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Turnover of Variant Surface Glycoprotein in Trypanosoma brucei Is Not Altered in Response to Specific Silencing. mSphere 2022; 7:e0012222. [PMID: 35727016 PMCID: PMC9429888 DOI: 10.1128/msphere.00122-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
African trypanosomes evade the immune system of the mammalian host by the antigenic variation of the predominant glycosylphosphatidylinositol (GPI)-anchored surface protein, variant surface glycoprotein (VSG). VSG is a very stable protein that is turned over from the cell surface with a long half-life (~26 h), allowing newly synthesized VSG to populate the surface. We have recently demonstrated that VSG turnover under normal growth is mediated by a combination of GPI hydrolysis and direct shedding with intact GPI anchors. VSG synthesis is tightly regulated in dividing trypanosomes, and when subjected to RNA interference (RNAi) silencing, cells display rapid cell cycle arrest in order to conserve VSG density on the cell surface (K. Sheader, S. Vaughan, J. Minchin, K. Hughes, et al., Proc Natl Acad Sci U S A 102:8716-8721, 2005, https://doi.org/10.1073/pnas.0501886102). Arrested cells also display an altered morphology of secretory organelles-engorgement of the trans-Golgi cisternae-that may reflect a disruption of post-Golgi secretory transport. We now ask whether trypanosomes under VSG silencing also reduce the rate of VSG turnover to further conserve coat density. Our data indicate that trypanosomes do not regulate VSG turnover according to VSG protein abundance, nor was there any effect on the post-Golgi transport of soluble or GPI-anchored secretory cargo. However, the surface morphology of silenced cells was altered from a typically rugose topology to a smoother profile, consistent with reduced overall membrane trafficking to the cell surface. IMPORTANCE African trypanosomes evade the host immune system by altering the expression of variant surface glycoproteins (VSGs) in a process called antigenic variation. VSG is essential, and when its synthesis is ablated by RNAi silencing, cells enter precytokinesis growth arrest as a means to maintain constant cell surface VSG levels. We have investigated whether arrested cells also alter the rate of natural VSG turnover as a means to conserve the surface coat. This work provides insights into the natural biology of the glycocalyx of this important human and veterinary parasite.
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Sáez Conde J, Dean S. Structure, function and druggability of the African trypanosome flagellum. J Cell Physiol 2022; 237:2654-2667. [PMID: 35616248 PMCID: PMC9323424 DOI: 10.1002/jcp.30778] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 04/20/2022] [Accepted: 04/25/2022] [Indexed: 11/29/2022]
Abstract
African trypanosomes are early branching protists that cause human and animal diseases, termed trypanosomiases. They have been under intensive study for more than 100 years and have contributed significantly to our understanding of eukaryotic biology. The combination of conserved and parasite‐specific features mean that their flagellum has gained particular attention. Here, we discuss the different structural features of the flagellum and their role in transmission and virulence. We highlight the possibilities of targeting flagellar function to cure trypanosome infections and help in the fight to eliminate trypanosomiases.
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Affiliation(s)
- Julia Sáez Conde
- Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, UK
| | - Samuel Dean
- Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, UK
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Marufu L, Coetzer THT. Homology modelling of Trypanosoma brucei major surface proteases and molecular docking of variant surface glycoproteins and inhibitor ligands for drug design. J Mol Graph Model 2021; 111:108104. [PMID: 34920394 DOI: 10.1016/j.jmgm.2021.108104] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 11/12/2021] [Accepted: 12/05/2021] [Indexed: 12/30/2022]
Abstract
Trypanosomes, which cause animal African trypanosomiasis, escape host immune responses by renewing their variable surface glycoprotein (VSG) coat. Chemotherapy is currently the only form of external intervention available. However, the efficacy of current trypanocides is poor due to overuse leading to an increase in drug resistance. Major surface proteases (MSPs) of trypanosomes, which are zinc-dependent metalloproteases, are possible drug targets. A Trypanosoma brucei MSP-B (TbMSP-B) mediates parasite antigenic variation via cleavage of 60% of VSG molecules. Whilst TbMSP-A has no apparent role in VSG cleavage; it is not known if TbMSP-C is involved in VSG cleavage. In this study, three-dimensional structures of TbMSP-A, TbMSP-B and TbMSP-C were modelled. By comparing the docking poses of the C-terminal domains of VSG substrates into the models, TbMSP-C showed an affinity for similar VSG substrate sites as TbMSP-B, but these sites differed from those recognised by TbMSP-A. This observation suggests that TbMSP-C may be involved in VSG cleavage during antigenic variation. Furthermore, by docking small inhibitor ligands into the TbMSP-B and TbMSP-C homology models, followed by molecular dynamics simulations, ligands with potential anti-trypanosomal activity were identified. Docking studies also revealed the depth of the S1' pockets of TbMSP-B and TbMSP-C, which is influential in ligand and substrate binding, thereby identifying the protease subsite pocket that should be targeted in drug design.
