Research Note: Intestinal avian defensin 2 and robustness of chicks

Poultry production is an important agricultural sector for human food worldwide. Chicks after hatch often face health problems leading to eco-nomic losses that are deleterious for breeders. Avian defensin 2 (AvBD2) is a prominent host defense peptide of the intestinal mucosa of cecum and is involved in the resistance of poultry to bacterial pathogens. This pep-tide could thus represent an innate immunity marker of robustness of birds. To test this hypothesis by compar-ing fast-growing and slow-growing lines in different conditions of breeding, the chick's cecal AvBD2 con-tent was analyzed according to animal quality and immunity indicators. Chick's cecal tissue sections labeled by immunohistochemistry with newly developed specific antibodies revealed the localization of AvBD2 in the mucosa with high individual variability, without showing differences attributable to quality indicators, but interestingly showing inverse correla-tion with seric IgM levels in the fast-growing line. The availability of our anti-AvBD2 antibodies to the scien-tific community opens perspectives to identify the cellular sources of this defensin in the cecal mucosa and to investigate the organization and function of innate immune arsenal of birds.