title: Characterization of a defensin from the sand fly Phlebotomus duboscqi induced by challenge with bacteria or the protozoan parasite Leishmania major.
abstract: Antimicrobial peptides are major components of the innate immune response of epithelial cells. In insect vectors, these peptides may play a role in the control of gut pathogens. We have analyzed antimicrobial peptides produced by the sand fly Phlebotomus duboscqi, after challenge by injected bacteria or feeding with bacteria or the protozoan parasite Leishmania major. A new hemolymph peptide with antimicrobial activity was identified and shown to be a member of the insect defensin family. Interestingly, this defensin exhibits an antiparasitic activity against the promastigote forms of L. major, which reside normally within the sand fly midgut. P. duboscqi defensin could be induced by both hemolymph or gut infections. Defensin mRNA was induced following infection by wild-type L. major, and this induction was much less following infections with L. major knockout mutants that survive poorly in sand flies, due to specific deficiencies in abundant cell surface glycoconjugates containing phosphoglycans (including lipophosphoglycan). The ability of gut pathogens to induce gut as well as fat body expression of defensin raises the possibility that this antimicrobial peptide might play a key role in the development of parasitic infections.
authors.affiliation: INSERM U392, ULP, Faculté de Pharmacie, 67400 Illkirch, France. nboulanger@aspirine.u-strasbg.fr
authors.forename: Nathalie
authors.initials: N
authors.lastname: Boulanger
authors.forename: Carl
authors.initials: C
authors.lastname: Lowenberger
authors.forename: Petr
authors.initials: P
authors.lastname: Volf
authors.forename: Raul
authors.initials: R
authors.lastname: Ursic
authors.forename: Lucie
authors.initials: L
authors.lastname: Sigutova
authors.forename: Laurence
authors.initials: L
authors.lastname: Sabatier
authors.forename: Milena
authors.initials: M
authors.lastname: Svobodova
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Beverley
authors.forename: Gerald
authors.initials: G
authors.lastname: Späth
authors.forename: Reto
authors.initials: R
authors.lastname: Brun
authors.forename: Bernard
authors.initials: B
authors.lastname: Pesson
authors.forename: Philippe
authors.initials: P
authors.lastname: Bulet
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001419:Bacteria / Q000276:immunology*; D001483:Base Sequence; D023082:Defensins / Q000096:biosynthesis* / Q000235:genetics / Q000494:pharmacology; D005260:Female; D006028:Glycosphingolipids / Q000502:physiology; D007113:Immunity, Innate; D018320:Leishmania major / Q000276:immunology*; D008297:Male; D008969:Molecular Sequence Data; D011576:Psychodidae / Q000276:immunology* / Q000382:microbiology / Q000469:parasitology; D012333:RNA, Messenger / Q000032:analysis; D011994:Recombinant Proteins / Q000494:pharmacology
chemical_list: D023082:Defensins; D006028:Glycosphingolipids; D012333:RNA, Messenger; D011994:Recombinant Proteins; C008290:lipophosphonoglycan