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Affiliation(s)
- Lucky Marufu
- Biochemistry, School of Life Sciences, University of KwaZulu-Natal (Pietermaritzburg Campus), Private Bag X01, Scottsville, 3209, South Africa
| | - Theresa H T Coetzer
- Biochemistry, School of Life Sciences, University of KwaZulu-Natal (Pietermaritzburg Campus), Private Bag X01, Scottsville, 3209, South Africa.
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Steketee PC, Giordani F, Vincent IM, Crouch K, Achcar F, Dickens NJ, Morrison LJ, MacLeod A, Barrett MP. Transcriptional differentiation of Trypanosoma brucei during in vitro acquisition of resistance to acoziborole. PLoS Negl Trop Dis 2021; 15:e0009939. [PMID: 34752454 PMCID: PMC8648117 DOI: 10.1371/journal.pntd.0009939] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 12/06/2021] [Accepted: 10/21/2021] [Indexed: 11/19/2022] Open
Abstract
Subspecies of the protozoan parasite Trypanosoma brucei are the causative agents of Human African Trypanosomiasis (HAT), a debilitating neglected tropical disease prevalent across sub-Saharan Africa. HAT case numbers have steadily decreased since the start of the century, and sustainable elimination of one form of the disease is in sight. However, key to this is the development of novel drugs to combat the disease. Acoziborole is a recently developed benzoxaborole, currently in advanced clinical trials, for treatment of stage 1 and stage 2 HAT. Importantly, acoziborole is orally bioavailable, and curative with one dose. Recent studies have made significant progress in determining the molecular mode of action of acoziborole. However, less is known about the potential mechanisms leading to acoziborole resistance in trypanosomes. In this study, an in vitro-derived acoziborole-resistant cell line was generated and characterised. The AcoR line exhibited significant cross-resistance with the methyltransferase inhibitor sinefungin as well as hypersensitisation to known trypanocides. Interestingly, transcriptomics analysis of AcoR cells indicated the parasites had obtained a procyclic- or stumpy-like transcriptome profile, with upregulation of procyclin surface proteins as well as differential regulation of key metabolic genes known to be expressed in a life cycle-specific manner, even in the absence of major morphological changes. However, no changes were observed in transcripts encoding CPSF3, the recently identified protein target of acoziborole. The results suggest that generation of resistance to this novel compound in vitro can be accompanied by transcriptomic switches resembling a procyclic- or stumpy-type phenotype.
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Affiliation(s)
- Pieter C. Steketee
- The Roslin Institute, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Midlothian, United Kingdom
| | - Federica Giordani
- Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, United Kingdom
| | - Isabel M. Vincent
- Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, United Kingdom
| | - Kathryn Crouch
- Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, United Kingdom
| | - Fiona Achcar
- Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, United Kingdom
| | - Nicholas J. Dickens
- Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, United Kingdom
| | - Liam J. Morrison
- The Roslin Institute, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Midlothian, United Kingdom
| | - Annette MacLeod
- Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, United Kingdom
| | - Michael P. Barrett
- Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, United Kingdom
- Glasgow Polyomics, University of Glasgow, United Kingdom
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Machado H, Bizarra-Rebelo T, Costa-Sequeira M, Trindade S, Carvalho T, Rijo-Ferreira F, Rentroia-Pacheco B, Serre K, Figueiredo LM. Trypanosoma brucei triggers a broad immune response in the adipose tissue. PLoS Pathog 2021; 17:e1009933. [PMID: 34525131 PMCID: PMC8476018 DOI: 10.1371/journal.ppat.1009933] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 09/27/2021] [Accepted: 08/31/2021] [Indexed: 12/13/2022] Open
Abstract
Adipose tissue is one of the major reservoirs of Trypanosoma brucei parasites, the causative agent of sleeping sickness, a fatal disease in humans. In mice, the gonadal adipose tissue (AT) typically harbors 2–5 million parasites, while most solid organs show 10 to 100-fold fewer parasites. In this study, we tested whether the AT environment responds immunologically to the presence of the parasite. Transcriptome analysis of T. brucei infected adipose tissue revealed that most upregulated host genes are involved in inflammation and immune cell functions. Histochemistry and flow cytometry confirmed an increasingly higher number of infiltrated macrophages, neutrophils and CD4+ and CD8+ T lymphocytes upon infection. A large proportion of these lymphocytes effectively produce the type 1 effector cytokines, IFN-γ and TNF-α. Additionally, the adipose tissue showed accumulation of antigen-specific IgM and IgG antibodies as infection progressed. Mice lacking T and/or B cells (Rag2-/-, Jht-/-), or the signature cytokine (Ifng-/-) displayed a higher parasite load both in circulation and in the AT, demonstrating the key role of the adaptive immune system in both compartments. Interestingly, infections of C3-/- mice showed that while complement system is dispensable to control parasite load in the blood, it is necessary in the AT and other solid tissues. We conclude that T. brucei infection triggers a broad and robust immune response in the AT, which requires the complement system to locally reduce parasite burden. African trypanosomiasis is a neglected disease with significant socio-economic burden in sub-Saharan Africa. The protozoan parasite Trypanosoma brucei, a causative agent of African trypanosomiasis, can be found in the blood and extra-vascular spaces of the infected host. For an unknown reason, T. brucei accumulates in adipose tissue (AT) in very high numbers. Here we used a multidisciplinary approach to assess whether an immune response was mounted in AT during a T. brucei infection. We found that as infection progresses, a broad variety of immune cells and antibodies accumulate in the AT. We also found that this broad immune response is partially able to control parasite numbers in the AT. Our study provides evidence that T. brucei parasites present in the AT are subjected to immune surveillance. The reason why T. brucei accumulates to such a high extent in AT remains to be elucidated.
