1
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Giuliano CJ, Wei KJ, Harling FM, Waldman BS, Farringer MA, Boydston EA, Lan TCT, Thomas RW, Herneisen AL, Sanderlin AG, Coppens I, Dvorin JD, Lourido S. CRISPR-based functional profiling of the Toxoplasma gondii genome during acute murine infection. Nat Microbiol 2024; 9:2323-2343. [PMID: 38977907 DOI: 10.1038/s41564-024-01754-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Accepted: 06/07/2024] [Indexed: 07/10/2024]
Abstract
Examining host-pathogen interactions in animals can capture aspects of infection that are obscured in cell culture. Using CRISPR-based screens, we functionally profile the entire genome of the apicomplexan parasite Toxoplasma gondii during murine infection. Barcoded gRNAs enabled bottleneck detection and mapping of population structures within parasite lineages. Over 300 genes with previously unknown roles in infection were found to modulate parasite fitness in mice. Candidates span multiple axes of host-parasite interaction. Rhoptry Apical Surface Protein 1 was characterized as a mediator of host-cell tropism that facilitates repeated invasion attempts. GTP cyclohydrolase I was also required for fitness in mice and druggable through a repurposed compound, 2,4-diamino-6-hydroxypyrimidine. This compound synergized with pyrimethamine against T. gondii and malaria-causing Plasmodium falciparum parasites. This work represents a complete survey of an apicomplexan genome during infection of an animal host and points to novel interfaces of host-parasite interaction.
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Affiliation(s)
| | - Kenneth J Wei
- Whitehead Institute, Cambridge, MA, USA
- Biology Department, MIT, Cambridge, MA, USA
| | | | - Benjamin S Waldman
- Whitehead Institute, Cambridge, MA, USA
- Biology Department, MIT, Cambridge, MA, USA
| | - Madeline A Farringer
- Division of Infectious Diseases, Boston Children's Hospital, Boston, MA, USA
- Biological Sciences in Public Health, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | | | | | - Raina W Thomas
- Whitehead Institute, Cambridge, MA, USA
- Biology Department, MIT, Cambridge, MA, USA
| | - Alice L Herneisen
- Whitehead Institute, Cambridge, MA, USA
- Biology Department, MIT, Cambridge, MA, USA
| | | | - Isabelle Coppens
- Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, USA
| | - Jeffrey D Dvorin
- Division of Infectious Diseases, Boston Children's Hospital, Boston, MA, USA
- Department of Pediatrics, Harvard Medical School, Boston, MA, USA
| | - Sebastian Lourido
- Whitehead Institute, Cambridge, MA, USA.
- Biology Department, MIT, Cambridge, MA, USA.
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2
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Valleau D, Sidik SM, Godoy LC, Acevedo‐Sánchez Y, Pasaje CFA, Huynh M, Carruthers VB, Niles JC, Lourido S. A conserved complex of microneme proteins mediates rhoptry discharge in Toxoplasma. EMBO J 2023; 42:e113155. [PMID: 37886905 PMCID: PMC10690463 DOI: 10.15252/embj.2022113155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2022] [Revised: 09/19/2023] [Accepted: 09/25/2023] [Indexed: 10/28/2023] Open
Abstract
Apicomplexan parasites discharge specialized organelles called rhoptries upon host cell contact to mediate invasion. The events that drive rhoptry discharge are poorly understood, yet essential to sustain the apicomplexan parasitic life cycle. Rhoptry discharge appears to depend on proteins secreted from another set of organelles called micronemes, which vary in function from allowing host cell binding to facilitation of gliding motility. Here we examine the function of the microneme protein CLAMP, which we previously found to be necessary for Toxoplasma gondii host cell invasion, and demonstrate its essential role in rhoptry discharge. CLAMP forms a distinct complex with two other microneme proteins, the invasion-associated SPATR, and a previously uncharacterized protein we name CLAMP-linked invasion protein (CLIP). CLAMP deficiency does not impact parasite adhesion or microneme protein secretion; however, knockdown of any member of the CLAMP complex affects rhoptry discharge. Phylogenetic analysis suggests orthologs of the essential complex components, CLAMP and CLIP, are ubiquitous across apicomplexans. SPATR appears to act as an accessory factor in Toxoplasma, but despite incomplete conservation is also essential for invasion during Plasmodium falciparum blood stages. Together, our results reveal a new protein complex that mediates rhoptry discharge following host-cell contact.
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Affiliation(s)
| | | | - Luiz C Godoy
- Department of Biological EngineeringMassachusetts Institute of TechnologyCambridgeMAUSA
| | | | | | - My‐Hang Huynh
- Department of Microbiology and ImmunologyUniversity of Michigan Medical SchoolAnn ArborMIUSA
| | - Vern B Carruthers
- Department of Microbiology and ImmunologyUniversity of Michigan Medical SchoolAnn ArborMIUSA
| | - Jacquin C Niles
- Department of Biological EngineeringMassachusetts Institute of TechnologyCambridgeMAUSA
| | - Sebastian Lourido
- Whitehead InstituteCambridgeMAUSA
- Biology DepartmentMassachusetts Institute of TechnologyCambridgeMAUSA
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3
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Giuliano CJ, Wei KJ, Harling FM, Waldman BS, Farringer MA, Boydston EA, Lan TCT, Thomas RW, Herneisen AL, Sanderlin AG, Coppens I, Dvorin JD, Lourido S. Functional profiling of the Toxoplasma genome during acute mouse infection. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.05.531216. [PMID: 36945434 PMCID: PMC10028831 DOI: 10.1101/2023.03.05.531216] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2023]
Abstract
Within a host, pathogens encounter a diverse and changing landscape of cell types, nutrients, and immune responses. Examining host-pathogen interactions in animal models can therefore reveal aspects of infection absent from cell culture. We use CRISPR-based screens to functionally profile the entire genome of the model apicomplexan parasite Toxoplasma gondii during mouse infection. Barcoded gRNAs were used to track mutant parasite lineages, enabling detection of bottlenecks and mapping of population structures. We uncovered over 300 genes that modulate parasite fitness in mice with previously unknown roles in infection. These candidates span multiple axes of host-parasite interaction, including determinants of tropism, host organelle remodeling, and metabolic rewiring. We mechanistically characterized three novel candidates, including GTP cyclohydrolase I, against which a small-molecule inhibitor could be repurposed as an antiparasitic compound. This compound exhibited antiparasitic activity against T. gondii and Plasmodium falciparum, the most lethal agent of malaria. Taken together, we present the first complete survey of an apicomplexan genome during infection of an animal host, and point to novel interfaces of host-parasite interaction that may offer new avenues for treatment.
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Affiliation(s)
| | - Kenneth J. Wei
- Whitehead Institute, Cambridge, MA
- Biology Department, MIT, Cambridge, MA
| | - Faye M. Harling
- Whitehead Institute, Cambridge, MA
- Biology Department, MIT, Cambridge, MA
| | | | - Madeline A. Farringer
- Division of Infectious Diseases, Boston Children’s Hospital, Boston, Massachusetts, USA
- Biological Sciences in Public Health, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
| | | | | | - Raina W. Thomas
- Whitehead Institute, Cambridge, MA
- Biology Department, MIT, Cambridge, MA
| | - Alice L. Herneisen
- Whitehead Institute, Cambridge, MA
- Biology Department, MIT, Cambridge, MA
| | | | - Isabelle Coppens
- Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD
| | - Jeffrey D. Dvorin
- Division of Infectious Diseases, Boston Children’s Hospital, Boston, Massachusetts, USA
- Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA
| | - Sebastian Lourido
- Whitehead Institute, Cambridge, MA
- Biology Department, MIT, Cambridge, MA
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4
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Paoletta MS, Wilkowsky SE. Thrombospondin Related Anonymous Protein Superfamily in Vector-Borne Apicomplexans: The Parasite’s Toolkit for Cell Invasion. Front Cell Infect Microbiol 2022; 12:831592. [PMID: 35463644 PMCID: PMC9019593 DOI: 10.3389/fcimb.2022.831592] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Accepted: 03/07/2022] [Indexed: 11/23/2022] Open
Abstract
Apicomplexan parasites transmitted by vectors, including Babesia spp. and Plasmodium spp., cause severe disease in both humans and animals. These parasites have a complex life cycle during which they migrate, invade, and replicate in contrasting hosts such as the mammal and the invertebrate vector. The interaction of parasites with the host cell is mediated by adhesive proteins which play a key role in the different cellular processes regarding successful progression of the life cycle. Thrombospondin related anonymous protein (TRAP) is a superfamily of adhesins that are involved in motility, invasion and egress of the parasite. These proteins are stored and released from apical organelles and have either one or two types of adhesive domains, namely thrombospondin type 1 repeat and von Willebrand factor type A, that upon secretion are located in the extracellular portion of the molecule. Proteins from the TRAP superfamily have been intensively studied in Plasmodium species and to a lesser extent in Babesia spp., where they have proven to be functionally relevant throughout the entire parasite’s journey both in the arthropod vector and in the mammalian host. In recent years new findings provided answers to the role of TRAP proteins and in some cases the function of these adhesins during the parasite’s life cycle was redefined. In this review we will discuss the current knowledge of the diverse roles of the TRAP superfamily in vector-borne parasites from Class Aconoidasida. We will focus on the varied approaches that allowed the understanding of protein function and the relevance of TRAP- superfamily throughout the entire parasite’s cell cycle.
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5
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Shang X, Wang C, Shen L, Sheng F, He X, Wang F, Fan Y, He X, Jiang M. PfAP2-EXP2, an Essential Transcription Factor for the Intraerythrocytic Development of Plasmodium falciparum. Front Cell Dev Biol 2022; 9:782293. [PMID: 35083215 PMCID: PMC8785209 DOI: 10.3389/fcell.2021.782293] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Accepted: 12/09/2021] [Indexed: 12/13/2022] Open
Abstract
Plasmodium falciparum undergoes a series of asexual replications in human erythrocytes after infection, which are effective targets for combatting malaria. Here, we report roles of an ApiAP2 transcription factor PfAP2-EXP2 (PF3D7_0611200) in the intraerythrocytic developmental cycle of P. falciparum. PfAP2-EXP2 conditional knockdown resulted in an asexual growth defect but without an appreciable effect on parasite morphology. Further ChIP-seq analysis revealed that PfAP2-EXP2 targeted genes related to virulence and interaction between erythrocytes and parasites. Especially, PfAP2-EXP2 regulation of euchromatic genes does not depend on recognizing specific DNA sequences, while a CCCTAAACCC motif is found in its heterochromatic binding sites. Combined with transcriptome profiling, we suggest that PfAP2-EXP2 is participated in the intraerythrocytic development by affecting the expression of genes related to cell remodeling at the schizont stage. In summary, this study explores an ApiAP2 member plays an important role for the P. falciparum blood-stage replication, which suggests a new perspective for malaria elimination.
