Salivarian trypanosomes comprise a group of extracellular anthroponotic and zoonotic parasites. The only sustainable method for global control of these infection is through vaccination of livestock animals. Despite multiple reports describing promising laboratory results, no single field-applicable solution has been successful so far. Conventionally, vaccine research focusses mostly on exposed immunogenic antigens, or the structural molecular knowledge of surface exposed invariant immunogens. Unfortunately, extracellular parasites (or parasites with extracellular life stages) have devised efficient defense systems against host antibody attacks, so they can deal with the mammalian humoral immune response. In the case of trypanosomes, it appears that these mechanisms have been perfected, leading to vaccine failure in natural hosts. Here, we provide two examples of potential vaccine candidates that, despite being immunogenic and accessible to the immune system, failed to induce a functionally protective memory response. First, trypanosomal enolase was tested as a vaccine candidate, as it was recently characterized as a highly conserved enzyme that is readily recognized during infection by the host antibody response. Secondly, we re-addressed a vaccine approach towards the Invariant Surface Glycoprotein ISG75, and showed that despite being highly immunogenic, trypanosomes can avoid anti-ISG75 mediated parasitemia control.

Department of Biochemistry and Microbiology Ghent University Ledeganckstraat 35 9000 Ghent Belgium

Department of Biomedical Molecular Biology Ghent University Technologiepark Zwijnaarde 71 9000 Ghent Belgium

Laboratory for Biomedical Research Department of Molecular Biotechnology Environment Technology and Food Technology Ghent University Global Campus Songdomunhwa Ro 119 5 Yeonsu Gu Incheon 406 840 Korea

Laboratory of Cellular and Molecular Immunology Department of Bioengineering Sciences Vrije Universiteit Brussel Pleinlaan 2 1050 Brussels Belgium

Laboratory of Medical Biochemistry and the Infla Med Centre of Excellence University of Antwerp Campus Drie Eiken Universiteitsplein 1 2610 Wilrijk Belgium

Laboratory of Structural Parasitology Institute of Organic Chemistry and Biochemistry Academy of Sciences of the Czech Republic Flemingovo Namesti 2 16610 Prague 6 Czech Republic

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Mogk S., Boßelmann C.M., Mudogo C.N., Stein J., Wolburg H., Duszenko M. African trypanosomes and brain infection—The unsolved question. Biol. Rev. 2017;92:1675–1687. doi: 10.1111/brv.12301. PubMed DOI

Kristensson K., Nygard M., Bertini G., Bentivoglio M. African trypanosome infections of the nervous system: Parasite entry and effects on sleep and synaptic functions. Prog. Neurobiol. 2010;91:152–171. doi: 10.1016/j.pneurobio.2009.12.001. PubMed DOI

Trindade S., Rijo-Ferreira F., Carvalho T., Pinto-Neves D., Guegan F., Aresta-Branco F., Bento F., Young S.A., Pinto A., Abbeele J.V.D., et al. Trypanosoma brucei Parasites Occupy and Functionally Adapt to the Adipose Tissue in Mice. Cell Host Microbe. 2016;19:837–848. doi: 10.1016/j.chom.2016.05.002. PubMed DOI PMC

Franco J.R., Simarro P.P., Diarra A., Jannin J.G. Epidemiology of human African trypanosomiasis. Clin. Epidemiol. 2014;6:257–275. doi: 10.2147/clep.s39728. PubMed DOI PMC

Radwanska M., Vereecke N., Deleeuw V., Pinto J., Magez S. Salivarian Trypanosomosis: A Review of Parasites Involved, Their Global Distribution and Their Interaction with the Innate and Adaptive Mammalian Host Immune System. Front. Immunol. 2018;9:2253. doi: 10.3389/fimmu.2018.02253. PubMed DOI PMC

Capewell P., Cooper A., Clucas C., Weir W., Macleod A. A co-evolutionary arms race: Trypanosomes shaping the human genome, humans shaping the trypanosome genome. Parasitology. 2015;142:S108–S119. doi: 10.1017/S0031182014000602. PubMed DOI PMC

Pays E., Vanhollebeke B., Uzureau P., Lecordier L., Pérez-Morga D. The molecular arms race between African trypanosomes and humans. Nat. Rev. Microbiol. 2014;12:575–584. doi: 10.1038/nrmicro3298. PubMed DOI

Zoll S., Lane-Serff H., Mehmood S., Schneider J., Robinson C.V., Carrington M., Higgins M.K. The structure of serum resistance-associated protein and its implications for human African trypanosomiasis. Nat. Microbiol. 2018;17:1–9. doi: 10.1038/s41564-017-0085-3. PubMed DOI

