Publications by authors named "Clair Rose"

8 Publications

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Tsetse salivary glycoproteins are modified with paucimannosidic N-glycans, are recognised by C-type lectins and bind to trypanosomes.

PLoS Negl Trop Dis 2021 Feb 2;15(2):e0009071. Epub 2021 Feb 2.

Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom.

African sleeping sickness is caused by Trypanosoma brucei, a parasite transmitted by the bite of a tsetse fly. Trypanosome infection induces a severe transcriptional downregulation of tsetse genes encoding for salivary proteins, which reduces its anti-hemostatic and anti-clotting properties. To better understand trypanosome transmission and the possible role of glycans in insect bloodfeeding, we characterized the N-glycome of tsetse saliva glycoproteins. Tsetse salivary N-glycans were enzymatically released, tagged with either 2-aminobenzamide (2-AB) or procainamide, and analyzed by HILIC-UHPLC-FLR coupled online with positive-ion ESI-LC-MS/MS. We found that the N-glycan profiles of T. brucei-infected and naïve tsetse salivary glycoproteins are almost identical, consisting mainly (>50%) of highly processed Man3GlcNAc2 in addition to several other paucimannose, high mannose, and few hybrid-type N-glycans. In overlay assays, these sugars were differentially recognized by the mannose receptor and DC-SIGN C-type lectins. We also show that salivary glycoproteins bind strongly to the surface of transmissible metacyclic trypanosomes. We suggest that although the repertoire of tsetse salivary N-glycans does not change during a trypanosome infection, the interactions with mannosylated glycoproteins may influence parasite transmission into the vertebrate host.
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http://dx.doi.org/10.1371/journal.pntd.0009071DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7880456PMC
February 2021

Repurposing the orphan drug nitisinone to control the transmission of African trypanosomiasis.

PLoS Biol 2021 Jan 26;19(1):e3000796. Epub 2021 Jan 26.

Department of Vector Biology, Liverpool School of Tropical Medicine, United Kingdom.

Tsetse transmit African trypanosomiasis, which is a disease fatal to both humans and animals. A vaccine to protect against this disease does not exist so transmission control relies on eliminating tsetse populations. Although neurotoxic insecticides are the gold standard for insect control, they negatively impact the environment and reduce populations of insect pollinator species. Here we present a promising, environment-friendly alternative to current insecticides that targets the insect tyrosine metabolism pathway. A bloodmeal contains high levels of tyrosine, which is toxic to haematophagous insects if it is not degraded and eliminated. RNA interference (RNAi) of either the first two enzymes in the tyrosine degradation pathway (tyrosine aminotransferase (TAT) and 4-hydroxyphenylpyruvate dioxygenase (HPPD)) was lethal to tsetse. Furthermore, nitisinone (NTBC), an FDA-approved tyrosine catabolism inhibitor, killed tsetse regardless if the drug was orally or topically applied. However, oral administration of NTBC to bumblebees did not affect their survival. Using a novel mathematical model, we show that NTBC could reduce the transmission of African trypanosomiasis in sub-Saharan Africa, thus accelerating current disease elimination programmes.
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http://dx.doi.org/10.1371/journal.pbio.3000796DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7837477PMC
January 2021

Trypanosoma brucei colonizes the tsetse gut via an immature peritrophic matrix in the proventriculus.

Nat Microbiol 2020 07 20;5(7):909-916. Epub 2020 Apr 20.

Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK.

The peritrophic matrix of blood-feeding insects is a chitinous structure that forms a protective barrier against oral pathogens and abrasive particles. Tsetse flies transmit Trypanosoma brucei, which is the parasite that causes human sleeping sickness and is also partially responsible for animal trypanosomiasis in Sub-Saharan Africa. For this parasite to establish an infection in flies, it must first colonize the area between the peritrophic matrix and gut epithelium called the ectoperitrophic space. Although unproven, it is generally accepted that trypanosomes reach the ectoperitrophic space by penetrating the peritrophic matrix in the anterior midgut. Here, we revisited this event using fluorescence- and electron-microscopy methodologies. We show that trypanosomes penetrate the ectoperitrophic space in which the newly made peritrophic matrix is synthesized by the proventriculus. Our model describes how these proventriculus-colonizing parasites can either migrate to the ectoperitrophic space or become trapped within peritrophic matrix layers to form cyst-like bodies that are passively pushed along the gut as the matrix gets remodelled. Furthermore, early proventricular colonization seems to be promoted by factors in trypanosome-infected blood that cause higher salivary gland infections and potentially increase parasite transmission.
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http://dx.doi.org/10.1038/s41564-020-0707-zDOI Listing
July 2020

Comparative genomic analysis of six Glossina genomes, vectors of African trypanosomes.