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Affiliation(s)
- Henrique Machado
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Tiago Bizarra-Rebelo
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Mariana Costa-Sequeira
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Sandra Trindade
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Tânia Carvalho
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Filipa Rijo-Ferreira
- Department of Neuroscience, Peter O’Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - Barbara Rentroia-Pacheco
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Karine Serre
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
- * E-mail: (KS); (LMF)
| | - Luisa M. Figueiredo
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
- * E-mail: (KS); (LMF)
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Dean S. Basic Biology of Trypanosoma brucei with Reference to the Development of Chemotherapies. Curr Pharm Des 2021; 27:1650-1670. [PMID: 33463458 DOI: 10.2174/1381612827666210119105008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 12/01/2020] [Accepted: 12/08/2020] [Indexed: 11/22/2022]
Abstract
Trypanosoma brucei are protozoan parasites that cause the lethal human disease African sleeping sickness and the economically devastating disease of cattle, Nagana. African sleeping sickness, also known as Human African Trypanosomiasis (HAT), threatens 65 million people and animal trypanosomiasis makes large areas of farmland unusable. There is no vaccine and licensed therapies against the most severe, late-stage disease are toxic, impractical and ineffective. Trypanosomes are transmitted by tsetse flies, and HAT is therefore predominantly confined to the tsetse fly belt in sub-Saharan Africa. They are exclusively extracellular and they differentiate between at least seven developmental forms that are highly adapted to host and vector niches. In the mammalian (human) host they inhabit the blood, cerebrospinal fluid (late-stage disease), skin, and adipose fat. In the tsetse fly vector they travel from the tsetse midgut to the salivary glands via the ectoperitrophic space and proventriculus. Trypanosomes are evolutionarily divergent compared with most branches of eukaryotic life. Perhaps most famous for their extraordinary mechanisms of monoallelic gene expression and antigenic variation, they have also been investigated because much of their biology is either highly unconventional or extreme. Moreover, in addition to their importance as pathogens, many researchers have been attracted to the field because trypanosomes have some of the most advanced molecular genetic tools and database resources of any model system. The following will cover just some aspects of trypanosome biology and how its divergent biochemistry has been leveraged to develop drugs to treat African sleeping sickness. This is by no means intended to be a comprehensive survey of trypanosome features. Rather, I hope to present trypanosomes as one of the most fascinating and tractable systems to do discovery biology.
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Affiliation(s)
- Samuel Dean
- Warwick Medical School, University of Warwick, Coventry, CV4 7AL, United Kingdom
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Levy DJ, Goundry A, Laires RSS, Costa TFR, Novo CM, Grab DJ, Mottram JC, Lima APCA. Role of the inhibitor of serine peptidase 2 (ISP2) of Trypanosoma brucei rhodesiense in parasite virulence and modulation of the inflammatory responses of the host. PLoS Negl Trop Dis 2021; 15:e0009526. [PMID: 34153047 PMCID: PMC8248637 DOI: 10.1371/journal.pntd.0009526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2020] [Revised: 07/01/2021] [Accepted: 06/01/2021] [Indexed: 11/18/2022] Open
Abstract
Trypanosoma brucei rhodesiense is one of the causative agents of Human African Trypanosomiasis (HAT), known as sleeping sickness. The parasite invades the central nervous system and causes severe encephalitis that is fatal if left untreated. We have previously identified ecotin-like inhibitors of serine peptidases, named ISPs, in trypanosomatid parasitic protozoa. Here, we investigated the role of ISP2 in bloodstream form T. b. rhodesiense. We generated gene-deficient mutants lacking ISP2 (Δisp2), which displayed a growth profile in vitro similar to that of wild-type (WT) parasites. C57BL/6 mice infected with Δisp2 displayed lower blood parasitemia, a delayed hind leg pathological phenotype and survived longer. The immune response was examined at two time-points that corresponded with two peaks of parasitemia. At 4 days, the spleens of Δisp2-infected mice had a greater percentage of NOS2+ myeloid cells, IFN-γ+-NK cells and increased TNF-α compared to those infected with WT and parasites re-expressing ISP2 (Δisp2:ISP2). By 13 days the increased NOS2+ population was sustained in Δisp2-infected mice, along with increased percentages of monocyte-derived dendritic cells, as well as CD19+ B lymphocytes, and CD8+ and CD4+ T lymphocytes. Taken together, these findings indicate that ISP2 contributes to T. b. rhodesiense virulence in mice and attenuates the inflammatory response during early infection.