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Affiliation(s)
- Xiaomin Shang
- Department of Medical Genetics, Shanghai Tenth People's Hospital, School of Medicine, Tongji University, Shanghai, China.,Department of Parasitology, Xiangya School of Medicine, Central South University, Changsha, China
| | - Changhong Wang
- Department of Medical Genetics, Shanghai Tenth People's Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Li Shen
- Department of Medical Genetics, Shanghai Tenth People's Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Fei Sheng
- Department of Medical Genetics, Shanghai Tenth People's Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Xiaohui He
- Department of Medical Genetics, Shanghai Tenth People's Hospital, School of Medicine, Tongji University, Shanghai, China.,National Health Commission Key Laboratory of Parasitic Disease Control and Prevention, Jiangsu Provincial Key Laboratory on Parasite and Vector Control Technology, Jiangsu Institute of Parasitic Diseases, Wuxi, China
| | - Fei Wang
- Department of Medical Genetics, Shanghai Tenth People's Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Yanting Fan
- Department of Medical Genetics, Shanghai Tenth People's Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Xiaoqin He
- National Health Commission Key Laboratory of Parasitic Disease Control and Prevention, Jiangsu Provincial Key Laboratory on Parasite and Vector Control Technology, Jiangsu Institute of Parasitic Diseases, Wuxi, China
| | - Mei Jiang
- Department of Medical Genetics, Shanghai Tenth People's Hospital, School of Medicine, Tongji University, Shanghai, China
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6
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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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7
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Singh S, Santos JM, Orchard LM, Yamada N, van Biljon R, Painter HJ, Mahony S, Llinás M. The PfAP2-G2 transcription factor is a critical regulator of gametocyte maturation. Mol Microbiol 2021; 115:1005-1024. [PMID: 33368818 PMCID: PMC8330521 DOI: 10.1111/mmi.14676] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Revised: 12/22/2020] [Accepted: 12/22/2020] [Indexed: 12/14/2022]
Abstract
Differentiation from asexual blood stages to mature sexual gametocytes is required for the transmission of malaria parasites. Here, we report that the ApiAP2 transcription factor, PfAP2-G2 (PF3D7_1408200) plays a critical role in the maturation of Plasmodium falciparum gametocytes. PfAP2-G2 binds to the promoters of a wide array of genes that are expressed at many stages of the parasite life cycle. Interestingly, we also find binding of PfAP2-G2 within the gene body of almost 3,000 genes, which strongly correlates with the location of H3K36me3 and several other histone modifications as well as Heterochromatin Protein 1 (HP1), suggesting that occupancy of PfAP2-G2 in gene bodies may serve as an alternative regulatory mechanism. Disruption of pfap2-g2 does not impact asexual development, but the majority of sexual parasites are unable to mature beyond stage III gametocytes. The absence of pfap2-g2 leads to overexpression of 28% of the genes bound by PfAP2-G2 and none of the PfAP2-G2 bound genes are downregulated, suggesting that it is a repressor. We also find that PfAP2-G2 interacts with chromatin remodeling proteins, a microrchidia (MORC) protein, and another ApiAP2 protein (PF3D7_1139300). Overall our data demonstrate that PfAP2-G2 establishes an essential gametocyte maturation program in association with other chromatin-related proteins.
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Affiliation(s)
- Suprita Singh
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA 16802, Huck Center for Malaria Research, The Pennsylvania State University, University Park, PA, USA 16802
| | - Joana M. Santos
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA 16802, Huck Center for Malaria Research, The Pennsylvania State University, University Park, PA, USA 16802
| | - Lindsey M. Orchard
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA 16802, Huck Center for Malaria Research, The Pennsylvania State University, University Park, PA, USA 16802
| | - Naomi Yamada
- Department of Chemistry, The Pennsylvania State University, University Park, PA, USA 16802
| | - Riëtte van Biljon
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA 16802, Huck Center for Malaria Research, The Pennsylvania State University, University Park, PA, USA 16802
| | - Heather J. Painter
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA 16802, Huck Center for Malaria Research, The Pennsylvania State University, University Park, PA, USA 16802
| | - Shaun Mahony
- Center for Eukaryotic Gene Regulation, Department of Biochemistry & Molecular Biology, The Pennsylvania State University, University Park, PA, USA 16802
| | - Manuel Llinás
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA 16802, Huck Center for Malaria Research, The Pennsylvania State University, University Park, PA, USA 16802
- Center for Eukaryotic Gene Regulation, Department of Biochemistry & Molecular Biology, The Pennsylvania State University, University Park, PA, USA 16802
- Department of Chemistry, The Pennsylvania State University, University Park, PA, USA 16802
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8
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Gupta R, Mishra A, Choudhary HH, Narwal SK, Nayak B, Srivastava PN, Mishra S. Secreted protein with altered thrombospondin repeat (SPATR) is essential for asexual blood stages but not required for hepatocyte invasion by the malaria parasite Plasmodium berghei. Mol Microbiol 2019; 113:478-491. [PMID: 31755154 DOI: 10.1111/mmi.14432] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 11/18/2019] [Accepted: 11/19/2019] [Indexed: 11/30/2022]
Abstract
Upon entering its mammalian host, the malaria parasite productively invades two distinct cell types, that is, hepatocytes and erythrocytes during which several adhesins/invasins are thought to be involved. Many surface-located proteins containing thrombospondin Type I repeat (TSR) which help establish host-parasite molecular crosstalk have been shown to be essential for mammalian infection. Previous reports indicated that antibodies produced against Plasmodium falciparum secreted protein with altered thrombospondin repeat (SPATR) block hepatocyte invasion by sporozoites but no genetic evidence of its contribution to invasion has been reported. After failing to generate Spatr knockout in Plasmodium berghei blood stages, a conditional mutagenesis system was employed. Here, we show that SPATR plays an essential role during parasite's blood stages. Mutant salivary gland sporozoites exhibit normal motility, hepatocyte invasion, liver stage development and rupture of the parasitophorous vacuole membrane resulting in merosome formation. But these mutant hepatic merozoites failed to establish a blood stage infection in vivo. We provide direct evidence that SPATR is not required for hepatocyte invasion but plays an essential role during the blood stages of P. berghei.
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Affiliation(s)
- Roshni Gupta
- Division of Molecular Parasitology and Immunology, CSIR-Central Drug Research Institute, Lucknow, India
| | - Akancha Mishra
- Division of Molecular Parasitology and Immunology, CSIR-Central Drug Research Institute, Lucknow, India.,Academy of Scientific and Innovative Research, Ghaziabad, India
| | - Hadi Hasan Choudhary
- Division of Molecular Parasitology and Immunology, CSIR-Central Drug Research Institute, Lucknow, India
| | - Sunil Kumar Narwal
- Division of Molecular Parasitology and Immunology, CSIR-Central Drug Research Institute, Lucknow, India
| | - Bandita Nayak
- Division of Molecular Parasitology and Immunology, CSIR-Central Drug Research Institute, Lucknow, India.,Academy of Scientific and Innovative Research, Ghaziabad, India
| | - Pratik Narain Srivastava
- Division of Molecular Parasitology and Immunology, CSIR-Central Drug Research Institute, Lucknow, India
| | - Satish Mishra
- Division of Molecular Parasitology and Immunology, CSIR-Central Drug Research Institute, Lucknow, India.,Academy of Scientific and Innovative Research, Ghaziabad, India
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9
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A Plasmodium falciparum C-mannosyltransferase is dispensable for parasite asexual blood stage development. Parasitology 2019; 146:1767-1772. [PMID: 31559936 PMCID: PMC6939167 DOI: 10.1017/s0031182019001380] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
C-mannosylation was recently identified in the thrombospondin-related anonymous protein (TRAP) from Plasmodium falciparum salivary gland sporozoites. A candidate P. falciparum C-mannosyltransferase (PfDPY-19) was demonstrated to modify thrombospondin type 1 repeat (TSR) domains in vitro, exhibiting a different acceptor specificity than their mammalian counterparts. According to the described minimal acceptor of PfDPY19, several TSR domain-containing proteins of P. falciparum could be C-mannosylated in vivo. However, the relevance of this protein modification for the parasite viability remains unknown. In the present study, we used CRISPR/Cas9 technology to generate a PfDPY19 null mutant, demonstrating that this glycosyltransferase is not essential for the asexual blood development of the parasite. PfDPY19 gene disruption was not associated with a growth phenotype, not even under endoplasmic reticulum-stressing conditions that could impair protein folding. The data presented in this work strongly suggest that PfDPY19 is unlikely to play a critical role in the asexual blood stages of the parasite, at least under in vitro conditions.
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10
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Sanz S, Aquilini E, Tweedell RE, Verma G, Hamerly T, Hritzo B, Tripathi A, Machado M, Churcher TS, Rodrigues JA, Izquierdo L, Dinglasan RR. Protein O-Fucosyltransferase 2 Is Not Essential for Plasmodium berghei Development. Front Cell Infect Microbiol 2019; 9:238. [PMID: 31334132 PMCID: PMC6616114 DOI: 10.3389/fcimb.2019.00238] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 06/17/2019] [Indexed: 11/13/2022] Open
Abstract
Thrombospondin type I repeat (TSR) domains are commonly O-fucosylated by protein O-fucosyltransferase 2 (PoFUT2), and this modification is required for optimal folding and secretion of TSR-containing proteins. The human malaria parasite Plasmodium falciparum expresses proteins containing TSR domains, such as the thrombospondin-related anonymous protein (TRAP) and circumsporozoite surface protein (CSP), which are O-fucosylated. TRAP and CSP are present on the surface of sporozoites and play essential roles in mosquito and human host invasion processes during the transmission stages. Here, we have generated PoFUT2 null-mutant P. falciparum and Plasmodium berghei (rodent) malaria parasites and, by phenotyping them throughout their complete life cycle, we show that PoFUT2 disruption does not affect the growth through the mosquito stages for both species. However, contrary to what has been described previously by others, P. berghei PoFUT2 null mutant sporozoites showed no deleterious motility phenotypes and successfully established blood stage infection in mice. This unexpected result indicates that the importance of O-fucosylation of TSR domains may differ between human and RODENT malaria parasites; complicating our understanding of glycosylation modifications in malaria biology.
