A Study On Subclinical Bovine Mastitis In Urumqi And Of Fnbp Gene Prokaryotic Expression Vector Of Staphylococcus Aureus

In this study, the infection situation of Subclinical mastitis was investigated in 6 farms and 4 families, which are raising cows, in suburban of Urumqi. Staphylococcus aureus, which was taken from the cows infected Subclinical mastitis, was isolated and identified, pilot study was also put up on its drug-resistance.It was shown that, in this investigation, average infection rate was 32.75% and the infected part of mammary quarters was 15.11%, average isolation rate of Staphylococcus aureus was 15.11% and isolation rate in mammary quarters was 6.32%. The test of the Antibiotic Susceptibility showed that the Staphylococcus aureus'in milk samples were similar among the different herd, bacteria selected from the different herd were all susceptible to Amikacin, Levofloxacin.Based on the Fnbp gene sequence of Staphylococcus aureus in the GenBank, the specific primers containing EcoRI and SalIenzyme digestion sites were designed. Fnbp gene was amplified by PCR using genomic DNA and inserted into pMD18-T vector, then transformed into the competent E.coli DH5α. The positive construction of pMD18-T-Fnbp and the expression vector pGEX-4T-3 were digested by restriction endonuclease digestion, then transformed into the competent E.coli BL21. Finally a recombinant plasmid named pGEX-4T-Fnbp was obtained, and was identified by restriction enzyme analysis and sequencing. Positive strains were induced with IPTG. The construction of Fnbp was named pGEX-4T-Fnbp,it will be used for further studies in diagnosis and immunity against mastitis, it is also useful in manufacture of subunit vaccine candidate.