Genome Biol 2019 09 2;20(1):187. Epub 2019 Sep 2.

Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT, USA.

Background: Tsetse flies (Glossina sp.) are the vectors of human and animal trypanosomiasis throughout sub-Saharan Africa. Tsetse flies are distinguished from other Diptera by unique adaptations, including lactation and the birthing of live young (obligate viviparity), a vertebrate blood-specific diet by both sexes, and obligate bacterial symbiosis. This work describes the comparative analysis of six Glossina genomes representing three sub-genera: Morsitans (G. morsitans morsitans, G. pallidipes, G. austeni), Palpalis (G. palpalis, G. fuscipes), and Fusca (G. brevipalpis) which represent different habitats, host preferences, and vectorial capacity.

Results: Genomic analyses validate established evolutionary relationships and sub-genera. Syntenic analysis of Glossina relative to Drosophila melanogaster shows reduced structural conservation across the sex-linked X chromosome. Sex-linked scaffolds show increased rates of female-specific gene expression and lower evolutionary rates relative to autosome associated genes. Tsetse-specific genes are enriched in protease, odorant-binding, and helicase activities. Lactation-associated genes are conserved across all Glossina species while male seminal proteins are rapidly evolving. Olfactory and gustatory genes are reduced across the genus relative to other insects. Vision-associated Rhodopsin genes show conservation of motion detection/tracking functions and variance in the Rhodopsin detecting colors in the blue wavelength ranges.

Conclusions: Expanded genomic discoveries reveal the genetics underlying Glossina biology and provide a rich body of knowledge for basic science and disease control. They also provide insight into the evolutionary biology underlying novel adaptations and are relevant to applied aspects of vector control such as trap design and discovery of novel pest and disease control strategies.
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http://dx.doi.org/10.1186/s13059-019-1768-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6721284PMC
September 2019

Characterization of a novel glycosylated glutathione transferase of , closest relative of the human river blindness parasite.

Parasitology 2019 12 3;146(14):1773-1784. Epub 2019 Jul 3.

Liverpool School of Tropical Medicine, Liverpool, UK.

Filarial nematodes possess glutathione transferases (GSTs), ubiquitous enzymes with the potential to detoxify xenobiotic and endogenous substrates, and modulate the host immune system, which may aid worm infection establishment, maintenance and survival in the host. Here we have identified and characterized a σ class glycosylated GST (OoGST1), from the cattle-infective filarial nematode Onchocerca ochengi, which is homologous (99% amino acid identity) with an immunodominant GST and potential vaccine candidate from the human parasite, O. volvulus, (OvGST1b). Onchocerca ochengi native GSTs were purified using a two-step affinity chromatography approach, resolved by 2D and 1D SDS-PAGE and subjected to enzymic deglycosylation revealing the existence of at least four glycoforms. A combination of lectin-blotting and mass spectrometry (MS) analyses of the released N-glycans indicated that OoGST1 contained mainly oligomannose Man5GlcNAc2 structure, but also hybrid- and larger oligommanose-type glycans in a lower proportion. Furthermore, purified OoGST1 showed prostaglandin synthase activity as confirmed by Liquid Chromatography (LC)/MS following a coupled-enzyme assay. This is only the second reported and characterized glycosylated GST and our study highlights its potential role in host-parasite interactions and use in the study of human onchocerciasis.
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http://dx.doi.org/10.1017/S0031182019000763DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6939172PMC
December 2019

Variations in the Peritrophic Matrix Composition of Heparan Sulphate from the Tsetse Fly, Glossina morsitans morsitans.

Pathogens 2018 Mar 19;7(1). Epub 2018 Mar 19.

Molecular & Structural Bioscience, School of Life Sciences, Keele University, Keele ST5 5BG, UK.

