Location: Food Safety and Enteric Pathogens Research
2021 Annual Report
Objectives
1. Characterize the microbiome of swine and turkeys and investigate the effects of antibiotics and non-antibiotic feed additives on the expression and transmission of virulence, fitness or antimicrobial resistance genes in intestinal microbial populations.
a. Determine the effects of industry-relevant antibiotics on the swine and turkey gut microbiotas and host gut tissues.
b. Test the efficacy of novel probiotics as non-antibiotic feed additives to improve gut health.
2. Assess the interaction of the intestinal immune system and commensal bacteria in swine and turkeys to determine how the microbiota or foodborne pathogens affect tissue innate immunity and acquired immunity, and evaluate non-antibiotic feed additives as an effective strategy to control colonization by foodborne pathogens.
a. Characterize the host response to Campylobacter spp. colonization and subsequent changes in intestinal microbiota.
b. Test whether microbiota-derived short-chain fatty acids (e.g., butyrate and proprionate) are involved in development of Treg cells in turkeys.
3. Evaluate environmental and host influences on gut bacterial ecological niches and foodborne pathogen control strategies, including vaccines, on phenotypic and genotypic characteristics of foodborne pathogens.
a. Identify microbes that initially colonize turkey poults following hatching and evaluate how host development interacts with microbiota succession through the 14-week growth cycle.
b. Develop and test novel mucosal vaccines for efficacy against Campylobacter spp. challenged turkeys.
Approach
The research addresses food safety at the first link in the food production chain, namely the food-producing animals on the farm. The research investigates the bacterial communities and the animal’s immune response in the intestinal tract, as well as the interactions between them that lead to health and food safety. Experiments are planned to: 1) examine the environmental, microbial, and immunological factors affecting Campylobacter colonization of turkeys by challenging gnotobiotic and conventional turkey poults with Campylobacter after a different dietary amendments and examining the resulting immune response and Campylobacter colonization; 2) investigate collateral effects of therapeutic antimicrobials on animal intestinal bacterial populations by administering antibiotics to young pigs or turkey poults and monitoring their microbiota and immune response over time, and gut tissues at necropsy; 3) define the bacterial and immunological events during initial colonization of the intestinal tract in newly-born piglets and turkeys by monitoring the bacterial colonization of the gut and the immune responses that ensue; 4) examine novel, antibiotic-free intervention strategies to improve animal health and to reduce foodborne pathogen carriage in animals by developing a vaccine against Campylobacter and by administering novel prophylactic treatments to pigs to prevent Salmonella Typhimurium colonization. This basic research will supply knowledge and tools in support of applied research to control foodborne pathogens.
Progress Report
This report summarizes progress and accomplishments for this bridge project which began December 2020 and terminates August 2021 (7 months). Refer to final report on expired 5030-32320-004-00D with the same title as this bridge project.
Accomplishments
1. Novel bacterial isolates from the pig intestine reveals functional and taxonomic diversity. Pigs are important agricultural animals and understanding the pig gut microbiome can improve development of methods to improve animal growth and disease resistance. However, the underlying mechanisms of host-microbe interactions in the gut are poorly understood and microbiome-based applications are hampered due to our limited knowledge of the microbiota members. ARS researchers in Ames, Iowa isolated, cultured, and characterized rare bacterial members of swine intestinal mucosa. Unique growth media was used to enrich for bacteria that survive solely on host-produced compounds. Six new genera or new species were identified, characterized, and had their genomes sequenced. These strains were included in a core swine microbiota culture collection, the first publicly available repository of cultured strains from the pig intestine for use in functional and biomedical research. Novel strains discovered as part this research have since been identified in other mammalian microbiomes, and characterization of their unique biochemical features, highlight their importance to gut health in multiple mammalian species.
2. Enhanced immune responses induced through common microbes. Modulating the animal’s immune response is one mechanism to reduce disease or limit antibiotic usage. Immune cells respond to common microbes through production of inflammatory mediators. In addition, the immune cell’s DNA may be altered such that subsequent stimulation by the same microbe results in production of more immune mediators and a more effective immune response. ARS researchers in Ames, Iowa, showed that exposure of a specific immune cell from the blood to the microbial compound beta-glucan from yeast or a common vaccine strain of bacteria led to changes in the cell that upon later bacterial stimulation, the cells were hyperresponsive, which could be beneficial in limiting disease. The experiments are the first necessary step in transition to animal studies to identify effectiveness of immunomodulation at the animal level. The priming of an animal’s immune response may enhance disease resistance and limit the need for antibiotics.
