51
|
Kudyba HM, Cobb DW, Fierro MA, Florentin A, Ljolje D, Singh B, Lucchi NW, Muralidharan V. The endoplasmic reticulum chaperone PfGRP170 is essential for asexual development and is linked to stress response in malaria parasites. Cell Microbiol 2019; 21:e13042. [PMID: 31087747 PMCID: PMC6699899 DOI: 10.1111/cmi.13042] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 04/09/2019] [Accepted: 05/09/2019] [Indexed: 12/24/2022]
Abstract
The vast majority of malaria mortality is attributed to one parasite species: Plasmodium falciparum. Asexual replication of the parasite within the red blood cell is responsible for the pathology of the disease. In Plasmodium, the endoplasmic reticulum (ER) is a central hub for protein folding and trafficking as well as stress response pathways. In this study, we tested the role of an uncharacterised ER protein, PfGRP170, in regulating these key functions by generating conditional mutants. Our data show that PfGRP170 localises to the ER and is essential for asexual growth, specifically required for proper development of schizonts. PfGRP170 is essential for surviving heat shock, suggesting a critical role in cellular stress response. The data demonstrate that PfGRP170 interacts with the Plasmodium orthologue of the ER chaperone, BiP. Finally, we found that loss of PfGRP170 function leads to the activation of the Plasmodium eIF2α kinase, PK4, suggesting a specific role for this protein in this parasite stress response pathway.
Collapse
Affiliation(s)
- Heather M Kudyba
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia.,Department of Cellular Biology, University of Georgia, Athens, Georgia
| | - David W Cobb
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia.,Department of Cellular Biology, University of Georgia, Athens, Georgia
| | - Manuel A Fierro
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia.,Department of Cellular Biology, University of Georgia, Athens, Georgia
| | - Anat Florentin
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia
| | - Dragan Ljolje
- Malaria Branch and Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Balwan Singh
- Malaria Branch and Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Naomi W Lucchi
- Malaria Branch and Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Vasant Muralidharan
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia.,Department of Cellular Biology, University of Georgia, Athens, Georgia
| |
Collapse
|
52
|
Ngernna S, Chim-Ong A, Roobsoong W, Sattabongkot J, Cui L, Nguitragool W. Efficient synchronization of Plasmodium knowlesi in vitro cultures using guanidine hydrochloride. Malar J 2019; 18:148. [PMID: 31023359 PMCID: PMC6482532 DOI: 10.1186/s12936-019-2783-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Accepted: 04/16/2019] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Long-term in vitro culture of blood stage Plasmodium parasites invariably leads to asynchronous parasite development. The most often used technique to synchronize Plasmodium falciparum culture is sorbitol treatment, which differentially induces osmotic lysis of trophozoite- and schizont-infected red blood cells due to presence of the new permeation pathways in the membranes of these cells. However, sorbitol treatment does not work well when used to synchronize the culture-adapted Plasmodium knowlesi A1-H.1 line. METHODS A number of common solutes were tested in lieu of sorbitol for synchronization of P. knowlesi A1-H.1 ring stage. RESULTS Guanidine hydrochloride was found to selectively lyse trophozoite- and schizont-infected red blood cells, yielding highly synchronous and viable rings. CONCLUSIONS A method for synchronization of P. knowlesi in human red blood cells was developed. Requiring only common laboratory reagents, this method is simple and should be applicable to most laboratory settings.
Collapse
Affiliation(s)
- Sutharinee Ngernna
- Department of Molecular Tropical Medicine, Faculty of Tropical Medicine, Mahidol University, 420/6 Ratchawithi Road, Ratchathewi, Bangkok, 10400, Thailand
| | - Anongruk Chim-Ong
- Department of Molecular Tropical Medicine, Faculty of Tropical Medicine, Mahidol University, 420/6 Ratchawithi Road, Ratchathewi, Bangkok, 10400, Thailand
| | - Wanlapa Roobsoong
- Mahidol Vivax Research Unit, Faculty of Tropical Medicine, Mahidol University, 420/6 Ratchawithi Road, Ratchathewi, Bangkok, 10400, Thailand
| | - Jetsumon Sattabongkot
- Mahidol Vivax Research Unit, Faculty of Tropical Medicine, Mahidol University, 420/6 Ratchawithi Road, Ratchathewi, Bangkok, 10400, Thailand
| | - Liwang Cui
- Department of Internal Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL, USA
| | - Wang Nguitragool
- Department of Molecular Tropical Medicine, Faculty of Tropical Medicine, Mahidol University, 420/6 Ratchawithi Road, Ratchathewi, Bangkok, 10400, Thailand.
| |
Collapse
|
53
|
Identification of Antimalarial Compounds That Require CLAG3 for Their Uptake by Plasmodium falciparum-Infected Erythrocytes. Antimicrob Agents Chemother 2019; 63:AAC.00052-19. [PMID: 30782998 DOI: 10.1128/aac.00052-19] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Accepted: 02/01/2019] [Indexed: 01/15/2023] Open
Abstract
During the intraerythrocytic asexual cycle malaria parasites acquire nutrients and other solutes through a broad selectivity channel localized at the membrane of the infected erythrocyte termed the plasmodial surface anion channel (PSAC). The protein product of the Plasmodium falciparum clonally variant clag3.1 and clag3.2 genes determines PSAC activity. Switches in the expression of clag3 genes, which are regulated by epigenetic mechanisms, are associated with changes in PSAC-dependent permeability that can result in resistance to compounds toxic for the parasite, such as blasticidin S. Here, we investigated whether other antimalarial drugs require CLAG3 to reach their intracellular target and consequently are prone to parasite resistance by epigenetic mechanisms. We found that the bis-thiazolium salts T3 (also known as albitiazolium) and T16 require the product of clag3 genes to enter infected erythrocytes. P. falciparum populations can develop resistance to these compounds via the selection of parasites with dramatically reduced expression of both genes. However, other compounds previously demonstrated or predicted to enter infected erythrocytes through transport pathways absent from noninfected erythrocytes, such as fosmidomycin, doxycycline, azithromycin, lumefantrine, or pentamidine, do not require expression of clag3 genes for their antimalarial activity. This suggests that they use alternative CLAG3-independent routes to access parasites. Our results demonstrate that P. falciparum can develop resistance to diverse antimalarial compounds by epigenetic changes in the expression of clag3 genes. This is of concern for drug development efforts because drug resistance by epigenetic mechanisms can arise quickly, even during the course of a single infection.
