Beschreibung:
<jats:title>ABSTRACT</jats:title><jats:p>Synthetic oligodeoxynucleotides (ODN) containing CpG motifs (CpG-ODN) have been shown to be effective immunoprotective agents in murine models for a variety of viral, intracellular bacterial, and protozoan infections. Until now, the use of CpG-ODN to protect against extracellular bacterial infections has not been reported. The objective of this study was to investigate the effect of CpG-ODN against cellulitis and colibacillosis in broiler chickens, using a well-established model. At 22 days of age, birds received CpG-ODN by either the subcutaneous or intramuscular route. Three days later, a virulent isolate of<jats:italic>Escherichia coli</jats:italic>was applied to a scratch site on the caudal abdominal skin. Birds were examined for 10 days after the<jats:italic>E. coli</jats:italic>challenge, and pathological and bacteriological assessments were conducted on all birds. The control group of birds receiving no CpG-ODN<jats:sup>(2007)</jats:sup>had a survival rate of 15%. In contrast, groups that received CpG-ODN<jats:sup>(2007)</jats:sup>, by either subcutaneous or intramuscular injection, had significantly higher survival rates (<jats:italic>P</jats:italic>< 0.0001). Furthermore, the size of the cellulitis lesion was significantly smaller in groups that received CpG-ODN<jats:sup>(2007)</jats:sup>by the subcutaneous route (<jats:italic>P</jats:italic>< 0.01). A dose of as little as 3.16 μg of CpG-ODN<jats:sup>(2007)</jats:sup>, delivered 3 days prior to challenge by either the subcutaneous or intramuscular route, significantly protected birds against<jats:italic>E. coli</jats:italic>infection (<jats:italic>P</jats:italic>< 0.01). This study demonstrates that CpG-ODN<jats:sup>(2007)</jats:sup>has both local and systemic protective effects in broiler chickens. This is the first time that CpG-ODN<jats:sup>(2007)</jats:sup>has been demonstrated to have an immunoprotective effect against an extracellular bacterial infection in any food animal species.</jats:p>