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Affiliation(s)
- David Jessula Levy
- Instituto de Biofisica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Av. Carlos Chagas Filho 373, Centro de Ciências da Saúde, Ilha do Fundão, Rio de Janeiro, RJ, Brazil
| | - Amy Goundry
- Instituto de Biofisica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Av. Carlos Chagas Filho 373, Centro de Ciências da Saúde, Ilha do Fundão, Rio de Janeiro, RJ, Brazil
| | - Raquel S. S. Laires
- Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Lisboa, Portugal
- Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Tatiana F. R. Costa
- Instituto de Biofisica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Av. Carlos Chagas Filho 373, Centro de Ciências da Saúde, Ilha do Fundão, Rio de Janeiro, RJ, Brazil
| | - Carlos Mendes Novo
- Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Lisboa, Portugal
| | - Dennis J. Grab
- Department of Pathology, Uniformed Services University of the Health Sciences, Bethesda, Maryland; Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Jeremy C. Mottram
- Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
- York Biomedical Research Institute and Department of Biology, University of York, York, United Kingdom
| | - Ana Paula C. A. Lima
- Instituto de Biofisica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Av. Carlos Chagas Filho 373, Centro de Ciências da Saúde, Ilha do Fundão, Rio de Janeiro, RJ, Brazil
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Lecordier L, Uzureau S, Vanwalleghem G, Deleu M, Crowet JM, Barry P, Moran B, Voorheis P, Dumitru AC, Yamaryo-Botté Y, Dieu M, Tebabi P, Vanhollebeke B, Lins L, Botté CY, Alsteens D, Dufrêne Y, Pérez-Morga D, Nolan DP, Pays E. The Trypanosoma Brucei KIFC1 Kinesin Ensures the Fast Antibody Clearance Required for Parasite Infectivity. iScience 2020; 23:101476. [PMID: 32889430 PMCID: PMC7479354 DOI: 10.1016/j.isci.2020.101476] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 07/30/2020] [Accepted: 08/17/2020] [Indexed: 12/24/2022] Open
Abstract
Human innate immunity to Trypanosoma brucei involves the trypanosome C-terminal kinesin TbKIFC1, which transports internalized trypanolytic factor apolipoprotein L1 (APOL1) within the parasite. We show that TbKIFC1 preferentially associates with cholesterol-containing membranes and is indispensable for mammalian infectivity. Knockdown of TbKIFC1 did not affect trypanosome growth in vitro but rendered the parasites unable to infect mice unless antibody synthesis was compromised. Surface clearance of Variant Surface Glycoprotein (VSG)-antibody complexes was far slower in these cells, which were more susceptible to capture by macrophages. This phenotype was not due to defects in VSG expression or trafficking but to decreased VSG mobility in a less fluid, stiffer surface membrane. This change can be attributed to increased cholesterol level in the surface membrane in TbKIFC1 knockdown cells. Clearance of surface-bound antibodies by T. brucei is therefore essential for infectivity and depends on high membrane fluidity maintained by the cholesterol-trafficking activity of TbKIFC1.
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Affiliation(s)
- Laurence Lecordier
- Laboratory of Molecular Parasitology, IBMM, Université Libre de Bruxelles, 12, rue des professeurs Jeener et Brachet, 6041 Gosselies, Belgium
| | - Sophie Uzureau
- Laboratory of Molecular Parasitology, IBMM, Université Libre de Bruxelles, 12, rue des professeurs Jeener et Brachet, 6041 Gosselies, Belgium
| | - Gilles Vanwalleghem
- Laboratory of Molecular Parasitology, IBMM, Université Libre de Bruxelles, 12, rue des professeurs Jeener et Brachet, 6041 Gosselies, Belgium
| | - Magali Deleu
- Laboratory of Molecular Biophysics at Interface (LBMI), University of Liège-Gembloux Agro Bio Tech, 2, Passage des Déportés, 5030 Gembloux, Belgium
| | - Jean-Marc Crowet
- Laboratory of Molecular Biophysics at Interface (LBMI), University of Liège-Gembloux Agro Bio Tech, 2, Passage des Déportés, 5030 Gembloux, Belgium
| | - Paul Barry
- School of Biochemistry and Immunology, Trinity College Dublin, Dublin 2, Ireland
| | - Barry Moran
- School of Biochemistry and Immunology, Trinity College Dublin, Dublin 2, Ireland
| | - Paul Voorheis
- School of Biochemistry and Immunology, Trinity College Dublin, Dublin 2, Ireland
| | - Andra-Cristina Dumitru
- Louvain Institute of Biomolecular Science and Technology, Catholic University of Louvain, Croix du Sud 4-5, 1348 Louvain-la-Neuve, Belgium
| | - Yoshiki Yamaryo-Botté
- Institute for Advanced Biosciences, CNRS UMR5309, Université Grenoble Alpes, INSERM U1209, 38700 La Tronche, France
| | - Marc Dieu
- MaSUN, Mass Spectrometry Facility, University of Namur, 61 Rue de Bruxelles, 5000 Namur, Belgium
| | - Patricia Tebabi
- Laboratory of Molecular Parasitology, IBMM, Université Libre de Bruxelles, 12, rue des professeurs Jeener et Brachet, 6041 Gosselies, Belgium
| | - Benoit Vanhollebeke