Collapse
|
54
|
Aroonsri A, Posayapisit N, Kongsee J, Siripan O, Vitsupakorn D, Utaida S, Uthaipibull C, Kamchonwongpaisan S, Shaw PJ. Validation of Plasmodium falciparum deoxyhypusine synthase as an antimalarial target. PeerJ 2019; 7:e6713. [PMID: 31024761 PMCID: PMC6475138 DOI: 10.7717/peerj.6713] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 03/05/2019] [Indexed: 11/20/2022] Open
Abstract
Background Hypusination is an essential post-translational modification in eukaryotes. The two enzymes required for this modification, namely deoxyhypusine synthase (DHS) and deoxyhypusine hydrolase are also conserved. Plasmodium falciparum human malaria parasites possess genes for both hypusination enzymes, which are hypothesized to be targets of antimalarial drugs. Methods Transgenic P. falciparum parasites with modification of the PF3D7_1412600 gene encoding PfDHS enzyme were created by insertion of the glmS riboswitch or the M9 inactive variant. The PfDHS protein was studied in transgenic parasites by confocal microscopy and Western immunoblotting. The biochemical function of PfDHS enzyme in parasites was assessed by hypusination and nascent protein synthesis assays. Gene essentiality was assessed by competitive growth assays and chemogenomic profiling. Results Clonal transgenic parasites with integration of glmS riboswitch downstream of the PfDHS gene were established. PfDHS protein was present in the cytoplasm of transgenic parasites in asexual stages. The PfDHS protein could be attenuated fivefold in transgenic parasites with an active riboswitch, whereas PfDHS protein expression was unaffected in control transgenic parasites with insertion of the riboswitch-inactive sequence. Attenuation of PfDHS expression for 72 h led to a significant reduction of hypusinated protein; however, global protein synthesis was unaffected. Parasites with attenuated PfDHS expression showed a significant growth defect, although their decline was not as rapid as parasites with attenuated dihydrofolate reductase-thymidylate synthase (PfDHFR-TS) expression. PfDHS-attenuated parasites showed increased sensitivity to N 1-guanyl-1,7-diaminoheptane, a structural analog of spermidine, and a known inhibitor of DHS enzymes. Discussion Loss of PfDHS function leads to reduced hypusination, which may be important for synthesis of some essential proteins. The growth defect in parasites with attenuated Pf DHS expression suggests that this gene is essential. However, the slower decline of PfDHS mutants compared with PfDHFR-TS mutants in competitive growth assays suggests that PfDHS is less vulnerable as an antimalarial target. Nevertheless, the data validate PfDHS as an antimalarial target which can be inhibited by spermidine-like compounds.
Collapse
Affiliation(s)
- Aiyada Aroonsri
- Protein-Ligand Engineering and Molecular Biology Laboratory, Medical Molecular Biology Research Unit, National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Pathum Thani, Thailand
| | - Navaporn Posayapisit
- Protein-Ligand Engineering and Molecular Biology Laboratory, Medical Molecular Biology Research Unit, National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Pathum Thani, Thailand
| | - Jindaporn Kongsee
- Department of Biotechnology, Faculty of Science and Technology, Thammasat University, Pathum Thani, Thailand
| | - Onsiri Siripan
- Protein-Ligand Engineering and Molecular Biology Laboratory, Medical Molecular Biology Research Unit, National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Pathum Thani, Thailand
| | - Danoo Vitsupakorn
- Protein-Ligand Engineering and Molecular Biology Laboratory, Medical Molecular Biology Research Unit, National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Pathum Thani, Thailand
| | - Sugunya Utaida
- Department of Biotechnology, Faculty of Science and Technology, Thammasat University, Pathum Thani, Thailand
| | - Chairat Uthaipibull
- Protein-Ligand Engineering and Molecular Biology Laboratory, Medical Molecular Biology Research Unit, National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Pathum Thani, Thailand
| | - Sumalee Kamchonwongpaisan
- Protein-Ligand Engineering and Molecular Biology Laboratory, Medical Molecular Biology Research Unit, National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Pathum Thani, Thailand
| | - Philip J Shaw
- Protein-Ligand Engineering and Molecular Biology Laboratory, Medical Molecular Biology Research Unit, National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Pathum Thani, Thailand
| |
Collapse
|
55
|
Matthews KM, Pitman EL, de Koning-Ward TF. Illuminating how malaria parasites export proteins into host erythrocytes. Cell Microbiol 2019; 21:e13009. [PMID: 30656810 DOI: 10.1111/cmi.13009] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Revised: 12/06/2018] [Accepted: 12/17/2018] [Indexed: 12/11/2022]
Abstract
Plasmodium parasites that cause the disease malaria have developed an elaborate trafficking pathway to facilitate the export of hundreds of effector proteins into their host cell, the erythrocyte. In this review, we outline how certain effector proteins contribute to parasite survival, virulence, and immune evasion. We also highlight how parasite proteins destined for export are recognised at the endoplasmic reticulum to facilitate entry into the export pathway and how the effector proteins are able to transverse the bounding parasitophorous vaculoar membrane via the Plasmodium translocon of exported proteins to gain access to the host cell. Some of the gaps in our understanding of the export pathway are also presented. Finally, we examine the degree of conservation of some of the key components of the Plasmodium export pathway in closely related apicomplexan parasites, which may provide insight into how the diverse apicomplexan parasites have adapted to survival pressures encountered within their respective host cells.
Collapse
Affiliation(s)
| | - Ethan L Pitman
- School of Medicine, Deakin University, Waurn Ponds, Victoria, Australia
| | | |
Collapse
|
56
|
Siau A, Huang X, Loh HP, Zhang N, Meng W, Sze SK, Renia L, Preiser P. Immunomic Identification of Malaria Antigens Associated With Protection in Mice. Mol Cell Proteomics 2019; 18:837-853. [PMID: 30718293 DOI: 10.1074/mcp.ra118.000997] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Revised: 01/22/2019] [Indexed: 11/06/2022] Open
Abstract
Efforts to develop vaccines against malaria represent a major research target. The observations that 1) sterile protection can be obtained when the host is exposed to live parasites and 2) the immunity against blood stage parasite is principally mediated by protective antibodies suggest that a protective vaccine is feasible. However, only a small number of proteins have been investigated so far and most of the Plasmodium proteome has yet to be explored. To date, only few immunodominant antigens have emerged for testing in clinical trials but no formulation has led to substantial protection in humans. The nature of parasite molecules associated with protection remains elusive. Here, immunomic screening of mice immune sera with different protection efficiencies against the whole parasite proteome allowed us to identify a large repertoire of antigens validated by screening a library expressing antigens. The calculation of weighted scores reflecting the likelihood of protection of each antigen using five predictive criteria derived from immunomic and proteomic data sets, highlighted a priority list of protective antigens. Altogether, the approach sheds light on conserved antigens across Plasmodium that are amenable to targeting by the host immune system upon merozoite invasion and blood stage development. Most of these antigens have preliminary protection data but have not been widely considered as candidate for vaccine trials, opening new perspectives that overcome the limited choice of immunodominant, poorly protective vaccines currently being the focus of malaria vaccine researches.