Truc P., Büscher P., Cuny G., Gonzatti M.I., Jannin J., Joshi P., Juyal P., Lun Z.-R., Mattioli R., Pays E., et al. Atypical Human Infections by Animal Trypanosomes. PLoS Neglect. Trop. Dis. 2013;7:e2256. doi: 10.1371/journal.pntd.0002256. PubMed DOI PMC

Chau N.V.V., Chau L.B., Desquesnes M., Herder S., Lan N.P.H., Campbell J.I., Cuong N.V., Yimming B., Chalermwong P., Jittapalapong S., et al. A Clinical and Epidemiological Investigation of the First Reported Human Infection with the Zoonotic Parasite Trypanosoma evansi in Southeast Asia. Clin. Infect. Dis. 2016;62:1002–1008. doi: 10.1093/cid/ciw052. PubMed DOI PMC

Vanhollebeke B., Truc P., Poelvoorde P., Pays A., Joshi P.P., Katti R., Jannin J.G., Pays E. Human Trypanosoma evansi Infection Linked to a Lack of Apolipoprotein L-I. N. Engl. J. Med. 2006;355:2752–2756. doi: 10.1056/NEJMoa063265. PubMed DOI

Osório A.L.A.R., Madruga C.R., Desquesnes M., Soares C.O., Ribeiro L.R.R., Costa S.C.G. da Trypanosoma (Duttonella) vivax: Its biology, epidemiology, pathogenesis, and introduction in the New World—A review. Memórias Inst. Oswaldo Cruz. 2008;103:1–13. doi: 10.1590/S0074-02762008000100001. PubMed DOI

Dyonisio G.H.S., Batista H.R., da Silva R.E., Azevedo R.C.D.F.E., Costa J.D.O.J., Manhes I.B.D.O., Tonhosolo R., Gennari S.M., Minervino A.H.H., Marcili A. Molecular Diagnosis and Prevalence of Trypanosoma vivax (Trypanosomatida: Trypanosomatidae) in Buffaloes and Ectoparasites in the Brazilian Amazon Region. J. Med. Entomol. 2020;58:403–407. doi: 10.1093/jme/tjaa145. PubMed DOI

Chávez-Larrea M.A., Medina-Pozo M.L., Cholota-Iza C.E., Jumbo-Moreira J.R., Saegerman C., Proaño-Pérez F., Ron-Román J., Reyna-Bello A. First report and molecular identification of Trypanosoma (Duttonella) vivax outbreak in cattle population from Ecuador. Transbound. Emerg. Dis. 2020;68:2422–2428. doi: 10.1111/tbed.13906. PubMed DOI

Desquesnes M., Holzmuller P., Lai D.-H., Dargantes A., Lun Z.-R., Jittaplapong S. Trypanosoma evansi and Surra: A Review and Perspectives on Origin, History, Distribution, Taxonomy, Morphology, Hosts, and Pathogenic Effects. BioMed Res. Int. 2013;2013:1–22. doi: 10.1155/2013/194176. PubMed DOI PMC

Desquesnes M., Dargantes A., Lai D.-H., Lun Z.-R., Holzmuller P., Jittapalapong S. Trypanosoma evansiand Surra: A Review and Perspectives on Transmission, Epidemiology and Control, Impact, and Zoonotic Aspects. BioMed Res. Int. 2013;2013:1–20. doi: 10.1155/2013/321237. PubMed DOI PMC

Gutierrez C., Desquesnes M., Touratier L., Büscher P. Trypanosoma evansi: Recent outbreaks in Europe. Vet. Parasitol. 2010;174:26–29. doi: 10.1016/j.vetpar.2010.08.012. PubMed DOI

Tamarit A., Gutierrez C., Arroyo R., Jimenez V., Zagalá G., Bosch I., Sirvent J., Alberola J., Alonso I., Caballero C. Trypanosoma evansi infection in mainland Spain. Vet. Parasitol. 2010;167:74–76. doi: 10.1016/j.vetpar.2009.09.050. PubMed DOI

Defontis M., Richartz J., Engelmann N., Bauer C., Schwierk V.M., Büscher P., Moritz A. Canine Trypanosoma evansi infection introduced into Germany. Vet. Clin. Path. 2012;41:369–374. doi: 10.1111/j.1939-165X.2012.00454.x. PubMed DOI

Desquesnes M., Bossard G., Patrel D., Herder S., Patout O., Lepetitcolin E., Thevenon S., Berthier D., Pavlovic D., Brugidou R., et al. First outbreak of Trypanosoma evansi in camels in metropolitan France. Vet. Rec. 2008;162:750–752. doi: 10.1136/vr.162.23.750. PubMed DOI

Rodríguez N.F., Tejedor-Junco M.T., González-Martín M., Gutierrez C. Stomoxys calcitrans as possible vector of Trypanosoma evansi among camels in an affected area of the Canary Islands, Spain. Rev. Soc. Bras. Med. Trop. 2014;47:510–512. doi: 10.1590/0037-8682-0210-2013. PubMed DOI

