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Wiedeman J, Harrison R, Etheridge RD. A limitation lifted: A conditional knockdown system reveals essential roles for Polo-like kinase and Aurora kinase 1 in Trypanosoma cruzi cell division. Proc Natl Acad Sci U S A 2025; 122:e2416009122. [PMID: 40106484 PMCID: PMC11874021 DOI: 10.1073/pnas.2416009122] [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: 08/07/2024] [Accepted: 12/20/2024] [Indexed: 03/22/2025] Open
Abstract
While advances in genome editing technologies have simplified gene disruption in many organisms, the study of essential genes requires development of conditional disruption or knockdown systems that are not available in most organisms. Such is the case for Trypanosoma cruzi, a parasite that causes Chagas disease, a severely neglected tropical disease endemic to Latin America that is often fatal. Our knowledge of the identity of essential genes and their functions in T. cruzi has been severely constrained by historical challenges in very basic genetic manipulation and the absence of RNA interference machinery. Here, we describe the development and use of self-cleaving RNA sequences to conditionally regulate essential gene expression in T. cruzi. Using these tools, we identified essential roles for Polo-like and Aurora kinases in T. cruzi cell division, mirroring their functions in Trypanosoma brucei. Importantly, we demonstrate conditional knockdown of essential genes in intracellular amastigotes, the disease-causing stage of the parasite in its human host. This conditional knockdown system enables the efficient and scalable functional characterization of essential genes in T. cruzi and provides a framework for the development of conditional gene knockdown systems for other nonmodel organisms.
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Affiliation(s)
- Justin Wiedeman
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA30602
- Department of Cellular Biology, University of Georgia, Athens, GA30602
| | - Ruby Harrison
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA30602
- Department of Cellular Biology, University of Georgia, Athens, GA30602
| | - Ronald Drew Etheridge
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA30602
- Department of Cellular Biology, University of Georgia, Athens, GA30602
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2
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Arranz-Solís D, Saeij JPJ. New Avenues to Design Toxoplasma Vaccines Based on Oocysts and Cysts. Front Immunol 2022; 13:910961. [PMID: 35734184 PMCID: PMC9207213 DOI: 10.3389/fimmu.2022.910961] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 05/17/2022] [Indexed: 12/14/2022] Open
Abstract
Toxoplasmosis is a worldwide disease affecting all warm-blooded animals, including humans. Vaccination strategies aimed at inducing an efficient immune response while preventing transmission have been attempted in the past. While many different approaches can partially protect immunized animals against subsequent infections, full and lasting protection is rarely attained and only with live-attenuated vaccines. In addition, vaccines based on mutant strains that are deficient in forming the chronic phase of the parasite (such as Toxovax™) cannot be extensively used due to their zoonotic potential and the possibility of reversion to virulent phenotypes. An increasing number of studies using emerging genetic-engineering tools have been conducted to design novel vaccines based on recombinant proteins, DNA or delivery systems such as nanoparticles. However, these are usually less efficient due to their antigenic simplicity. In this perspective article we discuss potential target genes and novel strategies to generate live-attenuated long-lasting vaccines based on tissue cysts and oocysts, which are the environmentally resistant chronic forms of Toxoplasma. By selectively disrupting genes important for parasite dissemination, cyst formation and/or sporozoite invasion, alone or in combination, a vaccine based on a live-attenuated strain that elicits a protective immune response while preventing the transmission of Toxoplasma could be created. Finally, further improvements of protocols to generate Toxoplasma sexual stages in vitro might lead to the production of oocysts from such a strain without the need for using mice or cats.
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Affiliation(s)
| | - Jeroen P. J. Saeij
- Pathology, Microbiology and Immunology department, School of Veterinary Medicine, University of California Davis, Davis, CA, United States
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3
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Smith TA, Lopez-Perez GS, Herneisen AL, Shortt E, Lourido S. Screening the Toxoplasma kinome with high-throughput tagging identifies a regulator of invasion and egress. Nat Microbiol 2022; 7:868-881. [PMID: 35484233 PMCID: PMC9167752 DOI: 10.1038/s41564-022-01104-0] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Accepted: 03/11/2022] [Indexed: 12/26/2022]
Abstract
Protein kinases regulate fundamental aspects of eukaryotic cell biology, making them attractive chemotherapeutic targets in parasites like Plasmodium spp. and Toxoplasma gondii. To systematically examine the parasite kinome, we developed a high-throughput tagging (HiT) strategy to endogenously label protein kinases with an auxin-inducible degron and fluorophore. Hundreds of tagging vectors were assembled from synthetic sequences in a single reaction and used to generate pools of mutants to determine localization and function. Examining 1,160 arrayed clones, we assigned 40 protein localizations and associated 15 kinases with distinct defects. The fitness of tagged alleles was also measured by pooled screening, distinguishing delayed from acute phenotypes. A previously unstudied kinase, associated with a delayed phenotype, was shown to be a regulator of invasion and egress. We named the kinase Store Potentiating/Activating Regulatory Kinase (SPARK), based on its impact on intracellular Ca2+ stores. Despite homology to mammalian 3-phosphoinositide-dependent protein kinase-1 (PDK1), SPARK lacks a lipid-binding domain, suggesting a rewiring of the pathway in parasites. HiT screening extends genome-wide approaches into complex cellular phenotypes, providing a scalable and versatile platform to dissect parasite biology.
