SHIGA TOXIN-PRODUCINGESCHERICHIA COLI(STEC) ARE MAJOR FOODBORNE PATHOGENS THAT CAUSE THOUSANDS OF HOSPITALIZATIONS EACH YEAR IN THE UNITED STATES. CATTLE ARE THE NATURAL RESERVOIR OF STEC AND ARE COLONIZED ASYMPTOMATICALLY AT THE RECTO-ANAL JUNCTION (RAJ). INTERVENTIONS THAT ERADICATE OR REDUCE THE INCIDENCE OF STEC IN CATTLE CAN PREVENT THESEBACTERIAL PATHOGENS FROM CONTAMINATING THE FOOD CHAIN. THE MOLECULAR MECHANISMS THAT ALLOWE. COLITO ADHERE TO THE RAJ ARE NOT FULLY UNDERSTOOD, IN PART BECAUSE MOST STUDIES OF STEC ADHERENCE FOCUS ON HUMAN CELL CULTURE MODELS. EVIDENCE SUGGESTS THATE. COLIUSE DISTINCT SETS OF GENES FOR ADHERENCE TO HUMAN CELLS AND BOVINE CELLS. THIS DISCREPANCY MUST BE ADDRESSED IN ORDER TO PROPERLY TARGET STEC AT THE SITE OF COLONIZATION IN THE ANIMAL RESERVOIR. WE THEREFORE PROPOSE TO IDENTIFY A SET OF BOVINE-SPECIFICE. COLIADHERENCE FACTORS USING COCULTURE AND COMPARATIVE GENOMICS. TO DO SO, WE WILL ISOLATERAJ SQUAMOUS EPITHELIAL (RSE) CELLS DIRECTLY FROM CATTLE AND CULTURE THEM TOGETHERWITHE. COLISTRAINS FROM BOVINE SOURCES, QUANTIFYINGTHEADHERENCE OF EACH BACTERIAL STRAIN. USING PUBLICLYAVAILABLE WHOLE-GENOME SEQUENCE DATAFORTHE E. COLIISOLATES, WE WILLDEFINE THE PANGENOME (I.E. THE CORE AND ACCESSORY GENE CONTENT) OF THESE STRAINS. BIOINFORMATIC TOOLS WILL ALLOW US TODETERMINE GENES IN THE PANGENOME THAT ARE ASSOCIATED WITH THE RSE ADHERENCE PHENOTYPE. FINALLY, WE WILL PERFORM A TRANSCRIPTIONAL ANALYSIS OF ADHERENCE GENES IN COCULTURE WITH RSE CELLS TO EVALUATE THEIR EXPRESSION.AS TIME PERMITS, WE WILL KNOCK OUT INDIVIDUAL ADHERENCE GENES IN STEC ANDINVESTIGATE THEIR FUNCTIONAL ROLES. AS A RESULT OF THIS WORK, WE MAY ULTIMATELY ESTABLISH NEW TARGETS FOR DRUG OR VACCINE DEVELOPMENTTHATWILL ENABLE A SAFER AND HEALTHIERFOOD SUPPLY.