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Yahiya S, Saunders CN, Hassan S, Straschil U, Fischer OJ, Rueda-Zubiaurre A, Haase S, Vizcay-Barrena G, Famodimu MT, Jordan S, Delves MJ, Tate EW, Barnard A, Fuchter MJ, Baum J. A novel class of sulphonamides potently block malaria transmission by targeting a Plasmodium vacuole membrane protein. Dis Model Mech 2023; 16:dmm049950. [PMID: 36715290 PMCID: PMC9934914 DOI: 10.1242/dmm.049950] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Accepted: 12/13/2022] [Indexed: 01/31/2023] Open
Abstract
Phenotypic cell-based screens are critical tools for discovering candidate drugs for development, yet identification of the cellular target and mode of action of a candidate drug is often lacking. Using an imaging-based screen, we recently discovered an N-[(4-hydroxychroman-4-yl)methyl]-sulphonamide (N-4HCS) compound, DDD01035881, that blocks male gamete formation in the malaria parasite life cycle and subsequent transmission of the parasite to the mosquito with nanomolar activity. To identify the target(s) of DDD01035881, and of the N-4HCS class of compounds more broadly, we synthesised a photoactivatable derivative, probe 2. Photoaffinity labelling of probe 2 coupled with mass spectrometry identified the 16 kDa Plasmodium falciparum parasitophorous vacuole membrane protein Pfs16 as a potential parasite target. Complementary methods including cellular thermal shift assays confirmed that the parent molecule DDD01035881 stabilised Pfs16 in lysates from activated mature gametocytes. Combined with high-resolution, fluorescence and electron microscopy data, which demonstrated that parasites inhibited with N-4HCS compounds phenocopy the targeted deletion of Pfs16 in gametocytes, these data implicate Pfs16 as a likely target of DDD01035881. This finding establishes N-4HCS compounds as being flexible and effective starting candidates from which transmission-blocking antimalarials can be developed in the future.
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Affiliation(s)
- Sabrina Yahiya
- Department of Life Sciences, Imperial College London, Sir Alexander Fleming Building, Exhibition Road, South Kensington, London SW7 2AZ, UK
| | - Charlie N. Saunders
- Department of Life Sciences, Imperial College London, Sir Alexander Fleming Building, Exhibition Road, South Kensington, London SW7 2AZ, UK
- Department of Chemistry, Imperial College London, Molecular Sciences Research Hub, White City Campus, Wood Lane, London W12 OBZ, UK
| | - Sarah Hassan
- Department of Chemistry, Imperial College London, Molecular Sciences Research Hub, White City Campus, Wood Lane, London W12 OBZ, UK
| | - Ursula Straschil
- Department of Life Sciences, Imperial College London, Sir Alexander Fleming Building, Exhibition Road, South Kensington, London SW7 2AZ, UK
| | - Oliver J. Fischer
- Department of Chemistry, Imperial College London, Molecular Sciences Research Hub, White City Campus, Wood Lane, London W12 OBZ, UK
| | - Ainoa Rueda-Zubiaurre
- Department of Chemistry, Imperial College London, Molecular Sciences Research Hub, White City Campus, Wood Lane, London W12 OBZ, UK
| | - Silvia Haase
- Department of Life Sciences, Imperial College London, Sir Alexander Fleming Building, Exhibition Road, South Kensington, London SW7 2AZ, UK
| | - Gema Vizcay-Barrena
- Centre for Ultrastructural Imaging, New Hunt's House, Guy's Campus, King's College London, London SE1 1UL, UK
| | - Mufuliat Toyin Famodimu
- Department of Life Sciences, Imperial College London, Sir Alexander Fleming Building, Exhibition Road, South Kensington, London SW7 2AZ, UK
| | - Sarah Jordan
- Department of Life Sciences, Imperial College London, Sir Alexander Fleming Building, Exhibition Road, South Kensington, London SW7 2AZ, UK
| | - Michael J. Delves
- Department of Life Sciences, Imperial College London, Sir Alexander Fleming Building, Exhibition Road, South Kensington, London SW7 2AZ, UK
| | - Edward W. Tate
- Department of Chemistry, Imperial College London, Molecular Sciences Research Hub, White City Campus, Wood Lane, London W12 OBZ, UK
| | - Anna Barnard
- Department of Chemistry, Imperial College London, Molecular Sciences Research Hub, White City Campus, Wood Lane, London W12 OBZ, UK
| | - Matthew J. Fuchter
- Department of Chemistry, Imperial College London, Molecular Sciences Research Hub, White City Campus, Wood Lane, London W12 OBZ, UK
| | - Jake Baum
- Department of Life Sciences, Imperial College London, Sir Alexander Fleming Building, Exhibition Road, South Kensington, London SW7 2AZ, UK
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2
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PfSRPK1 Regulates Asexual Blood Stage Schizogony and Is Essential for Male Gamete Formation. Microbiol Spectr 2022; 10:e0214122. [PMID: 36094218 PMCID: PMC9602455 DOI: 10.1128/spectrum.02141-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Serine/arginine-rich protein kinases (SRPKs) are cell cycle-regulated serine/threonine protein kinases and are important regulators of splicing factors. In this study, we functionally characterize SRPK1 of the human malaria parasite Plasmodium falciparum. P. falciparum SRPK1 (PfSRPK1) was expressed in asexual blood-stage and sexual-stage gametocytes. Pfsrpk1- parasites formed asexual schizonts that generated far fewer merozoites than wild-type parasites, causing reduced replication rates. Pfsrpk1- parasites also showed a severe defect in the differentiation of male gametes, causing a complete block in parasite transmission to mosquitoes. RNA sequencing (RNA-seq) analysis of wild-type PfNF54 and Pfsrpk1- stage V gametocytes suggested a role for PfSRPK1 in regulating transcript splicing and transcript abundance of genes coding for (i) microtubule/cilium morphogenesis-related proteins, (ii) proteins involved in cyclic nucleotide metabolic processes, (iii) proteins involved in signaling such as PfMAP2, (iv) lipid metabolism enzymes, (v) proteins of osmophilic bodies, and (vi) crystalloid components. Our study reveals an essential role for PfSRPK1 in parasite cell morphogenesis and suggests this kinase as a target to prevent malaria transmission from humans to mosquitoes. IMPORTANCE Plasmodium sexual stages represent a critical bottleneck in the parasite life cycle. Gametocytes taken up in an infectious blood meal by female anopheline mosquito get activated to form gametes and fuse to form short-lived zygotes, which transform into ookinetes to infect mosquitoes. In the present study, we demonstrate that PfSRPK1 is important for merozoite formation and critical for male gametogenesis and is involved in transcript homeostasis for numerous parasite genes. Targeting PfSRPK1 and its downstream pathways may reduce parasite replication and help achieve effective malaria transmission-blocking strategies.
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PfARID Regulates P. falciparum Malaria Parasite Male Gametogenesis and Female Fertility and Is Critical for Parasite Transmission to the Mosquito Vector. mBio 2022; 13:e0057822. [PMID: 35638735 PMCID: PMC9239086 DOI: 10.1128/mbio.00578-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Sexual reproduction of Plasmodium falciparum parasites is critical to the spread of malaria in the human population. The factors that regulate gene expression underlying formation of fertilization-competent gametes, however, remain unknown. Here, we report that P. falciparum expresses a protein with an AT-rich interaction domain (ARID) which, in other organisms, is part of chromatin remodeling complexes. P. falciparum ARID (PfARID) localized to the parasite nucleus and is critical for the formation of male gametes and fertility of female gametes. PfARID gene deletion (Pfarid–) gametocytes showed downregulation of gene expression important for gametogenesis, antigenic variation, and cell signaling and for parasite development in the mosquito. Our study identifies PfARID as a critical nuclear protein involved in regulating the gene expression landscape of mature gametocytes. This establishes fertility and also prepares the parasite for postfertilization events that are essential for infection of the mosquito vector.