- Laboratory of Neurovascular Signaling, Université Libre de Bruxelles, 12, Rue des Profs Jeener et Brachet, 6041 Gosselies, Belgium
| | - Laurence Lins
- Laboratory of Molecular Biophysics at Interface (LBMI), University of Liège-Gembloux Agro Bio Tech, 2, Passage des Déportés, 5030 Gembloux, Belgium
| | - Cyrille Y. Botté
- Institute for Advanced Biosciences, CNRS UMR5309, Université Grenoble Alpes, INSERM U1209, 38700 La Tronche, France
| | - David Alsteens
- Louvain Institute of Biomolecular Science and Technology, Catholic University of Louvain, Croix du Sud 4-5, 1348 Louvain-la-Neuve, Belgium
| | - Yves Dufrêne
- Louvain Institute of Biomolecular Science and Technology, Catholic University of Louvain, Croix du Sud 4-5, 1348 Louvain-la-Neuve, Belgium
| | - David Pérez-Morga
- Laboratory of Molecular Parasitology, IBMM, Université Libre de Bruxelles, 12, rue des professeurs Jeener et Brachet, 6041 Gosselies, Belgium
- Center for Microscopy and Molecular Imaging (CMMI), Université Libre de Bruxelles, 12, Rue des Profs Jeener et Brachet, 6041 Gosselies, Belgium
| | - Derek P. Nolan
- School of Biochemistry and Immunology, Trinity College Dublin, Dublin 2, Ireland
| | - Etienne Pays
- Laboratory of Molecular Parasitology, IBMM, Université Libre de Bruxelles, 12, rue des professeurs Jeener et Brachet, 6041 Gosselies, Belgium
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Xu ZS, Li FJ, Hide G, Lun ZR, Lai DH. Vacuolar ATPase depletion contributes to dysregulation of endocytosis in bloodstream forms of Trypanosoma brucei. Parasit Vectors 2020; 13:214. [PMID: 32334612 PMCID: PMC7183646 DOI: 10.1186/s13071-020-04068-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Accepted: 04/09/2020] [Indexed: 12/04/2022] Open
Abstract
Background Vacuolar H+-ATPase (V-ATPase) is a highly conserved protein complex which hydrolyzes ATP and pumps protons to acidify vacuolar vesicles. Beyond its role in pH maintenance, the involvement of V-ATPase in endocytosis is well documented in mammals and plants but is less clear in Trypanosoma brucei. Methods In this study, the subcellular localization of V-ATPase subunit B (TbVAB) of T. brucei was assessed via in situ N-terminal YFP-tagging and immunofluorescence assays. Transgenic bloodstream forms (BSF) of T. brucei were generated which comprised either a V-ATPase subunit B (TbVAB) conditional knockout or a V-ATPase subunit A (TbVAA) knockdown. Acridine orange and BCECF-AM were employed to assess the roles of V-ATPase in the pH regulation of BSF T. brucei. The endocytic activities of three markers were also characterized by flow cytometry analyses. Furthermore, trypanosomes were counted from trypanolysis treatment groups (either containing 1% or 5% NHS) and endocytosed trypanosome lytic factor (TLF) was also analyzed by an immunoblotting assay. Results TbVAB was found to localize to acidocalcisomes, lysosomes and probably also to endosomes of BSF of T. brucei and was demonstrated to be essential for cell growth. TbVAB depletion neutralized acidic organelles at 24 hours post-tetracycline depletion (hpd), meanwhile the steady state intracellular pH increased from 7.016 ± 0.013 to 7.422 ± 0.058. Trypanosomes with TbVAB depletion at 24 hpd were found to take up more transferrin (2.068 ± 0.277 fold) but less tomato lectin (49.31 ± 22.57%) by endocytosis, while no significant change was detected in dextran uptake. Similar endocytic dysregulated phenotypes were also observed in TbVAA knockdown cells. In addition, TbVAB depleted trypanosomes showed a low uptake of TLF and exhibited less sensitive to lysis in both 1% and 5% NHS treatments. Conclusions TbVAB is a key component of V-ATPase and was found to play a key function in endocytosis as well as exhibiting different effects in a receptor/cargo dependent manner in BSF of T. brucei. Besides vacuolar alkalinization, the dysregulation of endocytosis in TbVAB depleted T. brucei is considered to contribute to the reduced sensitivity to lysis by normal human serum.![]()
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Affiliation(s)
- Zhi-Shen Xu
- Center for Parasitic Organisms, State Key Laboratory of Biocontrol, School of Life Sciences, and Key Laboratory of Tropical Disease Control (Sun Yat-Sen University), Ministry of Education, Sun Yat-Sen University, Guangzhou, 510275, The People's Republic of China
| | - Feng-Jun Li
- Department of Biological Sciences, National University of Singapore, Singapore, 11754, Singapore
| | - Geoff Hide
- Biomedical Research Centre and Ecosystems and Environment Research Centre, School of Science, Engineering and Environment, University of Salford, Salford, M5 4WT, UK
| | - Zhao-Rong Lun
- Center for Parasitic Organisms, State Key Laboratory of Biocontrol, School of Life Sciences, and Key Laboratory of Tropical Disease Control (Sun Yat-Sen University), Ministry of Education, Sun Yat-Sen University, Guangzhou, 510275, The People's Republic of China. .,Biomedical Research Centre and Ecosystems and Environment Research Centre, School of Science, Engineering and Environment, University of Salford, Salford, M5 4WT, UK.