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Affiliation(s)
- Tyler A Smith
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | | | - Alice L Herneisen
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Emily Shortt
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA
| | - Sebastian Lourido
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA.
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA.
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4
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Briquet S, Gissot M, Silvie O. A toolbox for conditional control of gene expression in apicomplexan parasites. Mol Microbiol 2021; 117:618-631. [PMID: 34564906 PMCID: PMC9293482 DOI: 10.1111/mmi.14821] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Accepted: 09/23/2021] [Indexed: 01/29/2023]
Abstract
Apicomplexan parasites encompass diverse pathogens for humans and animals, including the causative agents of malaria and toxoplasmosis, Plasmodium spp. and Toxoplasma gondii. Genetic manipulation of these parasites has become central to explore parasite biology, unravel gene function and identify new targets for therapeutic strategies. Tremendous progress has been achieved over the past years with the advent of next generation sequencing and powerful genome editing methods. In particular, various methods for conditional gene expression have been developed in both Plasmodium and Toxoplasma to knockout or knockdown essential genes, or for inducible expression of master developmental regulators or mutant versions of proteins. Conditional gene expression can be achieved at three distinct levels. At the DNA level, inducible site‐specific recombinases allow conditional genome editing. At the RNA level, regulation can be achieved during transcription, using stage‐specific or regulatable promoters, or post‐transcriptionally through alteration of mRNA stability or translation. At the protein level, several systems have been developed for inducible degradation or displacement of a protein of interest. In this review, we provide an overview of current systems for conditional control of gene expression in Plasmodium and Toxoplasma parasites, highlighting the advantages and limitations of each approach.
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Affiliation(s)
- Sylvie Briquet
- INSERM, CNRS, Centre d'Immunologie et des Maladies Infectieuses, Sorbonne Université, Paris, France
| | - Mathieu Gissot
- CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, Center for Infection and Immunity of Lille, CIIL, Univ. Lille, Lille, France
| | - Olivier Silvie
- INSERM, CNRS, Centre d'Immunologie et des Maladies Infectieuses, Sorbonne Université, Paris, France
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5
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Toxoplasma gondii: One Organism, Multiple Models. Trends Parasitol 2016; 33:113-127. [PMID: 27988095 DOI: 10.1016/j.pt.2016.11.007] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Revised: 11/15/2016] [Accepted: 11/18/2016] [Indexed: 12/13/2022]
Abstract
Toxoplasma gondii is an intensely studied protozoan parasite. It is also used as a model organism to research additional clinically relevant human and veterinary parasites due to ease of in vitro culture and genetic manipulation. Recently, it has been developed as a model of inflammatory bowel disease, due to their similar pathologies. However, researchers vary widely in how they use T. gondii, which makes study comparisons and interpretation difficult. The aim of this review is to provide researchers with a tool to: (i) determine the appropriateness of the different T. gondii models to their research, (ii) interpret results from the wide range of study conditions, and (iii) consider new advances in technology which could improve or refine their experimental setup.
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6
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Wang JL, Huang SY, Behnke MS, Chen K, Shen B, Zhu XQ. The Past, Present, and Future of Genetic Manipulation in Toxoplasma gondii. Trends Parasitol 2016; 32:542-553. [PMID: 27184069 DOI: 10.1016/j.pt.2016.04.013] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 04/20/2016] [Accepted: 04/21/2016] [Indexed: 12/16/2022]
Abstract
Toxoplasma gondii is a classic model for studying obligate intracellular microorganisms as various genetic manipulation tools have been developed in T. gondii over the past 20 years. Here we summarize the major strategies for T. gondii genetic manipulation including genetic crosses, insertional mutagenesis, chemical mutagenesis, homologous gene replacement, conditional knockdown techniques, and the recently developed clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 system. We evaluate the advantages and limitations of each of these tools in a historical perspective. We also discuss additional applications of modified CRISPR-Cas9 systems for use in T. gondii, such as regulation of gene expression, labeling of specific genomic loci, and epigenetic modifications. These approaches have the potential to revolutionize the analysis of T. gondii biology and help us to better develop new drugs and vaccines.
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Affiliation(s)
- Jin-Lei Wang
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu Province 730046, PR China
| | - Si-Yang Huang
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu Province 730046, PR China; Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu Province 225009, PR China
| | - Michael S Behnke
- Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Kai Chen
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu Province 730046, PR China
| | - Bang Shen
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei Province 430070, PR China.
| | - Xing-Quan Zhu
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu Province 730046, PR China; Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu Province 225009, PR China.
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7
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Etheridge RD, Alaganan A, Tang K, Lou HJ, Turk BE, Sibley LD. The Toxoplasma pseudokinase ROP5 forms complexes with ROP18 and ROP17 kinases that synergize to control acute virulence in mice. Cell Host Microbe 2015; 15:537-50. [PMID: 24832449 DOI: 10.1016/j.chom.2014.04.002] [Citation(s) in RCA: 184] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Revised: 02/24/2014] [Accepted: 03/20/2014] [Indexed: 11/28/2022]
Abstract
Polymorphic rhoptry-secreted kinases (ROPs) are essential virulence factors of Toxoplasma gondii. In particular, the pseudokinase ROP5 is the major determinant of acute virulence in mice, but the underlying mechanisms are unclear. We developed a tandem affinity protein tagging and purification approach in T. gondii and used it to show that ROP5 complexes with the active kinases ROP18 and ROP17. Biochemical analyses indicate that ROP18 and ROP17 have evolved to target adjacent and essential threonine residues in switch region I of immunity-related guanosine triphosphatases (GTPases) (IRGs), a family of host defense molecules that function to control intracellular pathogens. The combined activities of ROP17 and ROP18 contribute to avoidance of IRG recruitment to the intracellular T. gondii-containing vacuole, thus protecting the parasite from clearance in interferon-activated macrophages. These studies reveal an intricate, multilayered parasite survival strategy involving pseudokinases that regulate multiple active kinase complexes to synergistically thwart innate immunity.
