Potent antibacterial activity against the Gram-negative bacterium E.coli ML-35, and against the Gram-positive bacterium L.monocytogenes EGD. Lacks antifungal activity against C.albicans. Expressed in circulating heterophil granulocytes and bone marrow (at protein level). Strong expression in the bone marrow, lung and testis. Moderate expression in the bursa and intestine. Low expression in the cloaca, gall bladder, brain, pancreas, trachea, air sacs and spleen. Expressed in the vagina, ovarian stroma and the theca layer of the ovarian follicle, but not in the granulosa layer of the ovarian follicle. Detected in the theca layer of the ovarian follicle in the white follicle (WF), F1, F3, F5, and postovulatory follicle stages. In the vagina expression is higher in laying hens than in non-laying hens, and is higher in older laying hens than in young laying hens. Not induced in the ovarian follicle by intravenous injection of LPS. Expression in cultured vaginal cells is increased by LPS and S.enteritidis. Belongs to the beta-defensin family.