| | - De-Hua Lai
- Center for Parasitic Organisms, State Key Laboratory of Biocontrol, School of Life Sciences, and Key Laboratory of Tropical Disease Control (Sun Yat-Sen University), Ministry of Education, Sun Yat-Sen University, Guangzhou, 510275, The People's Republic of China.
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10
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Magez S, Pinto Torres JE, Obishakin E, Radwanska M. Infections With Extracellular Trypanosomes Require Control by Efficient Innate Immune Mechanisms and Can Result in the Destruction of the Mammalian Humoral Immune System. Front Immunol 2020; 11:382. [PMID: 32218784 PMCID: PMC7078162 DOI: 10.3389/fimmu.2020.00382] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 02/18/2020] [Indexed: 12/17/2022] Open
Abstract
Salivarian trypanosomes are extracellular parasites that affect humans, livestock, and game animals around the world. Through co-evolution with the mammalian immune system, trypanosomes have developed defense mechanisms that allow them to thrive in blood, lymphoid vessels, and tissue environments such as the brain, the fat tissue, and testes. Trypanosomes have developed ways to circumvent antibody-mediated killing and block the activation of the lytic arm of the complement pathway. Hence, this makes the innate immune control of the infection a crucial part of the host-parasite interaction, determining infection susceptibility, and parasitemia control. Indeed, trypanosomes use a combination of several independent mechanisms to avoid clearance by the humoral immune system. First, perpetuated antigenic variation of the surface coat allows to escape antibody-mediated elimination. Secondly, when antibodies bind to the coat, they are efficiently transported toward the endocytosis pathway, where they are removed from the coat proteins. Finally, trypanosomes engage in the active destruction of the mammalian humoral immune response. This provides them with a rescue solution in case antigenic variation does not confer total immunological invisibility. Both antigenic variation and B cell destruction pose significant hurdles for the development of anti-trypanosome vaccine strategies. However, developing total immune escape capacity and unlimited growth capabilities within a mammalian host is not beneficial for any parasite, as it will result in the accelerated death of the host itself. Hence, trypanosomes have acquired a system of quorum sensing that results in density-dependent population growth arrest in order to prevent overpopulating the host. The same system could possibly sense the infection-associated host tissue damage resulting from inflammatory innate immune responses, in which case the quorum sensing serves to prevent excessive immunopathology and as such also promotes host survival. In order to put these concepts together, this review summarizes current knowledge on the interaction between trypanosomes and the mammalian innate immune system, the mechanisms involved in population growth regulation, antigenic variation and the immuno-destructive effect of trypanosomes on the humoral immune system. Vaccine trials and a discussion on the role of innate immune modulation in these trials are discussed at the end.
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Affiliation(s)
- Stefan Magez
- Laboratory for Biomedical Research, Ghent University Global Campus, Incheon, South Korea.,Department of Biochemistry and Microbiology, Ghent University, Ghent, Belgium.,Laboratory of Cellular and Molecular Immunology, Vrije Universiteit Brussel, Brussels, Belgium
| | | | - Emmanuel Obishakin
- Laboratory for Biomedical Research, Ghent University Global Campus, Incheon, South Korea.,Biotechnology Division, National Veterinary Research Institute, Vom, Nigeria
| | - Magdalena Radwanska
- Laboratory for Biomedical Research, Ghent University Global Campus, Incheon, South Korea.,Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
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11
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Walker BJ, Wheeler RJ. High-speed multifocal plane fluorescence microscopy for three-dimensional visualisation of beating flagella. J Cell Sci 2019; 132:jcs231795. [PMID: 31371486 PMCID: PMC6737910 DOI: 10.1242/jcs.231795] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2019] [Accepted: 07/22/2019] [Indexed: 01/04/2023] Open
Abstract
Analysis of flagellum and cilium beating in three dimensions (3D) is important for understanding cell motility, and using fluorescence microscopy to do so would be extremely powerful. Here, high-speed multifocal plane fluorescence microscopy, where the light path is split to visualise multiple focal planes simultaneously, was used to reconstruct Trypanosoma brucei and Leishmania mexicana movement in 3D. These species are uniflagellate unicellular parasites for which motility is vital. It was possible to use either a fluorescent stain or a genetically-encoded fluorescent protein to visualise flagellum and cell movement at 200 Hz frame rates. This addressed two open questions regarding Trypanosoma and Leishmania flagellum beating, which contributes to their swimming behaviours: 1) how planar is the L. mexicana flagellum beat, and 2) what is the nature of flagellum beating during T. brucei 'tumbling'? We showed that L. mexicana has notable deviations from a planar flagellum beat, and that during tumbling the T. brucei flagellum bends the cell and beats only in the distal portion to achieve cell reorientation. This demonstrates high-speed multifocal plane fluorescence microscopy as a powerful tool for the analysis of beating flagella.
