Prokaryotic expression and purification of L7/L12 protein of B. abortus.

Objective To express the L7/L12 protein of B.abortus in prokaryotic cells and purify the expressed product. Methods The genomic DNA of B.abortus S19 was extracted for amplification of L7/L12 gene by PCR.The amplified gene was identified by sequencing and cloned into vector pET-28a(+).The constructed recombinant plasmid pET-L7/L12 was transformed to E.coli BL21(DE3)for expression under induction of IPTG.The expressed product was analyzed for form and expression level by SDS-PAGE,then purified by affinity chromatography and identified by Western blot.Results Restriction analysis proved that recombinant plasmid pET-L7/L12 was constructed correctly.The expressed product,in a form of inclusion body,contained 33%of total somatic protein,reached a purity of 94%after purification and showed specific reaction with murine sera against B.abortus.Conclusion The L7/L12 protein of B.abortus was successfully expressed and purified,which laid a foundation of developing a novel method with high specificity for determination of B.abortus.