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Mansfield CR, Quan B, Chirgwin ME, Eduful B, Hughes PF, Neveu G, Sylvester K, Ryan DH, Kafsack BFC, Haystead TAJ, Leahy JW, Fitzgerald MC, Derbyshire ER. Selective targeting of Plasmodium falciparum Hsp90 disrupts the 26S proteasome. Cell Chem Biol 2024; 31:729-742.e13. [PMID: 38492573 PMCID: PMC11031320 DOI: 10.1016/j.chembiol.2024.02.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 11/09/2023] [Accepted: 02/22/2024] [Indexed: 03/18/2024]
Abstract
The molecular chaperone heat shock protein 90 (Hsp90) has an essential but largely undefined role in maintaining proteostasis in Plasmodium falciparum, the most lethal malaria parasite. Herein, we identify BX-2819 and XL888 as potent P. falciparum (Pf)Hsp90 inhibitors. Derivatization of XL888's scaffold led to the development of Tropane 1, as a PfHsp90-selective binder with nanomolar affinity. Hsp90 inhibitors exhibit anti-Plasmodium activity against the liver, asexual blood, and early gametocyte life stages. Thermal proteome profiling was implemented to assess PfHsp90-dependent proteome stability, and the proteasome-the main site of cellular protein recycling-was enriched among proteins with perturbed stability upon PfHsp90 inhibition. Subsequent biochemical and cellular studies suggest that PfHsp90 directly promotes proteasome hydrolysis by chaperoning the active 26S complex. These findings expand our knowledge of the PfHsp90-dependent proteome and protein quality control mechanisms in these pathogenic parasites, as well as further characterize this chaperone as a potential antimalarial drug target.
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Affiliation(s)
- Christopher R Mansfield
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, USA
| | - Baiyi Quan
- Department of Chemistry, Duke University, Durham, NC, USA
| | | | - Benjamin Eduful
- Department of Chemistry, University of South Florida, Tampa, FL, USA
| | - Philip F Hughes
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC, USA
| | - Gaëlle Neveu
- Department of Microbiology & Immunology, Weill Cornell Medicine, New York, NY, USA
| | - Kayla Sylvester
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, USA
| | - Daniel H Ryan
- Department of Chemistry, Duke University, Durham, NC, USA
| | - Björn F C Kafsack
- Department of Microbiology & Immunology, Weill Cornell Medicine, New York, NY, USA
| | - Timothy A J Haystead
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC, USA
| | - James W Leahy
- Department of Chemistry, University of South Florida, Tampa, FL, USA; Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL, USA; Center for Drug Discovery and Innovation, University of South Florida, Tampa, FL, USA
| | | | - Emily R Derbyshire
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, USA; Department of Chemistry, Duke University, Durham, NC, USA.
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Parreira KS, Scarpelli P, Rezende Lima W, Garcia RS. Contribution of Transcriptome to Elucidate the Biology of Plasmodium spp. Curr Top Med Chem 2022; 22:169-187. [PMID: 35021974 DOI: 10.2174/1568026622666220111140803] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 12/22/2021] [Accepted: 12/26/2021] [Indexed: 11/22/2022]
Abstract
In the present review, we discuss some of the new technologies that have been applied to elucidate how Plasmodium spp escape from the immune system and subvert the host physiology to orchestrate the regulation of its biological pathways. Our manuscript describes how techniques such as microarray approaches, RNA-Seq and single-cell RNA sequencing have contributed to the discovery of transcripts and changed the concept of gene expression regulation in closely related malaria parasite species. Moreover, the text highlights the contributions of high-throughput RNA sequencing for the current knowledge of malaria parasite biology, physiology, vaccine target and the revelation of new players in parasite signaling.