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Affiliation(s)
- Silvia Sanz
- ISGlobal, Barcelona Centre for International Health Research (CRESIB), Hospital Clínic-Universitat de Barcelona, Barcelona, Spain.,Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States.,Department of Infectious Diseases and Immunology, The University of Florida Emerging Pathogens Institute, Gainesville, FL, United States
| | - Eleonora Aquilini
- Instituto de Medicina Molecular, Unidade de Malária, Universidade de Lisboa, Lisbon, Portugal
| | - Rebecca E Tweedell
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States.,Department of Infectious Diseases and Immunology, The University of Florida Emerging Pathogens Institute, Gainesville, FL, United States
| | - Garima Verma
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States.,Department of Infectious Diseases and Immunology, The University of Florida Emerging Pathogens Institute, Gainesville, FL, United States
| | - Timothy Hamerly
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States.,Department of Infectious Diseases and Immunology, The University of Florida Emerging Pathogens Institute, Gainesville, FL, United States
| | - Bernadette Hritzo
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States
| | - Abhai Tripathi
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States
| | - Marta Machado
- Instituto de Medicina Molecular, Unidade de Malária, Universidade de Lisboa, Lisbon, Portugal
| | - Thomas S Churcher
- Department of Infectious Disease Epidemiology, MRC Centre for Outbreak Analysis and Modelling, Imperial College London, London, United Kingdom
| | - João A Rodrigues
- Instituto de Medicina Molecular, Unidade de Malária, Universidade de Lisboa, Lisbon, Portugal
| | - Luis Izquierdo
- ISGlobal, Barcelona Centre for International Health Research (CRESIB), Hospital Clínic-Universitat de Barcelona, Barcelona, Spain
| | - Rhoel R Dinglasan
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States.,Department of Infectious Diseases and Immunology, The University of Florida Emerging Pathogens Institute, Gainesville, FL, United States
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11
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Kefi M, Mavridis K, Simões ML, Dimopoulos G, Siden-Kiamos I, Vontas J. New rapid one-step PCR diagnostic assay for Plasmodium falciparum infective mosquitoes. Sci Rep 2018; 8:1462. [PMID: 29362379 PMCID: PMC5780459 DOI: 10.1038/s41598-018-19780-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 12/27/2017] [Indexed: 12/19/2022] Open
Abstract
An essential component of malaria vector control programmes is the detection of Plasmodium falciparum within its mosquito vectors, particularly in the salivary glands where the infective sporozoites reside. Several protocols have been developed for this purpose; however they require dissection of mosquito specimens prior to analysis. Here, a novel one-step RT-qPCR TaqMan diagnostic assay was developed for mosquitoes with infective Plasmodium falciparum sporozoites in the salivary glands. It is based on detection of the sporozoite-specific Pfslarp and Pfplp1 gene transcripts. These transcripts were chosen based on bioinformatics analysis, and experimentally verified to be overexpressed in the salivary gland sporozoite stage of the parasite compared to other mosquito parasite stages. The proof of principle and the performance of the assay were demonstrated using RNAlater preserved mosquito samples. Tests of analytical sensitivity showed the novel TaqMan assay to be 100% accurate, although its performance in the field needs to be further demonstrated. This method has no requirement for dissection and post-PCR processing and thus is simple and rapid to perform in individual mosquitoes or mosquito pools. It can be used in single or multiplex formats also targeting additional markers expressed in different tissues, such as detoxification enzymes associated with insecticide resistance.
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Affiliation(s)
- Mary Kefi
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, 70013, Greece.,Department of Biology, University of Crete, VassilikaVouton, Heraklion, 70013, Greece
| | - Konstantinos Mavridis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, 70013, Greece
| | - Maria L Simões
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, 615N Wolfe St, Baltimore, MD, 21205, USA
| | - George Dimopoulos
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, 615N Wolfe St, Baltimore, MD, 21205, USA
| | - Inga Siden-Kiamos
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, 70013, Greece.
| | - John Vontas
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, 70013, Greece.,Pesticide Science Laboratory, Department of Crop Science, Agricultural University of Athens, 11855, Athens, Greece
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Zheng B, Ding J, Chen X, Yu H, Lou D, Tong Q, Kong Q, Lu S. Immuno-Efficacy of a T. gondii Secreted Protein with an Altered Thrombospondin Repeat (TgSPATR) As a Novel DNA Vaccine Candidate against Acute Toxoplasmosis in BALB/c Mice. Front Microbiol 2017; 8:216. [PMID: 28261175 PMCID: PMC5313532 DOI: 10.3389/fmicb.2017.00216] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 01/31/2017] [Indexed: 11/24/2022] Open
Abstract
Toxoplasma gondii (T.gondii) is distributed worldwide and infects most species of warm-blooded animals, including humans. Toxoplasmosis has serious consequences, especially in people with an impaired or immature immune system. Thus, an effective vaccine is urgently required. Secretory microneme proteins are essential for the adhesion and invasion of T. gondii. The gene encoding the microneme protein, T. gondii secreted protein with an altered thrombospondin repeat (TgSPATR), we constructed a recombinant eukaryotic plasmid, pVAX1-TgSPATR, as a DNA vaccine, injected it intramuscularly into BALB/c mice and evaluated the induced immune response. Lymphocyte proliferation assays, cytokine (IFN-γ, IL-2, IL-4, IL-10), and antibody determinations showed that mice immunized with pVAX1-TgSPATR produced humoral and mixed Th1/Th2 type cellular immune responses. The survival times of mice immunized with pVAX1-TgSPATR were also significantly prolonged (15.7 ± 1.42 days) compared with control groups, which died within 7 days of challenge (p < 0.05). The current study indicated that pVAX1-TgSPATR induce a T. gondii specific immune response and might be a promising vaccine candidate against toxoplasmosis. To the best of our knowledge, this is the first report to evaluate the immunoprotective value of TgSPATR against T. gondii.
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Affiliation(s)
- Bin Zheng
- Immunology and Biochemistry Laboratory, Institute of Parasitic Diseases, Zhejiang Academy of Medical Sciences Hangzhou, China
| | - Jianzu Ding
- Immunology and Biochemistry Laboratory, Institute of Parasitic Diseases, Zhejiang Academy of Medical Sciences Hangzhou, China
| | - Xiaoheng Chen
- Immunology and Biochemistry Laboratory, Institute of Parasitic Diseases, Zhejiang Academy of Medical Sciences Hangzhou, China
| | - Haijie Yu
- Jiaxing Vocational Technical College Jiaxing, China
| | - Di Lou
- Immunology and Biochemistry Laboratory, Institute of Parasitic Diseases, Zhejiang Academy of Medical Sciences Hangzhou, China
| | - Qunbo Tong
- Immunology and Biochemistry Laboratory, Institute of Parasitic Diseases, Zhejiang Academy of Medical Sciences Hangzhou, China
| | - Qingming Kong
- Immunology and Biochemistry Laboratory, Institute of Parasitic Diseases, Zhejiang Academy of Medical Sciences Hangzhou, China
| | - Shaohong Lu
- Immunology and Biochemistry Laboratory, Institute of Parasitic Diseases, Zhejiang Academy of Medical Sciences Hangzhou, China
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13
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Sanz S, López-Gutiérrez B, Bandini G, Damerow S, Absalon S, Dinglasan RR, Samuelson J, Izquierdo L. The disruption of GDP-fucose de novo biosynthesis suggests the presence of a novel fucose-containing glycoconjugate in Plasmodium asexual blood stages. Sci Rep 2016; 6:37230. [PMID: 27849032 PMCID: PMC5110956 DOI: 10.1038/srep37230] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Accepted: 10/03/2016] [Indexed: 02/03/2023] Open
Abstract
Glycosylation is an important posttranslational protein modification in all eukaryotes. Besides glycosylphosphatidylinositol (GPI) anchors and N-glycosylation, O-fucosylation has been recently reported in key sporozoite proteins of the malaria parasite. Previous analyses showed the presence of GDP-fucose (GDP-Fuc), the precursor for all fucosylation reactions, in the blood stages of Plasmodium falciparum. The GDP-Fuc de novo pathway, which requires the action of GDP-mannose 4,6-dehydratase (GMD) and GDP-L-fucose synthase (FS), is conserved in the parasite genome, but the importance of fucose metabolism for the parasite is unknown. To functionally characterize the pathway we generated a PfGMD mutant and analyzed its phenotype. Although the labelling by the fucose-binding Ulex europaeus agglutinin I (UEA-I) was completely abrogated, GDP-Fuc was still detected in the mutant. This unexpected result suggests the presence of an alternative mechanism for maintaining GDP-Fuc in the parasite. Furthermore, PfGMD null mutant exhibited normal growth and invasion rates, revealing that the GDP-Fuc de novo metabolic pathway is not essential for the development in culture of the malaria parasite during the asexual blood stages. Nonetheless, the function of this metabolic route and the GDP-Fuc pool that is generated during this stage may be important for gametocytogenesis and sporogonic development in the mosquito.
