Cloning and expression of LTB in Escherichia coli and Bacillus subtilis

Abstract

LTB is the B subunit of heat labile toxins (LT) in Escherichia coli ETEC. This subunit is non-toxic but has a high immune response. Therefore, LTB is considered a suitable antigen for partial vaccine against the diarrhea caused by E. coli ETEC. The most important component of partial vaccine is antigen protein. Nowadays, with the advancement of recombinant protein technology, these antigens are mainly produced by the common bacterial expression system as E. coli. However, the recombinant proteins produced by E. coli are often miscellaneous with enterotoxins, which should be removed from pharmaceutical products. Thus, the production of antigen proteins in other expression system without endotoxins like Bacillus subtilis is in attention. We conducted the experiments of cloning and expressing LTB using a novel pHT plasmid that allow the protein to be expressed in both of E. coli and B. subtilis. We were successful to generate plasmid pHT326 and express the gene encoding for the fusion protein of LTB and LysSN-6xHis-TEV in B. subtilis and E. coli. The binding of fusion protein on the columns that have affinity with His-tag was confirmed. This result is about to be applied for the development of partial vaccine aganst the diarrhea as well as the development of some diagnostic kits for ETEC in food or medical waste and kits to detect antibodies against LTB in animals.