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Affiliation(s)
| | - Pedro Scarpelli
- Departamento de Análises Clínicas e Toxicológicas, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo - USP, São Paulo, Brazil
| | - Wânia Rezende Lima
- Departamento de Medicina, Instituto de Biotecnologia-Universidade Federal de Catalão
| | - R S Garcia
- Departamento de Análises Clínicas e Toxicológicas, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo - USP, São Paulo, Brazil
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3
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Bettencourt P. Current Challenges in the Identification of Pre-Erythrocytic Malaria Vaccine Candidate Antigens. Front Immunol 2020; 11:190. [PMID: 32153565 PMCID: PMC7046804 DOI: 10.3389/fimmu.2020.00190] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Accepted: 01/24/2020] [Indexed: 12/27/2022] Open
Abstract
Plasmodium spp.-infected mosquitos inject sporozoites into the skin of a mammalian host during a blood meal. These enter the host's circulatory system and establish an infection in the liver. After a silent metamorphosis, merozoites invade the blood leading to the symptomatic and transmissible stages of malaria. The silent pre-erythrocytic malaria stage represents a bottleneck in the disease which is ideal to block progression to clinical malaria, through chemotherapeutic and immunoprophylactic interventions. RTS,S/AS01, the only malaria vaccine close to licensure, although with poor efficacy, blocks the sporozoite invasion mainly through the action of antibodies against the CSP protein, a major component of the pellicle of the sporozoite. Strikingly, sterile protection against malaria can be obtained through immunization with radiation-attenuated sporozoites, genetically attenuated sporozoites or through chemoprophylaxis with infectious sporozoites in animals and humans, but the deployability of sporozoite-based live vaccines pose tremendous challenges. The protection induced by sporozoites occurs in the pre-erythrocytic stages and is mediated mainly by antibodies against the sporozoite and CD8+ T cells against peptides presented by MHC class I molecules in infected hepatocytes. Thus, the identification of malaria antigens expressed in the sporozoite and liver-stage may provide new vaccine candidates to be included, alone or in combination, as recombinant protein-based, virus-like particles or sub-unit virally-vectored vaccines. Here I review the efforts being made to identify Plasmodium falciparum antigens expressed during liver-stage with focus on the development of parasite, hepatocyte, mouse models, and resulting rate of infection in order to identify new vaccine candidates and to improve the efficacy of the current vaccines. Finally, I propose new approaches for the identification of liver-stage antigens based on immunopeptidomics.
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Posfai D, Eubanks AL, Keim AI, Lu KY, Wang GZ, Hughes PF, Kato N, Haystead TA, Derbyshire ER. Identification of Hsp90 Inhibitors with Anti-Plasmodium Activity. Antimicrob Agents Chemother 2018; 62:e01799-17. [PMID: 29339390 PMCID: PMC5913967 DOI: 10.1128/aac.01799-17] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Accepted: 01/05/2018] [Indexed: 12/17/2022] Open
Abstract
Malaria remains a global health burden partly due to Plasmodium parasite resistance to first-line therapeutics. The molecular chaperone heat shock protein 90 (Hsp90) has emerged as an essential protein for blood-stage Plasmodium parasites, but details about its function during malaria's elusive liver stage are unclear. We used target-based screens to identify compounds that bind to Plasmodium falciparum and human Hsp90, which revealed insights into chemotypes with species-selective binding. Using cell-based malaria assays, we demonstrate that all identified Hsp90-binding compounds are liver- and blood-stage Plasmodium inhibitors. Additionally, the Hsp90 inhibitor SNX-0723 in combination with the phosphatidylinositol 3-kinase inhibitor PIK-75 synergistically reduces the liver-stage parasite load. Time course inhibition studies with the Hsp90 inhibitors and expression analysis support a role for Plasmodium Hsp90 in late-liver-stage parasite development. Our results suggest that Plasmodium Hsp90 is essential to liver- and blood-stage parasite infections and highlight an attractive route for development of species-selective PfHsp90 inhibitors that may act synergistically in combination therapies to prevent and treat malaria.
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Affiliation(s)
- Dora Posfai
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, USA
| | - Amber L Eubanks
- Department of Chemistry, Duke University, Durham, North Carolina, USA
| | - Allison I Keim
- Department of Chemistry, Duke University, Durham, North Carolina, USA
| | - Kuan-Yi Lu
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, USA
| | - Grace Z Wang
- Department of Chemistry, Duke University, Durham, North Carolina, USA
| | - Philip F Hughes
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina, USA
| | | | - Timothy A Haystead
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina, USA
| | - Emily R Derbyshire
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, USA
- Department of Chemistry, Duke University, Durham, North Carolina, USA
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5
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Bruder JT, Chen P, Ekberg G, Smith EC, Lazarski CA, Myers BA, Bolton J, Sedegah M, Villasante E, Richie TL, King CR, Aguiar JC, Doolan DL, Brough DE. Profiling the Targets of Protective CD8 + T Cell Responses to Infection. MOLECULAR THERAPY-METHODS & CLINICAL DEVELOPMENT 2017; 7:20-31. [PMID: 28948187 PMCID: PMC5602877 DOI: 10.1016/j.omtm.2017.08.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 08/14/2017] [Indexed: 11/22/2022]
Abstract
T cells are critical effectors of host immunity that target intracellular pathogens, such as the causative agents of HIV, tuberculosis, and malaria. The development of vaccines that induce effective cell-mediated immunity against such pathogens has proved challenging; for tuberculosis and malaria, many of the antigens targeted by protective T cells are not known. Here, we report a novel approach for screening large numbers of antigens as potential targets of T cells. Malaria provides an excellent model to test this antigen discovery platform because T cells are critical mediators of protection following immunization with live sporozoite vaccines and the specific antigen targets are unknown. We generated an adenovirus array by cloning 312 highly expressed pre-erythrocytic Plasmodium yoelii antigens into adenovirus vectors using high-throughput methodologies. The array was screened to identify antigen-specific CD8+ T cells induced by a live sporozoite vaccine regimen known to provide high levels of sterile protection mediated by CD8+ T cells. We identified 69 antigens that were targeted by CD8+ T cells induced by this vaccine regimen. The antigen that recalled the highest frequency of CD8+ T cells, PY02605, induced protective responses in mice, demonstrating proof of principle for this approach in identifying antigens for vaccine development.
