Identification of overexpressed genes in Sodalis glossinidius inhabiting trypanosome-infected self-cured tsetse flies

Abstract

Sodalis glossinidius, one of the three tsetse fly maternally inherited symbionts, was previously shown to favor fly infection by trypanosomes, the parasites causing human sleeping sickness. Among a population of flies taking a trypanosome-infected blood meal, only a few individuals will acquire the parasite; the others will escape infection and be considered as refractory to trypanosome infection. The aim of the work was to investigate whether fly refractoriness could be associated with specific Sodalis gene expression. The transcriptome of S. glossinidius harbored by flies that were fed either with a non-infected blood meal (control) or with a trypanosome-infected meal but that did not develop infection were analyzed, using microarray technology, and compared. The analysis using the microarray procedure yielded 17 genes that were found to have a significant differential expression between the two groups. Interestingly, all these genes were overexpressed in self-cured (refractory) flies. Further analysis of functional annotation of these genes indicated that most associated biological process terms were related to metabolic and biosynthetic processes as well as to oxido-reduction mechanisms. These results evidence the occurrence of molecular crosstalk between the different partners, induced by the passage of the trypanosomes through the fly's gut even though the parasites were unable to establish in the gut and to develop a permanent infection.

Blood feeding tsetse flies as hosts and vectors of mammals-pre-adapted African Trypanosoma: current and expected research directions

“…The S. glossinidius genome comprises 2,683 genes that are distributed across one chromosome (representing 2,523 genes) and four plasmids (accounting for 91, 31, 25, and 13 genes). Analysis of S. glossinidius inhabiting trypanosome-infected flies revealed 176 differentially expressed genes (DEGs), which encode a large variety of proteins including type III secretion system proteins [ 81 , 82 ]. The corresponding genes are overexpressed in the symbionts of refractory tsetse flies and results in the enrichment of the KEGG pathway “bacterial secretion systems”.…”

“…The effective role of the type III secretion system (injectisome) has been reported in the case of P. aeruginosa , which secrete toxic proteins in the cytosol of target cells [ 83 ]. Moreover, an overexpression of lysis protein transcripts was recently revealed in Sodalis harbored by refractory flies, with a corresponding enrichment in the “cytolysis, lysozyme activity, catabolism of peptidoglycan, bacteriolytic enzyme” functions [ 81 , 82 ]. In this case, the degradation products of the bacterial cell wall peptidoglycan may be involved in activation of the immune system of tsetse flies.…”

Technical data of the transcriptomic analysis performed on tsetse fly symbionts, Sodalis glossinidius and Wigglesworthia glossinidia, harbored, respectively by non-infected, Trypanosoma brucei gambiense infected and self-cured Glossina palpalis gambiensis tsetse flies

“…b . gambiense infected experimentally according to the protocol reported by Geiger et al [1] and Hamidou Soumana et al [2] , [3] , [4] . Stabilate of T .…”

“…The tsetse fly symbiont custom-made density arrays (8 × 15 K format) were designed with 60-mer oligos specific to: * For Sodalis [2] , [3] : genes of the S . glossinidius chromosome (NCBI RefSeq: NC_007712.1; GenBank accession number AP008232 ), and genes of the Sodalis four plasmids pSG1 (NCBI RefSeq:NC_007183.1), pSG2 (NCBI RefSeq: NC_007184.1), pSG3 (NCBI RefSeq: NC_007186.1), and pSG4 (NCBI RefSeq: NC_007187.1) [8] , [9] .…”

“…( http://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE48360 ; http://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE48361 ) [2] , [3] ,…”