title: Imd pathway is involved in the interaction of Drosophila melanogaster with the entomopathogenic bacteria, Xenorhabdus nematophila and Photorhabdus luminescens.
abstract: Xenorhabdus nematophila/Steinernema carpocapsae and Photorhabdus luminescens/Heterorhabditis bacteriophora are nemato-bacterial complexes highly pathogenic for insects. Using a syringe as artificial vector, we have analyzed the effects of the two bacteria, X. nematophila and P. luminescens on the genetic tool insect, Drosophila melanogaster. Both bacteria were found to kill adult flies in a dose dependent manner with X. nematophila being the fastest. On the other hand, when an injection of non-pathogenic bacteria, Escherichia coli, is performed 1 day before challenge with the entomopathogenic bacteria, then the survival of Drosophila flies was prolonged by at least 20h. After injection of entomopathogenic bacteria, Drosophila mutant Dif(1), affected on the Toll pathway, showed a similar phenotype than wild-type flies whereas Drosophila mutant Dredd(D55), affected on the imd pathway, was not protected by a prior injection of E. coli. This suggested that members of the imd pathway might be targets of these entomopathogenic bacteria albeit synthesis of antimicrobial peptides through this signaling pathway was induced by X. nematophila as well as P. luminescens. Finally, P. luminescens phoP mutant, an avirulent mutant in the Lepidopteran insect, Spodoptera littoralis, was found poorly virulent for D. melanogaster. phoP mutant partially protected D. melanogaster flies if injected 1 day before the injection of P. luminescens wild-type TT01 to the same extent than the E. coli-induced protection. However, phoP recovered a level of pathogenicity comparable to P. luminescens wild-type TT01 when injected to Drosophila flies affected on the imd pathway.
authors.affiliation: UMR INRA-UM2 1133, Laboratoire Ecologie Microbienne des Insectes et Interactions hôte-Pathogène, France.
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Aymeric
authors.forename: Alain
authors.initials: A
authors.lastname: Givaudan
authors.forename: Bernard
authors.initials: B
authors.lastname: Duvic
mesh_terms: D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000096:biosynthesis; D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D020169:Caspases / Q000235:genetics / Q000276:immunology; D017931:DNA Primers / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000276:immunology; D029721:Drosophila Proteins / Q000235:genetics / Q000276:immunology*; D004331:Drosophila melanogaster / Q000235:genetics / Q000276:immunology* / Q000382:microbiology*; D004926:Escherichia coli / Q000276:immunology / Q000472:pathogenicity; D017344:Genes, Insect; D009154:Mutation; D020637:Photorhabdus / Q000235:genetics / Q000276:immunology / Q000472:pathogenicity*; D014157:Transcription Factors / Q000235:genetics / Q000276:immunology; D014774:Virulence / Q000235:genetics / Q000276:immunology; D020593:Xenorhabdus / Q000276:immunology / Q000472:pathogenicity*
chemical_list: D023181:Antimicrobial Cationic Peptides; D001426:Bacterial Proteins; D017931:DNA Primers; D004268:DNA-Binding Proteins; C084428:Dif protein, Drosophila; D029721:Drosophila Proteins; D014157:Transcription Factors; C439909:imd protein, Drosophila; C061064:PhoP protein, Bacteria; D020169:Caspases; C431887:dredd protein, Drosophila