Tsetse flies are the principal insect vectors of African -sleeping sickness in humans and Nagana in cattle. One of the tsetse fly species, , is host to the parasite, , a major cause of African trypanosomiasis. Precise details of the life cycle have yet to be established, but the parasite life cycle involves crossing the insect peritrophic matrix (PM). The PM consists of the polysaccharide chitin, several hundred proteins, and both glycosamino- and galactosaminoglycan (GAG) polysaccharides. Owing to the technical challenges of detecting small amounts of GAG polysaccharides, their conclusive identification and composition have not been possible until now. Following removal of PMs from the insects and the application of heparinases (bacterial lyase enzymes that are specific for heparan sulphate (HS) GAG polysaccharides), dot blots with a HS-specific antibody showed heparan sulphate proteoglycans (HSPGs) to be present, consistent with genome analysis, as well as the likely expression of the HSPGs syndecan and perlecan. Exhaustive HS digestion with heparinases, fluorescent labeling of the resulting disaccharides with BODIPY fluorophore, and separation by strong anion exchange chromatography then demonstrated the presence of HS for the first time and provided the disaccharide composition. There were no significant differences in the type of disaccharide species present between genders or between ages (24 vs 48 h post emergence), although the HS from female flies was more heavily sulphated overall. Significant differences, which may relate to differences in infection between genders or ages, were evident, however, in overall levels of 2--sulphation between sexes and, for females, between 24 and 48 h post-emergence, implying a change in expression or activity for the 2--sulphotransferase enzyme. The presence of significant quantities of disaccharides containing the monosaccharide GlcNAc6S contrasts with previous findings in and suggests subtle differences in HS fine structure between species of the .
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http://dx.doi.org/10.3390/pathogens7010032DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5874758PMC
March 2018

An investigation into the protein composition of the teneral Glossina morsitans morsitans peritrophic matrix.

PLoS Negl Trop Dis 2014 Apr 24;8(4):e2691. Epub 2014 Apr 24.

Department of Parasitology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom; Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom.

Background: Tsetse flies serve as biological vectors for several species of African trypanosomes. In order to survive, proliferate and establish a midgut infection, trypanosomes must cross the tsetse fly peritrophic matrix (PM), which is an acellular gut lining surrounding the blood meal. Crossing of this multi-layered structure occurs at least twice during parasite migration and development, but the mechanism of how trypanosomes do so is not understood. In order to better comprehend the molecular events surrounding trypanosome penetration of the tsetse PM, a mass spectrometry-based approach was applied to investigate the PM protein composition using Glossina morsitans morsitans as a model organism.

Methods: PMs from male teneral (young, unfed) flies were dissected, solubilised in urea/SDS buffer and the proteins precipitated with cold acetone/TCA. The PM proteins were either subjected to an in-solution tryptic digestion or fractionated on 1D SDS-PAGE, and the resulting bands digested using trypsin. The tryptic fragments from both preparations were purified and analysed by LC-MS/MS.

Results: Overall, nearly 300 proteins were identified from both analyses, several of those containing signature Chitin Binding Domains (CBD), including novel peritrophins and peritrophin-like glycoproteins, which are essential in maintaining PM architecture and may act as trypanosome adhesins. Furthermore, 27 proteins from the tsetse secondary endosymbiont, Sodalis glossinidius, were also identified, suggesting this bacterium is probably in close association with the tsetse PM.

Conclusion: To our knowledge this is the first report on the protein composition of teneral G. m. morsitans, an important vector of African trypanosomes. Further functional analyses of these proteins will lead to a better understanding of the tsetse physiology and may help identify potential molecular targets to block trypanosome development within the tsetse.
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http://dx.doi.org/10.1371/journal.pntd.0002691DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3998921PMC
April 2014

Flying tryps: survival and maturation of trypanosomes in tsetse flies.

Trends Parasitol 2013 Apr 16;29(4):188-96. Epub 2013 Mar 16.

Parasitology Department, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK.

Survival in and colonization of the tsetse fly midgut are essential steps in the transmission of many species of African trypanosomes. In the fly, bloodstream trypanosomes transform into the procyclic stage within the gut lumen and later migrate to the ectoperitrophic space, where they multiply, establishing an infection. Progression of the parasite infection in the fly depends on factors inherent to the biology of trypanosomes, tsetse, and the bloodmeal. Flies usually eradicate infection early on with both pre-existing and inducible factors. Parasites, in contrast, respond to these stimuli by undergoing developmental changes, allowing a few to both survive and migrate within the tsetse. Here we discuss parasite and fly factors determining trypanosome colonization of the tsetse, focusing mainly on the midgut.
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http://dx.doi.org/10.1016/j.pt.2013.02.003DOI Listing
April 2013