Collapse
Affiliation(s)
- Anthony Siau
- From the ‡Nanyang Technological University, School of Biological Sciences, Singapore;.
| | - Ximei Huang
- From the ‡Nanyang Technological University, School of Biological Sciences, Singapore;; From the ‡Nanyang Technological University, School of Biological Sciences, Singapore
| | - Han Ping Loh
- From the ‡Nanyang Technological University, School of Biological Sciences, Singapore;; From the ‡Nanyang Technological University, School of Biological Sciences, Singapore
| | - Neng Zhang
- From the ‡Nanyang Technological University, School of Biological Sciences, Singapore
| | - Wei Meng
- From the ‡Nanyang Technological University, School of Biological Sciences, Singapore
| | - Siu Kwan Sze
- From the ‡Nanyang Technological University, School of Biological Sciences, Singapore
| | - Laurent Renia
- §Singapore Immunology Network (SIgN), A*STAR, Biopolis, Singapore
| | - Peter Preiser
- From the ‡Nanyang Technological University, School of Biological Sciences, Singapore;.
| |
Collapse
|
57
|
Apolis L, Olivas J, Srinivasan P, Kushwaha AK, Desai SA. Multiple genetic loci define Ca ++ utilization by bloodstream malaria parasites. BMC Genomics 2019; 20:47. [PMID: 30651090 PMCID: PMC6335690 DOI: 10.1186/s12864-018-5418-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Accepted: 12/27/2018] [Indexed: 11/30/2022] Open
Abstract
Background Bloodstream malaria parasites require Ca++ for their development, but the sites and mechanisms of Ca++ utilization are not well understood. We hypothesized that there may be differences in Ca++ uptake or utilization by genetically distinct lines of P. falciparum. These differences, if identified, may provide insights into molecular mechanisms. Results Dose response studies with the Ca++ chelator EGTA (ethylene glycol-bis(β-aminoethyl ether)-N,N,N′,N′-tetraacetic acid) revealed stable differences in Ca++ requirement for six geographically divergent parasite lines used in previous genetic crosses, with the largest difference seen between the parents of the HB3 x Dd2 cross. Genetic mapping of Ca++ requirement yielded complex inheritance in 34 progeny clones with a single significant locus on chromosome 7 and possible contributions from other loci. Although encoded by a gene in the significant locus and a proposed Ca++ target, PfCRT (P. falciparum chloroquine resistance transporter), the primary determinant of clinical resistance to the antimalarial drug chloroquine, does not appear to contribute to this quantitative trait. Stage-specific application of extracellular EGTA also excluded determinants associated with merozoite egress and erythrocyte reinvasion. Conclusions We have identified differences in Ca++ utilization amongst P. falciparum lines. These differences are under genetic regulation, segregating as a complex trait in genetic cross progeny. Ca++ uptake and utilization throughout the bloodstream asexual cycle of malaria parasites represents an unexplored target for therapeutic intervention.
Collapse
Affiliation(s)
- Liana Apolis
- The Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA.,Florida State University College of Medicine, Tallahassee, Florida, USA
| | - Joanna Olivas
- The Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
| | - Prakash Srinivasan
- The Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA.,Department Molecular Microbiology and Immunology, Johns Hopkins Malaria Research Institute, Baltimore, MD, USA
| | - Ambuj K Kushwaha
- The Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
| | - Sanjay A Desai
- The Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA.
| |
Collapse
|
58
|
Balabaskaran-Nina P, Desai SA. Diverse target gene modifications in Plasmodium falciparum using Bxb1 integrase and an intronic attB. Parasit Vectors 2018; 11:548. [PMID: 30333047 PMCID: PMC6192176 DOI: 10.1186/s13071-018-3129-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Accepted: 10/01/2018] [Indexed: 12/26/2022] Open
Abstract
Genetic manipulation of the human malaria parasite Plasmodium falciparum is needed to explore pathogen biology and evaluate antimalarial targets. It is, however, aggravated by a low transfection efficiency, a paucity of selectable markers and a biased A/T-rich genome. While various enabling technologies have been introduced over the past two decades, facile and broad-range modification of essential genes remains challenging. We recently devised a new application of the Bxb1 integrase strategy to meet this need through an intronic attB sequence within the gene of interest. Although this attB is silent and without effect on intron splicing or protein translation and function, it allows efficient gene modification with minimal risk of unwanted changes at other genomic sites. We describe the range of applications for this new method as well as specific cases where it is preferred over CRISPR-Cas9 and other technologies. The advantages and limitations of various strategies for endogenous gene editing are also discussed.
Collapse
Affiliation(s)
- Praveen Balabaskaran-Nina
- The Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, 20852, USA.,Present Address: Department of Epidemiology and Public Health, Central University of Tamil Nadu, Thiruvarur, India
| | - Sanjay A Desai
- The Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, 20852, USA.
| |
Collapse
|
59
|
Ribeiro JM, Garriga M, Potchen N, Crater AK, Gupta A, Ito D, Desai SA. Guide RNA selection for CRISPR-Cas9 transfections in Plasmodium falciparum. Int J Parasitol 2018; 48:825-832. [PMID: 29906414 PMCID: PMC9093057 DOI: 10.1016/j.ijpara.2018.03.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2018] [Revised: 03/11/2018] [Accepted: 03/13/2018] [Indexed: 12/26/2022]
Abstract
CRISPR-Cas9 mediated genome editing is addressing key limitations in the transfection of malaria parasites. While this method has already simplified the needed molecular cloning and reduced the time required to generate mutants in the human pathogen Plasmodium falciparum, optimal selection of required guide RNAs and guidelines for successful transfections have not been well characterised, leading workers to use time-consuming trial and error approaches. We used a genome-wide computational approach to create a comprehensive and publicly accessible database of possible guide RNA sequences in the P. falciparum genome. For each guide, we report on-target efficiency and specificity scores as well as information about the genomic site relevant to optimal design of CRISPR-Cas9 transfections to modify, disrupt, or conditionally knockdown any gene. As many antimalarial drug and vaccine targets are encoded by multigene families, we also developed a new paralog specificity score that should facilitate modification of either a single family member of interest or multiple paralogs that serve overlapping roles. Finally, we tabulated features of successful transfections in our laboratory, providing broadly useful guidelines for parasite transfections. Molecular studies aimed at understanding parasite biology or characterising drug and vaccine targets in P. falciparum should be facilitated by this comprehensive database.
