure of mastitis can lead drug residues in milk due to bring the public food safety issue, so the vaccine is considered to be the best effective means to control the disease.Staphylococcus aureus capsular polysaccharide is the elements of the outermost protective structure and an important vaccine target. Different serotypes between the capsular polysaccharide have no cross-protection. Capsular polysaccharide is a TI antigen. To transform into TD antigens, Capsular polysaccharide need to combine with the carrier proton which can provide T cell epitopes.By the phage display technology, peptides or proteins can be displayed on the phage surface in the form of fusion protein and maintained a relatively independent conformation and biological activity. Using polysaccharide antibodies, peptides mimetic to the polysaccharide can be screening out from phage display peptide library to mimic the sugar-based epitope. Nucleic acid and protein technologies can be make use of to research and development the vaccines.In this study, mastitis occurrence rates in dairy cattle have been investigated in 2 farms. The results showed that the mastitis occurrence rates were 34.6 and 71.6%, 84.4% and 92.7% of the mastitis were caused by Staphylococcus aureus. CP5 and CP8 are the predominant serotypes and caused accounted for 75% of Staphylococcus aureus mastitis. These results can provide experimental basis for research, development and application of Staphylococcus aureus capsular polysaccharide vaccine in China.CP5-positive strains isolated were selected to identifi such culture conditions as preferred carbon source, media type. Then CP5 was produced, extracted and purified in the selected culture conditions. After identified, purified CP5 were coupled to BSA on optimal reaction conditions to prepare CP5 complete antigen. CP5 polyclonal antibodies were obtained by Inoculae mice. Anti-CP5 polyclonal antibodies were purified by Sepharose 4B affinity chromatography column.ELISA plates were coated with the purified polyclonal antibodies to screen peptide that may mimic CP5 from a phage 7-mer cyclic peptide library. After three round of screen, positive phage disseminated overnight with host bacteria. 32 randomly selected clones were identified by ELISA, of which 11 clones showed a strong combination of CP5. DNA sequencing results showed that the 11 cloned peptide sequences can be divided into four groups. Selected from the four groups, respectively, to conduct an immunization test in mice, of which three could be induced to part of the production of anti-CP antibodies in mice.