Baldacchino F., Desquesnes M., Mihok S., Foil L.D., Duvallet G., Jittapalapong S. Tabanids: Neglected subjects of research, but important vectors of disease agents! Infect. Genet. Evol. 2014;28:596–615. doi: 10.1016/j.meegid.2014.03.029. PubMed DOI

Aregawi W.G., Agga G.E., Abdi R.D., Büscher P. Systematic review and meta-analysis on the global distribution, host range, and prevalence of Trypanosoma evansi. Parasite Vector. 2019;12:1–25. doi: 10.1186/s13071-019-3311-4. PubMed DOI PMC

Magez S., Torres J.E.P., Oh S., Radwanska M. Salivarian Trypanosomes Have Adopted Intricate Host-Pathogen Interaction Mechanisms That Ensure Survival in Plain Sight of the Adaptive Immune System. Pathogens. 2021;10:679. doi: 10.3390/pathogens10060679. PubMed DOI PMC

Bangs J.D. Evolution of Antigenic Variation in African Trypanosomes: Variant Surface Glycoprotein Expression, Structure, and Function. Bioessays. 2018;40:1800181. doi: 10.1002/bies.201800181. PubMed DOI PMC

Schwede A., Macleod O.J.S., MacGregor P., Carrington M. How Does the VSG Coat of Bloodstream Form African Trypanosomes Interact with External Proteins? PLoS Pathog. 2015;11:e1005259. doi: 10.1371/journal.ppat.1005259. PubMed DOI PMC

Mugnier M.R., Cross G.A., Papavasiliou N. The in vivo dynamics of antigenic variation in Trypanosoma brucei. Science. 2015;347:1470–1473. doi: 10.1126/science.aaa4502. PubMed DOI PMC

McCulloch R., Cobbold C.A., Figueiredo L., Jackson A., Morrison L.J., Mugnier M.R., Papavasiliou N., Schnaufer A., Matthews K. Emerging challenges in understanding trypanosome antigenic variation. Emerg. Top. Life Sci. 2017;1:585–592. doi: 10.1042/etls20170104. PubMed DOI PMC

Pinger J., Nešić D., Ali L., Aresta-Branco F., Lilic M., Chowdhury S., Kim H.-S., Verdi J., Raper J., Ferguson M.A.J., et al. African trypanosomes evade immune clearance by O-glycosylation of the VSG surface coat. Nat. Microbiol. 2018;3:932–938. doi: 10.1038/s41564-018-0187-6. PubMed DOI PMC

Engstler M., Pfohl T., Herminghaus S., Boshart M., Wiegertjes G., Heddergott N., Overath P. Hydrodynamic Flow-Mediated Protein Sorting on the Cell Surface of Trypanosomes. Cell. 2007;131:505–515. doi: 10.1016/j.cell.2007.08.046. PubMed DOI

Dean S.D., Matthews K.R. Restless Gossamers: Antibody Clearance by Hydrodynamic Flow Forces Generated at the Surface of Motile Trypanosome Parasites. Cell Host Microbe. 2007;2:279–281. doi: 10.1016/j.chom.2007.10.006. PubMed DOI PMC

Devine D.V., Falk R.J., Balber A.E. Restriction of the alternative pathway of human complement by intact Trypanosoma brucei subsp. gambiense. Infect. Immun. 1986;52:223–229. doi: 10.1128/iai.52.1.223-229.1986. PubMed DOI PMC

Pinger J., Chowdhury S., Papavasiliou F.N. Variant surface glycoprotein density defines an immune evasion threshold for African trypanosomes undergoing antigenic variation. Nat. Commun. 2017;8:1–9. doi: 10.1038/s41467-017-00959-w. PubMed DOI PMC

Pan W., Ogunremi O., Wei G., Shi M., Tabel H. CR3 (CD11b/CD18) is the major macrophage receptor for IgM antibody-mediated phagocytosis of African trypanosomes: Diverse effect on subsequent synthesis of tumor necrosis factor α and nitric oxide. Microbes Infect. 2006;8:1209–1218. doi: 10.1016/j.micinf.2005.11.009. PubMed DOI

Liu G., Fu Y., Yosri M., Chen Y., Sun P., Xu J., Zhang M., Sun D., Strickland A.B., Mackey Z.B., et al. CRIg plays an essential role in intravascular clearance of bloodborne parasites by interacting with complement. Proc. Natl. Acad. Sci. USA. 2019;116:24214–24220. doi: 10.1073/pnas.1913443116. PubMed DOI PMC

Dagenais T.R., Demick K.P., Bangs J.D., Forest K.T., Paulnock D.M., Mansfield J.M. T-Cell Responses to the Trypanosome Variant Surface Glycoprotein Are Not Limited to Hypervariable Subregions. Infect. Immun. 2009;77:141–151. doi: 10.1128/IAI.00729-08. PubMed DOI PMC

