A Synthetic Platform for Non-Antibiotic Eradication of Bacterial Infections

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The discovery of antibiotics has transformed medicine, but the rising number of antibiotic resistant bacterial infections is becoming an alarming threat, leaving us in need of new antimicrobial methods. Development of new classical antibiotics can be costly and time consuming and bacteria can overcome these challenges quickly. In this work, we propose to pioneer a non-antibiotic platform to treat bacterial infections by engineering antimicrobial bacteria, in which we highjack bacterial sex to deliver toxic genes specific to disease causing pathogenic bacteria. If this approach is successful, it will facilitate the rapid development of new antimicrobial therapies at minimal cost. The treatment of bacterial infections with live engineered bacteria may be considered unorthodox however this kind of approach is already conceptually in use in the vaccination of the human population against deadly diseases as first demonstrated by Louis Pasteur. Bacterial sex is promiscuous and can deliver genes in a wide range of bacteria from planktonic to more structured biofilm forms via a sex pilus from donor to recipient bacterium. For the toxic component of our antimicrobial platform, we envision redirecting the bacterial immunity CRISPR/Cas system, an RNA based endonuclease protective mechanism. While CRISPR normally serves to protect the bacterium from invading DNA, it has been shown to be lethal to the host bacterium if targeted towards its own DNA. The CRISPR system is an exciting putative antimicrobial as the Cas nuclease can be targeted towards very specific SNPs of DNA only found in pathogenic bacteria. Thus, the engineered bacterium carries a conjugative plasmid encoding the Cas nuclease targeted to a desired pathogen SNP leaving the rest of the Microbiome intact in contrast to classical antibiotics. With this award, we propose to develop this novel antimicrobial platform combining the toxic genetic elements of the CRISPR/Cas system with different engineered bacterial conjugative apparatus in a harmless bacterial carrier. We will test this antimicrobial strategy by performing mating and viability assays against a variety of bacterial pathogens in vitro and translate these tests to animal model systems. Finally we will develop a controllable strategy to avoid possible unwanted propagation of our engineered bacteria into the wild. In the future, this work may lead to the development of a completely new field of biotherapeutic medicine and revolutionize treatment of bacterial diseases.