Induction of trained immunity in broiler chickens following delivery of oligodeoxynucleotide containing CpG motifs to protect against Escherichia coli septicemia

Oligodeoxynucleotides containing CpG motifs (CpG‑ODN) can promote antimicrobial immunity in chickens by enriching immune compartments and activating immune cells. Innate memory, or trained immunity, has been demonstrated in humans and mice, featuring the absence of specificity to the initial stimulus and subsequently cross‑protection against pathogens. We hypothesize that CpG‑ODN can induce trained immunity in chickens. We delivered single or multiple administrations of CpG‑ODN to birds and mitochondrial oxidative phosphorylation (OXPHOS) and glycolysis of peripheral blood mononuclear cells were quantified using Seahorse XFp. Next, chickens were administered with CpG‑ODN twice at 1 and 4 day of age and challenged with Escherichia coli at 27 days of age. The CpG‑ODN administered groups had significantly higher mitochondrial OXPHOS until 21 days of age while cellular glycolysis gradually declined by 14 days of age. The group administered with CpG‑ODN twice at 1 and 4 days of age had significantly higher survival, lower clinical score and bacterial load following challenge with E. coli at 27 d of age. This study demonstrated the induction of trained immunity in broiler chickens following administration of CpG‑ODN twice during the first 4 days of age to protect birds against E. coli septicemia at 27 days of age.