Collapse
Affiliation(s)
- Jose M Ribeiro
- The Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA
| | - Meera Garriga
- The Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA
| | - Nicole Potchen
- The Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA
| | - Anna K Crater
- The Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA
| | - Ankit Gupta
- The Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA
| | - Daisuke Ito
- The Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA
| | - Sanjay A Desai
- The Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA.
| |
Collapse
|
60
|
Garten M, Nasamu AS, Niles JC, Zimmerberg J, Goldberg DE, Beck JR. EXP2 is a nutrient-permeable channel in the vacuolar membrane of Plasmodium and is essential for protein export via PTEX. Nat Microbiol 2018; 3:1090-1098. [PMID: 30150733 PMCID: PMC6158082 DOI: 10.1038/s41564-018-0222-7] [Citation(s) in RCA: 84] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2018] [Accepted: 07/23/2018] [Indexed: 11/29/2022]
Affiliation(s)
- Matthias Garten
- Section on Integrative Biophysics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Armiyaw S Nasamu
- Departments of Medicine and Molecular Microbiology, Washington University School of Medicine, St. Louis, MO, USA
| | - Jacquin C Niles
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Joshua Zimmerberg
- Section on Integrative Biophysics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA.
| | - Daniel E Goldberg
- Departments of Medicine and Molecular Microbiology, Washington University School of Medicine, St. Louis, MO, USA.
| | - Josh R Beck
- Departments of Medicine and Molecular Microbiology, Washington University School of Medicine, St. Louis, MO, USA.,Department of Biomedical Sciences, Iowa State University, Ames, IA, USA
| |
Collapse
|
61
|
Baker DA, Drought LG, Flueck C, Nofal SD, Patel A, Penzo M, Walker EM. Cyclic nucleotide signalling in malaria parasites. Open Biol 2018; 7:rsob.170213. [PMID: 29263246 PMCID: PMC5746546 DOI: 10.1098/rsob.170213] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 11/28/2017] [Indexed: 12/22/2022] Open
Abstract
The cyclic nucleotides 3′, 5′-cyclic adenosine monophosphate (cAMP) and 3′, 5′-cyclic guanosine monophosphate (cGMP) are intracellular messengers found in most animal cell types. They usually mediate an extracellular stimulus to drive a change in cell function through activation of their respective cyclic nucleotide-dependent protein kinases, PKA and PKG. The enzymatic components of the malaria parasite cyclic nucleotide signalling pathways have been identified, and the genetic and biochemical studies of these enzymes carried out to date are reviewed herein. What has become very clear is that cyclic nucleotides play vital roles in controlling every stage of the complex malaria parasite life cycle. Our understanding of the involvement of cyclic nucleotide signalling in orchestrating the complex biology of malaria parasites is still in its infancy, but the recent advances in our genetic tools and the increasing interest in signalling will deliver more rapid progress in the coming years.
Collapse
Affiliation(s)
- David A Baker
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT, UK
| | - Laura G Drought
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT, UK
| | - Christian Flueck
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT, UK
| | - Stephanie D Nofal
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT, UK
| | - Avnish Patel
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT, UK
| | - Maria Penzo
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT, UK.,Tres Cantos Medicines Development Campus, Diseases of the Developing World, GlaxoSmithKline, Severo Ochoa 2, Tres Cantos, 28760, Madrid, Spain
| | - Eloise M Walker
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT, UK
| |
Collapse
|
62
|
Kushwaha AK, Apolis L, Ito D, Desai SA. Increased Ca ++ uptake by erythrocytes infected with malaria parasites: Evidence for exported proteins and novel inhibitors. Cell Microbiol 2018; 20:e12853. [PMID: 29726084 DOI: 10.1111/cmi.12853] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Revised: 04/18/2018] [Accepted: 04/24/2018] [Indexed: 12/12/2022]
Abstract
Malaria parasites export many proteins into their host erythrocytes and increase membrane permeability to diverse solutes. Although most solutes use a broad-selectivity channel known as the plasmodial surface anion channel, increased Ca++ uptake is mediated by a distinct, poorly characterised mechanism that appears to be essential for the intracellular parasite. Here, we examined infected cell Ca++ uptake with a kinetic fluorescence assay and the virulent human pathogen, Plasmodium falciparum. Cell surface labelling with N-hydroxysulfosuccinimide esters revealed differing effects on transport into infected and uninfected cells, indicating that Ca++ uptake at the infected cell surface is mediated by new or altered proteins at the host membrane. Conditional knockdown of PTEX, a translocon for export of parasite proteins into the host cell, significantly reduced infected cell Ca++ permeability, suggesting involvement of parasite-encoded proteins trafficked to the host membrane. A high-throughput chemical screen identified the first Ca++ transport inhibitors active against Plasmodium-infected cells. These novel chemical scaffolds inhibit both uptake and parasite growth; improved in vitro potency at reduced free [Ca++ ] is consistent with parasite killing specifically via action on one or more Ca++ transporters. These inhibitors should provide mechanistic insights into malaria parasite Ca++ transport and may be starting points for new antimalarial drugs.
Collapse
Affiliation(s)
- Ambuj K Kushwaha
- The Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, USA
| | - Liana Apolis
- The Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, USA
| | - Daisuke Ito
- The Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, USA
| | - Sanjay A Desai
- The Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, USA
| |
Collapse
|
63
|
CLAG3 Self-Associates in Malaria Parasites and Quantitatively Determines Nutrient Uptake Channels at the Host Membrane. mBio 2018; 9:mBio.02293-17. [PMID: 29739907 PMCID: PMC5941077 DOI: 10.1128/mbio.02293-17] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Malaria parasites increase host erythrocyte permeability to ions and nutrients via a broad-selectivity channel known as the plasmodial surface anion channel (PSAC), linked to parasite-encoded CLAG3 and two associated proteins. These proteins lack the multiple transmembrane domains typically present in channel-forming proteins, raising doubts about their precise roles. Using the virulent human Plasmodium falciparum parasite, we report that CLAG3 undergoes self-association and that this protein’s expression determines channel phenotype quantitatively. We overcame epigenetic silencing of clag3 paralogs and engineered parasites that express two CLAG3 isoforms simultaneously. Stoichiometric expression of these isoforms yielded intermediate channel phenotypes, in agreement with observed trafficking of both proteins to the host membrane. Coimmunoprecipitation and surface labeling revealed formation of CLAG3 oligomers. In vitro selections applied to these transfectant lines yielded distinct mutants with correlated changes in channel activity. These findings support involvement of the identified oligomers in PSAC formation and parasite nutrient acquisition. Malaria parasites are globally important pathogens that evade host immunity by replicating within circulating erythrocytes. To facilitate intracellular growth, these parasites increase erythrocyte nutrient uptake through an unusual ion channel. The parasite CLAG3 protein is a key determinant of this channel, but its lack of homology to known ion channels has raised questions about possible mechanisms. Using a new method that allows simultaneous expression of two different CLAG3 proteins, we identify self-association of CLAG3. The two expressed isoforms faithfully traffic to and insert in the host membrane, while remaining associated with two unrelated parasite proteins. Both the channel phenotypes and molecular changes produced upon selections with a highly specific channel inhibitor are consistent with a multiprotein complex that forms the nutrient pore. These studies support direct involvement of the CLAG3 protein in channel formation and are relevant to antimalarial drug discovery projects targeting parasite nutrient acquisition.