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Affiliation(s)
- Ronald D Etheridge
- Department of Molecular Microbiology, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA
| | - Aditi Alaganan
- Department of Molecular Microbiology, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA
| | - Keliang Tang
- Department of Molecular Microbiology, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA
| | - Hua Jane Lou
- Department of Pharmacology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA
| | - Benjamin E Turk
- Department of Pharmacology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA
| | - L David Sibley
- Department of Molecular Microbiology, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA.
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8
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Crater AK, Manni E, Ananvoranich S. Utilization of inherent miRNAs in functional analyses of Toxoplasma gondii genes. J Microbiol Methods 2015; 108:92-102. [DOI: 10.1016/j.mimet.2014.11.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 11/26/2014] [Accepted: 11/26/2014] [Indexed: 10/24/2022]
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9
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Vesicles bearing Toxoplasma apicoplast membrane proteins persist following loss of the relict plastid or Golgi body disruption. PLoS One 2014; 9:e112096. [PMID: 25369183 PMCID: PMC4219833 DOI: 10.1371/journal.pone.0112096] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2012] [Accepted: 10/13/2014] [Indexed: 12/16/2022] Open
Abstract
Toxoplasma gondii and malaria parasites contain a unique and essential relict plastid called the apicoplast. Most apicoplast proteins are encoded in the nucleus and are transported to the organelle via the endoplasmic reticulum (ER). Three trafficking routes have been proposed for apicoplast membrane proteins: (i) vesicular trafficking from the ER to the Golgi and then to the apicoplast, (ii) contiguity between the ER membrane and the apicoplast allowing direct flow of proteins, and (iii) vesicular transport directly from the ER to the apicoplast. Previously, we identified a set of membrane proteins of the T. gondii apicoplast which were also detected in large vesicles near the organelle. Data presented here show that the large vesicles bearing apicoplast membrane proteins are not the major carriers of luminal proteins. The vesicles continue to appear in parasites which have lost their plastid due to mis-segregation, indicating that the vesicles are not derived from the apicoplast. To test for a role of the Golgi body in vesicle formation, parasites were treated with brefeldin A or transiently transfected with a dominant-negative mutant of Sar1, a GTPase required for ER to Golgi trafficking. The immunofluorescence patterns showed little change. These findings were confirmed using stable transfectants, which expressed the toxic dominant-negative sar1 following Cre-loxP mediated promoter juxtaposition. Our data support the hypothesis that the large vesicles do not mediate the trafficking of luminal proteins to the apicoplast. The results further show that the large vesicles bearing apicoplast membrane proteins continue to be observed in the absence of Golgi and plastid function. These data raise the possibility that the apicoplast proteome is generated by two novel ER to plastid trafficking pathways, plus the small set of proteins encoded by the apicoplast genome.
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10
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Pereira LM, Yatsuda AP. The chloramphenicol acetyltransferase vector as a tool for stable tagging of Neospora caninum. Mol Biochem Parasitol 2014; 196:75-81. [PMID: 25127750 DOI: 10.1016/j.molbiopara.2014.08.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Revised: 07/03/2014] [Accepted: 08/04/2014] [Indexed: 11/16/2022]
Abstract
Neospora caninum is an obligate intracellular Apicomplexa, a phylum where one of the current methods for functional studies relies on molecular genetic tools. For Toxoplasma gondii, the first method described, in 1993, was based on resistance against chloramphenicol. As in T. gondii, we developed a vector constituted of the chloramphenicol acetyltransferase gene (CAT) flanked by the N. caninum dihydrofolate reductase-thymidylate synthase (DHFR-TS) 5' coding sequence flanking region. Five weeks after transfection and under the selection of chloramphenicol the expression of CAT increased compared to the wild type and the resistance was retained for more than one year. Between the stop codon of CAT and the 3' UTR of DHFR, a Lac-Z gene controlled by the N. caninum tubulin 5' coding sequence flanking region was ligated, resulting in a vector with a reporter gene (Ncdhfr-CAT/NcTub-tetO/Lac-Z). The stability was maintained through an episomal pattern for 14 months when the tachyzoites succumbed, which was an unexpected phenomenon compared to T. gondii. Stable parasites expressing the Lac-Z gene allowed the detection of tachyzoites after invasion by enzymatic reaction (CPRG) and were visualised macro- and microscopically by X-Gal precipitation and fluorescence. This work developed the first vector for stable expression of proteins based on chloramphenicol resistance and controlled exclusively by N. caninum promoters.
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Affiliation(s)
- Luiz Miguel Pereira
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Av do Café, sn/n, 14040-903 Ribeirão Preto, SP, Brazil; Núcleo de Apoio à Pesquisa em Produtos Naturais e Sintéticos, Universidade de São Paulo, Ribeirão Preto, SP, Brazil
| | - Ana Patrícia Yatsuda
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Av do Café, sn/n, 14040-903 Ribeirão Preto, SP, Brazil; Núcleo de Apoio à Pesquisa em Produtos Naturais e Sintéticos, Universidade de São Paulo, Ribeirão Preto, SP, Brazil.
