Dataset Information

Colonization of the tsetse fly midgut with commensal Kosakonia cowanii Zambiae inhibits trypanosome infection establishment.

ABSTRACT: Tsetse flies (Glossina spp.) vector pathogenic trypanosomes (Trypanosoma spp.) in sub-Saharan Africa. These parasites cause human and animal African trypanosomiases, which are debilitating diseases that inflict an enormous socio-economic burden on inhabitants of endemic regions. Current disease control strategies rely primarily on treating infected animals and reducing tsetse population densities. However, relevant programs are costly, labor intensive and difficult to sustain. As such, novel strategies aimed at reducing tsetse vector competence require development. Herein we investigated whether Kosakonia cowanii Zambiae (Kco_Z), which confers Anopheles gambiae with resistance to Plasmodium, is able to colonize tsetse and induce a trypanosome refractory phenotype in the fly. Kco_Z established stable infections in tsetse's gut and exhibited no adverse effect on the fly's survival. Flies with established Kco_Z infections in their gut were significantly more refractory to infection with two distinct trypanosome species (T. congolense, 6% infection; T. brucei, 32% infection) than were age-matched flies that did not house the exogenous bacterium (T. congolense, 36% infected; T. brucei, 70% infected). Additionally, 52% of Kco_Z colonized tsetse survived infection with entomopathogenic Serratia marcescens, compared with only 9% of their wild-type counterparts. These parasite and pathogen refractory phenotypes result from the fact that Kco_Z acidifies tsetse's midgut environment, which inhibits trypanosome and Serratia growth and thus infection establishment. Finally, we determined that Kco_Z infection does not impact the fecundity of male or female tsetse, nor the ability of male flies to compete with their wild-type counterparts for mates. We propose that Kco_Z could be used as one component of an integrated strategy aimed at reducing the ability of tsetse to transmit pathogenic trypanosomes.

SUBMITTER: Weiss BL

PROVIDER: S-EPMC6394900 | biostudies-literature | 2019 Feb

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Colonization of the tsetse fly midgut with commensal Kosakonia cowanii Zambiae inhibits trypanosome infection establishment.

Weiss Brian L BL Maltz Michele A MA Vigneron Aurélien A Wu Yineng Y Walter Katharine S KS O'Neill Michelle B MB Wang Jingwen J Aksoy Serap S

PLoS pathogens 20190228 2

Tsetse flies (Glossina spp.) vector pathogenic trypanosomes (Trypanosoma spp.) in sub-Saharan Africa. These parasites cause human and animal African trypanosomiases, which are debilitating diseases that inflict an enormous socio-economic burden on inhabitants of endemic regions. Current disease control strategies rely primarily on treating infected animals and reducing tsetse population densities. However, relevant programs are costly, labor intensive and difficult to sustain. As such, novel str ...[more]

PMID: 30817773

Similar Datasets

Project description:Tsetse flies (Glossina spp.) feed exclusively on vertebrate blood. After a blood meal, the enteric endosymbiont Sodalis glossinidius is exposed to various environmental stressors including high levels of heme. To investigate how S. glossinidius morsitans (Sgm), the Sodalis subspecies that resides within the gut of G. morsitans, tolerates the heme-induced oxidative environment of tsetse's midgut, we used RNAseq to identify bacterial genes that are differentially expressed in cells cultured in high versus lower heme environments. Our analysis identified 436 genes that were significantly differentially expressed (> or < 2-fold) in the presence of high heme [219 heme-induced genes (HIGs) and 217 heme-repressed genes (HRGs)]. HIGs were enriched in Gene Ontology (GO) terms related to regulation of a variety of biological functions, including gene expression and metabolic processes. We observed that 11 out of 13 Sgm genes that were heme regulated in vitro were similarly regulated in bacteria that resided within tsetse's midgut 24 hr (high heme environment) and 96 hr (low heme environment) after the flies had consumed a blood meal. We used intron mutagenesis to make insertion mutations in 12 Sgm HIGs and observed no significant change in growth in vitro in any of the mutant strains in high versus low heme conditions. However, Sgm strains that carried mutations in genes encoding a putative undefined phosphotransferase sugar (PTS) system component (SG2427), fucose transporter (SG0182), bacterioferritin (SG2280), and a DNA-binding protein (SGP1-0002), presented growth and/or survival defects in tsetse midguts as compared to normal Sgm. These findings suggest that the uptake up of sugars and storage of iron represent strategies that Sgm employs to successfully reside within the high heme environment of its tsetse host's midgut. Our results are of epidemiological relevance, as many hematophagous arthropods house gut-associated bacteria that mediate their host's competency as a vector of disease-causing pathogens.