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Affiliation(s)
- Sílvia Sanz
- ISGlobal, Barcelona Ctr. Int. Health Res. (CRESIB), Hospital Clínic - Universitat de Barcelona, Barcelona, Spain
| | - Borja López-Gutiérrez
- ISGlobal, Barcelona Ctr. Int. Health Res. (CRESIB), Hospital Clínic - Universitat de Barcelona, Barcelona, Spain
| | - Giulia Bandini
- Department of Molecular and Cell Biology, Boston University Goldman School of Dental Medicine, 72 East Concord St, Boston, MA 02118, USA
| | - Sebastian Damerow
- Division of Biological Chemistry and Drug Discovery, College of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom
| | - Sabrina Absalon
- Division of Infectious Diseases, Boston Children's Hospital and Harvard Medical School, Boston MA 02115, USA
| | - Rhoel R Dinglasan
- The University of Florida Emerging Pathogens Institute, Department of Infectious Diseases &Pathology, Gainesville FL 32611, USA
| | - John Samuelson
- Department of Molecular and Cell Biology, Boston University Goldman School of Dental Medicine, 72 East Concord St, Boston, MA 02118, USA
| | - Luis Izquierdo
- ISGlobal, Barcelona Ctr. Int. Health Res. (CRESIB), Hospital Clínic - Universitat de Barcelona, Barcelona, Spain
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Abstract
Parasites of the genus Plasmodium have a complex life cycle. They alternate between their final mosquito host and their intermediate hosts. The parasite can be either extra- or intracellular, depending on the stage of development. By modifying their shape, motility, and metabolic requirements, the parasite adapts to the different environments in their different hosts. The parasite has evolved to escape the multiple immune mechanisms in the host that try to block parasite development at the different stages of their development. In this article, we describe the mechanisms reported thus far that allow the Plasmodium parasite to evade innate and adaptive immune responses.
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Affiliation(s)
- Laurent Rénia
- Singapore Immunology Network, Agency for Science, Technology and Research (A*STAR), Singapore
| | - Yun Shan Goh
- Singapore Immunology Network, Agency for Science, Technology and Research (A*STAR), Singapore
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15
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Diaz SA, Martin SR, Howell SA, Grainger M, Moon RW, Green JL, Holder AA. The Binding of Plasmodium falciparum Adhesins and Erythrocyte Invasion Proteins to Aldolase Is Enhanced by Phosphorylation. PLoS One 2016; 11:e0161850. [PMID: 27607074 PMCID: PMC5015959 DOI: 10.1371/journal.pone.0161850] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Accepted: 08/14/2016] [Indexed: 02/07/2023] Open
Abstract
Aldolase has been implicated as a protein coupling the actomyosin motor and cell surface adhesins involved in motility and host cell invasion in the human malaria parasite Plasmodium falciparum. It binds to the cytoplasmic domain (CTD) of type 1 membrane proteins of the thrombospondin-related anonymous protein (TRAP) family. Other type 1 membrane proteins located in the apical organelles of merozoites, the form of the parasite that invades red blood cells, including apical membrane antigen 1 (AMA1) and members of the erythrocyte binding ligand (EBL) and reticulocyte binding homologue (RH) protein families have been implicated in host cell binding and invasion. Using a direct binding method we confirm that TRAP and merozoite TRAP (MTRAP) bind aldolase and show that the interaction is mediated by more than just the C-terminal six amino acid residues identified previously. Single amino acid substitutions in the MTRAP CTD abolished binding to aldolase. The CTDs of AMA1 and members of the EBL and RH protein families also bound to aldolase. MTRAP competed with AMA1 and RH4 for binding to aldolase, indicating overlapping binding sites. MTRAP CTD was phosphorylated in vitro by both calcium dependent kinase 1 (CDPK1) and protein kinase A, and this modification increased the affinity of binding to aldolase by ten-fold. Phosphorylation of the CTD of members of the EBL and RH protein families also increased their affinity for aldolase in some cases. To examine whether or not MTRAP expressed in asexual blood stage parasites is phosphorylated, it was tagged with GFP, purified and analysed, however no phosphorylation was detected. We propose that CTD binding to aldolase may be dynamically modulated by phosphorylation, and there may be competition for aldolase binding between different CTDs. The use and efficiency of alternate invasion pathways may be determined by the affinity of adhesins and cell invasion proteins for aldolase, in addition to their host ligand specificity.
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Affiliation(s)
- Suraya A. Diaz
- Malaria Parasitology Laboratory, The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, Mill Hill, London, NW7 1AA, United Kingdom
| | - Stephen R. Martin
- Structural Biology Science Technology Platform The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, Mill Hill, London, NW7 1AA, United Kingdom
| | - Steven A. Howell
- Mass Spectrometry Science Technology Platform, The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, Mill Hill, London, NW7 1AA, United Kingdom
| | - Munira Grainger
- Malaria Parasitology Laboratory, The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, Mill Hill, London, NW7 1AA, United Kingdom
| | - Robert W. Moon
- Malaria Parasitology Laboratory, The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, Mill Hill, London, NW7 1AA, United Kingdom
| | - Judith L. Green
- Malaria Parasitology Laboratory, The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, Mill Hill, London, NW7 1AA, United Kingdom
| | - Anthony A. Holder
- Malaria Parasitology Laboratory, The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, Mill Hill, London, NW7 1AA, United Kingdom
- * E-mail:
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16
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A Toxoplasma gondii Ortholog of Plasmodium GAMA Contributes to Parasite Attachment and Cell Invasion. mSphere 2016; 1:mSphere00012-16. [PMID: 27303694 PMCID: PMC4863602 DOI: 10.1128/msphere.00012-16] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Accepted: 01/14/2016] [Indexed: 12/31/2022] Open
Abstract
Toxoplasma gondii is a successful human pathogen in the same phylum as malaria-causing Plasmodium parasites. Invasion of a host cell is an essential process that begins with secretion of adhesive proteins onto the parasite surface for attachment and subsequent penetration of the host cell. Conserved invasion proteins likely play roles that were maintained through the divergence of these parasites. Here, we identify a new conserved invasion protein called glycosylphosphatidylinositol-anchored micronemal antigen (GAMA). Tachyzoites lacking TgGAMA were partially impaired in parasite attachment and invasion of host cells, yielding the first genetic evidence of a specific role in parasite entry into host cells. These findings widen our appreciation of the repertoire of conserved proteins that apicomplexan parasites employ for cell invasion. Toxoplasma gondii and its Plasmodium kin share a well-conserved invasion process, including sequential secretion of adhesive molecules for host cell attachment and invasion. However, only a few orthologs have been shown to be important for efficient invasion by both genera. Bioinformatic screening to uncover potential new players in invasion identified a previously unrecognized T. gondii ortholog of Plasmodium glycosylphosphatidylinositol-anchored micronemal antigen (TgGAMA). We show that TgGAMA localizes to the micronemes and is processed into several proteolytic products within the parasite prior to secretion onto the parasite surface during invasion. TgGAMA from parasite lysate bound to several different host cell types in vitro, suggesting a role in parasite attachment. Consistent with this function, tetracycline-regulatable TgGAMA and TgGAMA knockout strains showed significant reductions in host cell invasion at the attachment step, with no defects in any of the other stages of the parasite lytic cycle. Together, the results of this work reveal a new conserved component of the adhesive repertoire of apicomplexan parasites. IMPORTANCEToxoplasma gondii is a successful human pathogen in the same phylum as malaria-causing Plasmodium parasites. Invasion of a host cell is an essential process that begins with secretion of adhesive proteins onto the parasite surface for attachment and subsequent penetration of the host cell. Conserved invasion proteins likely play roles that were maintained through the divergence of these parasites. Here, we identify a new conserved invasion protein called glycosylphosphatidylinositol-anchored micronemal antigen (GAMA). Tachyzoites lacking TgGAMA were partially impaired in parasite attachment and invasion of host cells, yielding the first genetic evidence of a specific role in parasite entry into host cells. These findings widen our appreciation of the repertoire of conserved proteins that apicomplexan parasites employ for cell invasion.
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Spiegel H, Boes A, Voepel N, Beiss V, Edgue G, Rademacher T, Sack M, Schillberg S, Reimann A, Fischer R. Application of a Scalable Plant Transient Gene Expression Platform for Malaria Vaccine Development. FRONTIERS IN PLANT SCIENCE 2015; 6:1169. [PMID: 26779197 PMCID: PMC4688378 DOI: 10.3389/fpls.2015.01169] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Accepted: 12/07/2015] [Indexed: 05/23/2023]
Abstract
Despite decades of intensive research efforts there is currently no vaccine that provides sustained sterile immunity against malaria. In this context, a large number of targets from the different stages of the Plasmodium falciparum life cycle have been evaluated as vaccine candidates. None of these candidates has fulfilled expectations, and as long as we lack a single target that induces strain-transcending protective immune responses, combining key antigens from different life cycle stages seems to be the most promising route toward the development of efficacious malaria vaccines. After the identification of potential targets using approaches such as omics-based technology and reverse immunology, the rapid expression, purification, and characterization of these proteins, as well as the generation and analysis of fusion constructs combining different promising antigens or antigen domains before committing to expensive and time consuming clinical development, represents one of the bottlenecks in the vaccine development pipeline. The production of recombinant proteins by transient gene expression in plants is a robust and versatile alternative to cell-based microbial and eukaryotic production platforms. The transfection of plant tissues and/or whole plants using Agrobacterium tumefaciens offers a low technical entry barrier, low costs, and a high degree of flexibility embedded within a rapid and scalable workflow. Recombinant proteins can easily be targeted to different subcellular compartments according to their physicochemical requirements, including post-translational modifications, to ensure optimal yields of high quality product, and to support simple and economical downstream processing. Here, we demonstrate the use of a plant transient expression platform based on transfection with A. tumefaciens as essential component of a malaria vaccine development workflow involving screens for expression, solubility, and stability using fluorescent fusion proteins. Our results have been implemented for the evidence-based iterative design and expression of vaccine candidates combining suitable P. falciparum antigen domains. The antigens were also produced, purified, and characterized in further studies by taking advantage of the scalability of this platform.
