Cationic antimicrobial peptides are naturally occurring antibiotics that are actively being explored as a new class of anti-infective agents. We recently identified three cathelicidin antimicrobial peptides from chicken, which have potent and broad-spectrum antibacterial activitiesin vitro (Xiao Y, Cai Y, Bommineni YR, Fernando SC, Prakash O, Gilliland SE & Zhang G (2006)J Biol Chem281, 2858–2867).