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Affiliation(s)
- Joseph T. Bruder
- GenVec, Inc., 910 Clopper Road, Suite 220N, Gaithersburg, MD 20878, USA
- Corresponding author: Joseph T. Bruder, Summit Consulting, 567 Chestertown Street, Gaithersburg, MD 20878, USA.
| | - Ping Chen
- GenVec, Inc., 910 Clopper Road, Suite 220N, Gaithersburg, MD 20878, USA
| | - Greg Ekberg
- GenVec, Inc., 910 Clopper Road, Suite 220N, Gaithersburg, MD 20878, USA
| | - Emily C. Smith
- Malaria Department, Naval Medical Research Center (NMRC), 503 Robert Grant Avenue, Silver Spring, MD 20910, USA
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., 6720A Rockledge Drive, Suite 100, Bethesda, MD 20817, USA
| | | | - Bennett A. Myers
- GenVec, Inc., 910 Clopper Road, Suite 220N, Gaithersburg, MD 20878, USA
| | - Jessica Bolton
- Malaria Department, Naval Medical Research Center (NMRC), 503 Robert Grant Avenue, Silver Spring, MD 20910, USA
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., 6720A Rockledge Drive, Suite 100, Bethesda, MD 20817, USA
| | - Martha Sedegah
- Malaria Department, Naval Medical Research Center (NMRC), 503 Robert Grant Avenue, Silver Spring, MD 20910, USA
| | - Eileen Villasante
- Malaria Department, Naval Medical Research Center (NMRC), 503 Robert Grant Avenue, Silver Spring, MD 20910, USA
| | - Thomas L. Richie
- Malaria Department, Naval Medical Research Center (NMRC), 503 Robert Grant Avenue, Silver Spring, MD 20910, USA
| | - C. Richter King
- GenVec, Inc., 910 Clopper Road, Suite 220N, Gaithersburg, MD 20878, USA
| | - Joao C. Aguiar
- Malaria Department, Naval Medical Research Center (NMRC), 503 Robert Grant Avenue, Silver Spring, MD 20910, USA
- Camris International, 3 Bethesda Metro Center, 16th Floor, Bethesda, MD 20814, USA
| | - Denise L. Doolan
- Australian Institute of Tropical Health and Medicine, James Cook University, McGregor Road, Cairns, QLD 4870, Australia
| | - Douglas E. Brough
- GenVec, Inc., 910 Clopper Road, Suite 220N, Gaithersburg, MD 20878, USA
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Apicomplexa-specific tRip facilitates import of exogenous tRNAs into malaria parasites. Proc Natl Acad Sci U S A 2016; 113:4717-22. [PMID: 27071116 DOI: 10.1073/pnas.1600476113] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The malaria-causing Plasmodium parasites are transmitted to vertebrates by mosquitoes. To support their growth and replication, these intracellular parasites, which belong to the phylum Apicomplexa, have developed mechanisms to exploit their hosts. These mechanisms include expropriation of small metabolites from infected host cells, such as purine nucleotides and amino acids. Heretofore, no evidence suggested that transfer RNAs (tRNAs) could also be exploited. We identified an unusual gene in Apicomplexa with a coding sequence for membrane-docking and structure-specific tRNA binding. This Apicomplexa protein-designated tRip (tRNA import protein)-is anchored to the parasite plasma membrane and directs import of exogenous tRNAs. In the absence of tRip, the fitness of the parasite stage that multiplies in the blood is significantly reduced, indicating that the parasite may need host tRNAs to sustain its own translation and/or as regulatory RNAs. Plasmodium is thus the first example, to our knowledge, of a cell importing exogenous tRNAs, suggesting a remarkable adaptation of this parasite to extend its reach into host cell biology.
