DROSOPHILA HOST-DEFENSE - DIFFERENTIAL INDUCTION OF ANTIMICROBIAL PEPTIDE GENES AFTER INFECTION BY VARIOUS CLASSES OF MICROORGANISMS

Insects respond to microbial infection by the rapid and transient expr ession of several genes encoding potent antimicrobial peptides. Herein we demonstrate that this antimicrobial response of Drosophila is not aspecific but can discriminate between various classes of microorganis ms. We first observe that the genes encoding antibacterial and antifun gal peptides are differentially expressed after injection of distinct microorganisms. More strikingly, Drosophila that are naturally infecte d by entomopathogenic fungi exhibit an adapted response by producing o nly peptides with antifungal activities. This response is mediated thr ough the selective activation of the Toll pathway.