(174ab) Optimization of Chimeric Protein Production for Shiga Toxin-Producing Escherichia coli (STEC) Vaccines

Shiga toxin-producing Escherichia coli (STEC), a foodborne zoonotic pathogen, causes a spectrum of symptoms from mild intestinal acute and hemorrhagic diarrhea to severe extraintestinal conditions, including hemolytic uremic syndrome (HUS), end-stage renal disease, and death. Cattle, the primary animal reservoir, excrete the bacteria in their feces, contaminating the environment [1].

Vaccination of cattle has been proposed as a method to control STEC [2]. Two chimeric proteins (Prot 1 and Prot 4) were designed for vaccine formulations. The present work focused on the optimization of chimeric proteins’ production in recombinant E. coli, including the evaluation of different E. coli hosts (BL21(DE3) and ClearColi™) and cultivation conditions, such as cells concentration before induction (OD = 0.6 – 1.2), inductor concentration (0.1-1.0 mM IPTG), induction temperature (25-37°C) and induction time (4 or 16 h). An induction at 0.6 OD and 37°C during 16h showed the maximum protein production for both chimeric proteins. However, IPTG concentration had a different effect, where 0.1 mM IPTG was better for Prot 1 and 1.0 mM for Prot 4, probably due to a different effect of both proteins on cell metabolism.

[1] FAO and WHO. 2022. Control measures for Shiga toxin-producing Escherichia coli (STEC) associated with meat and dairy products – Meeting report. Microbiological Risk Assessment Series No. 39. Rome. <https://doi.org/10.4060/cc2402en>

[2] Vidal, R.M.; Montero, D.A.; Del Canto, F.; Salazar, et al. Immunization of mice with chimeric antigens displaying selected epitopes confers protection against intestinal colonization and renal damage caused by Shiga toxin-producing Escherichia coli. npj Vaccines (2020) 5:20. <https://doi.org/10.1038/s41541-020-0168-7>