Frenkel D., Zhang F., Guirnalda P., Haynes C., Bockstal V., Radwanska M., Magez S., Black S.J. Trypanosoma brucei Co-opts NK Cells to Kill Splenic B2 B Cells. PLoS Pathog. 2016;12:e1005733. doi: 10.1371/journal.ppat.1005733. PubMed DOI PMC

Bockstal V., Guirnalda P., Caljon G., Goenka R., Telfer J.C., Frenkel D., Radwanska M., Magez S., Black S.J. T. brucei Infection Reduces B Lymphopoiesis in Bone Marrow and Truncates Compensatory Splenic Lymphopoiesis through Transitional B-Cell Apoptosis. PLoS Pathog. 2011;7:e1002089. doi: 10.1371/journal.ppat.1002089. PubMed DOI PMC

Obishakin E., Trez C., Magez S. Chronic Trypanosoma congolense infections in mice cause a sustained disruption of the B-cell homeostasis in the bone marrow and spleen. Parasite Immunol. 2014;36:187–198. doi: 10.1111/pim.12099. PubMed DOI

Blom-Potar M.C., Chamond N., Cosson A., Jouvion G., Droin-Bergère S., Huerre M., Minoprio P. Trypanosoma vivax Infections: Pushing Ahead with Mouse Models for the Study of Nagana. II. Immunobiological Dysfunctions. PLoS Neglect. Trop. Dis. 2010;4:e793. doi: 10.1371/journal.pntd.0000793. PubMed DOI PMC

Radwanska M., Guirnalda P., Trez C.D., Ryffel B., Black S., Magez S. Trypanosomiasis-induced B cell apoptosis results in loss of protective anti-parasite antibody responses and abolishment of vaccine-induced memory responses. PLoS Pathog. 2008;4:e1000078. doi: 10.1371/journal.ppat.1000078. PubMed DOI PMC

Magez S., Schwegmann A., Atkinson R., Claes F., Drennan M., Baetselier P.D., Brombacher F. The Role of B-cells and IgM Antibodies in Parasitemia, Anemia, and VSG Switching in Trypanosoma brucei–Infected Mice. PLoS Pathog. 2008;4:e1000122. doi: 10.1371/journal.ppat.1000122. PubMed DOI PMC

McNae I.W., Kinkead J., Malik D., Yen L.-H., Walker M.K., Swain C., Webster S.P., Gray N., Fernandes P.M., Myburgh E., et al. Fast acting allosteric phosphofructokinase inhibitors block trypanosome glycolysis and cure acute African trypanosomiasis in mice. Nat. Commun. 2021;12:1–10. doi: 10.1038/s41467-021-21273-6. PubMed DOI PMC

Opperdoes F.R., Borst P. Localization of nine glycolytic enzymes in a microbody-like organelle in Trypanosoma brucei: The glycosome. Febs Lett. 1977;80:360–364. doi: 10.1016/0014-5793(77)80476-6. PubMed DOI

Visser N., Opperdoes F.R. Glycolysis in Trypanosoma brucei. Eur. J. Biochem. 1980;103:623–632. doi: 10.1111/j.1432-1033.1980.tb05988.x. PubMed DOI

Szöör B., Haanstra J.R., Gualdrón-López M., Michels P.A. Evolution, dynamics and specialized functions of glycosomes in metabolism and development of trypanosomatids. Curr. Opin. Microbiol. 2014;22:79–87. doi: 10.1016/j.mib.2014.09.006. PubMed DOI

Haanstra J.R., González-Marcano E.B., Gualdrón-López M., Michels P.A. Biogenesis, maintenance and dynamics of glycosomes in trypanosomatid parasites. Biochim. Biophys. Acta. 2016;1863:1038–1048. doi: 10.1016/j.bbamcr.2015.09.015. PubMed DOI

Richardson J.B., Lee K.-Y., Mireji P., Enyaru J., Sistrom M., Aksoy S., Zhao H., Caccone A. Genomic analyses of African Trypanozoon strains to assess evolutionary relationships and identify markers for strain identification. PLoS Neglect. Trop. Dis. 2017;11:e0005949. doi: 10.1371/journal.pntd.0005949. PubMed DOI PMC

Moreno S.A., Nava M. Trypanosoma evansi is alike to Trypanosoma brucei brucei in the subcellular localisation of glycolytic enzymes. Memórias Inst. Oswaldo Cruz. 2015;110:468–475. doi: 10.1590/0074-02760150024. PubMed DOI PMC

Rivero L.A., Concepción J.L., Quintero-Troconis E., Quiñones W., Michels P.A.M., Acosta H. Trypanosoma evansi contains two auxiliary enzymes of glycolytic metabolism: Phosphoenolpyruvate carboxykinase and pyruvate phosphate dikinase. Exp. Parasitol. 2016;165:7–15. doi: 10.1016/j.exppara.2016.03.003. PubMed DOI