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An In Silico Analysis of Malaria Pre-Erythrocytic-Stage Antigens Interpreting Worldwide Genetic Data to Suggest Vaccine Candidate Variants and Epitopes. Microorganisms 2022; 10:microorganisms10061090. [PMID: 35744609 PMCID: PMC9231253 DOI: 10.3390/microorganisms10061090] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 05/12/2022] [Accepted: 05/19/2022] [Indexed: 02/05/2023] Open
Abstract
Failure to account for genetic diversity of antigens during vaccine design may lead to vaccine escape. To evaluate the vaccine escape potential of antigens used in vaccines currently in development or clinical testing, we surveyed the genetic diversity, measured population differentiation, and performed in silico prediction and analysis of T-cell epitopes of ten such Plasmodium falciparum pre-erythrocytic-stage antigens using whole-genome sequence data from 1010 field isolates. Of these, 699 were collected in Africa (Burkina Faso, Cameroon, Guinea, Kenya, Malawi, Mali, and Tanzania), 69 in South America (Brazil, Colombia, French Guiana, and Peru), 59 in Oceania (Papua New Guinea), and 183 in Asia (Cambodia, Myanmar, and Thailand). Antigens surveyed include cell-traversal protein for ookinetes and sporozoites, circumsporozoite protein, liver-stage antigens 1 and 3, sporozoite surface proteins P36 and P52, sporozoite asparagine-rich protein-1, sporozoite microneme protein essential for cell traversal-2, and upregulated-in-infectious-sporozoite 3 and 4 proteins. The analyses showed that a limited number of these protein variants, when combined, would be representative of worldwide parasite populations. Moreover, predicted T-cell epitopes were identified that could be further explored for immunogenicity and protective efficacy. Findings can inform the rational design of a multivalent malaria vaccine.
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5
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Goswami D, Kumar S, Betz W, Armstrong JM, Haile MT, Camargo N, Parthiban C, Seilie AM, Murphy SC, Vaughan AM, Kappe SH. A Plasmodium falciparum ATP binding cassette transporter is essential for liver stage entry into schizogony. iScience 2022; 25:104224. [PMID: 35521513 PMCID: PMC9061783 DOI: 10.1016/j.isci.2022.104224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 03/01/2022] [Accepted: 04/06/2022] [Indexed: 11/27/2022] Open
Abstract
Plasmodium sporozoites invade hepatocytes and transform into liver stages within a parasitophorous vacuole (PV). The parasites then grow and replicate their genome to form exoerythrocytic merozoites that infect red blood cells. We report that the human malaria parasite Plasmodium falciparum (Pf) expresses a C-type ATP-binding cassette transporter, Pf ABCC2, which marks the transition from invasive sporozoite to intrahepatocytic early liver stage. Using a humanized mouse infection model, we show that Pf ABCC2 localizes to the parasite plasma membrane in early and mid-liver stage parasites but is not detectable in late liver stages. Pf abcc2— sporozoites invade hepatocytes, form a PV, and transform into liver stage trophozoites but cannot transition to exoerythrocytic schizogony and fail to transition to blood stage infection. Thus, Pf ABCC2 is an expression marker for early phases of parasite liver infection and plays an essential role in the successful initiation of liver stage replication. Pf ABCC2 expression marks the transition from sporozoite to early liver stage Pf ABCC2 localizes to the early and mid-liver stage plasma membrane Pf ABCC2 is critical for initiation of exoerythrocytic schizogony Pf abcc2– liver stages fail to transition to blood stage infection
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6
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Plasmodium falciparum Calcium-Dependent Protein Kinase 4 is Critical for Male Gametogenesis and Transmission to the Mosquito Vector. mBio 2021; 12:e0257521. [PMID: 34724830 PMCID: PMC8561384 DOI: 10.1128/mbio.02575-21] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Gametocytes of the malaria parasite Plasmodium are taken up by the mosquito vector with an infectious blood meal, representing a critical stage for parasite transmission. Calcium-independent protein kinases (CDPKs) play key roles in calcium-mediated signaling across the complex life cycle of the parasite. We sought to understand their role in human parasite transmission from the host to the mosquito vector and thus investigated the role of the human-infective parasite Plasmodium falciparum CDPK4 in the parasite life cycle. P. falciparumcdpk4− parasites created by targeted gene deletion showed no effect in blood stage development or gametocyte development. However, cdpk4− parasites showed a severe defect in male gametogenesis and the emergence of flagellated male gametes. To understand the molecular underpinnings of this defect, we performed mass spectrometry-based phosphoproteomic analyses of wild-type and Plasmodium falciparumcdpk4− late gametocyte stages to identify key CDPK4-mediated phosphorylation events that may be important for the regulation of male gametogenesis. We further employed in vitro assays to identify these putative substrates of Plasmodium falciparum CDPK4. This indicated that CDPK4 regulates male gametogenesis by directly or indirectly controlling key essential events, such as DNA replication, mRNA translation, and cell motility. Taken together, our work demonstrates that PfCDPK4 is a central kinase that regulates exflagellation and thereby is critical for parasite transmission to the mosquito vector.
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7
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Brandsma AM, Hilmer C, Rauch M, Matuschewski K, Montagna GN. Plasmodium early transcribed membrane proteins appear tailored to the host range of malaria parasites. Int J Parasitol 2021; 52:135-143. [PMID: 34715088 DOI: 10.1016/j.ijpara.2021.08.005] [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: 04/15/2021] [Revised: 08/11/2021] [Accepted: 08/18/2021] [Indexed: 11/05/2022]
Abstract
Early transcribed membrane proteins form a unique protein family in malaria parasites. These molecules are expressed during Plasmodium intracellular phases and inserted at the parasite parasitophorus vacuole membrane, which constitutes the host-parasite interface. Upregulated in infectious sporozoites 4 (UIS4) is an essential early transcribed membrane protein of liver stages of the murine malaria model parasite Plasmodium berghei. Despite its relevance for liver stage maturation, the molecular functions of UIS4 remain elusive, and UIS4 orthologs in human malaria parasites have not yet been identified. In order to characterise functional domains of UIS4, we generated P. berghei parasites carrying a carboxy-terminally truncated version of UIS4. We observed that uis4Δc parasites are severely impaired in liver stage development, similar to uis4(-) parasites, indicating an important role of the C-terminal domain for UIS4 function. To test whether members of the P. falciparum early transcribed membrane protein family are potential UIS4 orthologs, we selected candidates based on structural homology and parasitophorous vacuole membrane localization. We generated transgenic P. berghei parasites where UIS4 was replaced by Plasmodium falciparum ETRAMP8 or ETRAMP10.3. Both early transcribed membrane proteins were expressed in transgenic parasite lines, but liver stage maturation was impaired, indicating that the selected early transcribed membrane proteins failed to substitute the function of UIS4. As a control, we included the UIS4 ortholog from the murine parasite Plasmodium chaubaudi. We observed that PcUIS4 successfully restores UIS4 function in P. berghei. Together, these results suggest that Plasmodium parasites express tailor-made parasitophorous vacuole membrane proteins that might at least partially explain the narrow host range of malaria parasites.
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Affiliation(s)
- Arianne M Brandsma
- Parasitology Unit, Max Planck Institute for Infection Biology, 10117 Berlin, Germany; Princess Máxima Center for Pediatric Oncology, Heidelberg 25, 3584 CS Utrecht, The Netherlands
| | - Cecilie Hilmer
- Parasitology Unit, Max Planck Institute for Infection Biology, 10117 Berlin, Germany
| | - Manuel Rauch
- Parasitology Unit, Max Planck Institute for Infection Biology, 10117 Berlin, Germany; Dept. of Molecular Parasitology, Institute of Biology, Humboldt University, 10115 Berlin, Germany
| | - Kai Matuschewski
- Parasitology Unit, Max Planck Institute for Infection Biology, 10117 Berlin, Germany; Dept. of Molecular Parasitology, Institute of Biology, Humboldt University, 10115 Berlin, Germany
| | - Georgina N Montagna
- Parasitology Unit, Max Planck Institute for Infection Biology, 10117 Berlin, Germany; Instituto de Investigaciones Biotecnológicas Dr Rodolfo Ugalde' (IIBio), UNSAM-CONICET 1650 San Martín, Buenos Aires, Argentina.
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8
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Gadalla AAH, Siciliano G, Farid R, Alano P, Ranford-Cartwright L, McCarthy JS, Thompson J, Babiker HA. Real-time PCR assays for detection and quantification of early P. falciparum gametocyte stages. Sci Rep 2021; 11:19118. [PMID: 34580326 PMCID: PMC8476600 DOI: 10.1038/s41598-021-97456-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 08/25/2021] [Indexed: 11/11/2022] Open
Abstract
The use of quantitative qRT-PCR assays for detection and quantification of late gametocyte stages has revealed the high transmission capacity of the human malaria parasite, Plasmodium falciparum. To understand how the parasite adjusts its transmission in response to in-host environmental conditions including antimalarials requires simultaneous quantification of early and late gametocytes. Here, we describe qRT-PCR assays that specifically detect and quantify early-stage P. falciparum gametocytes. The assays are based on expression of known early and late gametocyte genes and were developed using purified stage II and stage V gametocytes and tested in natural and controlled human infections. Genes pfpeg4 and pfg27 are specifically expressed at significant levels in early gametocytes with a limit of quantification of 190 and 390 gametocytes/mL, respectively. In infected volunteers, transcripts of pfpeg4 and pfg27 were detected shortly after the onset of blood stage infection. In natural infections, both early (pfpeg4/pfg27) and late gametocyte transcripts (pfs25) were detected in 71.2% of individuals, only early gametocyte transcripts in 12.6%, and only late gametocyte transcripts in 15.2%. The pfpeg4/pfg27 qRT-PCR assays are sensitive and specific for quantification of circulating sexually committed ring stages/early gametocytes and can be used to increase our understanding of epidemiological processes that modulate P. falciparum transmission.
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Affiliation(s)
- Amal A H Gadalla
- College of Medicine and Health Sciences, Sultan Qaboos University, Muscat, Oman.,Division of Population Medicine, School of Medicine, College of Biomedical Sciences, Cardiff University, Cardiff, UK
| | - Giulia Siciliano
- Dipartimento di Malattie Infettive, Istituto Superiore di Sanità, Rome, Italy
| | - Ryan Farid
- QIMR Berghofer Medical Research Institute and University of Queensland, Brisbane, Australia
| | - Pietro Alano
- Dipartimento di Malattie Infettive, Istituto Superiore di Sanità, Rome, Italy
| | - Lisa Ranford-Cartwright
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - James S McCarthy
- QIMR Berghofer Medical Research Institute and University of Queensland, Brisbane, Australia
| | - Joanne Thompson
- Institute of Immunology and Infection Research, School of Biological Sciences, Ashworth Laboratories, University of Edinburgh, Edinburgh, UK
| | - Hamza A Babiker
- College of Medicine and Health Sciences, Sultan Qaboos University, Muscat, Oman.
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9
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Kolli SK, Salman AM, Ramesar J, Chevalley-Maurel S, Kroeze H, Geurten FGA, Miyazaki S, Mukhopadhyay E, Marin-Mogollon C, Franke-Fayard B, Hill AVS, Janse CJ. Screening of viral-vectored P. falciparum pre-erythrocytic candidate vaccine antigens using chimeric rodent parasites. PLoS One 2021; 16:e0254498. [PMID: 34252120 PMCID: PMC8274855 DOI: 10.1371/journal.pone.0254498] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Accepted: 06/28/2021] [Indexed: 11/19/2022] Open
Abstract
To screen for additional vaccine candidate antigens of Plasmodium pre-erythrocytic stages, fourteen P. falciparum proteins were selected based on expression in sporozoites or their role in establishment of hepatocyte infection. For preclinical evaluation of immunogenicity of these proteins in mice, chimeric P. berghei sporozoites were created that express the P. falciparum proteins in sporozoites as an additional copy gene under control of the uis4 gene promoter. All fourteen chimeric parasites produced sporozoites but sporozoites of eight lines failed to establish a liver infection, indicating a negative impact of these P. falciparum proteins on sporozoite infectivity. Immunogenicity of the other six proteins (SPELD, ETRAMP10.3, SIAP2, SPATR, HT, RPL3) was analyzed by immunization of inbred BALB/c and outbred CD-1 mice with viral-vectored (ChAd63 or ChAdOx1, MVA) vaccines, followed by challenge with chimeric sporozoites. Protective immunogenicity was determined by analyzing parasite liver load and prepatent period of blood stage infection after challenge. Of the six proteins only SPELD immunized mice showed partial protection. We discuss both the low protective immunogenicity of these proteins in the chimeric rodent malaria challenge model and the negative effect on P. berghei sporozoite infectivity of several P. falciparum proteins expressed in the chimeric sporozoites.
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Affiliation(s)
- Surendra Kumar Kolli
- Department of Parasitology, Leiden University Medical Center, Leiden, Netherlands
| | - Ahmed M. Salman
- Nuffield Department of Medicine, The Jenner Institute, University of Oxford, Oxford, United Kingdom
| | - Jai Ramesar
- Department of Parasitology, Leiden University Medical Center, Leiden, Netherlands
| | | | - Hans Kroeze
- Department of Parasitology, Leiden University Medical Center, Leiden, Netherlands
| | - Fiona G. A. Geurten
- Department of Parasitology, Leiden University Medical Center, Leiden, Netherlands
| | - Shinya Miyazaki
- Department of Parasitology, Leiden University Medical Center, Leiden, Netherlands
| | - Ekta Mukhopadhyay
- Nuffield Department of Medicine, The Jenner Institute, University of Oxford, Oxford, United Kingdom
| | | | | | - Adrian V. S. Hill
- Nuffield Department of Medicine, The Jenner Institute, University of Oxford, Oxford, United Kingdom
| | - Chris J. Janse
- Department of Parasitology, Leiden University Medical Center, Leiden, Netherlands
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10
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McLean KJ, Straimer J, Hopp CS, Vega-Rodriguez J, Small-Saunders JL, Kanatani S, Tripathi A, Mlambo G, Dumoulin PC, Harris CT, Tong X, Shears MJ, Ankarklev J, Kafsack BFC, Fidock DA, Sinnis P. Generation of Transmission-Competent Human Malaria Parasites with Chromosomally-Integrated Fluorescent Reporters. Sci Rep 2019; 9:13131. [PMID: 31511546 PMCID: PMC6739413 DOI: 10.1038/s41598-019-49348-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Accepted: 08/15/2019] [Indexed: 01/01/2023] Open
Abstract
Malaria parasites have a complex life cycle that includes specialized stages for transmission between their mosquito and human hosts. These stages are an understudied part of the lifecycle yet targeting them is an essential component of the effort to shrink the malaria map. The human parasite Plasmodium falciparum is responsible for the majority of deaths due to malaria. Our goal was to generate transgenic P. falciparum lines that could complete the lifecycle and produce fluorescent transmission stages for more in-depth and high-throughput studies. Using zinc-finger nuclease technology to engineer an integration site, we generated three transgenic P. falciparum lines in which tdtomato or gfp were stably integrated into the genome. Expression was driven by either stage-specific peg4 and csp promoters or the constitutive ef1a promoter. Phenotypic characterization of these lines demonstrates that they complete the life cycle with high infection rates and give rise to fluorescent mosquito stages. The transmission stages are sufficiently bright for intra-vital imaging, flow cytometry and scalable screening of chemical inhibitors and inhibitory antibodies.
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Affiliation(s)
- Kyle Jarrod McLean
- Department of Molecular Microbiology and Immunology, and Johns Hopkins Malaria Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, 21205, USA
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Judith Straimer
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, NY, 10032, USA
- Novartis Institutes for Biomedical Research, Novartis Institute for Tropical Diseases, Emeryville, CA, 94608, USA
| | - Christine S Hopp
- Department of Molecular Microbiology and Immunology, and Johns Hopkins Malaria Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, 21205, USA
- Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, USA
| | - Joel Vega-Rodriguez
- Department of Molecular Microbiology and Immunology, and Johns Hopkins Malaria Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, 21205, USA
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, 20892, USA
| | - Jennifer L Small-Saunders
- Division of Infectious Diseases, Department of Medicine, Columbia University Irving Medical Center, New York, NY, 10032, USA
| | - Sachie Kanatani
- Department of Molecular Microbiology and Immunology, and Johns Hopkins Malaria Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, 21205, USA
| | - Abhai Tripathi
- Department of Molecular Microbiology and Immunology, and Johns Hopkins Malaria Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, 21205, USA
| | - Godfree Mlambo
- Department of Molecular Microbiology and Immunology, and Johns Hopkins Malaria Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, 21205, USA
| | - Peter C Dumoulin
- Department of Molecular Microbiology and Immunology, and Johns Hopkins Malaria Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, 21205, USA
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, 02115, USA
| | - Chantal T Harris
- Department of Microbiology and Immunology, Weill Cornell School of Medicine, New York, NY, 10065, USA
| | - Xinran Tong
- Department of Microbiology and Immunology, Weill Cornell School of Medicine, New York, NY, 10065, USA
| | - Melanie J Shears
- Department of Molecular Microbiology and Immunology, and Johns Hopkins Malaria Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, 21205, USA
- Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle, WA, 98109, USA
| | - Johan Ankarklev
- Department of Microbiology and Immunology, Weill Cornell School of Medicine, New York, NY, 10065, USA
- Department of Molecular Biosciences, The Wenner Gren Institute, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Björn F C Kafsack
- Department of Microbiology and Immunology, Weill Cornell School of Medicine, New York, NY, 10065, USA
| | - David A Fidock
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, NY, 10032, USA.
- Division of Infectious Diseases, Department of Medicine, Columbia University Irving Medical Center, New York, NY, 10032, USA.
| | - Photini Sinnis
- Department of Molecular Microbiology and Immunology, and Johns Hopkins Malaria Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, 21205, USA.
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11
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Muller I, Jex AR, Kappe SHI, Mikolajczak SA, Sattabongkot J, Patrapuvich R, Lindner S, Flannery EL, Koepfli C, Ansell B, Lerch A, Emery-Corbin SJ, Charnaud S, Smith J, Merrienne N, Swearingen KE, Moritz RL, Petter M, Duffy MF, Chuenchob V. Transcriptome and histone epigenome of Plasmodium vivax salivary-gland sporozoites point to tight regulatory control and mechanisms for liver-stage differentiation in relapsing malaria. Int J Parasitol 2019; 49:501-513. [PMID: 31071319 PMCID: PMC9973533 DOI: 10.1016/j.ijpara.2019.02.007] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2018] [Revised: 02/01/2019] [Accepted: 02/07/2019] [Indexed: 01/21/2023]
Abstract
Plasmodium vivax is the key obstacle to malaria elimination in Asia and Latin America, largely attributed to its ability to form resilient hypnozoites (sleeper cells) in the host liver that escape treatment and cause relapsing infections. The decision to form hypnozoites is made early in the liver infection and may already be set in sporozoites prior to invasion. To better understand these early stages of infection, we undertook a comprehensive transcriptomic and histone epigenetic characterization of P. vivax sporozoites. Through comparisons with recently published proteomic data for the P. vivax sporozoite, our study found that although highly transcribed, transcripts associated with functions needed for early infection of the vertebrate host are not detectable as proteins and may be regulated through translational repression. We identified differential transcription between the sporozoite and published transcriptomes of asexual blood stages and mixed versus hypnozoite-enriched liver stages. These comparisons point to multiple layers of transcriptional, post-transcriptional and post-translational control that appear active in sporozoites and to a lesser extent hypnozoites, but are largely absent in replicating liver schizonts or mixed blood stages. We also characterised histone epigenetic modifications in the P. vivax sporozoite and explored their role in regulating transcription. Collectively, these data support the hypothesis that the sporozoite is a tightly programmed stage to infect the human host and identify mechanisms for hypnozoite formation that may be further explored in liver stage models.
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Affiliation(s)
| | - Ivo Muller
- Population Health and Immunity Division, The Walter and
Eliza Hall Institute for Medical Research, 1G Royal Parade, Parkville, Victoria,
3052, Australia,Malaria: Parasites & Hosts Unit, Institut Pasteur, 28
Rue de Dr. Roux, 75015, Paris, France,Department of Medical Biology, The University of Melbourne,
Victoria, 3010, Australia
| | - Aaron R. Jex
- Population Health and Immunity Division, The Walter and
Eliza Hall Institute for Medical Research, 1G Royal Parade, Parkville, Victoria,
3052, Australia,Department of Medical Biology, The University of Melbourne,
Victoria, 3010, Australia,Faculty of Veterinary and Agricultural Sciences, The
University of Melbourne, Corner of Park and Flemington Road, Parkville, Victoria,
3010, Australia
| | - Stefan H. I. Kappe
- Seattle Children’s Research Institute, 307 Westlake
Avenue North, Suite 500, Seattle, WA 98109, USA
| | - Sebastian A. Mikolajczak
- Seattle Children’s Research Institute, 307 Westlake
Avenue North, Suite 500, Seattle, WA 98109, USA
| | - Jetsumon Sattabongkot
- Mahidol Vivax Research Center, Faculty of Tropical
Medicine, Mahidol University, Bangkok 10400, Thailand
| | | | - Scott Lindner
- Department of Biochemistry and Molecular Biology, Center
for Malaria Research, Pennsylvania State University, University Park, PA 16802,
USA
| | - Erika L. Flannery
- Seattle Children’s Research Institute, 307 Westlake
Avenue North, Suite 500, Seattle, WA 98109, USA
| | - Cristian Koepfli
- Population Health and Immunity Division, The Walter and
Eliza Hall Institute for Medical Research, 1G Royal Parade, Parkville, Victoria,
3052, Australia
| | - Brendan Ansell
- Faculty of Veterinary and Agricultural Sciences, The
University of Melbourne, Corner of Park and Flemington Road, Parkville, Victoria,
3010, Australia
| | - Anita Lerch
- Population Health and Immunity Division, The Walter and
Eliza Hall Institute for Medical Research, 1G Royal Parade, Parkville, Victoria,
3052, Australia
| | - Samantha J Emery-Corbin
- Population Health and Immunity Division, The Walter and
Eliza Hall Institute for Medical Research, 1G Royal Parade, Parkville, Victoria,
3052, Australia
| | - Sarah Charnaud
- Population Health and Immunity Division, The Walter and
Eliza Hall Institute for Medical Research, 1G Royal Parade, Parkville, Victoria,
3052, Australia
| | - Jeffrey Smith
- Population Health and Immunity Division, The Walter and
Eliza Hall Institute for Medical Research, 1G Royal Parade, Parkville, Victoria,
3052, Australia
| | - Nicolas Merrienne
- Malaria: Parasites & Hosts Unit, Institut Pasteur, 28
Rue de Dr. Roux, 75015, Paris, France
| | | | | | - Michaela Petter
- Department of Medicine Royal Melbourne Hospital, The Peter
Doherty Institute, The University of Melbourne, 792 Elizabeth Street, Melbourne,
Victoria 3000, Australia,Institute of Microbiology, University Hospital Erlangen,
Erlangen 91054, Germany
| | - Michael F. Duffy
- Department of Medicine Royal Melbourne Hospital, The Peter
Doherty Institute, The University of Melbourne, 792 Elizabeth Street, Melbourne,
Victoria 3000, Australia
| | - Vorada Chuenchob
- Seattle Children’s Research Institute, 307 Westlake
Avenue North, Suite 500, Seattle, WA 98109, USA
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12
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Marin-Mogollon C, Salman AM, Koolen KMJ, Bolscher JM, van Pul FJA, Miyazaki S, Imai T, Othman AS, Ramesar J, van Gemert GJ, Kroeze H, Chevalley-Maurel S, Franke-Fayard B, Sauerwein RW, Hill AVS, Dechering KJ, Janse CJ, Khan SM. A P. falciparum NF54 Reporter Line Expressing mCherry-Luciferase in Gametocytes, Sporozoites, and Liver-Stages. Front Cell Infect Microbiol 2019; 9:96. [PMID: 31058097 PMCID: PMC6477837 DOI: 10.3389/fcimb.2019.00096] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Accepted: 03/22/2019] [Indexed: 12/16/2022] Open
Abstract
Transgenic malaria parasites expressing fluorescent and bioluminescent proteins are valuable tools to interrogate malaria-parasite biology and to evaluate drugs and vaccines. Using CRISPR/Cas9 methodology a transgenic Plasmodium falciparum (Pf) NF54 line was generated that expresses a fusion of mCherry and luciferase genes under the control of the Pf etramp10.3 gene promoter (line mCherry-luc@etramp10.3). Pf etramp10.3 is related to rodent Plasmodium uis4 and the uis4 promoter has been used to drive high transgene expression in rodent parasite sporozoites and liver-stages. We examined transgene expression throughout the complete life cycle and compared this expression to transgenic lines expressing mCherry-luciferase and GFP-luciferase under control of the constitutive gapdh and eef1a promoters. The mCherry-luc@etramp10.3 parasites express mCherry in gametocytes, sporozoites, and liver-stages. While no mCherry signal was detected in asexual blood-stage parasites above background levels, luciferase expression was detected in asexual blood-stages, as well as in gametocytes, sporozoites and liver-stages, with the highest levels of reporter expression detected in stage III-V gametocytes and in sporozoites. The expression of mCherry and luciferase in gametocytes and sporozoites makes this transgenic parasite line suitable to use in in vitro assays that examine the effect of transmission blocking inhibitors and to analyse gametocyte and sporozoite biology.
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Affiliation(s)
| | - Ahmed M Salman
- Nuffield Department of Medicine, The Jenner Institute, University of Oxford, Oxford, United Kingdom
| | | | | | - Fiona J A van Pul
- Department of Parasitology, Leiden University Medical Center, Leiden, Netherlands
| | - Shinya Miyazaki
- Department of Parasitology, Leiden University Medical Center, Leiden, Netherlands
| | - Takashi Imai
- Department of Parasitology, Leiden University Medical Center, Leiden, Netherlands.,Department of Infectious Diseases and Host Defense, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Ahmad Syibli Othman
- Department of Parasitology, Leiden University Medical Center, Leiden, Netherlands.,Faculty of Health Sciences, Universiti Sultan Zainal Abidin, Terengganu, Malaysia
| | - Jai Ramesar
- Department of Parasitology, Leiden University Medical Center, Leiden, Netherlands
| | - Geert-Jan van Gemert
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, Netherlands
| | - Hans Kroeze
- Department of Parasitology, Leiden University Medical Center, Leiden, Netherlands
| | | | | | - Robert W Sauerwein
- TropIQ Health Sciences, Nijmegen, Netherlands.,Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, Netherlands
| | - Adrian V S Hill
- Nuffield Department of Medicine, The Jenner Institute, University of Oxford, Oxford, United Kingdom
| | | | - Chris J Janse
- Department of Parasitology, Leiden University Medical Center, Leiden, Netherlands
| | - Shahid M Khan
- Department of Parasitology, Leiden University Medical Center, Leiden, Netherlands
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13
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Simam J, Rono M, Ngoi J, Nyonda M, Mok S, Marsh K, Bozdech Z, Mackinnon M. Gene copy number variation in natural populations of Plasmodium falciparum in Eastern Africa. BMC Genomics 2018; 19:372. [PMID: 29783949 PMCID: PMC5963192 DOI: 10.1186/s12864-018-4689-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 04/17/2018] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND Gene copy number variants (CNVs), which consist of deletions and amplifications of single or sets of contiguous genes, contribute to the great diversity in the Plasmodium falciparum genome. In vitro studies in the laboratory have revealed their important role in parasite fitness phenotypes such as red cell invasion, transmissibility and cytoadherence. Studies of natural parasite populations indicate that CNVs are also common in the field and thus may facilitate adaptation of the parasite to its local environment. RESULTS In a survey of 183 fresh field isolates from three populations in Eastern Africa with different malaria transmission intensities, we identified 94 CNV loci using microarrays. All CNVs had low population frequencies (minor allele frequency < 5%) but each parasite isolate carried an average of 8 CNVs. Nine CNVs showed high levels of population differentiation (FST > 0.3) and nine exhibited significant clines in population frequency across a gradient in transmission intensity. The clearest example of this was a large deletion on chromosome 9 previously reported only in laboratory-adapted isolates. This deletion was present in 33% of isolates from a population with low and highly seasonal malaria transmission, and in < 9% of isolates from populations with higher transmission. Subsets of CNVs were strongly correlated in their population frequencies, implying co-selection. CONCLUSIONS These results support the hypothesis that CNVs are the target of selection in natural populations of P. falciparum. Their environment-specific patterns observed here imply an important role for them in conferring adaptability to the parasite thus enabling it to persist in its highly diverse ecological environment.
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Affiliation(s)
| | - Martin Rono
- KEMRI-Wellcome Trust Research Program, Kilifi, Kenya.,Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK.,Pwani University Bioscience Research Centre, Pwani University, Kilifi, Kenya
| | - Joyce Ngoi
- KEMRI-Wellcome Trust Research Program, Kilifi, Kenya
| | - Mary Nyonda
- Department of Microbiology and Molecular Medicine, Medical Faculty, University of Geneva, Geneva, Switzerland
| | - Sachel Mok
- Department of Microbiology and Immunology, Columbia University, New York, USA
| | - Kevin Marsh
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
| | - Zbynek Bozdech
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
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14
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Posfai D, Sylvester K, Reddy A, Ganley JG, Wirth J, Cullen QE, Dave T, Kato N, Dave SS, Derbyshire ER. Plasmodium parasite exploits host aquaporin-3 during liver stage malaria infection. PLoS Pathog 2018; 14:e1007057. [PMID: 29775485 PMCID: PMC5979039 DOI: 10.1371/journal.ppat.1007057] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Revised: 05/31/2018] [Accepted: 04/25/2018] [Indexed: 12/22/2022] Open
Abstract
Within the liver a single Plasmodium parasite transforms into thousands of blood-infective forms to cause malaria. Here, we use RNA-sequencing to identify host genes that are upregulated upon Plasmodium berghei infection of hepatocytes with the hypothesis that host pathways are hijacked to benefit parasite development. We found that expression of aquaporin-3 (AQP3), a water and glycerol channel, is significantly induced in Plasmodium-infected hepatocytes compared to uninfected cells. This aquaglyceroporin localizes to the parasitophorous vacuole membrane, the compartmental interface between the host and pathogen, with a temporal pattern that correlates with the parasite’s expansion in the liver. Depletion or elimination of host AQP3 expression significantly reduces P. berghei parasite burden during the liver stage and chemical disruption by a known AQP3 inhibitor, auphen, reduces P. falciparum asexual blood stage and P. berghei liver stage parasite load. Further use of this inhibitor as a chemical probe suggests that AQP3-mediated nutrient transport is an important function for parasite development. This study reveals a previously unknown potential route for host-dependent nutrient acquisition by Plasmodium which was discovered by mapping the transcriptional changes that occur in hepatocytes throughout P. berghei infection. The dataset reported may be leveraged to identify additional host factors that are essential for Plasmodium liver stage infection and highlights Plasmodium’s dependence on host factors within hepatocytes. Plasmodium parasites undergo an obligatory morphogenesis and replication within the liver before they invade red blood cells and cause malaria. The liver stage is clinically silent but essential for the Plasmodium parasite to complete its life cycle. During this time, the parasite relies on the host cell to support a massive replication event, yet host factors that are critical to this expansion are largely unknown. We identify human aquaporin-3 (AQP3), a water and glycerol channel, as essential for the proper development of the parasite within the liver cell. AQP3 localizes to the parasitophorous vacuole membrane, the interface between the host cytoplasm and the parasite, possibly aiding in the nutritional uptake for the parasite. Genetic disruption or treatment with the AQP3 inhibitor auphen, reduces parasite load in liver and blood cells.
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Affiliation(s)
- Dora Posfai
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, North Carolina, United States of America
| | - Kayla Sylvester
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, North Carolina, United States of America
| | - Anupama Reddy
- Department of Medicine, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Jack G. Ganley
- Department of Chemistry, Duke University, Durham, North Carolina, United States of America
| | - Johannes Wirth
- Department of Chemistry, Duke University, Durham, North Carolina, United States of America
| | - Quinlan E. Cullen
- Department of Chemistry, Duke University, Durham, North Carolina, United States of America
| | - Tushar Dave
- Department of Medicine, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Nobutaka Kato
- The Broad Institute, 7 Cambridge Center, Cambridge, Massachusetts, United States of America
| | - Sandeep S. Dave
- Department of Medicine, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Emily R. Derbyshire
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, North Carolina, United States of America
- Department of Chemistry, Duke University, Durham, North Carolina, United States of America
- * E-mail:
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15
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Majji S, Wijayalath W, Shashikumar S, Brumeanu TD, Casares S. Humanized DRAGA mice immunized with Plasmodium falciparum sporozoites and chloroquine elicit protective pre-erythrocytic immunity. Malar J 2018. [PMID: 29540197 PMCID: PMC5853061 DOI: 10.1186/s12936-018-2264-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Background Human-immune-system humanized mouse models can bridge the gap between humans and conventional mice for testing human vaccines. The HLA-expressing humanized DRAGA (HLA-A2.HLA-DR4.Rag1KO.IL2RγcKO.NOD) mice reconstitute a functional human-immune-system and sustain the complete life cycle of Plasmodium falciparum. Herein, the DRAGA mice were investigated for immune responses following immunization with live P. falciparum sporozoites under chloroquine chemoprophylaxis (CPS-CQ), an immunization approach that showed in human trials to confer pre-erythrocytic immunity. Results The CPS-CQ immunized DRAGA mice (i) elicited human CD4 and CD8 T cell responses to antigens expressed by P. falciparum sporozoites (Pfspz) and by the infected-red blood cells (iRBC). The Pfspz-specific human T cell responses were found to be systemic (spleen and liver), whereas the iRBCs-specific human T cell responses were more localized to the liver, (ii) elicited stronger antibody responses to the Pfspz than to the iRBCs, and (iii) they were protected against challenge with infectious Pfspz but not against challenge with iRBCs. Conclusions The DRAGA mice represent a new pre-clinical model to investigate the immunogenicity and protective efficacy of P. falciparum malaria vaccine candidates. Electronic supplementary material The online version of this article (10.1186/s12936-018-2264-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Sai Majji
- US Military Malaria Vaccine Program, Naval Medical Research Center/Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - Wathsala Wijayalath
- US Military Malaria Vaccine Program, Naval Medical Research Center/Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - Soumya Shashikumar
- US Military Malaria Vaccine Program, Naval Medical Research Center/Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - Teodor D Brumeanu
- Department of Medicine, Uniformed Services University of Health Sciences, Bethesda, MD, USA
| | - Sofia Casares
- US Military Malaria Vaccine Program, Naval Medical Research Center/Walter Reed Army Institute of Research, Silver Spring, MD, USA. .,Department of Medicine, Uniformed Services University of Health Sciences, Bethesda, MD, USA.
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16
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Kreutzfeld O, Müller K, Matuschewski K. Engineering of Genetically Arrested Parasites (GAPs) For a Precision Malaria Vaccine. Front Cell Infect Microbiol 2017; 7:198. [PMID: 28620583 PMCID: PMC5450620 DOI: 10.3389/fcimb.2017.00198] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 05/04/2017] [Indexed: 01/08/2023] Open
Abstract
Continuous stage conversion and swift changes in the antigenic repertoire in response to acquired immunity are hallmarks of complex eukaryotic pathogens, including Plasmodium species, the causative agents of malaria. Efficient elimination of Plasmodium liver stages prior to blood infection is one of the most promising malaria vaccine strategies. Here, we describe different genetically arrested parasites (GAPs) that have been engineered in Plasmodium berghei, P. yoelii and P. falciparum and compare their vaccine potential. A better understanding of the immunological mechanisms of prime and boost by arrested sporozoites and experimental strategies to enhance vaccine efficacy by further engineering existing GAPs into a more immunogenic form hold promise for continuous improvements of GAP-based vaccines. A critical hurdle for vaccines that elicit long-lasting protection against malaria, such as GAPs, is safety and efficacy in vulnerable populations. Vaccine research should focus on solutions toward turning malaria into a vaccine-preventable disease, which would offer an exciting new path of malaria control.
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Affiliation(s)
- Oriana Kreutzfeld
- Department of Molecular Parasitology, Institute of Biology, Humboldt UniversityBerlin, Germany
| | - Katja Müller
- Department of Molecular Parasitology, Institute of Biology, Humboldt UniversityBerlin, Germany
| | - Kai Matuschewski
- Department of Molecular Parasitology, Institute of Biology, Humboldt UniversityBerlin, Germany
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17
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Silva PAGC, Guerreiro A, Santos JM, Braks JAM, Janse CJ, Mair GR. Translational Control of UIS4 Protein of the Host-Parasite Interface Is Mediated by the RNA Binding Protein Puf2 in Plasmodium berghei Sporozoites. PLoS One 2016; 11:e0147940. [PMID: 26808677 PMCID: PMC4726560 DOI: 10.1371/journal.pone.0147940] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Accepted: 01/11/2016] [Indexed: 11/19/2022] Open
Abstract
UIS4 is a key protein component of the host-parasite interface in the liver stage of the rodent malaria parasite Plasmodium berghei and required for parasite survival after invasion. In the infectious sporozoite, UIS4 protein has variably been shown to be translated but also been reported to be translationally repressed. Here we show that uis4 mRNA translation is regulated by the P. berghei RNA binding protein Pumilio-2 (PbPuf2 or Puf2 from here on forward) in infectious salivary gland sporozoites in the mosquito vector. Using RNA immunoprecipitation we show that uis4 mRNA is bound by Puf2 in salivary gland sporozoites. In the absence of Puf2, uis4 mRNA translation is de-regulated and UIS4 protein expression upregulated in salivary gland sporozoites. Here, using RNA immunoprecipitation, we reveal the first Puf2-regulated mRNA in this parasite.
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Affiliation(s)
- Patrícia A. G. C. Silva
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Av. Prof. Egas Moniz, 1649–028, Lisbon, Portugal
| | - Ana Guerreiro
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Av. Prof. Egas Moniz, 1649–028, Lisbon, Portugal
| | - Jorge M. Santos
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Av. Prof. Egas Moniz, 1649–028, Lisbon, Portugal
| | | | | | - Gunnar R. Mair
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Av. Prof. Egas Moniz, 1649–028, Lisbon, Portugal
- Parasitology, Department of Infectious Diseases, University of Heidelberg Medical School, Im Neuenheimer Feld 324, 69120, Heidelberg, Germany
- * E-mail:
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18
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Plasmodium vivax liver stage development and hypnozoite persistence in human liver-chimeric mice. Cell Host Microbe 2015; 17:526-35. [PMID: 25800544 DOI: 10.1016/j.chom.2015.02.011] [Citation(s) in RCA: 148] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Revised: 07/10/2014] [Accepted: 02/16/2015] [Indexed: 12/11/2022]
Abstract
Plasmodium vivax malaria is characterized by periodic relapses of symptomatic blood stage parasite infections likely initiated by activation of dormant liver stage parasites-hypnozoites. The lack of tractable P. vivax animal models constitutes an obstacle in examining P. vivax liver stage infection and drug efficacy. To overcome this obstacle, we have used human liver-chimeric (huHep) FRG KO mice as a model for P. vivax infection. FRG KO huHep mice support P. vivax sporozoite infection, liver stage development, and hypnozoite formation. We show complete P. vivax liver stage development, including maturation into infectious exo-erythrocytic merozoites as well as the formation and persistence of hypnozoites. Prophylaxis or treatment with the antimalarial primaquine can prevent and eliminate liver stage infection, respectively. Thus, P. vivax-infected FRG KO huHep mice are a model to investigate liver stage development and dormancy and may facilitate the discovery of drugs targeting relapsing malaria.
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19
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Wijayalath W, Majji S, Villasante EF, Brumeanu TD, Richie TL, Casares S. Humanized HLA-DR4.RagKO.IL2RγcKO.NOD (DRAG) mice sustain the complex vertebrate life cycle of Plasmodium falciparum malaria. Malar J 2014; 13:386. [PMID: 25266106 PMCID: PMC4197321 DOI: 10.1186/1475-2875-13-386] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Accepted: 09/18/2014] [Indexed: 12/28/2022] Open
Abstract
Background Malaria is a deadly infectious disease affecting millions of people in tropical and sub-tropical countries. Among the five species of Plasmodium parasites that infect humans, Plasmodium falciparum accounts for the highest morbidity and mortality associated with malaria. Since humans are the only natural hosts for P. falciparum, the lack of convenient animal models has hindered the understanding of disease pathogenesis and prompted the need of testing anti-malarial drugs and vaccines directly in human trials. Humanized mice hosting human cells represent new pre-clinical models for infectious diseases that affect only humans. In this study, the ability of human-immune-system humanized HLA-DR4.RagKO.IL2RγcKO.NOD (DRAG) mice to sustain infection with P. falciparum was explored. Methods Four week-old DRAG mice were infused with HLA-matched human haematopoietic stem cells (HSC) and examined for reconstitution of human liver cells and erythrocytes. Upon challenge with infectious P. falciparum sporozoites (NF54 strain) humanized DRAG mice were examined for liver stage infection, blood stage infection, and transmission to Anopheles stephensi mosquitoes. Results Humanized DRAG mice reconstituted human hepatocytes, Kupffer cells, liver endothelial cells, and erythrocytes. Upon intravenous challenge with P. falciparum sporozoites, DRAG mice sustained liver to blood stage infection (average 3–5 parasites/microlitre blood) and allowed transmission to An. stephensi mosquitoes. Infected DRAG mice elicited antibody and cellular responses to the blood stage parasites and self-cured the infection by day 45 post-challenge. Conclusions DRAG mice represent the first human-immune-system humanized mouse model that sustains the complex vertebrate life cycle of P. falciparum without the need of exogenous injection of human hepatocytes/erythrocytes or P. falciparum parasite adaptation. The ability of DRAG mice to elicit specific human immune responses to P. falciparum parasites may help deciphering immune correlates of protection and to identify protective malaria antigens.
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Affiliation(s)
| | | | | | | | | | - Sofia Casares
- US Military Malaria Vaccine Program, Naval Medical Research Center/Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, MD 20910, USA.
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20
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Silvie O, Briquet S, Müller K, Manzoni G, Matuschewski K. Post-transcriptional silencing of UIS4 in Plasmodium berghei sporozoites is important for host switch. Mol Microbiol 2014; 91:1200-13. [PMID: 24446886 DOI: 10.1111/mmi.12528] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/20/2014] [Indexed: 01/15/2023]
Abstract
Plasmodium sporozoites are transmitted by mosquitoes and first infect hepatocytes of their mammalian host, wherein they develop as liver stages, surrounded by the parasitophorous vacuole membrane (PVM). The parasite must rapidly adapt to its changing environment after switching host. Shortly after invasion, the PVM is remodelled by insertion of essential parasite proteins of the early transcribed membrane protein family such as UIS4. Here, using the rodent malaria model Plasmodium berghei, we show that transcripts encoding UIS4 are stored in a translationally repressed state in sporozoites, allowing UIS4 protein synthesis only after host cell invasion. Using a series of reporter transgenic parasite lines we could demonstrate that the open reading frame of UIS4 mRNA is critical for gene silencing, whereas the 5' and 3' untranslated regions are dispensable. Our data further indicate that the UIS4 translational repression machinery is present only in mature sporozoites in the mosquito salivary glands, and that premature expression of UIS4 protein results in a loss of parasite infectivity. Our findings reveal the importance of specific post-transcriptional control in sporozoites, and establish that host switch requires high levels of translationally silent UIS4 RNA, which permits stage conversion, yet avoids premature expression of this liver stage-specific protein.