Collapse
|
64
|
Miura T, Takeo S, Ntege EH, Otsuki H, Sawasaki T, Ishino T, Takashima E, Tsuboi T. The malaria parasite RhopH protein complex interacts with erythrocyte calmyrin identified from a comprehensive erythrocyte protein library. Biochem Biophys Res Commun 2018; 500:261-267. [PMID: 29653104 DOI: 10.1016/j.bbrc.2018.04.056] [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: 04/05/2018] [Accepted: 04/09/2018] [Indexed: 10/17/2022]
Abstract
Malaria merozoite apical organelles; microneme and rhoptry secreted proteins play functional roles during and following invasion of host erythrocytes. Among numerous proteins, the rhoptries discharge high molecular weight proteins known as RhopH complex. Recent reports suggest that the RhopH complex is essential for growth and survival of the malaria parasite within erythrocytes. However, an in-depth understanding of the host-parasite molecular interactions is indispensable. Here we utilized a comprehensive mouse erythrocyte protein library consisting of 443 proteins produced by a wheat germ cell-free system, combined with AlphaScreen technology to identify mouse erythrocyte calmyrin as an interacting molecule of the rodent malaria parasite Plasmodium yoelii RhopH complex (PyRhopH). The PyRhopH interaction was dependent on the calmyrin N-terminus and divalent cation capacity. The finding unveils a recommendable and invaluable usefulness of our comprehensive mouse erythrocyte protein library together with the AlphaScreen technology in investigating a wide-range of host-parasite molecular interactions.
Collapse
Affiliation(s)
- Toyokazu Miura
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Ehime 790-8577, Japan
| | - Satoru Takeo
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Ehime 790-8577, Japan
| | - Edward H Ntege
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Ehime 790-8577, Japan
| | - Hitoshi Otsuki
- Division of Medical Zoology, Department of Microbiology and Immunology, Faculty of Medicine, Tottori University, Yonago, Tottori 683-8503, Japan
| | - Tatsuya Sawasaki
- Division of Cell-Free Sciences, Proteo-Science Center, Ehime University, Matsuyama, Ehime 790-8577, Japan
| | - Tomoko Ishino
- Division of Molecular Parasitology, Proteo-Science Center, Ehime University, Shitsukawa, Toon, Ehime 791-0295, Japan
| | - Eizo Takashima
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Ehime 790-8577, Japan
| | - Takafumi Tsuboi
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Ehime 790-8577, Japan.
| |
Collapse
|
65
|
Brancucci NMB, De Niz M, Straub TJ, Ravel D, Sollelis L, Birren BW, Voss TS, Neafsey DE, Marti M. Probing Plasmodium falciparum sexual commitment at the single-cell level. Wellcome Open Res 2018; 3:70. [PMID: 30320226 PMCID: PMC6143928 DOI: 10.12688/wellcomeopenres.14645.3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/29/2018] [Indexed: 11/20/2022] Open
Abstract
Background: Malaria parasites go through major transitions during their complex life cycle, yet the underlying differentiation pathways remain obscure. Here we apply single cell transcriptomics to unravel the program inducing sexual differentiation in Plasmodium falciparum. Parasites have to make this essential life-cycle decision in preparation for human-to-mosquito transmission. Methods: By combining transcriptional profiling with quantitative imaging and genetics, we defined a transcriptional signature in sexually committed cells. Results: We found this transcriptional signature to be distinct from general changes in parasite metabolism that can be observed in response to commitment-inducing conditions. Conclusions: This proof-of-concept study provides a template to capture transcriptional diversity in parasite populations containing complex mixtures of different life-cycle stages and developmental programs, with important implications for our understanding of parasite biology and the ongoing malaria elimination campaign.
Collapse
Affiliation(s)
- Nicolas M B Brancucci
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.,Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
| | - Mariana De Niz
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Timothy J Straub
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA.,The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Deepali Ravel
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
| | - Lauriane Sollelis
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Bruce W Birren
- The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Till S Voss
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Daniel E Neafsey
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA.,The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Matthias Marti
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.,Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
| |
Collapse
|
66
|
Brancucci NMB, De Niz M, Straub TJ, Ravel D, Sollelis L, Birren BW, Voss TS, Neafsey DE, Marti M. Probing Plasmodium falciparum sexual commitment at the single-cell level. Wellcome Open Res 2018; 3:70. [PMID: 30320226 PMCID: PMC6143928 DOI: 10.12688/wellcomeopenres.14645.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/06/2018] [Indexed: 11/20/2022] Open
Abstract
Background: Malaria parasites go through major transitions during their complex life cycle, yet the underlying differentiation pathways remain obscure. Here we apply single cell transcriptomics to unravel the program inducing sexual differentiation in Plasmodium falciparum. Parasites have to make this essential life-cycle decision in preparation for human-to-mosquito transmission. Methods: By combining transcriptional profiling with quantitative imaging and genetics, we defined a transcriptional signature in sexually committed cells. Results: We found this transcriptional signature to be distinct from general changes in parasite metabolism that can be observed in response to commitment-inducing conditions. Conclusions: This proof-of-concept study provides a template to capture transcriptional diversity in parasite populations containing complex mixtures of different life-cycle stages and developmental programs, with important implications for our understanding of parasite biology and the ongoing malaria elimination campaign.
Collapse
Affiliation(s)
- Nicolas M B Brancucci
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.,Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
| | - Mariana De Niz
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Timothy J Straub
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA.,The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Deepali Ravel
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
| | - Lauriane Sollelis
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Bruce W Birren
- The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Till S Voss
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Daniel E Neafsey
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA.,The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Matthias Marti
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.,Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
| |
Collapse
|
67
|
Brancucci NMB, De Niz M, Straub TJ, Ravel D, Sollelis L, Birren BW, Voss TS, Neafsey DE, Marti M. Probing Plasmodium falciparum sexual commitment at the single-cell level. Wellcome Open Res 2018; 3:70. [PMID: 30320226 PMCID: PMC6143928 DOI: 10.12688/wellcomeopenres.14645.4] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/16/2018] [Indexed: 01/05/2023] Open
Abstract
Background: Malaria parasites go through major transitions during their complex life cycle, yet the underlying differentiation pathways remain obscure. Here we apply single cell transcriptomics to unravel the program inducing sexual differentiation in Plasmodium falciparum. Parasites have to make this essential life-cycle decision in preparation for human-to-mosquito transmission. Methods: By combining transcriptional profiling with quantitative imaging and genetics, we defined a transcriptional signature in sexually committed cells. Results: We found this transcriptional signature to be distinct from general changes in parasite metabolism that can be observed in response to commitment-inducing conditions. Conclusions: This proof-of-concept study provides a template to capture transcriptional diversity in parasite populations containing complex mixtures of different life-cycle stages and developmental programs, with important implications for our understanding of parasite biology and the ongoing malaria elimination campaign.
