Submitted to: FEMS Immunology and Medical Microbiology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/23/2004
Publication Date: 8/12/2004
Citation: He, H., Lowry, V.K., Swaggerty, C.L., Ferro, P.J., Kogut, M.H. 2004. In vitro activation of chicken leukocytes and in vivo protection against Salmonella enteritidis organ invasion and peritoneal S. enteritidis infection-induced mortality in neonatal chickens by immunostimulatory CpG oligodeoxynucleotide. FEMS Immunology and Medical Microbiology. 43:81-89. Interpretive Summary: DNA is the genetic blueprint of life and occurs in all cells. The DNA found in bacteria contains a chemically unique element, called CpG-DNA. Certain chicken immune cells can produce chemicals that kill bacteria. These naturally occurring bacteria-killing chemicals help chickens fight bacterial infections and stay healthy. The chicken immune cells were found to produce these bacteria-killing chemicals when exposed to the CpG-DNA. We further found that when injected with certain types of CpG-DNA, baby chicks were much more resistant against infections by Salmonella. For instance, chicks that had been given the CpG-ODN injection had a much smaller chance of having Salmonella living inside their body even when challenged with large amounts of Salmonella. This information is important to the pharmaceutical and poultry industries in the United States because it may offer a new method to help produce healthy chickens and reduce the use of antibiotics.
Technical Abstract: Unmethylated CpG dinucleotides (CpG-ODN) flanked by particular bases found in bacterial DNA are known to stimulate innate immune responses in mammals. In this study, the synthetic CpG-ODN was evaluated for its effect on the resistance to an experimental infection of Salmonella enteritidis (SE) in neonatal chicks. Day-old chicks were injected intraperitoneally (i.p.) with either synthetic CpG-ODN, control ODN containing no CpG motif, or were left untreated. Twenty-four hours later, all chicks were orally challenged with SE. The experimental chicks were killed 24 hr after the challenge and their organs (liver and spleen) cultured for SE. The results of the present study demonstrated a strong correlation between in vitro innate responses to the CpG-ODN stimulation and in vivo protection against SE organ invasion. The CpG-ODN containing GTCGTT motif, which in vitro stimulates innate immune responses in an avian macrophage cell line (HD11) to produce nitric oxide (NO) and up-regulate an inflammatory cytokine, interleukin-1beta (IL-1beta), gene expression, was found to reduce the organ invasion of SE significantly. Our study provided further evidence that innate immune system can be stimulated to enhance the resistance to infectious pathogens in neonatal chicks.