Hannaert V., Albert M.-A., Rigden D.J., Giotto M.T.D.S., Thiemann O., Garratt R.C., Roy J.V., Opperdoes F.R., Michels P.A. Kinetic characterization, structure modelling studies and crystallization of Trypanosoma brucei enolase. Eur. J. Biochem. 2003;270:3205–3213. doi: 10.1046/j.1432-1033.2003.03692.x. PubMed DOI

Giotto M.T.D.S., Hannaert V., Vertommen D., Navarro M.V.D.A.S., Rider M.H., Michels P.A., Garratt R.C., Rigden D.J. The Crystal Structure of Trypanosoma brucei Enolase: Visualisation of the Inhibitory Metal Binding Site III and Potential as Target for Selective, Irreversible Inhibition. J. Mol. Biol. 2003;331:653–665. doi: 10.1016/S0022-2836(03)00752-6. PubMed DOI

Navarro M.V.D.A.S., Dias S.M.G., Mello L.V., Giotto M.T.D.S., Gavalda S., Blonski C., Garratt R.C., Rigden D.J. Structural flexibility in Trypanosoma brucei enolase revealed by X-ray crystallography and molecular dynamics. FEBS J. 2007;274:5077–5089. doi: 10.1111/j.1742-4658.2007.06027.x. PubMed DOI

Grébaut P., Chuchana P., Brizard J.-P., Demettre E., Seveno M., Bossard G., Jouin P., Vincendeau P., Bengaly Z., Boulangé A., et al. Identification of total and differentially expressed excreted–secreted proteins from Trypanosoma congolense strains exhibiting different virulence and pathogenicity. Int. J. Parasitol. 2009;39:1137–1150. doi: 10.1016/j.ijpara.2009.02.018. PubMed DOI

Geiger A., Hirtz C., Bécue T., Bellard E., Centeno D., Gargani D., Rossignol M., Cuny G., Peltier J.-B. Exocytosis and protein secretion in Trypanosoma. BMC Microbiol. 2010;10:1–17. doi: 10.1186/1471-2180-10-20. PubMed DOI PMC

Nten C.M.A., Sommerer N., Rofidal V., Hirtz C., Rossignol M., Cuny G., Peltier J.-B., Geiger A. Excreted/Secreted Proteins from Trypanosome Procyclic Strains. J. Biomed. Biotechnol. 2010;2010:212817. doi: 10.1155/2010/212817. PubMed DOI PMC

Szempruch A.J., Sykes S.E., Kieft R., Dennison L., Becker A.C., Gartrell A., Martin W.J., Nakayasu E.S., Almeida I.C., Hajduk S.L., et al. Extracellular Vesicles from Trypanosoma brucei Mediate Virulence Factor Transfer and Cause Host Anemia. Cell. 2016;164:246–257. doi: 10.1016/j.cell.2015.11.051. PubMed DOI PMC

Li Z., Torres J.E.P., Goossens J., Vertommen D., Caljon G., Sterckx Y.G.J., Magez S. An Unbiased Immunization Strategy Results in the Identification of Enolase as a Potential Marker for Nanobody-Based Detection of Trypanosoma evansi. Vaccines. 2020;8:415. doi: 10.3390/vaccines8030415. PubMed DOI PMC

Avilán L., Gualdrón-López M., Quiñones W., González-González L., Hannaert V., Michels P.A., Concepción J.L. Enolase: A key player in the metabolism and a probable virulence factor of trypanosomatid parasites-perspectives for its use as a therapeutic target. Enzyme Res. 2011;2011:932549. doi: 10.4061/2011/932549. PubMed DOI PMC

Quiñones W., Peña P., Domingo-Sananes M., Cáceres A., Michels P.A.M., Avilan L., Concepción J.L. Leishmania mexicana: Molecular cloning and characterization of enolase. Exp. Parasitol. 2007;116:241–251. doi: 10.1016/j.exppara.2007.01.008. PubMed DOI

Vanegas G., Quiñones W., Carrasco-López C., Concepción J.L., Albericio F., Avilán L. Enolase as a plasminogen binding protein in Leishmania mexicana. Parasitol. Res. 2007;101:1511–1516. doi: 10.1007/s00436-007-0668-7. PubMed DOI

Alsford S., Eckert S., Baker N., Glover L., Sanchez-Flores A., Leung K.F., Turner D.J., Field M.C., Berriman M., Horn D. High-throughput decoding of antitrypanosomal drug efficacy and resistance. Nature. 2012;482:232–236. doi: 10.1038/nature10771. PubMed DOI PMC

