Insect immunity. Isolation from the lepidopteran Heliothis virescens of a novel insect defensin with potent antifungal activity.
Lepidoptera have been reported to produce several antibacterial peptides in response to septic injury. However, in marked contrast to other insect groups, no inducible antifungal molecules had been described so far in this insect order. Surprisingly, also cysteine-rich antimicrobial peptides, which predominate in the antimicrobial defense of other insects, had not been discovered in Lepidoptera. Here we report the isolation from the hemolymph of immune induced larvae of the lepidopteran Heliothis virescens of a cysteine-rich molecule with exclusive antifungal activity. We have fully characterized this antifungal molecule, which has significant homology with the insect defensins, a large family of antibacterial peptides directed against Gram-positive strains. Interestingly, the novel peptide shows also similarities with the antifungal peptide drosomycin from Drosophila. Thus, Lepidoptera appear to have built their humoral immune response against bacteria on cecropins and attacins. In addition, we report that Lepidoptera have conferred antifungal properties to the well conserved structure of antibacterial insect defensins through amino acid replacements.
Lamberty
M
M
Institut de Biologie Moléculaire et Cellulaire, Unité Propre de Recherche 9022, CNRS, "Réponse Immunitaire et Développement chez les Insectes," 15 rue René Descartes, 67084 Strasbourg Cedex, France.
Ades
S
S
Uttenweiler-Joseph
S
S
Brookhart
G
G
Bushey
D
D
Hoffmann
J A
JA
Bulet
P
P
D000595:Amino Acid Sequence; D000818:Animals; D000935:Antifungal Agents / Q000494:pharmacology*; D002851:Chromatography, High Pressure Liquid; D023082:Defensins; D004330:Drosophila; D029721:Drosophila Proteins; D019075:Electrophoresis, Capillary; D004926:Escherichia coli / Q000276:immunology; D006458:Hemolymph / Q000737:chemistry; D019476:Insect Proteins / Q000737:chemistry; D007814:Larva / Q000276:immunology; D007915:Lepidoptera / Q000737:chemistry / Q000276:immunology*; D016982:Micrococcus luteus / Q000276:immunology; D008969:Molecular Sequence Data; D011506:Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification*; D017386:Sequence Homology, Amino Acid
D000935:Antifungal Agents; D023082:Defensins; D029721:Drosophila Proteins; D019476:Insect Proteins; D011506:Proteins; C091227:DRS protein, Drosophila