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11
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Tang Q, Andenmatten N, Hortua Triana MA, Deng B, Meissner M, Moreno SNJ, Ballif BA, Ward GE. Calcium-dependent phosphorylation alters class XIVa myosin function in the protozoan parasite Toxoplasma gondii. Mol Biol Cell 2014; 25:2579-91. [PMID: 24989796 PMCID: PMC4148248 DOI: 10.1091/mbc.e13-11-0648] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Myosin A, an unconventional class XIV myosin of the protozoan parasite Toxoplasma gondii, undergoes calcium-dependent phosphorylation, providing a mechanism by which the parasite can regulate motility-based processes such as escape from the infected host cell at the end of the parasite's lytic cycle. Class XIVa myosins comprise a unique group of myosin motor proteins found in apicomplexan parasites, including those that cause malaria and toxoplasmosis. The founding member of the class XIVa family, Toxoplasma gondii myosin A (TgMyoA), is a monomeric unconventional myosin that functions at the parasite periphery to control gliding motility, host cell invasion, and host cell egress. How the motor activity of TgMyoA is regulated during these critical steps in the parasite's lytic cycle is unknown. We show here that a small-molecule enhancer of T. gondii motility and invasion (compound 130038) causes an increase in parasite intracellular calcium levels, leading to a calcium-dependent increase in TgMyoA phosphorylation. Mutation of the major sites of phosphorylation altered parasite motile behavior upon compound 130038 treatment, and parasites expressing a nonphosphorylatable mutant myosin egressed from host cells more slowly in response to treatment with calcium ionophore. These data demonstrate that TgMyoA undergoes calcium-dependent phosphorylation, which modulates myosin-driven processes in this important human pathogen.
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Affiliation(s)
- Qing Tang
- Department of Microbiology and Molecular Genetics, University of Vermont College of Medicine, Burlington, VT 05405
| | - Nicole Andenmatten
- Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Miryam A Hortua Triana
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, GA 30602
| | - Bin Deng
- Vermont Genetics Network Proteomics Facility, University of Vermont, Burlington, VT 05405 Department of Biology, University of Vermont, Burlington, VT 05405
| | - Markus Meissner
- Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Silvia N J Moreno
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, GA 30602
| | - Bryan A Ballif
- Department of Biology, University of Vermont, Burlington, VT 05405
| | - Gary E Ward
- Department of Microbiology and Molecular Genetics, University of Vermont College of Medicine, Burlington, VT 05405
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12
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Advantages and disadvantages of conditional systems for characterization of essential genes in Toxoplasma gondii. Parasitology 2014; 141:1390-8. [PMID: 24926834 DOI: 10.1017/s0031182014000559] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The dissection of apicomplexan biology has been highly influenced by the genetic tools available for manipulation of parasite DNA. Here, we describe different techniques available for the generation of conditional mutants. Comparison of the advantages and disadvantages of the three most commonly used regulation systems: the tetracycline inducible system, the regulation of protein stability and site-specific recombination are discussed. Using some previously described examples we explore some of the pitfalls involved in gene-function analysis using these systems that can lead to wrong or over-interpretation of phenotypes. We will also mention different options to standardize the application of these techniques for the characterization of gene function in high-throughput.
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13
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Pereira LM, Yatsuda AP. Comparison of an ELISA assay for the detection of adhesive/invasive Neospora caninum tachyzoites. REVISTA BRASILEIRA DE PARASITOLOGIA VETERINARIA 2014; 23:36-43. [DOI: 10.1590/s1984-29612014005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Accepted: 01/15/2014] [Indexed: 11/22/2022]
Abstract
Neospora caninum belongs to the phylum Apicomplexa, the causative agent of neosporosis, which leads to economic impacts on cattle production. A common feature among apicomplexan parasites is the invasive process driven mostly by the parasite. As a first evaluation of candidate molecules that play a possible role by interfering in this invasive process, the in vitro invasion assay is a fast and direct way to screen future agonists or antagonists. This work involved the development of a new cell culture ELISA and transient β-galactosidase activity applied to the semi-quantitative detection of N. caninum in Vero cell culture. Cell culture ELISA is based on histochemistry and immunology, resulting in a colorimetric reaction. The β-galactosidase activity was obtained by the transient transfection of the lacZ gene under control of RPS13 promoter of N. caninum. These methods were used to evaluate the effects of temperature (37°C and 85°C) on the invasion and adhesion of tachyzoites. The three tested methods (real time PCR, β-galactosidase activity and ELISA) showed a similar pattern, indicating that different methods may be complementary.
