ABSTRACT
A Staphylococcus aureus strain, designated zfb, was isolated from a clinical bovine mastitis case of a dairy cow. Staphylococcus aureus zfb can have resistance to methicillin and no lipase contrast by ATCC 25923. The production of the capsule was assessed by the diffuse colonial morphology in serumsoft agar. A mouse infection model was used to determine the LD50 and the invasiveness of SA zfb. The LD50 of SA 25923 to experimental mice was 10-2.5/mL, and the LD50 of SA zfb to experimental mice was 10-4.33/mL. The purpose to detect characteristics of SA zfb makes it an interesting candidate for the preparation and assay of an avirulent mutants against staphylococcal infections and further investigate on pathogenic mechanism.
ABSTRACT
Objective:? -Hemolysin of Staphylococcus aureus,which was expressed in E.coli BL21(DE3) with recombinant pET32a+-?-HL plasmid,was purified with gel filtration chromatography(GFC),and then the engineered subunit vaccine was developed. The immunity effectiveness of this vaccine was evaluated on mouse models.Method:The purified fusion protein was analyzed in SDS-PAGE,and subjected to the evaluation of its median hemolytic dose potency(HD50) was finally analyzed with rabbit erythrocyte. Protein concentration was determined by the method of Bradford. Antibody titers were evaluated on ELISA,and then challenged to gain the immunity protect index.Results:There is an expected protein band with molecular mass of 53kDa in SDS-PAGE,and the concentration is 0.1278mg/ml. The hemolysis activity is 8012.5 HU/mg. There are specific antibodies acquired in blood-serum from mice after vaccined and the antibody titers rising until it has arrive the max,then following down.Conclusion:The purified fusion protein has good fineness and hemolysis activity,the antibody titers initiated by the protein vaccine go with regulation and the immunoprotection is satisfied.