Characterization of a defensin from the sand fly Phlebotomus duboscqi induced by challenge with bacteria or the protozoan parasite Leishmania major.
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.
Boulanger
Nathalie
N
INSERM U392, ULP, Faculté de Pharmacie, 67400 Illkirch, France. nboulanger@aspirine.u-strasbg.fr
Lowenberger
Carl
C
Volf
Petr
P
Ursic
Raul
R
Sigutova
Lucie
L
Sabatier
Laurence
L
Svobodova
Milena
M
Beverley
Stephen M
SM
Späth
Gerald
G
Brun
Reto
R
Pesson
Bernard
B
Bulet
Philippe
P
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
D023082:Defensins; D006028:Glycosphingolipids; D012333:RNA, Messenger; D011994:Recombinant Proteins; C008290:lipophosphonoglycan