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Affiliation(s)
- Holger Spiegel
- Fraunhofer Institute for Molecular Biology and Applied Ecology IMEAachen, Germany
| | - Alexander Boes
- Fraunhofer Institute for Molecular Biology and Applied Ecology IMEAachen, Germany
- *Correspondence: Alexander Boes
| | - Nadja Voepel
- Fraunhofer Institute for Molecular Biology and Applied Ecology IMEAachen, Germany
| | - Veronique Beiss
- Fraunhofer Institute for Molecular Biology and Applied Ecology IMEAachen, Germany
| | - Gueven Edgue
- Fraunhofer Institute for Molecular Biology and Applied Ecology IMEAachen, Germany
| | - Thomas Rademacher
- Fraunhofer Institute for Molecular Biology and Applied Ecology IMEAachen, Germany
| | - Markus Sack
- Institute for Molecular Biotechnology, RWTH Aachen UniversityAachen, Germany
| | - Stefan Schillberg
- Fraunhofer Institute for Molecular Biology and Applied Ecology IMEAachen, Germany
| | - Andreas Reimann
- Fraunhofer Institute for Molecular Biology and Applied Ecology IMEAachen, Germany
| | - Rainer Fischer
- Fraunhofer Institute for Molecular Biology and Applied Ecology IMEAachen, Germany
- Institute for Molecular Biotechnology, RWTH Aachen UniversityAachen, Germany
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SSP3 is a novel Plasmodium yoelii sporozoite surface protein with a role in gliding motility. Infect Immun 2014; 82:4643-53. [PMID: 25156733 DOI: 10.1128/iai.01800-14] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Plasmodium sporozoites develop within oocysts in the mosquito midgut wall and then migrate to the salivary glands. After transmission, they embark on a complex journey to the mammalian liver, where they infect hepatocytes. Proteins on the sporozoite surface likely mediate multiple steps of this journey, yet only a few sporozoite surface proteins have been described. Here, we characterize a novel, conserved sporozoite surface protein (SSP3) in the rodent malaria parasite Plasmodium yoelii. SSP3 is a putative type I transmembrane protein unique to Plasmodium. By using epitope tagging and SSP3-specific antibodies in conjunction with immunofluorescence microscopy, we showed that SSP3 is expressed in mosquito midgut oocyst sporozoites, exhibiting an intracellular localization. In sporozoites derived from the mosquito salivary glands, however, SSP3 localized predominantly to the sporozoite surface as determined by immunoelectron microscopy. However, the ectodomain of SSP3 appeared to be inaccessible to antibodies in nonpermeabilized salivary gland sporozoites. Antibody-induced shedding of the major surface protein circumsporozoite protein (CSP) exposed the SSP3 ectodomain to antibodies in some sporozoites. Targeted deletion of SSP3 adversely affected in vitro sporozoite gliding motility, which, surprisingly, impacted neither their cell traversal capacity, host cell invasion in vitro, nor infectivity in vivo. Together, these data reveal a previously unappreciated complexity of the Plasmodium sporozoite surface proteome and the roles of surface proteins in distinct biological activities of sporozoites.
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A conserved apicomplexan microneme protein contributes to Toxoplasma gondii invasion and virulence. Infect Immun 2014; 82:4358-68. [PMID: 25092910 DOI: 10.1128/iai.01877-14] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The obligate intracellular parasite Toxoplasma gondii critically relies on host cell invasion during infection. Proteins secreted from the apical micronemes are central components for host cell recognition, invasion, egress, and virulence. Although previous work established that the sporozoite protein with an altered thrombospondin repeat (SPATR) is a micronemal protein conserved in other apicomplexan parasites, including Plasmodium, Neospora, and Eimeria, no genetic evidence of its contribution to invasion has been reported. SPATR contains a predicted epidermal growth factor domain and two thrombospondin type 1 repeats, implying a role in host cell recognition. In this study, we assess the contribution of T. gondii SPATR (TgSPATR) to T. gondii invasion by genetically ablating it and restoring its expression by genetic complementation. Δspatr parasites were ~50% reduced in invasion compared to parental strains, a defect that was reversed in the complemented strain. In mouse virulence assays, Δspatr parasites were significantly attenuated, with ~20% of mice surviving infection. Given the conservation of this protein among the Apicomplexa, we assessed whether the Plasmodium falciparum SPATR ortholog (PfSPATR) could complement the absence of the TgSPATR. Although PfSPATR showed correct micronemal localization, it did not reverse the invasion deficiency of Δspatr parasites, because of an apparent failure in secretion. Overall, the results suggest that TgSPATR contributes to invasion and virulence, findings that have implications for the many genera and life stages of apicomplexans that express SPATR.
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20
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Crosnier C, Wanaguru M, McDade B, Osier FH, Marsh K, Rayner JC, Wright GJ. A library of functional recombinant cell-surface and secreted P. falciparum merozoite proteins. Mol Cell Proteomics 2013; 12:3976-86. [PMID: 24043421 PMCID: PMC3861738 DOI: 10.1074/mcp.o113.028357] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Malaria, an infectious disease caused by parasites of the Plasmodium genus, is one of the world's major public health concerns causing up to a million deaths annually, mostly because of P. falciparum infections. All of the clinical symptoms are associated with the blood stage of the disease, an obligate part of the parasite life cycle, when a form of the parasite called the merozoite recognizes and invades host erythrocytes. During erythrocyte invasion, merozoites are directly exposed to the host humoral immune system making the blood stage of the parasite a conceptually attractive therapeutic target. Progress in the functional and molecular characterization of P. falciparum merozoite proteins, however, has been hampered by the technical challenges associated with expressing these proteins in a biochemically active recombinant form. This challenge is particularly acute for extracellular proteins, which are the likely targets of host antibody responses, because they contain structurally critical post-translational modifications that are not added by some recombinant expression systems. Here, we report the development of a method that uses a mammalian expression system to compile a protein resource containing the entire ectodomains of 42 P. falciparum merozoite secreted and cell surface proteins, many of which have not previously been characterized. Importantly, we are able to recapitulate known biochemical activities by showing that recombinant MSP1-MSP7 and P12-P41 directly interact, and that both recombinant EBA175 and EBA140 can bind human erythrocytes in a sialic acid-dependent manner. Finally, we use sera from malaria-exposed immune adults to profile the relative immunoreactivity of the proteins and show that the majority of the antigens contain conformational (heat-labile) epitopes. We envisage that this resource of recombinant proteins will make a valuable contribution toward a molecular understanding of the blood stage of P. falciparum infections and facilitate the comparative screening of antigens as blood-stage vaccine candidates.
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Affiliation(s)
- Cécile Crosnier
- Cell Surface Signalling laboratory, Wellcome Trust Sanger Institute, Cambridge CB10 1HH, UK
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21
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Palaeya V, Lau YL, Mahmud R, Chen Y, Fong MY. Cloning, expression, and immunocharacterization of surface protein containing an altered thrombospondin repeat domain (SPATR) from Plasmodium knowlesi. Malar J 2013; 12:182. [PMID: 23734702 PMCID: PMC3686638 DOI: 10.1186/1475-2875-12-182] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Accepted: 05/28/2013] [Indexed: 11/15/2022] Open
Abstract
Background Plasmodium knowlesi is the fifth species identified to cause malaria in humans and is often misdiagnosed as Plasmodium malariae due to morphological similarities. The development of an inexpensive, serological detection method utilizing antibodies specific to P. knowlesi would be a valuable tool for diagnosis. However, the identification of specific antigens for these parasites remains a major challenge for generating such assays. In this study, surface protein containing an altered thrombospondin repeat domain (SPATR) was selected as a potentially specific antigen from P. knowlesi. Its multistage expression by sporozoites, asexual erythrocytic forms and gametocytes, along with its possible role in liver cell invasion, suggests that SPATR could be used as a biomarker for diagnosis of P. knowlesi. Methods The spatr gene from P. knowlesi was codon optimized and cloned (pkhspatr). Recombinant pkHSPATR protein was expressed, purified, and evaluated for its sensitivity and specificity in immunoblot and ELISA-based assays for detecting P. knowlesi infection. Results The recombinant pkHSPATR protein allows sensitive detection of human P. knowlesi infection in serum samples by immunoblot and ELISA. Conclusions With further research, recombinant pkHSPATR protein could be exploited as a marker for detection of P. knowlesi infection in humans. Therefore, this finding should contribute to the development of immunodiagnostic assays for the species-specific detection of malaria.
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Affiliation(s)
- Vanitha Palaeya
- Department of Parasitology, TIDREC, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia
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Mongui A, Angel DI, Moreno-Perez DA, Villarreal-Gonzalez S, Almonacid H, Vanegas M, Patarroyo MA. Identification and characterization of the Plasmodium vivax thrombospondin-related apical merozoite protein. Malar J 2010; 9:283. [PMID: 20942952 PMCID: PMC3020679 DOI: 10.1186/1475-2875-9-283] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2010] [Accepted: 10/13/2010] [Indexed: 12/21/2022] Open
Abstract
Background Malaria caused by Plasmodium vivax is a major public health problem worldwide that affects 70-80 million people in the Middle East, Asia, Western Pacific, South America and the Caribbean. Despite its epidemiological importance, few antigens from this parasite species have been characterized to date compared to Plasmodium falciparum, due in part to the difficulties of maintaining an in vitro culture of P. vivax. This study describes the identification of the P. falciparum thrombospondin-related apical merozoite protein homologue in P. vivax (PvTRAMP) and examines its potential to be further evaluated as vaccine candidate. Methods The gene encoding PvTRAMP was identified through an extensive search of the databases hosting the genome sequence of P. vivax. Genes adjacent to pvtramp were identified in silico to determine the degree of similarity between the protein sequences encoded by equivalent chromosomic fragments in P. falciparum and Plasmodium knowlesi. The pvtramp gene was amplified from cDNA of P. vivax schizont stages, cloned and expressed in Escherichia coli. Anti-PvTRAMP antisera was obtained by inoculating rabbits with PvTRAMP B cell epitopes produced as synthetic peptides in order to assess its recognition in parasite lysates by Western blot and in intact parasites by indirect immunofluorescence. The recognition of recombinant PvTRAMP by sera from P. vivax-infected individuals living in endemic areas was also assessed by ELISA. Results The PfTRAMP homologue in P. vivax, here denoted as PvTRAMP, is a 340-amino-acid long antigen encoded by a single exon that could have a potential role in cytoadherence, as indicated by the presence of a thrombospondin structural homology repeat (TSR) domain. According to its transcription and expression profile, PvTRAMP is initially located at the parasite's apical end and later on the parasite surface. Recombinant PvTRAMP is recognized by sera from infected patients, therefore, indicating that it is targeted by the immune system during a natural infection with P. vivax. Conclusions The results of this work support conducting further studies with PvTRAMP to evaluate its immunogenicity and protection-inducing ability in the Aotus animal model.