Project description:Tsetse flies (Glossina spp.) vector pathogenic African trypanosomes, which cause sleeping sickness in humans and nagana in domesticated animals. Additionally, tsetse harbors 3 maternally transmitted endosymbiotic bacteria that modulate their host's physiology. Tsetse is highly resistant to infection with trypanosomes, and this phenotype depends on multiple physiological factors at the time of challenge. These factors include host age, density of maternally-derived trypanolytic effector molecules present in the gut, and symbiont status during development. In this study, we investigated the molecular mechanisms that result in tsetse's resistance to trypanosomes. We found that following parasite challenge, young susceptible tsetse present a highly attenuated immune response. In contrast, mature refractory flies express higher levels of genes associated with humoral (attacin and pgrp-lb) and epithelial (inducible nitric oxide synthase and dual oxidase) immunity. Additionally, we discovered that tsetse must harbor its endogenous microbiome during intrauterine larval development in order to present a parasite refractory phenotype during adulthood. Interestingly, mature aposymbiotic flies (Gmm(Apo)) present a strong immune response earlier in the infection process than do WT flies that harbor symbiotic bacteria throughout their entire lifecycle. However, this early response fails to confer significant resistance to trypanosomes. Gmm(Apo) adults present a structurally compromised peritrophic matrix (PM), which lines the fly midgut and serves as a physical barrier that separates luminal contents from immune responsive epithelial cells. We propose that the early immune response we observe in Gmm(Apo) flies following parasite challenge results from the premature exposure of gut epithelia to parasite-derived immunogens in the absence of a robust PM. Thus, tsetse's PM appears to regulate the timing of host immune induction following parasite challenge. Our results document a novel finding, which is the existence of a positive correlation between tsetse's larval microbiome and the integrity of the emerging adult PM gut immune barrier.

Project description:For their transmission, African trypanosomes rely on their blood feeding insect vector, the tsetse fly (Glossina sp.). The ingested Trypanosoma brucei parasites have to overcome a series of barriers in the tsetse fly alimentary tract to finally develop into the infective metacyclic forms in the salivary glands that are transmitted to a mammalian host by the tsetse bite. The parasite population in the salivary gland is dense with a significant number of trypanosomes tightly attached to the epithelial cells. Our current knowledge on the impact of the infection on the salivary gland functioning is very limited. Therefore, this study aimed to gain a deeper insight into the global gene expression changes in the salivary glands of Glossina morsitans morsitans in response to an infection with the T. brucei parasite. A detailed whole transcriptome comparison of midgut-infected tsetse with and without a mature salivary gland infection was performed to study the impact of a trypanosome infection on different aspects of the salivary gland functioning and the mechanisms that are induced in this tissue to tolerate the infection i.e. to control the negative impact of the parasite presence. Moreover, a transcriptome comparison with age-matched uninfected flies was done to see whether gene expression in the salivary glands is already affected by a trypanosome infection in the tsetse midgut.By a RNA-sequencing (RNA-seq) approach we compared the whole transcriptomes of flies with a T. brucei salivary gland/midgut infection versus flies with only a midgut infection or versus non-infected flies, all with the same age and feeding history. More than 7500 salivary gland transcripts were detected from which a core group of 1214 differentially expressed genes (768 up- and 446 down-regulated) were shared between the two transcriptional comparisons. Gene Ontology enrichment analysis and detailed gene expression comparisons showed a diverse impact at the gene transcript level. Increased expression was observed for transcripts encoding for proteins involved in immunity (like several genes of the Imd-signaling pathway, serine proteases, serpins and thioester-containing proteins), detoxification of reactive species, cell death, cytoskeleton organization, cell junction and repair. Decreased expression was observed for transcripts encoding the major secreted proteins such as 5'-nucleotidases, adenosine deaminases and the nucleic acid binding proteins Tsals. Moreover, expression of some gene categories in the salivary glands were found to be already affected by a trypanosome midgut infection, before the parasite reaches the salivary glands.This study reveals that the T. brucei population in the tsetse salivary gland has a negative impact on its functioning and on the integrity of the gland epithelium. Our RNA-seq data suggest induction of a strong local tissue response in order to control the epithelial cell damage, the ROS intoxication of the cellular environment and the parasite infection, resulting in the fly tolerance to the infection. The modified expression of some gene categories in the tsetse salivary glands by a trypanosome infection at the midgut level indicate a putative anticipatory response in the salivary glands, before the parasite reaches this tissue.