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Affiliation(s)
- Luiz Miguel Pereira
- Universidade de São Paulo ? USP, Brasil; Universidade de São Paulo ? USP, Brasil
| | - Ana Patrícia Yatsuda
- Universidade de São Paulo ? USP, Brasil; Universidade de São Paulo ? USP, Brasil
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14
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Pereira LM, Baroni L, Yatsuda AP. A transgenic Neospora caninum strain based on mutations of the dihydrofolate reductase-thymidylate synthase gene. Exp Parasitol 2014; 138:40-7. [PMID: 24440296 DOI: 10.1016/j.exppara.2014.01.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Accepted: 01/07/2014] [Indexed: 01/25/2023]
Abstract
Neospora caninum is an Apicomplexa parasite related to abortion and losses of fertility in cattle. The amenability of Toxoplasma gondii and Plasmodium to genetic manipulation offers several tools to determine the invasion and replication processes, which support posterior strategies related to the combat of these diseases. For Plasmodium the use of pyrimethamine as an auxiliary drug on malaria treatment has been affected by the rise of resistant strains and the analyses on Dihydrofolate reductase-thymidylate synthase (DHFR-TS) gene indicated several point mutations. In this work we developed a method for stable insertion of genes based on resistance to pyrimethamine. For that, the coding sequence of NcDHFR-TS (Dihydrofolate reductase-thymidylate synthase) was point mutated in two amino acids, generating DHFRM2M3. The DHFRM2M3 flanked by the promoter and 3'UTR of Ncdhfr-ts (Ncdhfr-DHFRM2M3) conferred resistance to pyrimethamine after transfection. For illustration of stability and expression, the cassette Ncdhfr-DHFRM2M3 was ligated to the reporter gene Lac-Z (β-galactosidase enzyme) controlled by the N. caninum tubulin promoter and was transfected and selected in N. caninum. The cassette was integrated into the genome and the selected tachyzoites expressed Lac-Z, allowing the detection of tachyzoites by the CPRG reaction and X-gal precipitation. The obtainment of transgenic N. caninum resistant to pyrimethamine confirms the effects on DHFR-TS among the Apicomplexa members and will support future approaches on pholate inhibitors for N. caninum prophylaxis. The construction of stable tachyzoites based on vectors with N. caninum promoters initiates the molecular manipulation of this parasite independently of T. gondii.
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Affiliation(s)
- Luiz Miguel Pereira
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Av do Café, sn/n, 14040-903 Ribeirão Preto, SP, Brazil; Núcleo de Apoio à Pesquisa em Produtos Naturais e Sintéticos, Universidade de São Paulo, Ribeirão Preto, SP, Brazil
| | - Luciana Baroni
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Av do Café, sn/n, 14040-903 Ribeirão Preto, SP, Brazil; Núcleo de Apoio à Pesquisa em Produtos Naturais e Sintéticos, Universidade de São Paulo, Ribeirão Preto, SP, Brazil
| | - Ana Patrícia Yatsuda
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Av do Café, sn/n, 14040-903 Ribeirão Preto, SP, Brazil; Núcleo de Apoio à Pesquisa em Produtos Naturais e Sintéticos, Universidade de São Paulo, Ribeirão Preto, SP, Brazil.
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15
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A systematic screen to discover and analyze apicoplast proteins identifies a conserved and essential protein import factor. PLoS Pathog 2011; 7:e1002392. [PMID: 22144892 PMCID: PMC3228799 DOI: 10.1371/journal.ppat.1002392] [Citation(s) in RCA: 175] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2011] [Accepted: 10/06/2011] [Indexed: 11/26/2022] Open
Abstract
Parasites of the phylum Apicomplexa cause diseases that impact global health and economy. These unicellular eukaryotes possess a relict plastid, the apicoplast, which is an essential organelle and a validated drug target. However, much of its biology remains poorly understood, in particular its elaborate compartmentalization: four membranes defining four different spaces. Only a small number of organellar proteins have been identified in particular few proteins are known for non-luminal apicoplast compartments. We hypothesized that enlarging the catalogue of apicoplast proteins will contribute toward identifying new organellar functions and expand the realm of targets beyond a limited set of characterized pathways. We developed a bioinformatic screen based on mRNA abundance over the cell cycle and on phyletic distribution. We experimentally assessed 57 genes, and of 30 successful epitope tagged candidates eleven novel apicoplast proteins were identified. Of those, seven appear to target to the lumen of the organelle, and four localize to peripheral compartments. To address their function we then developed a robust system for the construction of conditional mutants via a promoter replacement strategy. We confirm the feasibility of this system by establishing conditional mutants for two selected genes – a luminal and a peripheral apicoplast protein. The latter is particularly intriguing as it encodes a hypothetical protein that is conserved in and unique to Apicomplexan parasites and other related organisms that maintain a red algal endosymbiont. Our studies suggest that this peripheral plastid protein, PPP1, is likely localized to the periplastid compartment. Conditional disruption of PPP1 demonstrated that it is essential for parasite survival. Phenotypic analysis of this mutant is consistent with a role of the PPP1 protein in apicoplast biogenesis, specifically in import of nuclear-encoded proteins into the organelle. Apicomplexa are a group of parasites that cause important diseases, including malaria and several AIDS associated opportunistic infections. The parasites depend on an algal endosymbiont, the apicoplast, and this provides an Achilles' heel for drug development. We use Toxoplasma gondii as a model to characterize the biology and function of the apicoplast. In this study we apply a strategy to identify new apicoplast proteins and to prioritize them as potential targets through the analysis of genetic mutants. To aid this goal we develop a new parasite line and a protocol enabling the streamlined construction of conditional mutants. Using this new approach we discover numerous new apicoplast proteins, many of them have no assigned function yet. We demonstrate that function can be deduced using our genetic approach by establishing the essential role in apicoplast protein import for a new factor with intriguing localization and evolutionary history.
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Limenitakis J, Soldati-Favre D. Functional genetics in Apicomplexa: potentials and limits. FEBS Lett 2011; 585:1579-88. [PMID: 21557944 DOI: 10.1016/j.febslet.2011.05.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2011] [Revised: 05/02/2011] [Accepted: 05/03/2011] [Indexed: 01/15/2023]
Abstract
The Apicomplexans are obligate intracellular protozoan parasites and the causative agents of severe diseases in humans and animals. Although complete genome sequences are available since many years and for several parasites, they are replete with putative genes of unassigned function. Forward and reverse genetic approaches are limited only to a few Apicomplexans that can either be propagated in vitro or in a convenient animal model. This review will compare and contrast the most recent strategies developed for the genetic manipulation of Plasmodium falciparum, Plasmodium berghei and Toxoplasma gondii that have taken advantage of the intrinsic features of their respective genomes. Efforts towards the improvement of the transfection efficiencies in malaria parasites, the development of approaches to study essential genes and the elaboration of high-throughput methods for the identification of gene function will be discussed.
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Affiliation(s)
- Julien Limenitakis
- Department of Microbiology and Molecular Medicine, CMU, University of Geneva, Geneva, Switzerland.
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17
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Jammallo L, Eidell K, Davis PH, Dufort FJ, Cronin C, Thirugnanam S, Chiles TC, Roos DS, Gubbels MJ. An insertional trap for conditional gene expression in Toxoplasma gondii: identification of TAF250 as an essential gene. Mol Biochem Parasitol 2011; 175:133-43. [PMID: 21035508 PMCID: PMC3053073 DOI: 10.1016/j.molbiopara.2010.10.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2010] [Revised: 10/18/2010] [Accepted: 10/19/2010] [Indexed: 11/18/2022]
Abstract
Toxoplasmosis is characterized by fast lytic replication cycles leading to severe tissue lesions. Successful host cell invasion is essential for pathogenesis. The division cycle of Toxoplasma gondii is characterized by an unusual cell cycle progression and a distinct internal budding mechanism. To identify essential genes involved in the lytic cycle we devised an insertional gene trapping strategy using the Tet-transactivator system. In essence, a random, active promoter is displaced with a tetracycline regulatable promoter, which if in an essential gene, will result in a conditionally lethal phenotype upon tetracycline addition. We isolated eight mutants with growth defects, two of which displayed modest invasion defects, one of which had an additional cell cycle defect. The trapped loci were identified using expression microarrays, exploiting the tetracycline dependent expression of the trapped genes. In mutant 3.3H6 we identified TCP-1, a component of the chaperonin protein folding machinery under the control of the Tet promoter. However, this gene was not critical for growth of mutant 3.3H6. Subsequently, we identified a suppressor gene encoding a protein with a hypothetical function by guided cosmid complementation. In mutant 4.3B13, we identified TAF250, an RNA polymerase II complex component, as the trapped, essential gene. Furthermore, by mapping the plasmid insertion boundaries we identified multiple genomic rearrangements, which hint at a potential replication dependent DNA repair mechanism. Furthermore, these rearrangements provide an explanation for inconsistent locus rescue results observed by molecular biological approaches. Taken together, we have added an approach to identify and study essential genes in Toxoplasma.
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Affiliation(s)
| | - Keith Eidell
- Department of Biology, Boston College, Chestnut Hill, MA
| | - Paul H. Davis
- Department of Biology and Penn Genomics Institute, University of Pennsylvania, Philadelphia, PA
| | - Fay J. Dufort
- Department of Biology, Boston College, Chestnut Hill, MA
| | | | | | | | - David S. Roos
- Department of Biology and Penn Genomics Institute, University of Pennsylvania, Philadelphia, PA
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18
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Gaji RY, Behnke MS, Lehmann MM, White MW, Carruthers VB. Cell cycle-dependent, intercellular transmission of Toxoplasma gondii is accompanied by marked changes in parasite gene expression. Mol Microbiol 2011; 79:192-204. [PMID: 21166903 PMCID: PMC3075969 DOI: 10.1111/j.1365-2958.2010.07441.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Intracellular microbes have evolved efficient strategies for transitioning from one cell to another in a process termed intercellular transmission. Here we show that host cell transmission of the obligate intracellular parasite Toxoplasma gondii is closely tied to specific cell cycle distributions, with egress and reinvasion occurring most proficiently by parasites in the G1 phase. We also reveal that Toxoplasma undergoes marked changes in mRNA expression when transitioning from the extracellular environment to its intracellular niche. These mRNA level changes reflect a modal switch from expression of proteins involved in invasion, motility and signal transduction in extracellular parasites to expression of metabolic and DNA replication proteins in intracellular parasites. Host cell binding and signalling associated with the discharge of parasite secretory proteins was not sufficient to induce this switch in gene expression, suggesting that the regulatory mechanisms responsible are tied to the establishment of the intracellular environment. The genes whose expression increased after parasite invasion belong to a progressive cascade known to underlie the parasite division cycle indicating that the unique relationship between the G1 phase and invasion effectively synchronizes short-term population growth. This work provides new insight into how this highly successful parasite competently transits from cell to cell.
