Beta defensins are a family of vertebrate defensins. The beta defensins are antimicrobial peptides implicated in the resistance of epithelial surfaces to microbial colonization.

Defensins are 2 to 6 kDa, cationic, microbicidal peptides active against many Gram-negative and Gram-positive bacteria, fungi, and enveloped viruses, containing three pairs of intramolecular disulfide bonds. On the basis of their size and pattern of disulfide bonding, mammalian