Wiedemar N., Zwyer M., Zoltner M., Cal M., Field M.C., Mäser P. Expression of a specific variant surface glycoprotein has a major impact on suramin sensitivity and endocytosis in Trypanosoma brucei. Faseb Bioadv. 2019;1:595–608. doi: 10.1096/fba.2019-00033. PubMed DOI PMC

Zoltner M., Campagnaro G.D., Taleva G., Burrell A., Cerone M., Leung K.F., Achcar F., Horn D., Vaughan S., Gadelha C., et al. Suramin exposure alters cellular metabolism and mitochondrial energy production in African trypanosomes. J. Biol. Chem. 2020;295:8331–8347. doi: 10.1074/jbc.RA120.012355. PubMed DOI PMC

Ziegelbauer K., Overath P. Organization of two invariant surface glycoproteins in the surface coat of Trypanosoma brucei. Infect. Immun. 1993;61:4540–4545. doi: 10.1128/iai.61.11.4540-4545.1993. PubMed DOI PMC

Ziegelbauer K., Overath P. Identification of invariant surface glycoproteins in the bloodstream stage of Trypanosoma brucei. J. Biol. Chem. 1992;267:10791–10796. doi: 10.1016/S0021-9258(19)50088-6. PubMed DOI

Ziegelbauer K., Multhaup G., Overath P. Molecular characterization of two invariant surface glycoproteins specific for the bloodstream stage of Trypanosoma brucei. J. Biol. Chem. 1992;267:10797–10803. doi: 10.1016/S0021-9258(19)50089-8. PubMed DOI

Radwanska M., Magez S., Michel A., Stijlemans B., Geuskens M., Pays E. Comparative Analysis of Antibody Responses against HSP60, Invariant Surface Glycoprotein 70, and Variant Surface Glycoprotein Reveals a Complex Antigen-Specific Pattern of Immunoglobulin Isotype Switching during Infection by Trypanosoma brucei. Infect. Immun. 2000;68:848–860. doi: 10.1128/IAI.68.2.848-860.2000. PubMed DOI PMC

Sullivan L., Wall S.J., Carrington M., Ferguson M.A.J. Proteomic Selection of Immunodiagnostic Antigens for Human African Trypanosomiasis and Generation of a Prototype Lateral Flow Immunodiagnostic Device. PLoS Neglect. Trop. Dis. 2013;7:e2087. doi: 10.1371/journal.pntd.0002087. PubMed DOI PMC

Biéler S., Waltenberger H., Barrett M.P., McCulloch R., Mottram J.C., Carrington M., Schwaeble W., McKerrow J., Phillips M.A., Michels P.A., et al. Evaluation of Antigens for Development of a Serological Test for Human African Trypanosomiasis. PLoS ONE. 2016;11:e0168074. doi: 10.1371/journal.pone.0168074. PubMed DOI PMC

Rudramurthy G.R., Sengupta P.P., Metilda B., Balamurugan V., Prabhudas K., Rahman H. Development of an enzyme immunoassay using recombinant invariant surface glycoprotein (rISG) 75 for serodiagnosis of bovine trypanosomosis. Indian J. Exp. Biol. 2015;53:7–15. PubMed

Rudramurthy G.R., Sengupta P.P., Ligi M., Rahman H. An inhibition enzyme immuno assay exploring recombinant invariant surface glycoprotein and monoclonal antibodies for surveillance of surra in animals. Biologicals. 2017;46:148–152. doi: 10.1016/j.biologicals.2017.02.004. PubMed DOI

Koumandou V.L., Boehm C., Horder K.A., Field M.C. Evidence for Recycling of Invariant Surface Transmembrane Domain Proteins in African Trypanosomes. Eukaryot. Cell. 2013;12:330–342. doi: 10.1128/EC.00273-12. PubMed DOI PMC

Leung K.F., Riley F.S., Carrington M., Field M.C. Ubiquitylation and Developmental Regulation of Invariant Surface Protein Expression in Trypanosomes. Eukaryot. Cell. 2011;10:916–931. doi: 10.1128/EC.05012-11. PubMed DOI PMC

Radwanska M., Magez S., Dumont N., Pays A., Nolan D., Pays E. Antibodies raised against the flagellar pocket fraction of Trypanosoma brucei preferentially recognize HSP60 in cDNA expression library. Parasite Immunol. 2000;22:639–650. doi: 10.1046/j.1365-3024.2000.00348.x. PubMed DOI

Aricescu A.R., Lu W., Jones E.Y. A time- and cost-efficient system for high-level protein production in mammalian cells. Acta Crystallogr. Sect. D Biol. Crystallogr. 2006;62:1243–1250. doi: 10.1107/S0907444906029799. PubMed DOI

Whitmore L., Wallace B.A. Protein secondary structure analyses from circular dichroism spectroscopy: Methods and reference databases. Biopolymers. 2008;89:392–400. doi: 10.1002/bip.20853. PubMed DOI