Collapse
Affiliation(s)
- Nicolas M B Brancucci
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.,Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
| | - Mariana De Niz
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Timothy J Straub
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA.,The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Deepali Ravel
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
| | - Lauriane Sollelis
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Bruce W Birren
- The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Till S Voss
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Daniel E Neafsey
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA.,The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Matthias Marti
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.,Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
| |
Collapse
|
68
|
Brancucci NMB, De Niz M, Straub TJ, Ravel D, Sollelis L, Birren BW, Voss TS, Neafsey DE, Marti M. Probing Plasmodium falciparum sexual commitment at the single-cell level. Wellcome Open Res 2018; 3:70. [PMID: 30320226 PMCID: PMC6143928 DOI: 10.12688/wellcomeopenres.14645.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/24/2018] [Indexed: 11/20/2022] Open
Abstract
Background: Malaria parasites go through major transitions during their complex life cycle, yet the underlying differentiation pathways remain obscure. Here we apply single cell transcriptomics to unravel the program inducing sexual differentiation in Plasmodium falciparum. Parasites have to make this essential life-cycle decision in preparation for human-to-mosquito transmission. Methods: By combining transcriptional profiling with quantitative imaging and genetics, we defined a transcriptional signature in sexually committed cells. Results: We found this transcriptional signature to be distinct from general changes in parasite metabolism that can be observed in response to commitment-inducing conditions. Conclusions: This proof-of-concept study provides a template to capture transcriptional diversity in parasite populations containing complex mixtures of different life-cycle stages and developmental programs, with important implications for our understanding of parasite biology and the ongoing malaria elimination campaign.
Collapse
Affiliation(s)
- Nicolas M B Brancucci
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.,Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
| | - Mariana De Niz
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Timothy J Straub
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA.,The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Deepali Ravel
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
| | - Lauriane Sollelis
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Bruce W Birren
- The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Till S Voss
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Daniel E Neafsey
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA.,The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Matthias Marti
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.,Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
| |
Collapse
|
69
|
Transmembrane solute transport in the apicomplexan parasite Plasmodium. Emerg Top Life Sci 2017; 1:553-561. [PMID: 33525850 DOI: 10.1042/etls20170097] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2017] [Revised: 11/12/2017] [Accepted: 11/16/2017] [Indexed: 12/22/2022]
Abstract
Apicomplexa are a large group of eukaryotic, single-celled parasites, with complex life cycles that occur within a wide range of different microenvironments. They include important human pathogens such as Plasmodium, the causal agent of malaria, and Toxoplasma, which causes toxoplasmosis most often in immunocompromised individuals. Despite environmental differences in their life cycles, these parasites retain the ability to obtain nutrients, remove waste products, and control ion balances. They achieve this flexibility by relying on proteins that can deliver and remove solutes. This reliance on transport proteins for essential functions makes these pathways excellent potential targets for drug development programmes. Transport proteins are frequently key mediators of drug resistance by their ability to remove drugs from their sites of action. The study of transport processes mediated by integral membrane proteins and, in particular, identification of their physiological functions and localisation, and differentiation from host orthologues has already established new validated drug targets. Our understanding of how apicomplexan parasites have adapted to changing environmental challenges has also increased through the study of their transporters. This brief introduction to membrane transporters of apicomplexans highlights recent discoveries focusing on Plasmodium and emphasises future directions.
Collapse
|
70
|
Abdi A, Yu L, Goulding D, Rono MK, Bejon P, Choudhary J, Rayner J. Proteomic analysis of extracellular vesicles from a Plasmodium falciparum Kenyan clinical isolate defines a core parasite secretome. Wellcome Open Res 2017; 2:50. [PMID: 28944300 PMCID: PMC5583745 DOI: 10.12688/wellcomeopenres.11910.2] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/23/2017] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Many pathogens secrete effector molecules to subvert host immune responses, to acquire nutrients, and/or to prepare host cells for invasion. One of the ways that effector molecules are secreted is through extracellular vesicles (EVs) such as exosomes. Recently, the malaria parasite P. falciparum has been shown to produce EVs that can mediate transfer of genetic material between parasites and induce sexual commitment. Characterizing the content of these vesicles may improve our understanding of P. falciparum pathogenesis and virulence. METHODS Previous studies of P. falciparum EVs have been limited to long-term adapted laboratory isolates. In this study, we isolated EVs from a Kenyan P. falciparum clinical isolate adapted to in vitro culture for a short period and characterized their protein content by mass spectrometry (data are available via ProteomeXchange, with identifier PXD006925). RESULTS We show that P. falciparum extracellular vesicles ( PfEVs) are enriched in proteins found within the exomembrane compartments of infected erythrocytes such as Maurer's clefts (MCs), as well as the secretory endomembrane compartments in the apical end of the merozoites, suggesting that these proteins play a role in parasite-host interactions. Comparison of this novel clinically relevant dataset with previously published datasets helps to define a core secretome present in Plasmodium EVs. CONCLUSIONS P. falciparum extracellular vesicles contain virulence-associated parasite proteins. Therefore, analysis of PfEVs contents from a range of clinical isolates, and their functional validation may improve our understanding of the virulence mechanisms of the parasite, and potentially identify targets for interventions or diagnostics.
Collapse
Affiliation(s)
- Abdirahman Abdi
- Pwani University Bioscience Research Centre, Pwani University, Kilifi, Kenya.,KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Lu Yu
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - David Goulding
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Martin K Rono
- Pwani University Bioscience Research Centre, Pwani University, Kilifi, Kenya.,KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Philip Bejon
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Jyoti Choudhary
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Julian Rayner
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| |
Collapse
|
71
|
Abdi A, Yu L, Goulding D, Rono MK, Bejon P, Choudhary J, Rayner J. Proteomic analysis of extracellular vesicles from a Plasmodium falciparum Kenyan clinical isolate defines a core parasite secretome. Wellcome Open Res 2017. [PMID: 28944300 DOI: 10.12688/wellcomeopenres.11910.1] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Many pathogens secrete effector molecules to subvert host immune responses, to acquire nutrients, and/or to prepare host cells for invasion. One of the ways that effector molecules are secreted is through extracellular vesicles (EVs) such as exosomes. Recently, the malaria parasite P. falciparum has been shown to produce EVs that can mediate transfer of genetic material between parasites and induce sexual commitment. Characterizing the content of these vesicles may improve our understanding of P. falciparum pathogenesis and virulence. METHODS Previous studies of P. falciparum EVs have been limited to long-term adapted laboratory isolates. In this study, we isolated EVs from a Kenyan P. falciparum clinical isolate adapted to in vitro culture for a short period and characterized their protein content by mass spectrometry (data are available via ProteomeXchange, with identifier PXD006925). RESULTS We show that P. falciparum extracellular vesicles ( PfEVs) are enriched in proteins found within the exomembrane compartments of infected erythrocytes such as Maurer's clefts (MCs), as well as the secretory endomembrane compartments in the apical end of the merozoites, suggesting that these proteins play a role in parasite-host interactions. Comparison of this novel clinically relevant dataset with previously published datasets helps to define a core secretome present in Plasmodium EVs. CONCLUSIONS P. falciparum extracellular vesicles contain virulence-associated parasite proteins. Therefore, analysis of PfEVs contents from a range of clinical isolates, and their functional validation may improve our understanding of the virulence mechanisms of the parasite, and potentially identify targets for interventions or diagnostics.
Collapse
Affiliation(s)
- Abdirahman Abdi
- Pwani University Bioscience Research Centre, Pwani University, Kilifi, Kenya.,KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Lu Yu
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - David Goulding
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Martin K Rono
- Pwani University Bioscience Research Centre, Pwani University, Kilifi, Kenya.,KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Philip Bejon
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Jyoti Choudhary
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Julian Rayner
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| |
Collapse
|
72
|
Leba LJ, Popovici J, Estevez Y, Pelleau S, Legrand E, Musset L, Duplais C. Antiplasmodial activities of dyes against Plasmodium falciparum asexual and sexual stages: Contrasted uptakes of triarylmethanes Brilliant green, Green S (E142), and Patent Blue V (E131) by erythrocytes. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2017; 7:314-320. [PMID: 28886443 PMCID: PMC5587875 DOI: 10.1016/j.ijpddr.2017.07.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Revised: 07/27/2017] [Accepted: 07/31/2017] [Indexed: 11/07/2022]
Abstract
The search for safe antimalarial compounds acting against asexual symptom-responsible stages and sexual transmission-responsible forms of Plasmodium species is one of the major challenges in malaria elimination programs. So far, among current drugs approved for human use, only primaquine has transmission-blocking activity. The discovery of small molecules targeting different Plasmodium falciparum life stages remains a priority in antimalarial drug research. In this context, several independent studies have recently reported antiplasmodial and transmission-blocking activities of commonly used stains, dyes and fluorescent probes against P. falciparum including chloroquine-resistant isolates. Herein we have studied the antimalarial activities of dyes with different scaffold and we report that the triarylmethane dye (TRAM) Brilliant green inhibits the growth of asexual stages (IC50 ≤ 2 μM) and has exflagellation-blocking activity (IC50 ≤ 800 nM) against P. falciparum reference strains (3D7, 7G8) and chloroquine-resistant clinical isolate (Q206). In a second step we have investigated the antiplasmodial activities of two polysulfonated triarylmethane food dyes. Green S (E142) is weakly active against P. falciparum asexual stage (IC50 ≃ 17 μM) whereas Patent Blue V (E131) is inactive in both antimalarial assays. By applying liquid chromatography techniques for the culture supernatant analysis after cell washings and lysis, we report the detection of Brilliant green in erythrocytes, the selective uptake of Green S (E142) by infected erythrocytes, whereas Patent Blue V (E131) could not be detected within non-infected and 3D7-infected erythrocytes. Overall, our results suggest that two polysulfonated food dyes might display different affinity with transporters or channels on infected RBC membrane. Dyes are tested against P. falciparum 3D7, 7G8 lines, CQ-resistant field isolate Q206. Brilliant green is active against asexual and sexual stages of Plasmodium falciparum. Food dye Green S (E142) is weakly active against Plasmodium falciparum asexual forms. Food dye Green S (E142) is found in the cellular content of infected erythrocytes. Polysulfonated triarylmethane possibly interact with plasmodial surface anion channel.
Collapse
Affiliation(s)
- Louis-Jérôme Leba
- Laboratoire de parasitologie, CNR du paludisme, Institut Pasteur de la Guyane, Cayenne, French Guiana, France; UMR QualiSud, Université de Guyane, 97300 Cayenne, France
| | - Jean Popovici
- Malaria Molecular Epidemiology Unit, Institut Pasteur in Cambodia, Phnom Penh, Cambodia
| | - Yannick Estevez
- CNRS, UMR8172 EcoFoG, AgroParisTech, Cirad, INRA, Université des Antilles, Université de Guyane, 97300 Cayenne, French Guiana, France
| | - Stéphane Pelleau
- Laboratoire de parasitologie, CNR du paludisme, Institut Pasteur de la Guyane, Cayenne, French Guiana, France
| | - Eric Legrand
- Laboratoire de parasitologie, CNR du paludisme, Institut Pasteur de la Guyane, Cayenne, French Guiana, France; Research Unit of Genetics and Genomics of Insect Vectors Institut Pasteur, Paris, France
| | - Lise Musset
- Laboratoire de parasitologie, CNR du paludisme, Institut Pasteur de la Guyane, Cayenne, French Guiana, France
| | - Christophe Duplais
- CNRS, UMR8172 EcoFoG, AgroParisTech, Cirad, INRA, Université des Antilles, Université de Guyane, 97300 Cayenne, French Guiana, France.
| |
Collapse
|
73
|
Santos JM, Josling G, Ross P, Joshi P, Orchard L, Campbell T, Schieler A, Cristea IM, Llinás M. Red Blood Cell Invasion by the Malaria Parasite Is Coordinated by the PfAP2-I Transcription Factor. Cell Host Microbe 2017; 21:731-741.e10. [PMID: 28618269 PMCID: PMC5855115 DOI: 10.1016/j.chom.2017.05.006] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Revised: 02/16/2017] [Accepted: 05/23/2017] [Indexed: 10/19/2022]
Abstract
Obligate intracellular parasites must efficiently invade host cells in order to mature and be transmitted. For the malaria parasite Plasmodium falciparum, invasion of host red blood cells (RBCs) is essential. Here we describe a parasite-specific transcription factor PfAP2-I, belonging to the Apicomplexan AP2 (ApiAP2) family, that is responsible for regulating the expression of genes involved in RBC invasion. Our genome-wide analysis by ChIP-seq shows that PfAP2-I interacts with a specific DNA motif in the promoters of target genes. Although PfAP2-I contains three AP2 DNA-binding domains, only one is required for binding of the target genes during blood stage development. Furthermore, we find that PfAP2-I associates with several chromatin-associated proteins, including the Plasmodium bromodomain protein PfBDP1 and that complex formation is associated with transcriptional regulation. As a key regulator of red blood cell invasion, PfAP2-I represents a potential new antimalarial therapeutic target.