Project description:BACKGROUND:Tsetse flies (Glossina spp.) are the prominent vector of African trypanosome parasites (Trypanosoma spp.) in sub-Saharan Africa, and Glossina pallidipes is the most widely distributed species in Kenya. This species displays strong resistance to infection by parasites, which are typically eliminated in the midgut shortly after acquisition from the mammalian host. Although extensive molecular information on immunity for the related species Glossina morsitans morsitans exists, similar information is scarce for G. pallidipes. METHODS:To determine temporal transcriptional responses of G. pallidipes to Trypanosoma brucei brucei challenge, we conducted Illumina based RNA-seq on midgut organ and carcass from teneral females G. pallidipes at 24 and 48 h post-challenge (hpc) with T. b. brucei relative to their respective controls that received normal blood meals (without the parasite). We used a suite of bioinformatics tools to determine differentially expressed and enriched transcripts between and among tissues, and to identify expanded transcripts in G. pallidipes relative to their orthologs G. m. morsitans. RESULTS:Midgut transcripts induced at 24 hpc encoded proteins were associated with lipid remodelling, proteolysis, collagen metabolism, apoptosis, and cell growth. Midgut transcripts induced at 48 hpc encoded proteins linked to embryonic growth and development, serine endopeptidases and proteosomal degradation of the target protein, mRNA translation and neuronal development. Temporal expression of immune responsive transcripts at 48 relative to 24 hpc was pronounced, indicative of a gradual induction of host immune responses the following challenge. We also searched for G. m. morsitans orthologous groups that may have experienced expansions in the G. pallidipes genome. We identified ten expanded groups in G. pallidipes with putative immunity-related functions, which may play a role in the higher refractoriness exhibited by this species. CONCLUSIONS:There appears to be a lack of strong immune responses elicited by gut epithelia of teneral adults. This in combination with a compromised peritrophic matrix at this stage during the initial phase of T. b. brucei challenge may facilitate the increased parasite infection establishment noted in teneral flies relative to older adults. Although teneral flies are more susceptible than older adults, the majority of tenerals are still able to eliminate parasite infections. Hence, robust responses elicited at a later time point, such as 72 hpc, may clear parasite infections from the majority of flies. The expanded G. m. morsitans orthologous groups in G. pallidipes may also be functionally associated with the enhanced refractoriness to trypanosome infections reported in G. pallidipes relative to G. m. morsitans.

Project description:In the glucose-free environment that is the midgut of the tsetse fly vector, the procyclic form of Trypanosoma brucei primarily uses proline to feed its central carbon and energy metabolism. In these conditions, the parasite needs to produce glucose 6-phosphate (G6P) through gluconeogenesis from metabolism of non-glycolytic carbon source(s). We showed here that two phosphoenolpyruvate-producing enzymes, PEP carboxykinase (PEPCK) and pyruvate phosphate dikinase (PPDK) have a redundant function for the essential gluconeogenesis from proline. Indeed, incorporation of 13C-enriched proline into G6P was abolished in the PEPCK/PPDK null double mutant (?ppdk/?pepck), but not in the single ?ppdk and ?pepck mutant cell lines. The procyclic trypanosome also uses the glycerol conversion pathway to feed gluconeogenesis, since the death of the ?ppdk/?pepck double null mutant in glucose-free conditions is only observed after RNAi-mediated down-regulation of the expression of the glycerol kinase, the first enzyme of the glycerol conversion pathways. Deletion of the gene encoding fructose-1,6-bisphosphatase (?fbpase), a key gluconeogenic enzyme irreversibly producing fructose 6-phosphate from fructose 1,6-bisphosphate, considerably reduced, but not abolished, incorporation of 13C-enriched proline into G6P. In addition, the ?fbpase cell line is viable in glucose-free conditions, suggesting that an alternative pathway can be used for G6P production in vitro. However, FBPase is essential in vivo, as shown by the incapacity of the ?fbpase null mutant to colonise the fly vector salivary glands, while the parental phenotype is restored in the ?fbpase rescued cell line re-expressing FBPase. The essential role of FBPase for the development of T. brucei in the tsetse was confirmed by taking advantage of an in vitro differentiation assay based on the RNA-binding protein 6 over-expression, in which the procyclic forms differentiate into epimastigote forms but not into mammalian-infective metacyclic parasites. In total, morphology, immunofluorescence and cytometry analyses showed that the differentiation of the epimastigote stages into the metacyclic forms is abolished in the ?fbpase mutant.

Dataset Information

Colonization of the tsetse fly midgut with commensal Kosakonia cowanii Zambiae inhibits trypanosome infection establishment.

Publications

Colonization of the tsetse fly midgut with commensal Kosakonia cowanii Zambiae inhibits trypanosome infection establishment.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets