title: Erwinia carotovora Evf antagonizes the elimination of bacteria in the gut of Drosophila larvae.
abstract: Erwinia Virulence Factor (Evf) has been identified in Erwinia carotovora carotovora 15 (Ecc15) as a virulence factor that promotes colonization of the Drosophila larval gut and provokes the triggering of a systemic immune response. Here we have analysed how Evf promotes persistence and colonization of bacteria inside the larval gut. Erwinia evf mutants do not persist in immune-deficient Drosophila, indicating that Evf does not act by counteracting immunity. The results indicated that Evf is not a toxin because various gram-negative bacteria expressing evf can persist without affecting viability of Drosophila larvae. Evf did not appear to be a factor antagonizing a host-specific reaction because in vitro assays failed to reveal detoxifying enzymatic activities against various compounds thought to contribute to the hostile environment of the gut. These findings were corroborated by the observation that Evf is not required for survival in midgut organ cultures. By contrast, bacteria expressing evf allow persistence in trans of bacteria lacking evf indicating that Evf promotes the accumulation of gram-negative bacteria in the anterior midgut by affecting gut physiology.
authors.affiliation: Centre de Génétique Moléculaire du CNRS, Bâtiment 26, 1 Avenue de la Terrasse, 91198 Gif-sur-Yvette, France.
authors.forename: Carlos
authors.initials: C
authors.lastname: Acosta Muniz
authors.forename: Danielle
authors.initials: D
authors.lastname: Jaillard
authors.forename: Bruno
authors.initials: B
authors.lastname: Lemaitre
authors.forename: Frédéric
authors.initials: F
authors.lastname: Boccard
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D004064:Digestive System / Q000382:microbiology; D004330:Drosophila / Q000382:microbiology*; D006090:Gram-Negative Bacteria / Q000254:growth & development*; D066298:In Vitro Techniques; D007814:Larva / Q000382:microbiology; D016973:Pectobacterium carotovorum / Q000737:chemistry / Q000254:growth & development / Q000472:pathogenicity*; D037521:Virulence Factors / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D037521:Virulence Factors