Manalastas-Cantos K., Konarev P.V., Hajizadeh N.R., Kikhney A.G., Petoukhov M.V., Molodenskiy D.S., Panjkovich A., Mertens H.D.T., Gruzinov A., Borges C., et al. ATSAS 3.0: Expanded functionality and new tools for small-angle scattering data analysis. J. Appl. Crystallogr. 2021;54:343–355. doi: 10.1107/S1600576720013412. PubMed DOI PMC

Svergun D.I. Determination of the regularization parameter in indirect-transform methods using perceptual criteria. J. Appl. Crystallogr. 1992;25:495–503. doi: 10.1107/S0021889892001663. DOI

Hajizadeh N.R., Franke D., Jeffries C.M., Svergun D.I. Consensus Bayesian assessment of protein molecular mass from solution X-ray scattering data. Sci. Rep. 2018;8:1–13. doi: 10.1038/s41598-018-25355-2. PubMed DOI PMC

Franke D., Svergun D.I. DAMMIF, a program for rapid ab-initio shape determination in small-angle scattering. J. Appl. Cryst. 2009;42:342–346. doi: 10.1107/S0021889809000338. PubMed DOI PMC

Pettersen E.F., Goddard T.D., Huang C.C., Couch G.S., Greenblatt D.M., Meng E.C., Ferrin T.E. UCSF Chimera—A visualization system for exploratory research and analysis. J. Comput. Chem. 2004;25:1605–1612. doi: 10.1002/jcc.20084. PubMed DOI

Pettersen E.F., Goddard T.D., Huang C.C., Meng E.C., Couch G.S., Croll T.I., Morris J.H., Ferrin T.E. UCSF ChimeraX: Structure visualization for researchers, educators, and developers. Protein Sci. 2020;30:70–82. doi: 10.1002/pro.3943. PubMed DOI PMC

Deleeuw V., Phạm H.T.T., Poorter I.D., Janssens I., Trez C.D., Radwanska M., Magez S. Trypanosoma brucei brucei causes a rapid and persistent influx of neutrophils in the spleen of infected mice. Parasite Immunol. 2019;41:e12664. doi: 10.1111/pim.12664. PubMed DOI PMC

Higgins M.K., Carrington M. Sequence variation and structural conservation allows development of novel function and immune evasion in parasite surface protein families. Protein Sci. 2014;23:354–365. doi: 10.1002/pro.2428. PubMed DOI PMC

Blum M., Down J., Gurnett A., Carrington M., Turner M., Wiley D. A structural motif in the variant surface glycoproteins of Trypanosoma brucei. Nature. 1993;362:603–609. doi: 10.1038/362603a0. PubMed DOI

Trevor C.E., Gonzalez-Munoz A.L., Macleod O.J.S., Woodcock P.G., Rust S., Vaughan T.J., Garman E.F., Minter R., Carrington M., Higgins M.K. Structure of the trypanosome transferrin receptor reveals mechanisms of ligand recognition and immune evasion. Nat. Microbiol. 2019;4:2074–2081. doi: 10.1038/s41564-019-0589-0. PubMed DOI PMC

Bartossek T., Jones N.G., Schäfer C.S., Cvitković M.C., Glogger M., Mott H.R., Kuper J., Brennich M., Carrington M., Smith A.-S., et al. Structural basis for the shielding function of the dynamic trypanosome variant surface glycoprotein coat. Nat. Microbiol. 2017;2:1523–1532. doi: 10.1038/s41564-017-0013-6. PubMed DOI

Higgins M.K., Tkachenko O., Brown A., Reed J., Raper J., Carrington M. Structure of the trypanosome haptoglobin-hemoglobin receptor and implications for nutrient uptake and innate immunity. Proc. Natl. Acad. Sci. USA. 2013;110:1905–1910. doi: 10.1073/pnas.1214943110. PubMed DOI PMC

Iwasaki A., Omer S.B. Why and How Vaccines Work. Cell. 2020;183:290–295. doi: 10.1016/j.cell.2020.09.040. PubMed DOI PMC

Pollard A.J., Bijker E.M. A guide to vaccinology: From basic principles to new developments. Nat. Rev. Immunol. 2021;21:83–100. doi: 10.1038/s41577-020-00479-7. PubMed DOI PMC

Lewnard J.A., Lo N.C., Arinaminpathy N., Frost I., Laxminarayan R. Childhood vaccines and antibiotic use in low- and middle-income countries. Nature. 2020;581:94–99. doi: 10.1038/s41586-020-2238-4. PubMed DOI PMC

Wainwright M. Dyes, trypanosomiasis and DNA: A historical and critical review. Biotech. Histochem. 2010;85:341–354. doi: 10.3109/10520290903297528. PubMed DOI

