Controlling Salmonella: strategies for feed, the farm, and the processing plant

Authors: OBE, TOMI - University Of Arkansas; BOLTZ, TIMOTHY - Mississippi State University; Kogut, Michael - Mike; RICKE, STEVEN - University Of Wisconsin; BROOKS, LASHEDA - Auburn University; MACKLIN, KEN - Mississippi State University; PETERSON, ASHLEY - National Chicken Council

Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/29/2023
Publication Date: 12/2/2023
Citation: Obe, T., Boltz, T., Kogut, M.H., Ricke, S.C., Brooks, L.A., Macklin, K., Peterson, A. 2023. Controlling Salmonella: strategies for feed, the farm, and the processing plant. Poultry Science. 102(12). Article 103086. https://doi.org/10.1016/j.psj.2023.103086.
DOI: https://doi.org/10.1016/j.psj.2023.103086

Interpretive Summary: Chicks can get infected with Salmonella bugs early in life, and the bugs are able to survive in the chicks throughout their lifespan. Because of this, the bugs can be consistently released from the birds and then infect the other chicks around them. The presence of these bugs in the chicks, when they go to market, means that these bugs can get into chicken meat products where they can cause food poisoning in humans. The purpose of these experiments was to try to understand how Salmonella can survive in chicks for so long without being "seen" by the chick's immune system. We found that Salmonella causes a change in the immune response of the baby chicks so that they are "invisible" to the immune system. Thus, the immune cells cannot attack this bug and kill it. These results are important to the pharmaceutical industry because we have identified a specific target to stimulate the bird's immune system and provide protection against infection.

Technical Abstract: To combat infections, hosts employ a combination of antagonistic and cooperative host defense strategies. The former refers to pathogen killing mediated by resistance mechanisms (disease resistance), while the latter refers to physiological defense mechanisms that promote host health during infection independent of pathogen killing, leading to an apparent cooperation between the host and the pathogen (diseases tolerance). In chickens, the paratyphoid Salmonella have evolved the capacity to survive the initial robust immune response and persist in the avian ceca for months without triggering clinical signs. The persistent phase of a Salmonella infection in the avian host involves a complex balance of antagonistic and cooperative host defense strategies. The initial phase (4-48 h post-infection) in the chicken cecum is characteristically an innate pro-inflammatory response that controls bacterial invasion. The second phase (4-14 days post-infection) is characterized by an expansion of the T regulatory cell population in the cecum of Salmonella-infected chickens followed by distinct alterations of the immune and metabolic pathways that dramatically changes the local immunometabolic phenotype from pro-inflammatory to an anti-inflammatory environment. Our work has demonstrated that the paratyphoid Salmonella have evolved a unique survival strategy in poultry that minimizes host defenses (disease resistance) during the initial infection and then exploits and/or induces a dramatic immunometabolic reprogramming in the cecum that alters the host defense to disease tolerance. These results provide a basic understanding of how host metabolic adaptations during infection promote co- operative defenses between a host and enteric pathogens to drive asymptomatic carriage. Studies are planned to define the metabolic needs of the three players (host, microbiota, and pathogen) in an avian Salmonella persistent infection, the mechanisms through which they acquire nutrients, and whether each participant cooperates or competes to meet their own metabolic demands during infection has the potential to reveal new targets aimed at reducing Salmonella infections on the farm.