INSECT IMMUNITY - ISOLATION OF 3 NOVEL INDUCIBLE ANTIBACTERIAL DEFENSINS FROM THE VECTOR MOSQUITO, AEDES-AEGYPTI

The injection of Escherichia coli and Micrococcus luteus into the hemo coel of Aedes aegypti induces a potent antibacterial activity in the h emolymph. We have purified and fully characterized three 40-residue an tibacterial peptides from the hemolymph of bacteria-challenged mosquit oes that are absent in naive mosquitoes. The peptides are potently act ive against Gram-positive bacteria and against one of the Gram-negativ e bacteria that were tested. The amino acid sequences clearly show tha t the three peptides are novel isoforms of the insect defensin family of antibacterial peptides. They differ from each other by one or two a mino acid residues. We present here the complete amino acid sequences of the three isoforms and the activity spectrum of the predominant Aed es defensin.