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Affiliation(s)
- Olivier Silvie
- Sorbonne Universités, UPMC Univ Paris 06, CR7, 75013, Paris, France; INSERM, U1135, 75013, Paris, France; CNRS, ERL 8255, 75013, Paris, France
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21
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KAI407, a potent non-8-aminoquinoline compound that kills Plasmodium cynomolgi early dormant liver stage parasites in vitro. Antimicrob Agents Chemother 2013; 58:1586-95. [PMID: 24366744 PMCID: PMC3957848 DOI: 10.1128/aac.01927-13] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Preventing relapses of Plasmodium vivax malaria through a radical cure depends on use of the 8-aminoquinoline primaquine, which is associated with safety and compliance issues. For future malaria eradication strategies, new, safer radical curative compounds that efficiently kill dormant liver stages (hypnozoites) will be essential. A new compound with potential radical cure activity was identified using a low-throughput assay of in vitro-cultured hypnozoite forms of Plasmodium cynomolgi (an excellent and accessible model for Plasmodium vivax). In this assay, primary rhesus hepatocytes are infected with P. cynomolgi sporozoites, and exoerythrocytic development is monitored in the presence of compounds. Liver stage cultures are fixed after 6 days and stained with anti-Hsp70 antibodies, and the relative proportions of small (hypnozoite) and large (schizont) forms relative to the untreated controls are determined. This assay was used to screen a series of 18 known antimalarials and 14 new non-8-aminoquinolines (preselected for blood and/or liver stage activity) in three-point 10-fold dilutions (0.1, 1, and 10 μM final concentrations). A novel compound, designated KAI407 showed an activity profile similar to that of primaquine (PQ), efficiently killing the earliest stages of the parasites that become either primary hepatic schizonts or hypnozoites (50% inhibitory concentration [IC50] for hypnozoites, KAI407, 0.69 μM, and PQ, 0.84 μM; for developing liver stages, KAI407, 0.64 μM, and PQ, 0.37 μM). When given as causal prophylaxis, a single oral dose of 100 mg/kg of body weight prevented blood stage parasitemia in mice. From these results, we conclude that KAI407 may represent a new compound class for P. vivax malaria prophylaxis and potentially a radical cure.
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22
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Currà C, Di Luca M, Picci L, de Sousa Silva Gomes dos Santos C, Siden-Kiamos I, Pace T, Ponzi M. The ETRAMP family member SEP2 is expressed throughout Plasmodium berghei life cycle and is released during sporozoite gliding motility. PLoS One 2013; 8:e67238. [PMID: 23840634 PMCID: PMC3696012 DOI: 10.1371/journal.pone.0067238] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2013] [Accepted: 05/15/2013] [Indexed: 12/02/2022] Open
Abstract
The early transcribed membrane proteins ETRAMPs belong to a family of small, transmembrane molecules unique to Plasmodium parasite, which share a signal peptide followed by a short lysine-rich stretch, a transmembrane domain and a variable, highly charged C-terminal region. ETRAMPs are usually expressed in a stage-specific manner. In the blood stages they localize to the parasitophorous vacuole membrane and, in described cases, to vesicle-like structures exported to the host erythrocyte cytosol. Two family members of the rodent parasite Plasmodium berghei, uis3 and uis4, localize to secretory organelles of sporozoites and to the parasitophorous membrane vacuole of the liver stages. By the use of specific antibodies and the generation of transgenic lines, we showed that the P. berghei ETRAMP family member SEP2 is abundantly expressed in gametocytes as well as in mosquito and liver stages. In intracellular parasite stages, SEP2 is routed to the parasitophorous vacuole membrane while, in invasive ookinete and sporozoite stages, it localizes to the parasite surface. To date SEP2 is the only ETRAMP protein detected throughout the parasite life cycle. Furthermore, SEP2 is also released during gliding motility of salivary gland sporozoites. A limited number of proteins are known to be involved in this key function and the best characterized, the CSP and TRAP, are both promising transmission-blocking candidates. Our results suggest that ETRAMP members may be viewed as new potential candidates for malaria control.
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Affiliation(s)
- Chiara Currà
- Istituto Superiore di Sanità, Dipartimento di Malattie Infettive, Parassitarie ed Immunomediate, Roma, Italy
| | - Marco Di Luca
- Istituto Superiore di Sanità, Dipartimento di Malattie Infettive, Parassitarie ed Immunomediate, Roma, Italy
| | - Leonardo Picci
- Istituto Superiore di Sanità, Dipartimento di Malattie Infettive, Parassitarie ed Immunomediate, Roma, Italy
| | | | - Inga Siden-Kiamos
- Institute of Molecular Biology and Biotechnology, FORTH, Heraklion, Greece
| | - Tomasino Pace
- Istituto Superiore di Sanità, Dipartimento di Malattie Infettive, Parassitarie ed Immunomediate, Roma, Italy
| | - Marta Ponzi
- Istituto Superiore di Sanità, Dipartimento di Malattie Infettive, Parassitarie ed Immunomediate, Roma, Italy
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Abstract
The life cycles of apicomplexan parasites such as Plasmodium spp. and Toxoplasma gondii are complex, consisting of proliferative and latent stages within multiple hosts. Dramatic transformations take place during the cycles, and they demand precise control of gene expression at all levels, including translation. This review focuses on the mechanisms that regulate translational control in Plasmodium and Toxoplasma, with a particular emphasis on the phosphorylation of the α subunit of eukaryotic translation initiation factor 2 (eIF2α). Phosphorylation of eIF2α (eIF2α∼P) is a conserved mechanism that eukaryotic cells use to repress global protein synthesis while enhancing gene-specific translation of a subset of mRNAs. Elevated levels of eIF2α∼P have been observed during latent stages in both Toxoplasma and Plasmodium, indicating that translational control plays a role in maintaining dormancy. Parasite-specific eIF2α kinases and phosphatases are also required for proper developmental transitions and adaptation to cellular stresses encountered during the life cycle. Identification of small-molecule inhibitors of apicomplexan eIF2α kinases may selectively interfere with parasite translational control and lead to the development of new therapies to treat malaria and toxoplasmosis.
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Vaughan AM, Mikolajczak SA, Wilson EM, Grompe M, Kaushansky A, Camargo N, Bial J, Ploss A, Kappe SHI. Complete Plasmodium falciparum liver-stage development in liver-chimeric mice. J Clin Invest 2012; 122:3618-28. [PMID: 22996664 DOI: 10.1172/jci62684] [Citation(s) in RCA: 163] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2012] [Accepted: 07/12/2012] [Indexed: 11/17/2022] Open
Abstract
Plasmodium falciparum, which causes the most lethal form of human malaria, replicates in the host liver during the initial stage of infection. However, in vivo malaria liver-stage (LS) studies in humans are virtually impossible, and in vitro models of LS development do not reconstitute relevant parasite growth conditions. To overcome these obstacles, we have adopted a robust mouse model for the study of P. falciparum LS in vivo: the immunocompromised and fumarylacetoacetate hydrolase-deficient mouse (Fah-/-, Rag2-/-, Il2rg-/-, termed the FRG mouse) engrafted with human hepatocytes (FRG huHep). FRG huHep mice supported vigorous, quantifiable P. falciparum LS development that culminated in complete maturation of LS at approximately 7 days after infection, providing a relevant model for LS development in humans. The infections allowed observations of previously unknown expression of proteins in LS, including P. falciparum translocon of exported proteins 150 (PTEX150) and exported protein-2 (EXP-2), components of a known parasite protein export machinery. LS schizonts exhibited exoerythrocytic merozoite formation and merosome release. Furthermore, FRG mice backcrossed to the NOD background and repopulated with huHeps and human red blood cells supported reproducible transition from LS infection to blood-stage infection. Thus, these mice constitute reliable models to study human LS directly in vivo and demonstrate utility for studies of LS-to-blood-stage transition of a human malaria parasite.
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Affiliation(s)
- Ashley M Vaughan
- Seattle Biomedical Research Institute, Seattle, Washington 98109, USA
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25
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Vaughan AM, Kappe SHI, Ploss A, Mikolajczak SA. Development of humanized mouse models to study human malaria parasite infection. Future Microbiol 2012; 7:657-65. [PMID: 22568719 DOI: 10.2217/fmb.12.27] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Malaria is a disease caused by infection with Plasmodium parasites that are transmitted by mosquito bite. Five different species of Plasmodium infect humans with severe disease, but human malaria is primarily caused by Plasmodium falciparum. The burden of malaria on the developing world is enormous, and a fully protective vaccine is still elusive. One of the biggest challenges in the quest for the development of new antimalarial drugs and vaccines is the lack of accessible animal models to study P. falciparum infection because the parasite is restricted to the great apes and human hosts. Here, we review the current state of research in this field and provide an outlook of the development of humanized small animal models to study P. falciparum infection that will accelerate fundamental research into human parasite biology and could accelerate drug and vaccine design in the future.
