Location: Food and Feed Safety Research
Project Number: 3091-32000-037-010-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Sep 15, 2022
End Date: Sep 14, 2024
Objective:
Probiotics are commonly fed to chickens to improve production through modulating the gut microbiota. Though successful in improving functions like feed efficiency and pathogen resistance, modern probiotics require continuous addition in feed to maintain their effects and even serve as a potential reservoir for antibiotic resistance. Thus, a more cost-effective probiotic that impacts the gut in early life, stimulates the development and maturation of the intestinal immune system, and does not require daily supplementation would be very beneficial to the poultry industry. Data has shown that Salmonella have a unique survival strategy in broiler chickens that minimizes host defenses (disease resistance) during the initial infection and then exploits and/or induces a dramatic immunometabolic reprogramming in the cecum. This alters the host defense from resistance to disease tolerance (increases T regulatory cell differentiation and function) allowing the pathogen to survive in the gut as a commensal and enabling the bacteria to be shed in feces resulting in the ongoing human food safety dilemma. We will use a novel immunomodulating segmented filamentous bacteria (SFB) probiotic to bolster and maintain the gut disease resistance phenotype upon exposure to enteric bacterial pathogens.
Approach:
1. Prepare the SFB spores inoculum and inoculate newly-hatched broilers.
2. Compare and define the intestinal immunometabolic intestinal phenotype and the alterations in the microbial communities in the cecum of chickens treated or not with SFB.
3. Evaluate the effects of SFB on the parameters of Objective 2 following challenge with Salmonella.
Objective 1: SFB inoculum will be prepared using in vitro culture and purification. Spore enumeration and purity will be assessed using microscopy, RT-qPCR and 16S sequencing. Newly-hatched broilers will be orally inoculated. Objective 2: On days 1, 4, and 8 post-hatch, cecal tissue from at least 5 birds/day will be homogenized and analyzed via kinome array to describe the baseline immune and metabolic signal transduction changes elicited by SFB. Further, a metagenomic analysis will be performed with the cecal contents from these same birds to determine the microbiota succession following inoculation with or without SFB probiotic. Objective 3: SFB-treated and non-treated day-old chicks will be challenged 24 h later with S. enterica (Enteritidis, Typhimurium, Heidelberg, or Infantis). On days 1, 4, and 8 post-challenge, cecal tissue and cecal contents (5 birds/day) will be isolated and used for kinome and microbiota analysis as described above. Further, the cecal tonsil will be removed from each bird and T regulatory cells will be isolated, Treg suppressive properties will be analyzed using a Treg immunosuppression assay, and the Tregs will also be analyzed for IL-10, TGF-ß, and IL-2 mRNA transcription by RT-qPCR.