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Derbyshire ER, Zuzarte-Luís V, Magalhães AD, Kato N, Sanschagrin PC, Wang J, Zhou W, Miduturu CV, Mazitschek R, Sliz P, Mota MM, Gray NS, Clardy J. Chemical interrogation of the malaria kinome. Chembiochem 2014; 15:1920-30. [PMID: 25111632 DOI: 10.1002/cbic.201400025] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Indexed: 01/10/2023]
Abstract
Malaria, an infectious disease caused by eukaryotic parasites of the genus Plasmodium, afflicts hundreds of millions of people every year. Both the parasite and its host utilize protein kinases to regulate essential cellular processes. Bioinformatic analyses of parasite genomes predict at least 65 protein kinases, but their biological functions and therapeutic potential are largely unknown. We profiled 1358 small-molecule kinase inhibitors to evaluate the role of both the human and the malaria kinomes in Plasmodium infection of liver cells, the parasites' obligatory but transient developmental stage that precedes the symptomatic blood stage. The screen identified several small molecules that inhibit parasite load in liver cells, some with nanomolar efficacy, and each compound was subsequently assessed for activity against blood-stage malaria. Most of the screening hits inhibited both liver- and blood-stage malaria parasites, which have dissimilar gene expression profiles and infect different host cells. Evaluation of existing kinase activity profiling data for the library members suggests that several kinases are essential to malaria parasites, including cyclin-dependent kinases (CDKs), glycogen synthase kinases, and phosphoinositide-3-kinases. CDK inhibitors were found to bind to Plasmodium protein kinase 5, but it is likely that these compounds target multiple parasite kinases. The dual-stage inhibition of the identified kinase inhibitors makes them useful chemical probes and promising starting points for antimalarial development.
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Affiliation(s)
- Emily R Derbyshire
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115 (USA).
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Dihydroquinazolinone inhibitors of proliferation of blood and liver stage malaria parasites. Antimicrob Agents Chemother 2013; 58:1516-22. [PMID: 24366746 DOI: 10.1128/aac.02148-13] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Drugs that target both the liver and blood stages of malaria will be needed to reduce the disease's substantial worldwide morbidity and mortality. Evaluation of a 259-member library of compounds that block proliferation of the blood stage of malaria revealed several scaffolds--dihydroquinazolinones, phenyldiazenylpyridines, piperazinyl methyl quinolones, and bis-benzimidazoles--with promising activity against the liver stage. Focused structure-activity studies on the dihydroquinazolinone scaffold revealed several molecules with excellent potency against both blood and liver stages. One promising early lead with dual activity is 2-(p-bromophenyl)-3-(2-(diethylamino)ethyl)-2,3-dihydroquinazolin-4(1H)-one with 50% effective concentrations (EC50s) of 0.46 μM and 0.34 μM against liver stage Plasmodium berghei ANKA and blood stage Plasmodium falciparum 3D7 parasites, respectively. Structure-activity relationships revealed that liver stage activity for this compound class requires a 3-dialkyl amino ethyl group and is abolished by substitution at the ortho-position of the phenyl moiety. These compounds have minimal toxicity to mammalian cells and are thus attractive compounds for further development.
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Lauinger IL, Vivas L, Perozzo R, Stairiker C, Tarun A, Zloh M, Zhang X, Xu H, Tonge PJ, Franzblau SG, Pham DH, Esguerra CV, Crawford AD, Maes L, Tasdemir D. Potential of lichen secondary metabolites against Plasmodium liver stage parasites with FAS-II as the potential target. JOURNAL OF NATURAL PRODUCTS 2013; 76:1064-70. [PMID: 23806111 PMCID: PMC4119598 DOI: 10.1021/np400083k] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Chemicals targeting the liver stage (LS) of the malaria parasite are useful for causal prophylaxis of malaria. In this study, four lichen metabolites, evernic acid (1), vulpic acid (2), psoromic acid (3), and (+)-usnic acid (4), were evaluated against LS parasites of Plasmodium berghei. Inhibition of P. falciparum blood stage (BS) parasites was also assessed to determine stage specificity. Compound 4 displayed the highest LS activity and stage specificity (LS IC50 value 2.3 μM, BS IC50 value 47.3 μM). The compounds 1-3 inhibited one or more enzymes (PfFabI, PfFabG, and PfFabZ) from the plasmodial fatty acid biosynthesis (FAS-II) pathway, a potential drug target for LS activity. To determine species specificity and to clarify the mechanism of reported antibacterial effects, 1-4 were also evaluated against FabI homologues and whole cells of various pathogens (S. aureus, E. coli, M. tuberculosis). Molecular modeling studies suggest that lichen acids act indirectly via binding to allosteric sites on the protein surface of the FAS-II enzymes. Potential toxicity of compounds was assessed in human hepatocyte and cancer cells (in vitro) as well as in a zebrafish model (in vivo). This study indicates the therapeutic and prophylactic potential of lichen metabolites as antibacterial and antiplasmodial agents.