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Affiliation(s)
- Alvaro Mongui
- Fundación Instituto de Inmunología de Colombia (FIDIC), Bogotá, Colombia
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Characterization of a novel thrombospondin-related protein in Toxoplasma gondii. Parasitol Int 2010; 59:211-6. [DOI: 10.1016/j.parint.2010.02.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2009] [Revised: 01/22/2010] [Accepted: 02/02/2010] [Indexed: 11/17/2022]
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Transcriptional profiling of growth perturbations of the human malaria parasite Plasmodium falciparum. Nat Biotechnol 2009; 28:91-8. [PMID: 20037583 DOI: 10.1038/nbt.1597] [Citation(s) in RCA: 152] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2009] [Accepted: 12/06/2009] [Indexed: 12/25/2022]
Abstract
Functions have yet to be defined for the majority of genes of Plasmodium falciparum, the agent responsible for the most serious form of human malaria. Here we report changes in P. falciparum gene expression induced by 20 compounds that inhibit growth of the schizont stage of the intraerythrocytic development cycle. In contrast with previous studies, which reported only minimal changes in response to chemically induced perturbations of P. falciparum growth, we find that approximately 59% of its coding genes display over three-fold changes in expression in response to at least one of the chemicals we tested. We use this compendium for guilt-by-association prediction of protein function using an interaction network constructed from gene co-expression, sequence homology, domain-domain and yeast two-hybrid data. The subcellular localizations of 31 of 42 proteins linked with merozoite invasion is consistent with their role in this process, a key target for malaria control. Our network may facilitate identification of novel antimalarial drugs and vaccines.
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Characterization of the Babesia gibsoni 12-kDa protein as a potential antigen for the serodiagnosis. Parasitol Int 2009; 58:55-60. [DOI: 10.1016/j.parint.2008.10.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2008] [Revised: 10/02/2008] [Accepted: 10/04/2008] [Indexed: 10/21/2022]
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Tagging of endogenous genes in a Toxoplasma gondii strain lacking Ku80. EUKARYOTIC CELL 2009; 8:530-9. [PMID: 19218426 DOI: 10.1128/ec.00358-08] [Citation(s) in RCA: 383] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
As with other organisms with a completed genome sequence, opportunities for performing large-scale studies, such as expression and localization, on Toxoplasma gondii are now much more feasible. We present a system for tagging genes endogenously with yellow fluorescent protein (YFP) in a Deltaku80 strain. Ku80 is involved in DNA strand repair and nonhomologous DNA end joining; previous studies in other organisms have shown that in its absence, random integration is eliminated, allowing the insertion of constructs with homologous sequences into the proper loci. We generated a vector consisting of YFP and a dihydrofolate reductase-thymidylate synthase selectable marker. The YFP is preceded by a ligation-independent cloning (LIC) cassette, which allows the insertion of PCR products containing complementary LIC sequences. We demonstrated that the Deltaku80 strain is more effective and efficient in integrating the YFP-tagged constructs into the correct locus than wild-type strain RH. We then selected several hypothetical proteins that were identified by a proteomic screen of excreted-secreted antigens and that displayed microarray expression profiles similar to known micronemal proteins, with the thought that these could potentially be new proteins with roles in cell invasion. We localized these hypothetical proteins by YFP fluorescence and showed expression by immunoblotting. Our findings demonstrate that the combination of the Deltaku80 strain and the pYFP.LIC constructs reduces both the time and cost required to determine localization of a new gene of interest. This should allow the opportunity for performing larger-scale studies of novel T. gondii genes.
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Morahan BJ, Wang L, Coppel RL. No TRAP, no invasion. Trends Parasitol 2008; 25:77-84. [PMID: 19101208 DOI: 10.1016/j.pt.2008.11.004] [Citation(s) in RCA: 115] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2008] [Revised: 11/06/2008] [Accepted: 11/07/2008] [Indexed: 11/19/2022]
Abstract
Host-cell invasion by apicomplexan parasites is a unique process that is powered by the gliding motility motor and requires a transmembrane link between the parasite cytoskeleton and the host cell. The thrombospondin-related anonymous protein (TRAP) from Plasmodium plays such a part during sporozoite invasion by linking to actin through its cytoplasmic tail while binding to hepatocytes via its extracellular portion. In recent years, there have been major advances in the identification and characterization of TRAP-family proteins in the other invasive stages of Plasmodium as well as other Apicomplexa. This review summarizes the recent experimental data on these TRAP-family proteins, focusing on their structure and function.
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Affiliation(s)
- Belinda J Morahan
- Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia
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Curtidor H, García J, Vanegas M, Puentes F, Forero M, Patarroyo ME. Identification of peptides with high red blood cell and hepatocyte binding activity in the Plasmodium falciparum multi-stage invasion proteins: PfSPATR and MCP-1. Biochimie 2008; 90:1750-9. [DOI: 10.1016/j.biochi.2008.08.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2008] [Accepted: 08/25/2008] [Indexed: 11/30/2022]
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Proteomic profiling of Plasmodium sporozoite maturation identifies new proteins essential for parasite development and infectivity. PLoS Pathog 2008; 4:e1000195. [PMID: 18974882 PMCID: PMC2570797 DOI: 10.1371/journal.ppat.1000195] [Citation(s) in RCA: 167] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2008] [Accepted: 10/09/2008] [Indexed: 12/12/2022] Open
Abstract
Plasmodium falciparum sporozoites that develop and mature inside an Anopheles mosquito initiate a malaria infection in humans. Here we report the first proteomic comparison of different parasite stages from the mosquito—early and late oocysts containing midgut sporozoites, and the mature, infectious salivary gland sporozoites. Despite the morphological similarity between midgut and salivary gland sporozoites, their proteomes are markedly different, in agreement with their increase in hepatocyte infectivity. The different sporozoite proteomes contain a large number of stage specific proteins whose annotation suggest an involvement in sporozoite maturation, motility, infection of the human host and associated metabolic adjustments. Analyses of proteins identified in the P. falciparum sporozoite proteomes by orthologous gene disruption in the rodent malaria parasite, P. berghei, revealed three previously uncharacterized Plasmodium proteins that appear to be essential for sporozoite development at distinct points of maturation in the mosquito. This study sheds light on the development and maturation of the malaria parasite in an Anopheles mosquito and also identifies proteins that may be essential for sporozoite infectivity to humans. Human malaria is caused by Plasmodium falciparum, a unicellular protozoan parasite that is transmitted by Anopheles mosquitoes. An infectious mosquito injects saliva containing sporozoite forms of the parasite and these then migrate from the skin to the liver, where they establish an infection. Many intervention strategies are currently focused on preventing the establishment of infection by sporozoites. Clearly, an understanding of the biology of the sporozoite is essential for developing new intervention strategies. Sporozoites are produced within the oocyst, located on the outside wall of the mosquito midgut, and migrate after release from the oocysts to the salivary glands where they are stored as mature infectious forms. Comparison of the proteomes of sporozoites derived from either the oocyst or from the salivary gland reveals remarkable differences in the protein content of these stages despite their similar morphology. The changes in protein content reflect the very specific preparations the sporozoites make in order to establish an infection of the liver. Analysis of the function of several previously uncharacterized, conserved proteins revealed proteins essential for sporozoite development at distinct points of their maturation.
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Temperature shift and host cell contact up-regulate sporozoite expression of Plasmodium falciparum genes involved in hepatocyte infection. PLoS Pathog 2008; 4:e1000121. [PMID: 18688281 PMCID: PMC2488394 DOI: 10.1371/journal.ppat.1000121] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2008] [Accepted: 07/10/2008] [Indexed: 11/19/2022] Open
Abstract
Plasmodium sporozoites are deposited in the skin by Anopheles mosquitoes. They then find their way to the liver, where they specifically invade hepatocytes in which they develop to yield merozoites infective to red blood cells. Relatively little is known of the molecular interactions during these initial obligatory phases of the infection. Recent data suggested that many of the inoculated sporozoites invade hepatocytes an hour or more after the infective bite. We hypothesised that this pre-invasive period in the mammalian host prepares sporozoites for successful hepatocyte infection. Therefore, the genes whose expression becomes modified prior to hepatocyte invasion would be those likely to code for proteins implicated in the subsequent events of invasion and development. We have used P. falciparum sporozoites and their natural host cells, primary human hepatocytes, in in vitro co-culture system as a model for the pre-invasive period. We first established that under co-culture conditions, sporozoites maintain infectivity for an hour or more, in contrast to a drastic loss in infectivity when hepatocytes were not included. Thus, a differential transcriptome of salivary gland sporozoites versus sporozoites co-cultured with hepatocytes was established using a pan-genomic P. falciparum microarray. The expression of 532 genes was found to have been up-regulated following co-culture. A fifth of these genes had no orthologues in the genomes of Plasmodium species used in rodent models of malaria. Quantitative RT-PCR analysis of a selection of 21 genes confirmed the reliability of the microarray data. Time-course analysis further indicated two patterns of up-regulation following sporozoite co-culture, one transient and the other sustained, suggesting roles in hepatocyte invasion and liver stage development, respectively. This was supported by functional studies of four hitherto uncharacterized proteins of which two were shown to be sporozoite surface proteins involved in hepatocyte invasion, while the other two were predominantly expressed during hepatic parasite development. The genome-wide up-regulation of expression observed supports the hypothesis that the shift from the mosquito to the mammalian host contributes to activate quiescent salivary gland sporozoites into a state of readiness for the hepatic stages. Functional studies on four of the up-regulated genes validated our approach as one means to determine the repertoire of proteins implicated during the early events of the Plasmodium infection, and in this case that of P. falciparum, the species responsible for the severest forms of malaria. Sporozoites, the infective form of the malaria parasites Plasmodium, are deposited in the skin by Anopheles mosquitoes. They then find their way to the liver where they specifically invade hepatocytes, in which they develop to yield another form, the merozoite, infective to red blood cells. Relatively little is known of the molecular interactions during these initial obligatory phases of the infection. We studied the changes in gene expression in sporozoites, from the parasite species P. falciparum that infects humans, in an in vitro system where they were co-cultured with their natural host cells, primary human hepatocytes. The whole genome transcriptome profiling carried out led to the identification of 532 genes that were up-regulated following co-culture. This genome-wide up-regulation of expression supports the hypothesis that the shift from the mosquito to the mammalian host contributes to activate quiescent salivary gland sporozoites into a state of readiness for the hepatic stages. Functional studies on four of the up-regulated genes we identified validated our approach as one means to determine the repertoire of proteins implicated during the early events in the infection by P. falciparum, the species responsible for the severest forms of malaria.