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Affiliation(s)
- Rajshekhar Y. Gaji
- Department of Microbiology and Immunology, University of Michigan Medical School, 1150 W. Medical Center Dr., Ann Arbor, MI 48109 USA
| | - Michael S. Behnke
- Department of Veterinary Molecular Biology, Montana State University, Bozeman, MT 59717 USA
| | - Margaret M. Lehmann
- Department of Veterinary Molecular Biology, Montana State University, Bozeman, MT 59717 USA
| | - Michael W. White
- Departments of Molecular Medicine & Global Health, University of South Florida, Tampa, FL 33612 USA
| | - Vern B. Carruthers
- Department of Microbiology and Immunology, University of Michigan Medical School, 1150 W. Medical Center Dr., Ann Arbor, MI 48109 USA
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19
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Hutson SL, Mui E, Kinsley K, Witola WH, Behnke MS, El Bissati K, Muench SP, Rohrman B, Liu SR, Wollmann R, Ogata Y, Sarkeshik A, Yates JR, McLeod R. T. gondii RP promoters & knockdown reveal molecular pathways associated with proliferation and cell-cycle arrest. PLoS One 2010; 5:e14057. [PMID: 21124925 PMCID: PMC2989910 DOI: 10.1371/journal.pone.0014057] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2010] [Accepted: 10/25/2010] [Indexed: 01/16/2023] Open
Abstract
Molecular pathways regulating rapid proliferation and persistence are fundamental for pathogens but are not elucidated fully in Toxoplasma gondii. Promoters of T. gondii ribosomal proteins (RPs) were analyzed by EMSAs and ChIP. One RP promoter domain, known to bind an Apetela 2, bound to nuclear extract proteins. Promoter domains appeared to associate with histone acetyl transferases. To study effects of a RP gene's regulation in T. gondii, mutant parasites (Δrps13) were engineered with integration of tetracycline repressor (TetR) response elements in a critical location in the rps13 promoter and transfection of a yellow fluorescent-tetracycline repressor (YFP-TetR). This permitted conditional knockdown of rps13 expression in a tightly regulated manner. Δrps13 parasites were studied in the presence (+ATc) or absence of anhydrotetracycline (-ATc) in culture. -ATc, transcription of the rps13 gene and expression of RPS13 protein were markedly diminished, with concomitant cessation of parasite replication. Study of Δrps13 expressing Myc-tagged RPL22, -ATc, showed RPL22 diminished but at a slower rate. Quantitation of RNA showed diminution of 18S RNA. Depletion of RPS13 caused arrest of parasites in the G1 cell cycle phase, thereby stopping parasite proliferation. Transcriptional differences ±ATc implicate molecules likely to function in regulation of these processes. In vitro, -ATc, Δrps13 persists for months and the proliferation phenotype can be rescued with ATc. In vivo, however, Δrps13 could only be rescued when ATc was given simultaneously and not at any time after 1 week, even when L-NAME and ATc were administered. Immunization with Δrps13 parasites protects mice completely against subsequent challenge with wildtype clonal Type 1 parasites, and robustly protects mice against wildtype clonal Type 2 parasites. Our results demonstrate that G1 arrest by ribosomal protein depletion is associated with persistence of T. gondii in a model system in vitro and immunization with Δrps13 protects mice against subsequent challenge with wildtype parasites.
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Affiliation(s)
- Samuel L. Hutson
- Department of Surgery (Ophthalmology), The University of Chicago, Chicago, Illinois, United States of America
| | - Ernest Mui
- Department of Surgery (Ophthalmology), The University of Chicago, Chicago, Illinois, United States of America
| | - Karen Kinsley
- Department of Surgery (Ophthalmology), The University of Chicago, Chicago, Illinois, United States of America
| | - William H. Witola
- Department of Surgery (Ophthalmology), The University of Chicago, Chicago, Illinois, United States of America
| | - Michael S. Behnke
- Department of Veterinary Molecular Biology, Montana State University, Bozeman, Montana, United States of America
| | - Kamal El Bissati
- Department of Surgery (Ophthalmology), The University of Chicago, Chicago, Illinois, United States of America
| | - Stephen P. Muench
- Institute of Membrane and Systems Biology, University of Leeds, Leeds, United Kingdom
| | - Brittany Rohrman
- Department of Surgery (Ophthalmology), The University of Chicago, Chicago, Illinois, United States of America
| | - Susan R. Liu
- Department of Surgery (Ophthalmology), The University of Chicago, Chicago, Illinois, United States of America
| | - Robert Wollmann
- Department of Pathology, The University of Chicago, Chicago, Illinois, United States of America
| | - Yuko Ogata
- Seattle Biomedical Research Institute, Seattle, Washington, United States of America
| | - Ali Sarkeshik
- Department of Chemical Physiology, Scripps Research Institute, La Jolla, California, United States of America
| | - John R. Yates
- Department of Chemical Physiology, Scripps Research Institute, La Jolla, California, United States of America
| | - Rima McLeod
- Department of Surgery (Ophthalmology), The University of Chicago, Chicago, Illinois, United States of America
- Department of Pediatrics (Infectious Disease), The University of Chicago, Chicago, Illinois, United States of America
- Committees on Immunology, Molecular Medicine, and Genetics, Institute of Genomics and Systems Biology, The College, The University of Chicago, Chicago, Illinois, United States of America
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20
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Roberts CW, Henriquez FL. Drug target identification, validation, characterisation and exploitation for treatment of Acanthamoeba (species) infections. Exp Parasitol 2009; 126:91-6. [PMID: 20035751 DOI: 10.1016/j.exppara.2009.11.016] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2009] [Revised: 11/19/2009] [Accepted: 11/30/2009] [Indexed: 12/15/2022]
Abstract
New more efficacious antimicrobials as required for the treatment of Acanthamoeba infections as those currently available require arduous treatment regimes, are not always effective and are poorly active against the cystic stages. Herein, we review potential drug targets including tubulin, alternative oxidase, amino acid biosynthesis and myosin. In addition, we review the literature for current missing tools and resources for the identification, validation and development of new antimicrobials for this organism. Additional targets should come to light through a concerted genome sequencing effort.
