Engineered Probiotics for Cholera Treatment and Diagnosis

New synthetic biology techniques have enabled us to engineer the human microbiota for therapeutic purposes. In this project, we have engineered the lactic acid bacterium Lactococcus lactis to detect Vibrio cholerae, the causative agent of the infectious disease cholera, and may initiate therapeutic and diagnostic functions in situ. For the pathogen detection module, we used the CqsS sensor domain from the V. cholerae CAI-1 quorum-sensing system to create a hybrid two component system in L. lactis that can directly detect the V. cholerae CAI-1 signal. Incorporation of a TetR-based signal inverter into the circuit allowed us to couple CAI-1 recognition to activation of the output module. For the output modules, we are developing functions for therapeutic and diagnostic applications. We identified two antimicrobial peptides (AMPs) that inhibit V. cholerae growth, and are working to develop an efficient AMP release mechanism in L. lactis. When coupled to the V. cholerae detection module, we will be able to produce a detect-and-kill genetic circuit. In parallel, we have developed a colorimetric output module, based on Ã?-lactamase production, that can serve as a diagnostic function in L. lactis. We have tested the circuit in an in vitro co-culture system and will conduct in vivo tests in a V. cholerae mouse infection model. Such engineered â??smartâ? probiotics will provide a cost-effective, point-of-care solution to the prophylaxis, diagnosis and treatment of cholera in the low-resource settings of a cholera endemic area.