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Weedall GD, Polley SD, Conway DJ. Gene-specific signatures of elevated non-synonymous substitution rates correlate poorly across the Plasmodium genus. PLoS One 2008; 3:e2281. [PMID: 18509456 PMCID: PMC2384006 DOI: 10.1371/journal.pone.0002281] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2008] [Accepted: 04/13/2008] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Comparative genome analyses of parasites allow large scale investigation of selective pressures shaping their evolution. An acute limitation to such analysis of Plasmodium falciparum is that there is only very partial low-coverage genome sequence of the most closely related species, the chimpanzee parasite P. reichenowi. However, if orthologous genes have been under similar selective pressures throughout the Plasmodium genus then positive selection on the P. falciparum lineage might be predicted to some extent by analysis of other lineages. PRINCIPAL FINDINGS Here, three independent pairs of closely related species in different sub-generic clades (P. falciparum and P. reichenowi; P. vivax and P. knowlesi; P. yoelii and P. berghei) were compared for a set of 43 candidate ligand genes considered likely to be under positive directional selection and a set of 102 control genes for which there was no selective hypothesis. The ratios of non-synonymous to synonymous substitutions (dN/dS) were significantly elevated in the candidate ligand genes compared to control genes in each of the three clades. However, the rank order correlation of dN/dS ratios for individual candidate genes was very low, less than the correlation for the control genes. SIGNIFICANCE The inability to predict positive selection on a gene in one lineage by identifying elevated dN/dS ratios in the orthologue within another lineage needs to be noted, as it reflects that adaptive mutations are generally rare events that lead to fixation in individual lineages. Thus it is essential to complete the genome sequences of particular species of phylogenetic importance, such as P. reichenowi.
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Affiliation(s)
- Gareth D Weedall
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom.
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Kawase O, Nishikawa Y, Bannai H, Zhang H, Zhang G, Jin S, Lee EG, Xuan X. Proteomic analysis of calcium-dependent secretion in Toxoplasma gondii. Proteomics 2007; 7:3718-25. [PMID: 17880006 DOI: 10.1002/pmic.200700362] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Toxoplasma gondii is an intracellular protozoan parasite that invades a wide range of nucleated cells. In the course of intracellular parasitism, the parasite releases a large variety of proteins from three secretory organelles, namely, micronemes, rhoptries and dense granules. Elevation of intracellular Ca(2+) in the parasite causes microneme discharge, and microneme secretion is essential for the invasion. In this study, we performed a proteomic analysis of the Ca(2+)-dependent secretion to evaluate the protein repertoire. We found that Ca(2+)-mobilising agents, such as thapsigargin, NH(4)Cl, ethanol and a Ca(2+) ionophore, A23187, promoted the secretion of the parasite proteins. The proteins, artificially secreted by A23187, were used in a comparative proteomic analysis by 2-DE followed by PMF analysis and/or N-terminal sequencing. Major known microneme proteins (MICs), such as MIC2, MIC4, MIC6 and MIC10 and apical membrane antigen 1 (AMA1), were identified, indicating that the proteomic analysis worked accurately. Interestingly, new members of secretory proteins, namely rhoptry protein 9 (ROP9) and Toxoplasma SPATR (TgSPATR), which was a homologue of a Plasmodium secreted protein with an altered thrombospondin repeat (SPATR), were detected in Ca(2+)-dependent secretion. Thus, we succeeded in detecting Ca(2+)-dependent secretory proteins in T. gondii, which contained novel secretory proteins.
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Affiliation(s)
- Osamu Kawase
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido, Japan
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33
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Calderón JC, Curtidor H, González O, Cifuentes G, Reyes C, Patarroyo ME. High affinity interactions between red blood cell receptors and synthetic Plasmodium thrombospondin-related apical merozoite protein (PTRAMP) peptides. Biochimie 2007; 90:802-10. [PMID: 18158923 DOI: 10.1016/j.biochi.2007.11.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2007] [Accepted: 11/30/2007] [Indexed: 11/19/2022]
Abstract
Plasmodium falciparum thrombospondin-related apical merozoite protein (PTRAMP) has a thrombospondin related (TSR) domain which in many proteins has been reported as a fragment involved in pathogen-host and cell-interactions. Receptor-ligand studies using eighteen non-overlapping 20-aminoacid-long synthetic peptides from this protein were carried out to determine regions involved in parasite invasion of red blood cells (RBC). Two high activity binding peptides (HABPs) were determined, 33405 (21YISSNDLTSTNLKVRNNWEH40) and 33413 (180LEGPIQFSLGKSSGAFRINY199), presenting high dissociation constants and positive cooperativity. One of the HABPs displayed a modified Plasmodium export element (PEXEL), suggesting that this protein could be involved in the merozoite cytoplasmic reticulum, parasitophorous vacuole, red blood cell (RBC) cytosol, and probably infected RBC (iRBC) membrane transport of some other molecules and nutrients. Enzymatic treatment of RBCs increased HABP 33405 binding to them whilst it decreased HABP 33413 binding. Merozoite invasion assays revealed that HABPs have around 57% ability to inhibit new RBC invasion. Circular dichroism revealed the presence of possible alpha-helical elements in both HABPs structures. RBC binding interaction specificity and the presence of a PEXEL motif make these 2 HABPs good candidates for being included in further studies to develop a new multi-antigenic, multi-stage, subunit-based, chemically-synthesised, anti-malarial vaccine.
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Hoffman BU, Chattopadhyay R. Plasmodium falciparum: effect of radiation on levels of gene transcripts in sporozoites. Exp Parasitol 2007; 118:247-52. [PMID: 17935717 DOI: 10.1016/j.exppara.2007.08.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2007] [Revised: 08/13/2007] [Accepted: 08/28/2007] [Indexed: 10/22/2022]
Abstract
Humans immunized by the bites of irradiated Plasmodium falciparum (Pf) sporozoite-infected mosquitoes are protected against malaria. Radiation attenuates the sporozoites preventing them from fully developing and replicating in hepatocytes, but the effects of radiation on gene expression in sporozoites are unknown. We used RT-PCR (35 cycles of PCR followed by densitometry) to assess the expression of ten genes in Pf sporozoites, and in sporozoites irradiated with 15,000cGy. Irradiation reduced expression substantially (>60%) of two DNA repair genes; moderately (30-60%) of PfUIS3, the Pf orthologue of PbUIS3, a gene up-regulated in Plasmodium berghei sporozoites and of a third DNA repair gene; and minimally (<30%) of the Pf18S ribosomal RNA, PfCSP, PfSSP2/TRAP, and PfCELTOS genes. Irradiation increased expression of PfSPATR minimally. PfLSA1 RNA was not detectable in sporozoites. These results establish that radiation of sporozoites affects gene expression levels and provide the foundation for studies to identify specific genes involved in attenuation and protective immunity.
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Affiliation(s)
- Benjamin U Hoffman
- Protein Potential LLC, 9800 Medical Center Drive, Rockville, MD 20850, USA.
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Sinnis P, Coppi A. A long and winding road: the Plasmodium sporozoite's journey in the mammalian host. Parasitol Int 2007; 56:171-8. [PMID: 17513164 PMCID: PMC1995443 DOI: 10.1016/j.parint.2007.04.002] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2007] [Accepted: 04/17/2007] [Indexed: 11/21/2022]
Abstract
The Plasmodium sporozoite, the infectious stage of the malaria parasite, makes a remarkable journey in its mammalian host. Here we review our current knowledge of the molecular and cellular basis of this journey, which begins in the skin and ends in the hepatocyte.
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Affiliation(s)
- Photini Sinnis
- Department of Medical Parasitology, New York University School of Medicine, 341 East 25th Street, New York, NY 10010, United States.
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36
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Garcia JE, Puentes A, Patarroyo ME. Developmental biology of sporozoite-host interactions in Plasmodium falciparum malaria: implications for vaccine design. Clin Microbiol Rev 2006; 19:686-707. [PMID: 17041140 PMCID: PMC1592691 DOI: 10.1128/cmr.00063-05] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Plasmodium falciparum sporozoite infects different types of cells in a mosquito's salivary glands and human epithelial and Kuppfer cells and hepatocytes. These become differentiated later on, transforming themselves into the invasive red blood cell form, the merozoite. The ability of sporozoites to interact with different types of cells requires a wide variety of mechanisms allowing them to survive in both hosts: mobility, receptor-ligand interactions with different cellular receptors, and transformation and development into other invasive parasite forms, which are vitally important for parasite survival. Sporozoite complexity is reflected in the large quantity of proteins that can be expressed. Some of them have been extensively studied, such as CSP, TRAP, STARP, LSA-1, LSA-3, SALSA, SPECT1, SPECT2, MAEBL, and SPATR, due to their importance in infection and their potential use as vaccines. Our work has been focused on the search for the molecular mechanisms of parasite-host cellular receptor-ligand interactions by identifying amino acid sequences and the critical binding residues from these proteins relevant to parasite invasion. Once such sequences have been identified, it will be possible to modify them to induce a strong immune response against P. falciparum in the experimental Aotus monkey model. This all leads towards developing multistage, multicomponent, subunit-based vaccines that will be effective in eradicating or controlling malaria caused by P. falciparum.
