This book draws together contributions from many leading scientists and reviews the most significant recent advances in the development of mammalian host defense peptides. These short, cationic single gene products have been isolated from a vast array of higher and lower organisms, and the conservation of function across so many species is an indication of their importance. Antimicrobial peptides are also the only new class of antimicrobial agent discovered in recent years, and there is interest in them as alternatives to conventional antibiotics.