title: The transcriptional signatures of Sodalis glossinidius in the Glossina palpalis gambiensis flies negative for Trypanosoma brucei gambiense contrast with those of this symbiont in tsetse flies positive for the parasite: possible involvement of a Sodalis-hosted prophage in fly Trypanosoma refractoriness?
abstract: Tsetse flies, such as Glossina palpalis gambiensis, are blood-feeding insects that could be subverted as hosts of the parasite Trypanosoma brucei gambiense: initiated in the tsetse fly mid gut, the developmental program of this parasite further proceeds in the salivary glands. The flies act as vectors of this human-invasive parasite when their salivary glands sustain the generation of metacyclic trypomastigotes, the exclusive morphotypes pre-programmed to further develop in the human individuals. Briefly, once the metacyclic trypomastigotes have been deposited in the skin of humans from whom the parasite-hosting tsetse flies are taking their blood meals, the complex developmental program of this Trypanosoma brucei subspecies can result in a severe disease named sleeping sickness. Unveiling the processes that could prevent, in tsetse flies, the developmental program of T. b. gambiense could contribute reducing the prevalence of the disease. Using a global approach, we were curious to extract transcriptional signatures of Sodalis glossinidius, a symbiont hosted by three distinct groups of tsetse flies. To meet this objective, the transcriptome of S. glossinidius from susceptible and refractory tsetse flies was analyzed at 3, 10 and 20 days after flies blood feed on T. b. gambiense-hosting mice. Within this temporal window, 176 trypanosome responsive genes were shown to interact in well-defined patterns making it possible to distinguish flies susceptible to the parasite infection from refractory flies. Among the modulated transcripts in the symbiont population of flies refractory to trypanosome infection many were shown to cluster within the following networks: "lysozyme activity, bacteriolytic enzyme, bacterial cytolysis, cell wall macromolecule catabolic process". These novel data are further delineated in the following questions: could the activation of prophage hosted by S. glossinidius lead to the release of bacterial agonists that trigger the tsetse fly immune system along a profile that no more allows the parasite developmental program?
authors.affiliation: UMR 177, IRD-CIRAD, CIRAD TA A-17/G, Campus International de Baillarguet, 34398 Montpellier Cedex 5, France.
authors.forename: Illiassou
authors.initials: I
authors.lastname: Hamidou Soumana
authors.affiliation: UMR1090 TAGC, INSERM, Marseille F-13288, France; Aix-Marseille University, Marseille F-13288, France.
authors.forename: Béatrice
authors.initials: B
authors.lastname: Loriod
authors.affiliation: UMR 177, IRD-CIRAD, CIRAD TA A-17/G, Campus International de Baillarguet, 34398 Montpellier Cedex 5, France.
authors.forename: Sophie
authors.initials: S
authors.lastname: Ravel
authors.affiliation: UMR 177, IRD-CIRAD, CIRAD TA A-17/G, Campus International de Baillarguet, 34398 Montpellier Cedex 5, France.
authors.forename: Bernadette
authors.initials: B
authors.lastname: Tchicaya
authors.affiliation: Department of Biochemistry, Faculty of Science, University of Dschang, Dschang, Cameroon.
authors.forename: Gustave
authors.initials: G
authors.lastname: Simo
authors.affiliation: UMR1090 TAGC, INSERM, Marseille F-13288, France; Aix-Marseille University, Marseille F-13288, France.
authors.forename: Pascal
authors.initials: P
authors.lastname: Rihet
authors.affiliation: UMR 177, IRD-CIRAD, CIRAD TA A-17/G, Campus International de Baillarguet, 34398 Montpellier Cedex 5, France. Electronic address: anne.geiger@ird.fr.
authors.forename: Anne
authors.initials: A
authors.lastname: Geiger
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000235:genetics; D004755:Enterobacteriaceae / Q000235:genetics* / Q000821:virology; D009113:Muramidase / Q000096:biosynthesis / Q000235:genetics; D009238:N-Acetylmuramoyl-L-alanine Amidase / Q000096:biosynthesis / Q000235:genetics; D010457:Peptidoglycan / Q000378:metabolism; D039002:Prophages / Q000235:genetics* / Q000254:growth & development; D012469:Salivary Glands / Q000469:parasitology; D014347:Trypanosoma brucei gambiense; D014353:Trypanosomiasis, African / Q000469:parasitology / Q000635:transmission; D014370:Tsetse Flies / Q000382:microbiology* / Q000469:parasitology*; D014764:Viral Proteins / Q000096:biosynthesis / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D010457:Peptidoglycan; D014764:Viral Proteins; D009113:Muramidase; D009238:N-Acetylmuramoyl-L-alanine Amidase
keywords: Bacteriophage; Refractoriness; Sodalis glossinidius; Tripartite interactions; Trypanosoma brucei gambiense; Tsetse fly