Submitted to: Foodborne Pathogens and Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/14/2009
Publication Date: 1/1/2010
Publication URL: http://handle.nal.usda.gov/10113/57371
Citation: Kogut, M.H., He, H., Genovese, K.J., Jiang, Y. 2010. Feeding the BT cationic peptides to chickens at hatch reduces cecal colonization by Salmonella enterica serovar Enteritidis and primes innate immune cell functional activity. Foodborne Pathogens and Disease. 7:23-30. Interpretive Summary: There is a great deal of controversy concerning the use of antibiotics in animal feed. The biggest problem that critics have with this practice is the possibility of antibiotic resistant bacteria causing disease in humans. Therefore, we are interested in identifying chemicals that can protect animals from bacterial contamination without causing the bacteria to be resistant to antibiotics and other drugs that are used to treat human diseases. In this study, we added a newly discovered compound to chicken ration and fed it to baby chickens to see if it could protect the chicks from Salmonella infection. What makes this compound unique is that it has no direct killing effect on bacteria. We found that feeding this compound to the chicks did protect them from bacterial infection by “turning on” the chicks immune system. In this way, the chick was able to use its own internal defenses to fight off a bacterial infection. The results of this experiment are important to the pharmaceutical industry in the United States because it shows that we can feed a compound to stimulate the chick’s immune system to protect itself from infection. In addition, there is no danger of the bacteria developing resistance to the compound because it has no direct effect on the bacteria. Thus, the number of antibiotic-resistant bacteria could drop dramatically in poultry meat products.
Technical Abstract: The BT/TAMUS 2032 (BT) cationic peptides are a group of related cationic peptides produced by a Gram-positive soil bacterium, Brevibacillus texasporus. Cationic amphiphilic peptides produced by host cells have been found to stimulate or prime the innate immune responses in mammals, but little information is available on the effects of bacterial produced peptides on host immunity. We have previously shown that BT, provided as a feed additive for 4 days post-hatch, significantly induced protection against extraintestinal colonization by Salmonella enterica serovar Enteritidis (SE). We also found that feeding BT significantly up-regulated the functional efficiency of heterophils, the avian equivalent to mammalian neutrophils. The objective of the present study was to further evaluate the effect of BT as a non-antibiotic, anti-bacterial compound, and a stimulator of the innate immune response of young chickens. BT, provided as a feed additive at three different concentrations (12, 24, or 48 ppm) for 4 days post-hatch, significantly increased protection against SE cecal colonization in a concentration-dependent manner. We also confirmed our previous results that the functional activities of heterophils from chickens fed the BT rations were significantly up-regulated. In addition, we also found the functional activities of peripheral blood monocytes were significantly increased in a concentration-dependent manner when compared to monocytes isolated from chickens fed a control diet. This is the first report of bacterial cationic peptides providing protection against Salmonella cecal colonization. The significance of these data is that the orally delivered cationic peptides stimulate the innate response during the first week post-hatch, normally a time of immunologic inefficiency and increased susceptibility to bacterial infections. We speculate that BT given as a feed additive during the first week post-hatch could provide increased protection against a variety of bacterial pathogens because of the non-specific nature of the innate response.