Optimization of the 503 antigen induction strategy of Leishmania infantum chagasi expressed in Escherichia coli M15.

Leishmaniosis is a complex of diseases that can be fatal, if not given proper attention. Despite its relevance in the public health system, there is no vaccine capable of preventing the disease in humans so far and its treatment is expensive and aggressive to human health. The present study aims to optimize the induction parameters of the 503 Leishmania i. chagasi antigen expressed in recombinant Escherichia coli M15. The induction at different cell densities was evaluated in order to analyze the influence of the induction time on the yield of the protein of interest. In this segment, lactose and isopropyl-β-d-thiogalactopyranoside (IPTG) were used as inducer molecules, using various concentrations: 0.1 g/L, 1.0 g/L, and 10 g/L for lactose and 20 μM, 100 μM, 500 μM, and 1000 μM for IPTG. The results presented that the concentration of IPTG that obtained the higher antigen levels was that of 100 μM (0.087 g/L), a 10-fold lower concentration than was being previously used in this type of system and for lactose, it was 1 g/L (0.016 g/L). Thus, the induction with 100 μM allowed obtaining the antigen with a concentration 5.6 times higher than the lactose induction maximum concentration.