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Infection and Immunity, December 2004, p. 7140-7146, Vol. 72, No. 12
0019-9567/04/$08.00+0     DOI: 10.1128/IAI.72.12.7140-7146.2004
Copyright © 2004, American Society for Microbiology. All Rights Reserved.

Characterization of a Defensin from the Sand Fly Phlebotomus duboscqi Induced by Challenge with Bacteria or the Protozoan Parasite Leishmania major

Nathalie Boulanger,^1* Carl Lowenberger,² Petr Volf,³ Raul Ursic,² Lucie Sigutova,³ Laurence Sabatier,⁴ Milena Svobodova,³ Stephen M. Beverley,⁵ Gerald Späth,⁵ Reto Brun,⁶ Bernard Pesson,⁷ and Philippe Bulet^4,

INSERM U392,¹ Faculté de Pharmacie, Illkirch,⁷ IBMC, Strasbourg, France,⁴ Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada,² Faculty of Sciences, Charles University, Prague, Czech Republic,³ Department of Molecular Microbiology, Washington University School of Medicine, St Louis, Missouri,⁵ Swiss Tropical Institute, Basel, Switzerland⁶

Received 5 December 2003/ Returned for modification 12 January 2004/ Accepted 1 August 2004

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.

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* Corresponding author. Mailing address: INSERM U392, ULP, Faculté de Pharmacie, 67400 Illkirch, France. Phone: (33) 3 90 24 41 51. Fax: (33) 3 90 24 43 08. E-mail: nboulanger{at}aspirine.u-strasbg.fr.

Editor: W. A. Petri, Jr.

Present address: Atheris Laboratories, CH-1233 Bernex-Geneva, Switzerland.

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Infection and Immunity, December 2004, p. 7140-7146, Vol. 72, No. 12
0019-9567/04/$08.00+0     DOI: 10.1128/IAI.72.12.7140-7146.2004
Copyright © 2004, American Society for Microbiology. All Rights Reserved.

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