Submitted to: International Immunopharmacology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/22/2007
Publication Date: 7/2/2007
Citation: Kogut, M.H., Genovese, K.J., He, H., Li, M.A., Jiang, Y.W. 2007. The effects of BT/TAMUS 2032 cationic peptides on innate immunity and susceptibility of young chickens to extraintestinal Salmonella enterica serovar Enteritidis infection. International Immunopharmacology. 7:912-919.
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 growing number of antibiotic resistant bacteria that are 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 affect 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 effects on the bacteria.
Technical Abstract: The BT/TAMUS 2032 cationic peptides are a group of related cationic peptides produced by a Gram-positive bacterium. Cationic amphiphilic peptides have been found to stimulate or prime the innate immune responses in mammals. The innate immune system of poultry is functionally inefficient during the first week posthatch enabling pathogens such as Salmonella enterica serovar Enteritidis (SE) to invade and colonize the visceral organs of these immature birds. The objective of the present study was to evaluate the effect of BT as an immunostimulator of the innate immune response of young chickens. BT was provided as a feed additive at three different concentrations (12, 24, or 48 ppm) for 4 days post-hatch significantly increased protection against SE organ invasion in a concentration-dependent manner. The functional efficiency of heterophils isolated from chickens fed the BT rations at the three concentrations was significantly up-regulated when compared to heterophils isolated from chickens fed a control starter ration as determined with an array of functional assays. Phagocytosis, oxidative burst, and degranulation were all significantly increased in a concentration-dependent manner in heterophils isolated from chickens fed the BT diets. This is the first report of bacterial cationic peptides inducing the up-regulation of the avian innate immune response that provides protection against extra-intestinal Salmonella infections. The significance of these data is that the orally delivered cationic peptides stimulate the innate response at a time of immunologic inefficiency and increased susceptibility to bacterial infections (first week post-hatch). Because of the non-specific nature of the innate response, we speculate that TAMUS given as a feed additive during the first week post-hatch, could provide increased protection against a variety of bacterial pathogens.