3. Campylobacter coli induces acute inflammation in the turkey cecum following colonization, but the pathogen continues to be shed even after inflammation ceases. Campylobacter coli and C. jejuni infections result in disease in humans, and ingesting contaminated poultry is the most common route by which humans are infected. Understanding the immunological response after C. coli infection in turkeys may provide insights on intervention strategies to limit bird carriage. ARS researchers in Ames, Iowa, developed a research model to study the host-response in the intestinal tract of turkeys colonized with C. coli. An acute response was detected after C. coli infection of turkeys, including elevated inflammation markers in serum and an increase in tissue lesions. Gene expression analysis suggested the presence of acute inflammation in the infected birds. However, the inflammation resolved without C. coli clearance, suggesting that after a short lived inflammatory response, the immune system of turkeys switches to tolerate the organism in the intestine. The identification of differences in host genes expressed following Campylobacter colonization of turkeys is a critical first step to develop Campylobacter intervention strategies that promote a safe food supply.
Review Publications
Meneguzzi, M., Pissetti, C., Rebelatto, R., Trachsel, J.M., Satomi Kuchiishie, S., Reisf, A.T., Guedesg, R.M., Leãoh, J.A., Reichena, C., Deon, J.K. 2021. Reemergency of Salmonellosis in hog farms: outbreak and bacteriological characterization. Microorganisms. 9(5). Article 947. https://doi.org/10.3390/microorganisms9050947.
Byrne, K.A., Tuggle, C., Loving, C.L. 2020. Differential induction of innate memory in porcine monocytes by B-glucan or bacillus Calmette-Guerin. Innate Immunity. https://doi.org/10.1177/1753425920951607.
Bearson, B.L., Trachsel, J.M., Shippy, D.C., Sivasankaran, S.K., Kerr, B.J., Loving, C.L., Brunelle, B.W., Curry, S.M., Gabler, N.K., Bearson, S.M. 2020. The role of Salmonella Genomic Island 4 in metal tolerance of Salmonella enterica serovar I 4,[5],12:i:- pork outbreak isolate USDA15WA-1. Genes. 11(11). Article 1291. https://doi.org/10.3390/genes11111291.
Uribe, J.H., Liu, H., Byrne, K.A., Bond, Z.F., Loving, C.L., Tuggle, C. 2020. Changes in H3K27ac at gene regulatory regions in porcine alveolar macrophages following LPS or PolyIC exposure. Frontiers in Genetics. 11. https://doi.org/10.3389/fgene.2020.00817.
Schaut, R.G., Palmer, M.V., Boggiatto, P.M., Kudva, I.T., Loving, C.L., Sharma, V.K. 2021. Mucosal IFN-¿ production and potential role in protection in Escherichia coli O157:H7 vaccinated and challenged cattle. Infection and Immunity. 11. Article 9769. https://doi.org/10.1038/s41598-021-89113-7.
Negretti, N.M., Ye, Y., Malavasi, L.M., Pokharel, S.M., Huynh, S., Noh, S.M., Klima, C.L., Gourley, C.R., Ragle, C.A., Bose, S., Looft, T.P., Parker, C., Clair, G., Adkins, J.N., Konkel, M.E. 2020. A porcine ligated loop model reveals new insight into the host immune response against Campylobacter jejuni. Gut Microbes. 12(1). Article 1814121. https://doi.org/10.1080/19490976.2020.1814121.
Wylensek, D., Hitch, T.C., Riedel, T., Afrizal, A., Kumar, N., Wortmann, E., Liu, T., Devendran, S., Lesker, T.R., Cumbo, F., Wyschkon, M., Looft, T.P., Parreira, V.R., Abt, B., Agostino, P.D., Doden, H.L., Ly, L., Alves, J.M., Reichlin, M., Flisikowski, K., Navarro Suarez, L., Neumann, A.P., Suen, G., Wells, J., Wouters, T., Rohn, S., Lagkouvardos, I., Allen-Vercoe, E., Neuhaus, K., Schnieke, A., Segata, N., Strowig, T., Ridlon, J.M., Gulder, T.A., Overmann, J., Clavel, T. 2020. A collection of bacterial isolates from the pig intestine reveals functional and taxonomic diversity. Nature Communications. 11. Article 6389. https://doi.org/10.1038/s41467-020-19929-w.
Sylte, M.J., Sivasankaran, S.K., Trachsel, J.M., Sato, Y., Wu, Z., Johnson, T.A., Chandra, L.C., Zhang, Q., Looft, T.P. 2021. The acute host-response of turkeys colonized with Campylobacter coli. Frontiers in Veterinary Science. 8. Article 613203. https://doi.org/10.3389/fvets.2021.613203.
