Improved performance of Eimeria-infected chickens fed corn expressing a single-domain antibody against interleukin-10

Antimicrobial resistance is a significant challenge for human and animal health, and developing effective antibiotic-free treatments is a strategy to help mitigate microbial resistance. The global poultry industry faces growing challenges from Eimeria-induced coccidiosis, a serious enteric disease of chickens that currently requires treatment using ionophore antibiotics. Eimeria stimulates interleukin-10 (IL-10) expression in the small intestine and caecum of infected chickens, suppressing their immune response and facilitating disease progression. Single-domain antibodies raised from llamas immunized with chicken IL-10 (cIL-10) were developed that bind cIL-10 in vitro, block cIL-10 receptor binding and induce interferon gamma (IFN-γ) secretion from cIL-10-repressed primary chicken splenocytes. Single-domain antibodies expressed in transgenic corn demonstrated significant accumulation in phenotypically normal plants. When fed to Eimeria-challenged chickens, the transgenic corn significantly improved body weight gain (equal to that of salinomycin-treated animals), normalized the feed conversion ratio (to the same level as uninfected control animals), lowered E. tenella lesion scores to those of salinomycin-treated control animals, and reduced oocyst counts below those of infected untreated control animals. Here, we propose that transgenic corn may have a role in reducing the use of antibiotics in poultry production and maintaining animal health and productivity, and may contribute to efforts against global antimicrobial resistance. Poultry coccidiosis results in about US$3 billion global production losses per year, and is managed by prophylactic antimicrobial use. Lessard et al. have developed chicken feed based on transgenic corn for mitigating coccidiosis, resulting in reduced intestinal lesions and improved body weight and feed conversion in Eimeria-infected corn-fed animals compared to untreated controls. Corn-fed and salinomycin-treated birds had comparable outcomes, indicating potential for antimicrobial-free management of coccidiosis.