Expression in Escherichia coli of flaB, the gene coding for a periplasmic flagellin of Leptospira interrogans serovar pomona.

A periplasmic flagellin gene, flaB, of Leptospira interrogans serovar pomona (strain Pomona) was expressed in Escherichia coli for the production and antigenic characterisation of the protein. The flaB structural gene, which was previously cloned into pUC118, was derived by PCR from the recombinant plasmid and used to generate an expression construct with the trc promoter-driven pProEx HT system. Under the conditions employed, the flaB was expressed as inclusion bodies formed within E. coli, yielding c. 120 mg of the recombinant protein/L of culture. A polyhistidine tag introduced at the amino-acid terminus of the FlaB protein allowed for the purification of the protein by nickel-chelate affinity chromatography. The expressed protein reacted with both mouse and bovine antisera to L. interrogans on Western blots, indicating that it could be of use in the diagnosis of leptospirosis. The recombinant leptospiral flagellin may also be of value in studying its role in the pathogenesis of leptospirosis.