FUNCTIONAL GENOMICS AND GENETIC ANALYSIS OF THE INNATE IMMUNE RESPONSE REQUIRED TO RESIST FOOD-BORNE BACTERIAL INFECTIONS IN POULTRY
Location: Food and Feed Safety Research
Title: Expression profile of toll-like receptors within the gastrointestinal tract of 2-day-old Salmonella enteriditis-infected broiler chickens
Submitted to: Infection and Immunity
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 12, 2009
Publication Date: June 1, 2009
Citation: MacKinnon, K.M., He, H., Nerren, J.R., Swaggerty, C.L., Genovese, K.J., Kogut, M.H. 2009. Expression profile of toll-like receptors within the gastrointestinal tract of 2-day-old Salmonella enteriditis-infected broiler chickens. Infection and Immunity. 137:313-319.
Interpretive Summary: Baby chickens can become infected with disease-causing bacteria, such as Salmonella, soon after hatching. If these bacteria are still present when the chicken is processed for consumption, they can cause humans to become sick. Immune cells in baby chickens can recognize the bacteria with proteins called toll-like receptors that bind to bacteria and send a signal to destroy the bacteria. We measured how many of these proteins were being made in the intestines, the location of bacterial infection in healthy and Salmonella-infected baby chickens. This information is important because it tells us how well the baby chicken can recognize the bacteria and which proteins are more important for getting rid of the bacteria. We can then use this information to select baby chickens that make more of the proteins and fight-off Salmonella infections.
Salmonella enterica serovar Enteriditis (SE) causes a majority of the cases of food-borne illness in the U.S. Human infections can occur through consumption and handling of infected poultry and eggs, but this could be reduced if the avian innate immune response limits bacterial colonization. However, little is known about the distribution of innate immune receptors in the gastrointestinal (GI) tract, in particular the toll-like receptors (TLR), and how these receptors respond to SE colonization. We used real-time quantitative RT-PCR to investigate the effect of SE infection on expression of TLR 1LA, 2A, 2B, 3, 4, 5, 7, and 15 in the duodenum, jejunum, ileum, cecal tonsil, ceca, and large intestine of 2-day-old broiler chickens. We infected and collected samples soon after hatch to approximate natural SE exposure and measure changes in the initial immune response to infection. All TLRs had measurable expression within the duodenum, jejunum, ileum, cecal tonsil, ceca, and large intestine. The general expression pattern showed distal intestinal segments had greater TLR mRNA expression than proximal segments with increased TLR 1LA, 2A, 4, and 15 in the distal region during infection. However, increased mRNA expression of TLR 2B, 3, and 15 was even found in proximal segments, including the duodenum, during infection. Interestingly, TLR 5 mRNA expression decreased and TLR 7 had no change after infection. We provide a comprehensive report of mRNA expression profiles of the TLR family of innate immune receptors in the gastrointestinal tract of 2-day-old broilers and their differential response to SE colonization.