Live-Attenuated Oral Vaccines to Reduce Colonization in Poultry.

The control of in poultry at the pre-harvest level is critical to reducing foodborne infections with since the consumption of contaminated poultry is the most frequent cause of human campylobacteriosis. Although poultry vaccination is suggested as useful intervention measures, no vaccines are currently available. To develop live-attenuated oral vaccines, in this study, we evaluated the efficacy of pre-colonization by oxidative stress defense mutants, including knockout mutants of , , and , in preventing from colonizing poultry. Interestingly, when chickens were pre-colonized with and mutants, rather than the mutant, the level of colonization was significantly reduced within 35 days. Further studies demonstrated when chickens were pre-colonized with the mutant by oral challenge with a high dose (ca., 5 × 10 CFU/bird) and a low dose (ca., 5 × 10 CFU/bird), it twice reduced the level of by 3.9 logCFU/g feces and 3 logCFU/g feces after 42 days, respectively, compared to the untreated control. Due to a colonization defect, the mutant was removed from chickens within 42 days. After excretion from the host, moreover, the mutant cannot survive in aerobic environments because of compromised aerotolerance. Our findings suggest that the mutant has a great potential for on-farm application to control at the pre-harvest level.