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Affiliation(s)
- Ina L. Lauinger
- Department of Pharmaceutical and Biological Chemistry, School of Pharmacy, University of London, London WC1N 1AX, UK
| | - Livia Vivas
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK
| | - Remo Perozzo
- School of Pharmaceutical Sciences, University of Geneva, CH-1211 Geneva 4, Switzerland
| | - Christopher Stairiker
- Department of Infectious Diseases and Microbiology, University of Pittsburgh, Pittsburgh, PA 152614, USA
| | - Alice Tarun
- Department of Infectious Diseases and Microbiology, University of Pittsburgh, Pittsburgh, PA 152614, USA
| | - Mire Zloh
- Department of Pharmaceutical and Biological Chemistry, School of Pharmacy, University of London, London WC1N 1AX, UK
| | - Xujie Zhang
- Institute for Chemical Biology and Drug Discovery, Department of Chemistry, Stony Brook University, NY 11794, USA
| | - Hua Xu
- Institute for Chemical Biology and Drug Discovery, Department of Chemistry, Stony Brook University, NY 11794, USA
| | - Peter J. Tonge
- Institute for Chemical Biology and Drug Discovery, Department of Chemistry, Stony Brook University, NY 11794, USA
| | - Scott G. Franzblau
- Institute for Tuberculosis Research, College of Pharmacy, University of Illinois at Chicago, Chicago, IL 60612, USA
| | - Duc-Hung Pham
- Laboratory for Molecular Biodiscovery, Department of Pharmaceutical and Pharmacological Sciences, University of Leuven, 3000 Leuven, Belgium
| | - Camila V. Esguerra
- Laboratory for Molecular Biodiscovery, Department of Pharmaceutical and Pharmacological Sciences, University of Leuven, 3000 Leuven, Belgium
| | - Alexander D. Crawford
- Laboratory for Molecular Biodiscovery, Department of Pharmaceutical and Pharmacological Sciences, University of Leuven, 3000 Leuven, Belgium
| | - Louis Maes
- Faculty of Pharmaceutical, Biomedical and Veterinary Sciences, University of Antwerp, 2610 Antwerp, Belgium
| | - Deniz Tasdemir
- Department of Pharmaceutical and Biological Chemistry, School of Pharmacy, University of London, London WC1N 1AX, UK
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Duffy PE, Sahu T, Akue A, Milman N, Anderson C. Pre-erythrocytic malaria vaccines: identifying the targets. Expert Rev Vaccines 2013; 11:1261-80. [PMID: 23176657 DOI: 10.1586/erv.12.92] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Pre-erythrocytic malaria vaccines target Plasmodium during its sporozoite and liver stages, and can prevent progression to blood-stage disease, which causes a million deaths each year. Whole organism sporozoite vaccines induce sterile immunity in animals and humans and guide subunit vaccine development. A recombinant protein-in-adjuvant pre-erythrocytic vaccine called RTS,S reduces clinical malaria without preventing infection in field studies and additional antigens may be required to achieve sterile immunity. Although few vaccine antigens have progressed to human testing, new insights into parasite biology, expression profiles and immunobiology have offered new targets for intervention. Future advances require human trials of additional antigens, as well as platforms to induce the durable antibody and cellular responses including CD8(+) T cells that contribute to sterile protection.
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Affiliation(s)
- Patrick E Duffy
- Laboratory of Malaria Immunology & Vaccinology, Division of Intramural Research, NIAID, NIH, Rockville, MD, USA.