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26
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Spielmann T, Montagna GN, Hecht L, Matuschewski K. Molecular make-up of the Plasmodium parasitophorous vacuolar membrane. Int J Med Microbiol 2012; 302:179-86. [PMID: 22898489 DOI: 10.1016/j.ijmm.2012.07.011] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
Abstract
Plasmodium, the causative agent of malaria, is an obligate, intracellular, eukaryotic cell that invades, replicates, and differentiates within hepatocytes and erythrocytes. Inside a host cell, a second membrane delineates the developing pathogen in addition to the parasite plasma membrane, resulting in a distinct cellular compartment, termed parasitophorous vacuole (PV). The PV membrane (PVM) constitutes the parasite-host cell interface and is likely central to nutrient acquisition, host cell remodeling, waste disposal, environmental sensing, and protection from innate defense. Over the past two decades, a number of parasite-encoded PVM proteins have been identified. They include multigene families and protein complexes, such as early-transcribed membrane proteins (ETRAMPs) and the Plasmodium translocon for exported proteins (PTEX). Nearly all Plasmodium PVM proteins are restricted to this genus and display transient and stage-specific expression. Here, we provide an overview of the PVM proteins of Plasmodium blood and liver stages. Biochemical and experimental genetics data suggest that some PVM proteins are ideal targets for novel anti-malarial intervention strategies.
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Affiliation(s)
- Tobias Spielmann
- Department of Molecular Parasitology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany.
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27
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Adame-Gallegos JR, Shi J, McIntosh RS, Pleass RJ. The generation and evaluation of two panels of epitope-matched mouse IgG1, IgG2a, IgG2b and IgG3 antibodies specific for Plasmodium falciparum and Plasmodium yoelii merozoite surface protein 1-19 (MSP1(19)). Exp Parasitol 2012; 130:384-93. [PMID: 22343045 PMCID: PMC3336205 DOI: 10.1016/j.exppara.2012.02.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2011] [Revised: 01/28/2012] [Accepted: 02/02/2012] [Indexed: 11/28/2022]
Abstract
Murine immunoglobulin G (IgG) plays an important role in mediating protective immune responses to malaria. We still know relatively little about which IgG subclasses protect against this disease in mouse models, although IgG2a and IgG2b are considered to be the most potent and dominate in successful passive transfer experiments in rodent malarias. To explore the mechanism(s) by which the different mouse IgG subclasses may mediate a protective effect, we generated mouse IgG1, IgG2a, IgG2b and IgG3 specific for the C-terminal 19-kDa region of Plasmodium falciparum merozoite surface protein 1 (PfMSP119), and to the homologous antigen from Plasmodium yoelii (P. yoelii), both major targets of protective immune responses. This panel of eight IgGs bound antigen with an affinity comparable to that seen for their epitope-matched parental monoclonal antibodies (mAbs) from which they were derived, although for reasons of yield, we were only able to explore the function of mouse IgG1 recognizing PfMSP119 in detail, both in vitro and in vivo. Murine IgG1 was as effective as the parental human IgG from which it was derived at inducing NADPH-mediated oxidative bursts and degranulation from neutrophils. Despite showing efficacy in in vitro functional assays with neutrophils, the mouse IgG1 failed to protect against parasite challenge in vivo. The lack of protection afforded by MSP119-specific IgG1 against parasite challenge in wild type mice suggests that this Ab class does not play a major role in the control of infection with mouse malaria in the Plasmodium berghei transgenic model.
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Affiliation(s)
- Jaime R Adame-Gallegos
- Lab C4, Institute of Genetics, Queen's Medical Centre, University of Nottingham, Nottingham NG7 2UH, UK.
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28
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Currà C, Pace T, Franke-Fayard BMD, Picci L, Bertuccini L, Ponzi M. Erythrocyte remodeling in Plasmodium berghei infection: the contribution of SEP family members. Traffic 2011; 13:388-99. [PMID: 22106924 DOI: 10.1111/j.1600-0854.2011.01313.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2011] [Revised: 11/18/2011] [Accepted: 11/22/2011] [Indexed: 02/06/2023]
Abstract
The malaria parasite Plasmodium largely modifies the infected erythrocyte through the export of proteins to multiple sites within the host cell. This remodeling is crucial for pathology and translocation of virulence factors to the erythrocyte surface. In this study, we investigated localization and export of small exported proteins/early transcribed membrane proteins (SEP/ETRAMPs), conserved within Plasmodium genus. This protein family is characterized by a predicted signal peptide, a short lysine-rich stretch, an internal transmembrane domain and a highly charged C-terminal region of variable length. We show here that members of the rodent Plasmodium berghei family are components of the parasitophorous vacuole membrane (PVM), which surrounds the parasite throughout the erythrocytic cycle. During P. berghei development, vesicle-like structures containing these proteins detach from the PVM en route to the host cytosol. These SEP-containing vesicles remain associated with the infected erythrocyte ghosts most probably anchored to the membrane skeleton. Transgenic lines expressing the green fluorescent protein appended to different portions of sep-coding region allowed us to define motifs required for protein export. The highly charged terminal region appears to be involved in protein-protein interactions.
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Affiliation(s)
- Chiara Currà
- Dipartimento di Malattie Infettive, Parassitarie ed Immunomediate, Rome, Italy
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29
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MacKellar DC, Vaughan AM, Aly ASI, DeLeon S, Kappe SHI. A systematic analysis of the early transcribed membrane protein family throughout the life cycle of Plasmodium yoelii. Cell Microbiol 2011; 13:1755-67. [PMID: 21819513 DOI: 10.1111/j.1462-5822.2011.01656.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The early transcribed membrane proteins (ETRAMPs) are a family of small, highly charged transmembrane proteins unique to malaria parasites. Some members of the ETRAMP family have been localized to the parasitophorous vacuole membrane that separates the intracellular parasite from the host cell and thus presumably have a role in host-parasite interactions. Although it was previously shown that two ETRAMPs are critical for rodent malaria parasite liver-stage development, the importance of most ETRAMPs during the parasite life cycle remains unknown. Here, we comprehensively identify nine new etramps in the genome of the rodent malaria parasite Plasmodium yoelii, and elucidate their conservation in other malaria parasites. etramp expression profiles are diverse throughout the parasite life cycle as measured by RT-PCR. Epitope tagging of two ETRAMPs demonstrates protein expression in blood and liver stages, and reveals differences in both their timing of expression and their subcellular localization. Gene targeting studies of each of the nine uncharacterized etramps show that two are refractory to deletion and thus likely essential for blood-stage replication. Seven etramps are not essential for any life cycle stage. Systematic characterization of the members of the ETRAMP family reveals the diversity in importance of each family member at the interface between host and parasite throughout the developmental cycle of the malaria parasite.
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Affiliation(s)
- Drew C MacKellar
- Molecular and Cellular Biology Program, University of Washington, Seattle, WA, USA
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30
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Protein targeting to the parasitophorous vacuole membrane of Plasmodium falciparum. EUKARYOTIC CELL 2011; 10:744-52. [PMID: 21498641 DOI: 10.1128/ec.00008-11] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Red blood cell (RBC) invasion and parasitophorous vacuole (PV) formation by Plasmodium falciparum are critical for the development and pathogenesis of malaria, a continuing global health problem. Expansion of the PV membrane (PVM) during growth is orchestrated by the parasite. This is particularly important in mature RBCs, which lack internal organelles and no longer actively synthesize membranes. Pfs16, a 16-kDa integral PVM protein expressed by gametocytes, was chosen as a model for studying the trafficking of material from the parasite across the PV space to the PVM. The locations of Pfs16-green fluorescent protein (GFP) reporter proteins containing distinct regions of Pfs16 were tracked from RBC invasion to emergence. Inclusion of the 53 C-terminal amino acids (aa) of Pfs16 to a GFP reporter construct already containing the N-terminal secretory signal sequence was sufficient for targeting to and retention on the PVM. An amino acid motif identified in this region was also found in seven other known PVM proteins. Removal of the 11 C-terminal aa did not affect PVM targeting, but membrane retention was decreased. Additionally, during emergence from the PVM and RBC, native Pfs16 and the full-length Pfs16-GFP reporter protein were found to concentrate on the ends of the gametocyte. Capping was not observed in constructs lacking the amino acids between the N-terminal secretory signal sequence and the transmembrane domain, suggesting that this region, which is not required for PVM targeting, is involved in capping. This is the first report to define the amino acid domains required for targeting to the P. falciparum PVM.
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