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Affiliation(s)
- Benjamin J Walker
- Wolfson Centre for Mathematical Biology, Mathematical Institute, University of Oxford, Oxford OX2 6GG, UK
| | - Richard J Wheeler
- Peter Medawar Building for Pathogen Research, Nuffield Department of Medicine, University of Oxford, Oxford OX1 3SY, UK
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12
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Varikuti S, Jha BK, Volpedo G, Ryan NM, Halsey G, Hamza OM, McGwire BS, Satoskar AR. Host-Directed Drug Therapies for Neglected Tropical Diseases Caused by Protozoan Parasites. Front Microbiol 2018; 9:2655. [PMID: 30555425 PMCID: PMC6284052 DOI: 10.3389/fmicb.2018.02655] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 10/17/2018] [Indexed: 12/11/2022] Open
Abstract
The neglected tropical diseases (NTDs) caused by protozoan parasites are responsible for significant morbidity and mortality worldwide. Current treatments using anti-parasitic drugs are toxic and prolonged with poor patient compliance. In addition, emergence of drug-resistant parasites is increasing worldwide. Hence, there is a need for safer and better therapeutics for these infections. Host-directed therapy using drugs that target host pathways required for pathogen survival or its clearance is a promising approach for treating infections. This review will give a summary of the current status and advances of host-targeted therapies for treating NTDs caused by protozoa.
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Affiliation(s)
- Sanjay Varikuti
- Department of Pathology, Wexner Medical Center, The Ohio State University, Columbus, OH, United States
| | - Bijay Kumar Jha
- Division of Infectious Diseases, Department of Internal Medicine, The Ohio State University, Columbus, OH, United States
| | - Greta Volpedo
- Department of Pathology, Wexner Medical Center, The Ohio State University, Columbus, OH, United States.,Department of Microbiology, The Ohio State University, Columbus, OH, United States
| | - Nathan M Ryan
- Department of Pathology, Wexner Medical Center, The Ohio State University, Columbus, OH, United States
| | - Gregory Halsey
- Department of Pathology, Wexner Medical Center, The Ohio State University, Columbus, OH, United States
| | - Omar M Hamza
- Department of Pathology, Wexner Medical Center, The Ohio State University, Columbus, OH, United States
| | - Bradford S McGwire
- Division of Infectious Diseases, Department of Internal Medicine, The Ohio State University, Columbus, OH, United States
| | - Abhay R Satoskar
- Department of Pathology, Wexner Medical Center, The Ohio State University, Columbus, OH, United States.,Department of Microbiology, The Ohio State University, Columbus, OH, United States
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13
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Parasite motility is critical for virulence of African trypanosomes. Sci Rep 2018; 8:9122. [PMID: 29904094 PMCID: PMC6002391 DOI: 10.1038/s41598-018-27228-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Accepted: 05/23/2018] [Indexed: 12/19/2022] Open
Abstract
African trypanosomes, Trypanosoma brucei spp., are lethal pathogens that cause substantial human suffering and limit economic development in some of the world's most impoverished regions. The name Trypanosoma ("auger cell") derives from the parasite's distinctive motility, which is driven by a single flagellum. However, despite decades of study, a requirement for trypanosome motility in mammalian host infection has not been established. LC1 is a conserved dynein subunit required for flagellar motility. Prior studies with a conditional RNAi-based LC1 mutant, RNAi-K/R, revealed that parasites with defective motility could infect mice. However, RNAi-K/R retained residual expression of wild-type LC1 and residual motility, thus precluding definitive interpretation. To overcome these limitations, here we generate constitutive mutants in which both LC1 alleles are replaced with mutant versions. These double knock-in mutants show reduced motility compared to RNAi-K/R and are viable in culture, but are unable to maintain bloodstream infection in mice. The virulence defect is independent of infection route but dependent on an intact host immune system. By comparing different mutants, we also reveal a critical dependence on the LC1 N-terminus for motility and virulence. Our findings demonstrate that trypanosome motility is critical for establishment and maintenance of bloodstream infection, implicating dynein-dependent flagellar motility as a potential drug target.