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Affiliation(s)
- Craig W Roberts
- Strathclyde Institute for Pharmacy & Biomedical Sciences, University of Strathclyde, Glasgow G4 0NR, UK
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21
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Fox BA, Ristuccia JG, Gigley JP, Bzik DJ. Efficient gene replacements in Toxoplasma gondii strains deficient for nonhomologous end joining. EUKARYOTIC CELL 2009; 8:520-9. [PMID: 19218423 PMCID: PMC2669201 DOI: 10.1128/ec.00357-08] [Citation(s) in RCA: 205] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 10/31/2008] [Accepted: 02/02/2009] [Indexed: 11/20/2022]
Abstract
A high frequency of nonhomologous recombination has hampered gene targeting approaches in the model apicomplexan parasite Toxoplasma gondii. To address whether the nonhomologous end-joining (NHEJ) DNA repair pathway could be disrupted in this obligate intracellular parasite, putative KU proteins were identified and a predicted KU80 gene was deleted. The efficiency of gene targeting via double-crossover homologous recombination at several genetic loci was found to be greater than 97% of the total transformants in KU80 knockouts. Gene replacement efficiency was markedly increased (300- to 400-fold) in KU80 knockouts compared to wild-type strains. Target DNA flanks of only approximately 500 bp were found to be sufficient for efficient gene replacements in KU80 knockouts. KU80 knockouts stably retained a normal growth rate in vitro and the high virulence phenotype of type I strains but exhibited an increased sensitivity to double-strand DNA breaks induced by treatment with phleomycin or gamma-irradiation. Collectively, these results revealed that a significant KU-dependent NHEJ DNA repair pathway is present in Toxoplasma gondii. Integration essentially occurs only at the homologous targeted sites in the KU80 knockout background, making this genetic background an efficient host for gene targeting to speed postgenome functional analysis and genetic dissection of parasite biology.
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Affiliation(s)
- Barbara A Fox
- Department of Microbiology and Immunology, Dartmouth Medical School, Lebanon, NH 03756, USA
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22
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Heldens JGM, Patel JR, Chanter N, Ten Thij GJ, Gravendijck M, Schijns VEJC, Langen A, Schetters TPM. Veterinary vaccine development from an industrial perspective. Vet J 2008; 178:7-20. [PMID: 18313956 PMCID: PMC7110856 DOI: 10.1016/j.tvjl.2007.11.009] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2007] [Revised: 09/26/2007] [Accepted: 11/12/2007] [Indexed: 11/20/2022]
Abstract
Veterinary vaccines currently available in Europe and in other parts of the world are developed by the veterinary pharmaceutical industry. The development of a vaccine for veterinary use is an economic endeavour that takes many years. There are many obstacles along the path to the successful development and launch of a vaccine. The industrial development of a vaccine for veterinary use usually starts after the proof of concept that is based on robust academic research. A vaccine can only be made available to the veterinary community once marketing authorisation has been granted by the veterinary authorities. This review gives a brief description of the regulatory requirements which have to be fulfilled before a vaccine can be admitted to the market. Vaccines have to be produced in a quality controlled environment to guarantee delivery of a product of consistent quality with well defined animal and consumer safety and efficacy characteristics. The regulatory and manufacturing legislative framework in which the development takes place is described, as well as the trend in developments in production systems. Recent developments in bacterial, viral and parasite vaccine research and development are also addressed and the development of novel adjuvants that use the expanding knowledge of immunology and disease pathology are described.
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Affiliation(s)
- J G M Heldens
- Department for Virological R&D, Nobilon International BV, Exportstraat 39b, 5830 AH Boxmeer, The Netherlands.
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23
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Meissner M, Agop-Nersesian C, Sullivan WJ. Molecular tools for analysis of gene function in parasitic microorganisms. Appl Microbiol Biotechnol 2007; 75:963-75. [PMID: 17401559 DOI: 10.1007/s00253-007-0946-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2007] [Revised: 03/12/2007] [Accepted: 03/12/2007] [Indexed: 01/01/2023]
Abstract
With the completion of several genome sequences for parasitic protozoa, research in molecular parasitology entered the "post-genomic" era. Accompanied by global transcriptome and proteome analysis, huge datasets have been generated that have added many novel candidates to the list of drug and vaccine targets. The challenge is now to validate these factors and to bring science back to the bench to perform a detailed characterization. In some parasites, like Trypanosoma brucei, high-throughput genetic screens have been established using RNA interference [for a detailed review, see Motyka and Englund (2004)]. In most protozoan parasites, however, more time-consuming approaches have to be employed to identify and characterize the function of promising candidates in detail. This review aims to summarize the status of molecular genetic tools available for a variety of protozoan pathogens and discuss how they can be implemented to advance our understanding of parasite biology.
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Affiliation(s)
- Markus Meissner
- Hygieneinstitut, Abteilung Parasitologie, Universitätsklinikum Heidelberg, Im Neuenheimer Feld 324, 69120, Heidelberg, Germany.
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