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Affiliation(s)
- Javier E Garcia
- Fundacion Instituto de Immunología de Colombia, Carrera 50 #26-00, Bogotá, Colombia
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37
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Tossavainen H, Pihlajamaa T, Huttunen TK, Raulo E, Rauvala H, Permi P, Kilpeläinen I. The layered fold of the TSR domain of P. falciparum TRAP contains a heparin binding site. Protein Sci 2006; 15:1760-8. [PMID: 16815922 PMCID: PMC2242559 DOI: 10.1110/ps.052068506] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Thrombospondin-related anonymous protein, TRAP, has a critical role in the hepatocyte invasion step of Plasmodium sporozoites, the transmissible form of the parasite causing malaria. The extracellular domains of this sporozoite surface protein interact with hepatocyte surface receptors whereas its intracellular domain acts as a link to the sporozoite actomyosin motor system. Liver heparan sulfate proteoglycans have been identified as potential ligands for TRAP. Proteoglycan binding has been associated with the A- and TSR domains of TRAP. We present the solution NMR structure of the TSR domain of TRAP and a chemical shift mapping study of its heparin binding epitope. The domain has an elongated structure stabilized by an array of tryptophan and arginine residues as well as disulfide bonds. The fold is very similar to those of thrombospondin type-1 (TSP-1) and F-spondin TSRs. The heparin binding site of TRAP-TSR is located in the N-terminal half of the structure, the layered side chains forming an integral part of the site. The smallest heparin fragment capable of binding to TRAP-TSR is a tetrasaccharide.
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Affiliation(s)
- Helena Tossavainen
- Program in Structural Biology and Biophysics, NMR Laboratory, Institute of Biotechnology, Neuroscience Center, Department of Chemistry, University of Helsinki, Finland
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Baum J, Richard D, Healer J, Rug M, Krnajski Z, Gilberger TW, Green JL, Holder AA, Cowman AF. A conserved molecular motor drives cell invasion and gliding motility across malaria life cycle stages and other apicomplexan parasites. J Biol Chem 2005; 281:5197-208. [PMID: 16321976 DOI: 10.1074/jbc.m509807200] [Citation(s) in RCA: 268] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Apicomplexan parasites constitute one of the most significant groups of pathogens infecting humans and animals. The liver stage sporozoites of Plasmodium spp. and tachyzoites of Toxoplasma gondii, the causative agents of malaria and toxoplasmosis, respectively, use a unique mode of locomotion termed gliding motility to invade host cells and cross cell substrates. This amoeboid-like movement uses a parasite adhesin from the thrombospondin-related anonymous protein (TRAP) family and a set of proteins linking the extracellular adhesin, via an actin-myosin motor, to the inner membrane complex. The Plasmodium blood stage merozoite, however, does not exhibit gliding motility. Here we show that homologues of the key proteins that make up the motor complex, including the recently identified glideosome-associated proteins 45 and 50 (GAP40 and GAP50), are present in P. falciparum merozoites and appear to function in erythrocyte invasion. Furthermore, we identify a merozoite TRAP homologue, termed MTRAP, a micronemal protein that shares key features with TRAP, including a thrombospondin repeat domain, a putative rhomboid-protease cleavage site, and a cytoplasmic tail that, in vitro, binds the actin-binding protein aldolase. Analysis of other parasite genomes shows that the components of this motor complex are conserved across diverse Apicomplexan genera. Conservation of the motor complex suggests that a common molecular mechanism underlies all Apicomplexan motility, which, given its unique properties, highlights a number of novel targets for drug intervention to treat major diseases of humans and livestock.
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Affiliation(s)
- Jake Baum
- Division of Infection and Immunity, The Walter & Eliza Hall Institute of Medical Research, Parkville, Victoria 3050, Australia
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Mahajan B, Jani D, Chattopadhyay R, Nagarkatti R, Zheng H, Majam V, Weiss W, Kumar S, Rathore D. Identification, cloning, expression, and characterization of the gene for Plasmodium knowlesi surface protein containing an altered thrombospondin repeat domain. Infect Immun 2005; 73:5402-9. [PMID: 16113256 PMCID: PMC1231135 DOI: 10.1128/iai.73.9.5402-5409.2005] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Proteins present on the surface of malaria parasites that participate in the process of invasion and adhesion to host cells are considered attractive vaccine targets. Aided by the availability of the partially completed genome sequence of the simian malaria parasite Plasmodium knowlesi, we have identified a 786-bp DNA sequence that encodes a 262-amino-acid-long protein, containing an altered version of the thrombospondin type I repeat domain (SPATR). Thrombospondin type 1 repeat domains participate in biologically diverse functions, such as cell attachment, mobility, proliferation, and extracellular protease activities. The SPATR from P. knowlesi (PkSPATR) shares 61% and 58% sequence identity with its Plasmodium falciparum and Plasmodium yoelii orthologs, respectively. By immunofluorescence analysis, we determined that PkSPATR is a multistage antigen that is expressed on the surface of P. knowlesi sporozoite and erythrocytic stage parasites. Recombinant PkSPATR produced in Escherichia coli binds to a human hepatoma cell line, HepG2, suggesting that PkSPATR is a parasite ligand that could be involved in sporozoite invasion of liver cells. Furthermore, recombinant PkSPATR reacted with pooled sera from P. knowlesi-infected rhesus monkeys, indicating that native PkSPATR is immunogenic during infection. Further efficacy evaluation studies in the P. knowlesi-rhesus monkey sporozoite challenge model will help to decide whether the SPATR molecule should be developed as a vaccine against human malarias.
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Affiliation(s)
- Babita Mahajan
- Division of Emerging and Transfusion Transmitted Diseases, Center for Biologics Evaluation and Research, Food and Drug Administration, 1401 Rockville Pike, Rockville, MD 20852, USA
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40
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Abstract
Malaria infection is initiated when Plasmodium sporozoites are injected into a host during the bite of an infected mosquito. In the mammal, the sporozoite must rapidly reach an intravacuolar niche within a hepatocyte, where it will generate the parasite stage that invades red blood cells and causes the symptoms of the disease. Herein, we describe our understanding of the way in which sporozoites travel from the site of the mosquito bite to the liver, arrest in the liver, cross the sinusoidal barrier and eventually gain access to hepatocytes. We also highlight some of the recent advances in our understanding of these processes at the molecular level.
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Affiliation(s)
- Patricia Baldacci
- Unité de Biologie et Génétique du Paludisme, Institut Pasteur, Paris, France
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Rathore D, Nagarkatti R, Jani D, Chattopadhyay R, de la Vega P, Kumar S, McCutchan TF. An immunologically cryptic epitope of Plasmodium falciparum circumsporozoite protein facilitates liver cell recognition and induces protective antibodies that block liver cell invasion. J Biol Chem 2005; 280:20524-9. [PMID: 15781464 DOI: 10.1074/jbc.m414254200] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Circumsporozoite, a predominant surface protein, is involved in invasion of liver cells by Plasmodium sporozoites, which leads to malaria. We have previously reported that the amino terminus region (amino acids 27-117) of P. falciparum circumsporozoite protein plays a critical role in the invasion of liver cells by the parasite. Here we show that invasion-blocking antibodies are induced by a polypeptide encoding these 91 amino acids, only when it is presented in the absence of the rest of the protein. This suggests that when present in the whole protein, the amino terminus remains immunologically cryptic. A single reactive epitope was identified and mapped to a stretch of 21 amino acids from position 93 to 113. The epitope is configurational in nature, since its recognition was affected by deleting as little as 3 amino acids from either end of the 21-residue peptide. Lysine 104, the only known polymorphic position in the epitope, affected its recognition by the antibodies, and its conversion to leucine in the protein led to a substantial loss of binding activity of the protein to the hepatocytes. This indicated that in the protein, the epitope serves as a binding ligand and facilitates the interaction between sporozoite and hepatic cells. When considered along with the observation that in its native state this motif is immunologically unresponsive, we suggest that hiding functional moieties of the protein from the immune system is an evasion strategy to preserve liver cell binding function and may be of importance in designing anti-sporozoite vaccines.
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Affiliation(s)
- Dharmendar Rathore
- Virginia Bioinformatics Institute, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA.
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42
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Abstract
Plasmodium sporozoites display complex phenotypes including gliding motility and invasion of and transmigration through cells in the mosquito vector and the vertebrate host. Sporozoite studies have been difficult to perform because of technical concerns. Nevertheless, they have already provided insights into several aspects of sporozoite biology, shared in part with other apicomplexan invasive stages. Structure/function analysis of the thrombospondin-related anonymous protein paved the way to the understanding of the molecular mechanisms of apicomplexan gliding motility and host cell invasion. Functional studies of circumsporozoite protein revealed its role in Plasmodium sporozoite morphogenesis in addition to its well-known function in host cell invasion. Transcriptional surveys, which facilitate the investigation of gene expression programs that control sporozoite phenotypes, have revealed a high degree of previously unappreciated complexity and novel proteins that mediate sporozoite host cell infection.
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Affiliation(s)
- Stefan H I Kappe
- Seattle Biomedical Research Institute, Seattle, WA 98109-1651, USA.
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Thompson J, Cooke RE, Moore S, Anderson LF, Janse CJ, Waters AP. PTRAMP; a conserved Plasmodium thrombospondin-related apical merozoite protein. Mol Biochem Parasitol 2004; 134:225-32. [PMID: 15003842 DOI: 10.1016/j.molbiopara.2003.12.003] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2003] [Revised: 12/10/2003] [Accepted: 12/11/2003] [Indexed: 11/18/2022]
Abstract
A gene encoding a 352 amino acid protein with a putative signal sequence, transmembrane domain and thrombospondin structural homology repeat was identified in the genome of the human malaria parasite, Plasmodium falciparum and the rodent malaria parasite, Plasmodium berghei. The protein localises in the apical organelles of P. falciparum and P. berghei merozoites within intraerythrocytic schizonts and has, therefore, been termed the Plasmodium thrombospondin-related apical merozoite protein (PTRAMP). PTRAMP co-localises with the Apical Merozoite Antigen-1 (AMA-1) in developing micronemes and subsequently relocates onto the merozoite surface. Although the gene appears to be specific to the Plasmodium genus, orthologues are present in the genomes of all malaria parasite species examined suggesting a conserved function in host-cell invasion. PTRAMP, therefore, has all the features to merit further evaluation as a malaria vaccine candidate.
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Affiliation(s)
- Joanne Thompson
- Institute of Cell, Animal and Population Biology, Ashworth Laboratories, The King's Buildings, Edinburgh EH9 3JT, UK.
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