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Schlarman MS, Roberts RN, Kariuki MM, LaCrue AN, Ou R, Beerntsen BT. PFE0565w, a Plasmodium falciparum protein expressed in salivary gland sporozoites. Am J Trop Med Hyg 2012; 86:943-54. [PMID: 22665598 DOI: 10.4269/ajtmh.2012.11-0797] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Because malaria is still a significant problem worldwide, additional control methods need to be developed. The Plasmodium sporozoite is a good target for control measures because it displays dual infectivity for both mosquito and vertebrate host tissues. The Plasmodium falciparum gene, PFE0565w, was chosen as a candidate for study based on data from PlasmoDB, the Plasmodium database, indicating that it is expressed both at the transcriptional and protein levels in sporozoites, likely encodes a putative surface protein, and may have a potential role in the invasion of host tissues. Additional sequence analysis shows that the PFE0565w protein has orthologs in other Plasmodium species, but none outside of the genus Plasmodium. PFE0565w expresses transcript during both the sporozoite and erythrocytic stages of the parasite life cycle, where an alternative transcript was discovered during the erythrocytic stages. Data show that transcript is not present during axenic exoerythrocytic stages. Despite transcript being present in several life cycle stages, the PFE0565w protein is present only during the salivary gland sporozoite stage. Because the PFE0565w protein is present in salivary gland sporozoites, it could be a novel candidate for a pre-erythrocytic stage vaccine.
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Affiliation(s)
- Maggie S Schlarman
- Department of Veterinary Pathobiology, University of Missouri, Columbia, MO 65211, USA.
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12
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Liver-stage malaria parasites vulnerable to diverse chemical scaffolds. Proc Natl Acad Sci U S A 2012; 109:8511-6. [PMID: 22586124 DOI: 10.1073/pnas.1118370109] [Citation(s) in RCA: 103] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Human malaria infection begins with a one-time asymptomatic liver stage followed by a cyclic symptomatic blood stage. All high-throughput malaria drug discovery efforts have focused on the cyclic blood stage, which has limited potential for the prophylaxis, transmission blocking, and eradication efforts that will be needed in the future. To address these unmet needs, a high-throughput phenotypic liver-stage Plasmodium parasite screen was developed to systematically identify molecules with liver-stage efficacy. The screen recapitulates liver-stage infection by isolating luciferase-expressing Plasmodium berghei parasites directly from the salivary glands of infected mosquitoes, adding them to confluent human liver cells in 384-well plates, and measuring luciferase activity after a suitable incubation period. Screening 5,375 known bioactive compounds identified 37 liver-stage malaria inhibitors with diverse modes of action, as shown by inhibition time course experiments. Further analysis of the hits in the Food and Drug Administration-approved drug subset revealed compounds that seem to act specifically on the liver stage of infection, suggesting that this phase of the parasite's life cycle presents a promising area for new drug discovery. Notably, many active compounds in this screen have molecular structures and putative targets distinctly different from those of known antimalarial agents.
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13
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Schlarman MS, Roberts RN, Kariuki MM, LaCrue AN, Ou R, Beerntsen BT. Transcript and protein expression profile of PF11_0394, a Plasmodium falciparum protein expressed in salivary gland sporozoites. Malar J 2012; 11:80. [PMID: 22443220 PMCID: PMC3355004 DOI: 10.1186/1475-2875-11-80] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2011] [Accepted: 03/23/2012] [Indexed: 11/12/2022] Open
Abstract
Background Plasmodium falciparum malaria is a significant problem around the world today, thus there is still a need for new control methods to be developed. Because the sporozoite displays dual infectivity for both the mosquito salivary glands and vertebrate host tissue, it is a good target for vaccine development. Methods The P. falciparum gene, PF11_0394, was chosen as a candidate for study due to its potential role in the invasion of host tissues. This gene, which was selected using a data mining approach from PlasmoDB, is expressed both at the transcriptional and protein levels in sporozoites and likely encodes a putative surface protein. Using reverse transcription-polymerase chain reaction (RT-PCR) and green fluorescent protein (GFP)-trafficking studies, a transcript and protein expression profile of PF11_0394 was determined. Results The PF11_0394 protein has orthologs in other Plasmodium species and Apicomplexans, but none outside of the group Apicomplexa. PF11_0394 transcript was found to be present during both the sporozoite and erythrocytic stages of the parasite life cycle, but no transcript was detected during axenic exoerythrocytic stages. Despite the presence of transcript throughout several life cycle stages, the PF11_0394 protein was only detected in salivary gland sporozoites. Conclusions PF11_0394 appears to be a protein uniquely detected in salivary gland sporozoites. Even though a specific function of PF11_0394 has not been determined in P. falciparum biology, it could be another candidate for a new vaccine.
