Production of Brugia malayi BmSXP recombinant protein expressed in Escherichia coli

A rapid antibody detection test is very useful for detection of lymphatic filariasis, especially for certification and surveillance of post-mass drug administration. One such kit, panLF RapidTM (commercialized by Malaysian Bio- Diagnostic Research Sdn. Bhd.) had been developed in our laboratory for the detection of all species of filarial infections. It is based on the detection of anti-filarial IgG4 antibodies that react with recombinant Brugia malayi antigens, BmR1 and BmSXP. In this study, the growth of recombinant bacteria that produce BmSXP was optimized under shake flask fermentation for high yield of the recombinant antigen. The optimizations involved selection of suitable growth medium, IPTG concentration and induction time. The medium that yielded the highest biomass as well as total protein was Terrific Broth (TB) medium, which is an undefined medium. Initiation of induction of protein expression was found to be best at mid-log phase (OD600 = 1.5), with IPTG concentration of 1.0 mM, and harvest time at 9 h post-induction. This study showed that under the optimized conditions, the shake flask culture produced 4 g/L biomass (dry cell weight) of recombinant Escherichia coli BmSXP/pPROEXHTa/TOP10F’, which yielded 2.42 mg/L of purified BmSXP recombinant antigen. The purified antigen was analyzed by SDS-PAGE and the antigenicity of protein was confirmed by Western blot.