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14
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Ooi CP, Smith TK, Gluenz E, Wand NV, Vaughan S, Rudenko G. Blocking variant surface glycoprotein synthesis alters endoplasmic reticulum exit sites/Golgi homeostasis in Trypanosoma brucei. Traffic 2018; 19:391-405. [PMID: 29533496 PMCID: PMC6001540 DOI: 10.1111/tra.12561] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Revised: 03/08/2018] [Accepted: 03/08/2018] [Indexed: 12/31/2022]
Abstract
The predominant secretory cargo of bloodstream form Trypanosoma brucei is variant surface glycoprotein (VSG), comprising ~10% total protein and forming a dense protective layer. Blocking VSG translation using Morpholino oligonucleotides triggered a precise pre‐cytokinesis arrest. We investigated the effect of blocking VSG synthesis on the secretory pathway. The number of Golgi decreased, particularly in post‐mitotic cells, from 3.5 ± 0.6 to 2.0 ± 0.04 per cell. Similarly, the number of endoplasmic reticulum exit sites (ERES) in post‐mitotic cells dropped from 3.9 ± 0.6 to 2.7 ± 0.1 eight hours after blocking VSG synthesis. The secretory pathway was still functional in these stalled cells, as monitored using Cathepsin L. Rates of phospholipid and glycosylphosphatidylinositol‐anchor biosynthesis remained relatively unaffected, except for the level of sphingomyelin which increased. However, both endoplasmic reticulum and Golgi morphology became distorted, with the Golgi cisternae becoming significantly dilated, particularly at the trans‐face. Membrane accumulation in these structures is possibly caused by reduced budding of nascent vesicles due to the drastic reduction in the total amount of secretory cargo, that is, VSG. These data argue that the total flux of secretory cargo impacts upon the biogenesis and maintenance of secretory structures and organelles in T. brucei, including the ERES and Golgi.
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Affiliation(s)
- Cher-Pheng Ooi
- Department of Life Sciences, Imperial College London, London, UK
| | - Terry K Smith
- BSRC, School of Biology, University of St. Andrews, St. Andrews, UK
| | - Eva Gluenz
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | | | - Sue Vaughan
- Department of Biological and Medical Sciences, Oxford Brookes University, Oxford, UK
| | - Gloria Rudenko
- Department of Life Sciences, Imperial College London, London, UK
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15
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How to create coats for all seasons: elucidating antigenic variation in African trypanosomes. Emerg Top Life Sci 2017; 1:593-600. [PMID: 33525853 PMCID: PMC7289013 DOI: 10.1042/etls20170105] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Revised: 11/08/2017] [Accepted: 11/10/2017] [Indexed: 11/17/2022]
Abstract
Extracellular parasites of the mammalian bloodstream face considerable challenges including incessant assault by the immune system. African trypanosomes are consummate survivors in this inclement environment and are renowned for their supremely sophisticated strategy of antigenic variation of their protective surface coat during the course of chronic infections. Recent developments are making us realize how complex this antigenic machinery is and are allowing us to tackle previously intractable problems. However, many of the simplest (and arguably the most important) questions still remain unanswered!
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16
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The Deadly Dance of B Cells with Trypanosomatids. Trends Parasitol 2017; 34:155-171. [PMID: 29089182 DOI: 10.1016/j.pt.2017.10.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 09/29/2017] [Accepted: 10/06/2017] [Indexed: 01/18/2023]
Abstract
B cells are notorious actors for the host's protection against several infectious diseases. So much so that early vaccinology seated its principles upon their long-term protective antibody secretion capabilities. Indeed, there are many examples of acute infectious diseases that are combated by functional humoral responses. However, some chronic infectious diseases actively induce immune deregulations that often lead to defective, if not deleterious, humoral immune responses. In this review we summarize how Leishmania and Trypanosoma spp. directly manipulate B cell responses to induce polyclonal B cell activation, hypergammaglobulinemia, low-specificity antibodies, limited B cell survival, and regulatory B cells, contributing therefore to immunopathology and the establishment of persistent infections.
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17
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Castillo-Acosta VM, Balzarini J, González-Pacanowska D. Surface Glycans: A Therapeutic Opportunity for Kinetoplastid Diseases. Trends Parasitol 2017; 33:775-787. [PMID: 28760415 DOI: 10.1016/j.pt.2017.06.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 05/29/2017] [Accepted: 06/22/2017] [Indexed: 11/30/2022]
Abstract
Trypanosomal diseases are in need of innovative therapies that exploit novel mechanisms of action. The cell surface of trypanosomatid parasites is characterized by a dense coat of glycoconjugates with important functions in host cell recognition, immune evasion, infectivity, and cell function. The nature of parasite surface glycans is highly dynamic and changes during differentiation and in response to different stimuli through the action of glycosyltransferases and glycosidases. Here we propose a new approach to antiparasitic drug discovery that involves the use of carbohydrate-binding agents that bind specifically to cell-surface glycans, giving rise to cytotoxic events and parasite death. The potential and limitations of this strategy are addressed with a specific focus on the treatment of sleeping sickness.
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Affiliation(s)
- Víctor M Castillo-Acosta
- Instituto de Parasitología y Biomedicina 'López-Neyra', Consejo Superior de Investigaciones Científicas, Parque Tecnológico de Ciencias de la Salud, Avenida del Conocimiento, s/n 18016-Armilla (Granada), Spain
| | - Jan Balzarini
- Rega Institute for Medical Research, KU Leuven, Herestraat 49, B-3000 Leuven, Belgium
| | - Dolores González-Pacanowska
- Instituto de Parasitología y Biomedicina 'López-Neyra', Consejo Superior de Investigaciones Científicas, Parque Tecnológico de Ciencias de la Salud, Avenida del Conocimiento, s/n 18016-Armilla (Granada), Spain.
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