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Affiliation(s)
- Maggie S Schlarman
- Department of Veterinary Pathobiology, University of Missouri, Columbia, MO, USA
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14
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Derbyshire ER, Mazitschek R, Clardy J. Characterization of Plasmodium liver stage inhibition by halofuginone. ChemMedChem 2012; 7:844-9. [PMID: 22438279 DOI: 10.1002/cmdc.201200045] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2012] [Revised: 02/23/2012] [Indexed: 12/21/2022]
Abstract
Malaria is a devastating parasitic disease that afflicts one-third of the world's population. Antimalarial drugs in common use address few targets, and their efficacy is being undermined by parasite resistance. Most therapeutics target blood-stage malaria, whereas only few compounds are active against malaria's liver stage, the first stage of the Plasmodium parasite's life cycle within the human host. The identification of inhibitors active against liver-stage malaria would benefit the development of chemical probes to elucidate the poorly understood biology of this phase of the parasite life cycle and could provide agents to prevent and eliminate the disease. Herein we report the development of a live-cell parasite traversal assay in 384-well format amenable to high-throughput screening that exploits the wounding of liver cells by the parasite. This method identifies small molecules that may inhibit the parasite's actin-myosin motor system. The traversal assay, in addition to established methods, was used to evaluate the activity of halofuginone, a synthetic halogenated derivative of the natural alkaloid febrifugine, against liver-stage Plasmodium berghei parasites. Halofuginone was found to inhibit P. berghei sporozoite load in HepG2 cells with an IC(50) value of 17 nM. While the compound does not affect parasite traversal through human liver cells, an inhibition time course assay indicates that it affects essential processes in both early- and late-stage parasite development.
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Affiliation(s)
- Emily R Derbyshire
- Department of Biological Chemistry & Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
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Rodrigues T, Prudêncio M, Moreira R, Mota MM, Lopes F. Targeting the liver stage of malaria parasites: a yet unmet goal. J Med Chem 2011; 55:995-1012. [PMID: 22122518 DOI: 10.1021/jm201095h] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Tiago Rodrigues
- Research Institute for Medicines and Pharmaceutical Sciences (iMed.UL), Faculty of Pharmacy, University of Lisbon, Av. Prof. Gama Pinto, 1649-019 Lisbon, Portugal
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Affiliation(s)
- Emily R. Derbyshire
- Deparment of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Maria M. Mota
- Unidade de Malária, Instituto de Medicina Molecular, Faculdade de Medicina Universidade de Lisboa, Lisboa, Portugal
| | - Jon Clardy
- Deparment of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail:
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Chattopadhyay R, de la Vega P, Paik SH, Murata Y, Ferguson EW, Richie TL, Ooi GT. Early transcriptional responses of HepG2-A16 liver cells to infection by Plasmodium falciparum sporozoites. J Biol Chem 2011; 286:26396-405. [PMID: 21652718 PMCID: PMC3143603 DOI: 10.1074/jbc.m111.240879] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2011] [Revised: 06/01/2011] [Indexed: 11/06/2022] Open
Abstract
Invasion of hepatocytes by Plasmodium sporozoites deposited by Anopheles mosquitoes, and their subsequent transformation into infective merozoites is an obligatory step in the initiation of malaria. Interactions between the sporozoites and hepatocytes lead to a distinct, complex and coordinated cellular and systemic host response. Little is known about host liver cell response to sporozoite invasion, or whether it is primarily adaptive for the parasite, for the host, or for both. Our present study used gene expression profiling of human HepG2-A16 liver cells infected with Plasmodium falciparum sporozoites to understand the host early cellular events and factors influencing parasite infectivity and sporozoite development. Our results show that as early as 30 min following wild-type, non-irradiated sporozoite exposure, the expressions of at least 742 genes was selectively altered. These genes regulate diverse biological functions, such as immune processes, cell adhesion and communications, metabolism pathways, cell cycle regulation, and signal transduction. These functions reflect cellular events consistent with initial host cell defense responses, as well as alterations in host cells to sustain sporozoites growth and survival. Irradiated sporozoites gave very similar gene expression pattern changes, but direct comparative analysis between liver gene expression profiles caused by irradiated and non-irradiated sporozoites identified 29 genes, including glypican-3, that were specifically up-regulated only in irradiated sporozoites. Elucidating the role of this subset of genes may help identify the molecular basis for the irradiated sporozoites inability to develop intrahepatically, and their usefulness as an immunogen for developing protective immunity against pre-erythrocytic stage malaria.