Collapse
Affiliation(s)
- Joana Mendonca Santos
- Department of Biochemistry and Molecular Biology and Huck Center for Malaria Research, Pennsylvania State University, State College, PA 16802, USA; Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA; Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA
| | - Gabrielle Josling
- Department of Biochemistry and Molecular Biology and Huck Center for Malaria Research, Pennsylvania State University, State College, PA 16802, USA
| | - Philipp Ross
- Department of Biochemistry and Molecular Biology and Huck Center for Malaria Research, Pennsylvania State University, State College, PA 16802, USA
| | - Preeti Joshi
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | - Lindsey Orchard
- Department of Biochemistry and Molecular Biology and Huck Center for Malaria Research, Pennsylvania State University, State College, PA 16802, USA
| | - Tracey Campbell
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA; Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA
| | - Ariel Schieler
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA; Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA
| | - Ileana M Cristea
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | - Manuel Llinás
- Department of Biochemistry and Molecular Biology and Huck Center for Malaria Research, Pennsylvania State University, State College, PA 16802, USA; Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA; Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA; Department of Chemistry and Huck Center for Infectious Disease Dynamics, Pennsylvania State University, State College, PA 16802, USA.
| |
Collapse
|
74
|
Sherling ES, Knuepfer E, Brzostowski JA, Miller LH, Blackman MJ, van Ooij C. The Plasmodium falciparum rhoptry protein RhopH3 plays essential roles in host cell invasion and nutrient uptake. eLife 2017; 6. [PMID: 28252384 PMCID: PMC5365315 DOI: 10.7554/elife.23239] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2016] [Accepted: 02/26/2017] [Indexed: 11/18/2022] Open
Abstract
Merozoites of the protozoan parasite responsible for the most virulent form of malaria, Plasmodium falciparum, invade erythrocytes. Invasion involves discharge of rhoptries, specialized secretory organelles. Once intracellular, parasites induce increased nutrient uptake by generating new permeability pathways (NPP) including a Plasmodium surface anion channel (PSAC). RhopH1/Clag3, one member of the three-protein RhopH complex, is important for PSAC/NPP activity. However, the roles of the other members of the RhopH complex in PSAC/NPP establishment are unknown and it is unclear whether any of the RhopH proteins play a role in invasion. Here we demonstrate that RhopH3, the smallest component of the complex, is essential for parasite survival. Conditional truncation of RhopH3 substantially reduces invasive capacity. Those mutant parasites that do invade are defective in nutrient import and die. Our results identify a dual role for RhopH3 that links erythrocyte invasion to formation of the PSAC/NPP essential for parasite survival within host erythrocytes. DOI:http://dx.doi.org/10.7554/eLife.23239.001 Malaria is a life-threatening disease that affects millions of people around the world. The parasites that cause malaria have a complex life cycle that involves infecting both mosquitoes and mammals, including humans. In humans, the parasites spend part of their life cycle inside red blood cells, which causes the symptoms of the disease. In order to survive and multiply, malaria parasites need to make the red blood cell more permeable so that it can absorb nutrients from the blood stream and get rid of the toxic waste products they generate. It remains unclear how the parasites do this, but previous research has shown that the parasites produce channel-like proteins that make red blood cells more permeable to nutrients. One of the proteins involved in this process forms part of a complex with two other proteins, called RhopH2 and RhopH3. It is not known what these other two proteins do, and whether they are necessary for creating the new nutrient channels. Sherling et al. studied the RhopH3 protein to see if it is required to make red blood cells more permeable. The experiments used a genetically modified version of the parasite, in which RhopH3 no longer interacted with the two other proteins. The findings show that RhopH3 has two important roles: first, parasites need it to invade the red blood cells, and second, parasites cannot get nutrients into the red blood cell without RhopH3. Most antimalarial drugs work by preventing parasite replication in red blood cells, but parasites are becoming increasingly resistant to these drugs. Understanding which proteins allow parasites to invade and grow within blood cells will further the development of new malaria medication. The next step will be to understand the molecular mechanisms by which RhopH3 promotes invasion and subsequently facilitates nutrient uptake, and will help researchers to explore its potential as a drug target. DOI:http://dx.doi.org/10.7554/eLife.23239.002
Collapse
Affiliation(s)
- Emma S Sherling
- Malaria Biochemistry Laboratory, The Francis Crick Institute, London, United Kingdom.,Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, United States
| | - Ellen Knuepfer
- Malaria Parasitology Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Joseph A Brzostowski
- Laboratory of Immunogenetics Imaging Facility, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, United States
| | - Louis H Miller
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, United States
| | - Michael J Blackman
- Malaria Biochemistry Laboratory, The Francis Crick Institute, London, United Kingdom.,Department of Pathogen Molecular Biology, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Christiaan van Ooij
- Malaria Biochemistry Laboratory, The Francis Crick Institute, London, United Kingdom
| |
Collapse
|
75
|
Counihan NA, Chisholm SA, Bullen HE, Srivastava A, Sanders PR, Jonsdottir TK, Weiss GE, Ghosh S, Crabb BS, Creek DJ, Gilson PR, de Koning-Ward TF. Plasmodium falciparum parasites deploy RhopH2 into the host erythrocyte to obtain nutrients, grow and replicate. eLife 2017; 6. [PMID: 28252383 PMCID: PMC5365316 DOI: 10.7554/elife.23217] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2016] [Accepted: 02/26/2017] [Indexed: 11/13/2022] Open
Abstract
Plasmodium falciparum parasites, the causative agents of malaria, modify their host erythrocyte to render them permeable to supplementary nutrient uptake from the plasma and for removal of toxic waste. Here we investigate the contribution of the rhoptry protein RhopH2, in the formation of new permeability pathways (NPPs) in Plasmodium-infected erythrocytes. We show RhopH2 interacts with RhopH1, RhopH3, the erythrocyte cytoskeleton and exported proteins involved in host cell remodeling. Knockdown of RhopH2 expression in cycle one leads to a depletion of essential vitamins and cofactors and decreased de novo synthesis of pyrimidines in cycle two. There is also a significant impact on parasite growth, replication and transition into cycle three. The uptake of solutes that use NPPs to enter erythrocytes is also reduced upon RhopH2 knockdown. These findings provide direct genetic support for the contribution of the RhopH complex in NPP activity and highlight the importance of NPPs to parasite survival.
Collapse
Affiliation(s)
| | | | | | - Anubhav Srivastava
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia
| | | | - Thorey K Jonsdottir
- Burnet Institute, Melbourne, Australia.,Department of Medicine, University of Melbourne, Parkville, Australia
| | | | - Sreejoyee Ghosh
- School of Medicine, Deakin University, Waurn Ponds, Australia
| | - Brendan S Crabb
- Burnet Institute, Melbourne, Australia.,Department of Medicine, University of Melbourne, Parkville, Australia.,Monash University, Melbourne, Australia
| | - Darren J Creek
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia
| | - Paul R Gilson
- Burnet Institute, Melbourne, Australia.,Monash University, Melbourne, Australia
| | | |
Collapse
|