Research And Development Of Anti-Staphylococcus Aureus Mastitis Vaccine

Staphylococcus aureus is an important pathogen that can cause widespread infection. Early in infection, Staphylococcus aureus invades the host cell by the surface adhesions, and then the host cell becomes colonization place of the Staphylococcus aureus. FnbpA and ClfA, two key members of the surface adhesions, play a crucial role in this process. Given the infection mechanism of Staphylococcus aureus, pcDNA3.1-FnbpA, pcDNA3.1-LTB-FnbpA,pcDNA3.1- ClfA and pcDNA3.1-ClfA-FnbpA were constructed. FnbpA and ClfA were used as immunization gene, and heat-labile enterotoxin B (LTB) of E.coli was used as mucosal immunization adjuvant. DNA vaccine can induce stronger cell-mediated immunity, but the antibody titer is less than ideal. Corresponding prokaryotic expression vector was constructed in order to express protein efficiently. The strategy of "Plasmid immunization / Protein to strengthen" was adopted, and the nasal immunization model of mouse was used for evaluation of the immune effect.ELISA experimental data shows that the level of IgG inspired by ClfA group, is slightly higher than that in FnbpA group, but the difference is not significant (P>0.05); while the level of IgA inspired by FnbpA group, is significantly higher than that in ClfA group (P<0.01). These indicate that FnbpA can stimulate a more effective mucosal immunity than ClfA. The activity of serum experiment shows that both of the FnbpA group and the ClfA group can successfully stimulate the anti-adhesion proteins of the Staphylococcus aureus, which are antibodies with specific activity of immune regulation. The adhesion inhibition rate and the macrophage phagocytosis of the EnbpA group are significantly stronger than that of the ClfA group (P<0.05). Drug-attack protection rate of the FnbpA group is 13.49% higher than that of the ClfA group in the drug-attack toxicity test. Although the immune effect of FnbpA group is stronger than that of ClfA group, the immune effect of the two groups is not very satisfactory in totality. However, the integration group of ClfA and FnbpA has shown a strong immunity. No matter antibody stimulation, or serum activity detection, or even breast infection, the experimental dates of the integration group are distinctly better than those of the other groups (P<0.05).In brief, the fusion of ClfA and FnbpA can stimulate immune response of mice well. While in these two genes, FnbpA plays an important role. The ability of LTB as a mucosal immunization adjuvant to enhance immune function was also confirmed. Whether the immune effect of the fusion of ltb, ClfA and FnbpA is better, further experiment is needed.