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Affiliation(s)
- Rana Chattopadhyay
- From the Malaria Program, United States Military Malaria Vaccine Program
| | - Patricia de la Vega
- From the Malaria Program, United States Military Malaria Vaccine Program
- Walter Reed Army Institute of Research and
| | - Sun H. Paik
- Sun BioMedical Technologies Inc., Ridgecrest, California 93555
| | - Yoko Murata
- Sun BioMedical Technologies Inc., Ridgecrest, California 93555
| | | | - Thomas L. Richie
- From the Malaria Program, United States Military Malaria Vaccine Program
- the Naval Medical Research Center, Silver Spring, Maryland 20910-7500 and
| | - Guck T. Ooi
- Sun BioMedical Technologies Inc., Ridgecrest, California 93555
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Abstract
Malaria is a vector-borne infectious disease caused by unicellular parasites of the genus Plasmodium. These obligate intracellular parasites have the unique capacity to infect and replicate within erythrocytes, which are terminally differentiated host cells that lack antigen presentation pathways. Prior to the cyclic erythrocytic infections that cause the characteristic clinical symptoms of malaria, the parasite undergoes an essential and clinically silent expansion phase in the liver. By infecting privileged host cells, employing programs of complex life stage conversions and expressing varying immunodominant antigens, Plasmodium parasites have evolved mechanisms to downmodulate protective immune responses against ongoing and even future infections. Consequently, anti-malaria immunity develops only gradually over many years of repeated and multiple infections in endemic areas. The identification of immune correlates of protection among the abundant non-protective host responses remains a research priority. Understanding the molecular and immunological mechanisms of the crosstalk between the parasite and the host is a prerequisite for the rational discovery and development of a safe, affordable, and protective anti-malaria vaccine.
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Affiliation(s)
- Julius Clemence Hafalla
- Department of Immunology and Infection, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK.
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Sedegah M, Kim Y, Peters B, McGrath S, Ganeshan H, Lejano J, Abot E, Banania G, Belmonte M, Sayo R, Farooq F, Doolan DL, Regis D, Tamminga C, Chuang I, Bruder JT, King CR, Ockenhouse CF, Faber B, Remarque E, Hollingdale MR, Richie TL, Sette A. Identification and localization of minimal MHC-restricted CD8+ T cell epitopes within the Plasmodium falciparum AMA1 protein. Malar J 2010; 9:241. [PMID: 20735847 PMCID: PMC2939619 DOI: 10.1186/1475-2875-9-241] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2010] [Accepted: 08/24/2010] [Indexed: 12/14/2022] Open
Abstract
Background Plasmodium falciparum apical membrane antigen-1 (AMA1) is a leading malaria vaccine candidate antigen that is expressed by sporozoite, liver and blood stage parasites. Since CD8+ T cell responses have been implicated in protection against pre-erythrocytic stage malaria, this study was designed to identify MHC class I-restricted epitopes within AMA1. Methods A recombinant adenovirus serotype 5 vector expressing P. falciparum AMA1 was highly immunogenic when administered to healthy, malaria-naive adult volunteers as determined by IFN-γ ELISpot responses to peptide pools containing overlapping 15-mer peptides spanning full-length AMA1. Computerized algorithms (NetMHC software) were used to predict minimal MHC-restricted 8-10-mer epitope sequences within AMA1 15-mer peptides active in ELISpot. A subset of epitopes was synthesized and tested for induction of CD8+ T cell IFN-γ responses by ELISpot depletion and ICS assays. A 3-dimensional model combining Domains I + II of P. falciparum AMA1 and Domain III of P. vivax AMA1 was used to map these epitopes. Results Fourteen 8-10-mer epitopes were predicted to bind to HLA supertypes A01 (3 epitopes), A02 (4 epitopes), B08 (2 epitopes) and B44 (5 epitopes). Nine of the 14 predicted epitopes were recognized in ELISpot or ELISpot and ICS assays by one or more volunteers. Depletion of T cell subsets confirmed that these epitopes were CD8+ T cell-dependent. A mixture of the 14 minimal epitopes was capable of recalling CD8+ T cell IFN-γ responses from PBMC of immunized volunteers. Thirteen of the 14 predicted epitopes were polymorphic and the majority localized to the more conserved front surface of the AMA1 model structure. Conclusions This study predicted 14 and confirmed nine MHC class I-restricted CD8+ T cell epitopes on AMA1 recognized in the context of seven HLA alleles. These HLA alleles belong to four HLA supertypes that have a phenotypic frequency between 23% - 100% in different human populations.
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Affiliation(s)
- Martha Sedegah
- USMMVP, Malaria Department, NMRC, Silver Spring, MD 20910, USA
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