Rouzer C.A., Cerami A. Hypertriglyceridemia associated with Trypanosoma brucei brucei infection in rabbits: Role of defective triglyceride removal. Mol. Biochem. Parasit. 1980;2:31–38. doi: 10.1016/0166-6851(80)90046-8. PubMed DOI

Beutler B., Cerami A. Cachectin and tumour necrosis factor as two sides of the same biological coin. Nature. 1986;320:584–588. doi: 10.1038/320584a0. PubMed DOI

Cross G.A.M. Antigenic variation in trypanosomes. Proc. Royal. Soc. Lond. Ser. B Biol. Sci. 1978;202:55–72. doi: 10.4269/ajtmh.1977.26.240. PubMed DOI

Cross G.A.M. Identification, purification and properties of clone-specific glycoprotein antigens constituting the surface coat of Trypanosoma brucei. Parasitology. 1975;71:393–417. doi: 10.1017/S003118200004717X. PubMed DOI

Vickerman K. Antigenic variation in trypanosomes. Nature. 1978;273:613–617. doi: 10.1038/273613a0. PubMed DOI

Cornelissen A.W.C.A., Bakkeren G.A.M., Barry J.D., Michels P.A.M., Borst P. Characteristics of trypanosome variant antigen genes active in the tsetse fly. Nucleic Acids Res. 1985;13:4661–4676. doi: 10.1093/nar/13.13.4661. PubMed DOI PMC

Uzcanga G.L., Perrone T., Noda J.A., Pérez-Pazos J., Medina R., Hoebeke J., Bubis J. Variant Surface Glycoprotein from Trypanosoma evansi Is Partially Responsible for the Cross-Reaction between Trypanosoma evansi and Trypanosoma vivax. Biochemistry. 2004;43:595–606. doi: 10.1021/bi0301946. PubMed DOI

Magez S., Torres J.E.P., 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. doi: 10.3389/fimmu.2020.00382. PubMed DOI PMC

Radwanska M., Nguyen H.T.T., Moon S., Obishakin E., Magez S. Trypanosomatids, Methods and Protocols. Methods Mol. Biol. 2020;2116:721–738. doi: 10.1007/978-1-0716-0294-2_42. PubMed DOI

Maharana B.R., Sudhakar N.R., Jawalagatti V., Saravanan B.C., Blake D.P., Tewari A.K. Evaluation of the Immunoprotective Potential of Recombinant Paraflagellar Rod Proteins of Trypanosoma evansi in Mice. Vaccines. 2020;8:84. doi: 10.3390/vaccines8010084. PubMed DOI PMC

Autheman D., Crosnier C., Clare S., Goulding D.A., Brandt C., Harcourt K., Tolley C., Galaway F., Khushu M., Ong H., et al. An invariant Trypanosoma vivax vaccine antigen induces protective immunity. Nature. 2021;595:1–5. doi: 10.1038/s41586-021-03597-x. PubMed DOI

Mkunza F., Olaho W.M., Powell C.N. Partial protection against natural trypanosomiasis after vaccination with a flagellar pocket antigen from Trypanosoma brucei rhodesiense. Vaccine. 1995;13:151–154. doi: 10.1016/0264-410X(95)93128-V. PubMed DOI

Southon H.A.W., Cunningham M.P. Infectivity of Trypanosomes derived from Individual Glossina morsitans Westw. Nature. 1966;212:1477–1478. doi: 10.1038/2121477a0. PubMed DOI

Russo D.C., Grab D.J., Lonsdale-Eccles J.D., Shaw M.K., Williams D.J. Directional movement of variable surface glycoprotein-antibody complexes in Trypanosoma brucei. Eur. J. Cell Biol. 1993;62:432–441. PubMed

Dickie E.A., Giordani F., Gould M.K., Mäser P., Burri C., Mottram J.C., Rao S.P.S., Barrett M.P. New Drugs for Human African Trypanosomiasis: A Twenty First Century Success Story. Trop. Med. Infect. Dis. 2020;5:29. doi: 10.3390/tropicalmed5010029. PubMed DOI PMC

Guedes R.L.M., Rodrigues C.M.F., Coatnoan N., Cosson A., Cadioli F.A., Garcia H.A., Gerber A.L., Machado R.Z., Minoprio P.M.C., Teixeira M.M.G., et al. A comparative in silico linear B-cell epitope prediction and characterization for South American and African Trypanosoma vivax strains. Genomics. 2019;111:407–417. doi: 10.1016/j.ygeno.2018.02.017. PubMed DOI

Liu T., Shi K., Li W. Deep learning methods improve linear B-cell epitope prediction. Biodata Min. 2020;13:1–3. doi: 10.1186/s13040-020-00211-0. PubMed DOI PMC

Beyond the VSG layer: Exploring the role of intrinsic disorder in the invariant surface glycoproteins of African trypanosomes