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Aljieli M, Rivière C, Lantier L, Moiré N, Lakhrif Z, Boussemart AF, Cnudde T, Lajoie L, Aubrey N, Ahmed EM, Dimier-Poisson I, Di-Tommaso A, Mévélec MN. Specific Cell Targeting by Toxoplasma gondii Displaying Functional Single-Chain Variable Fragment as a Novel Strategy; A Proof of Principle. Cells 2024; 13:975. [PMID: 38891106 PMCID: PMC11172386 DOI: 10.3390/cells13110975] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2024] [Revised: 05/27/2024] [Accepted: 05/31/2024] [Indexed: 06/21/2024] Open
Abstract
Toxoplasma gondii holds significant therapeutic potential; however, its nonspecific invasiveness results in off-target effects. The purpose of this study is to evaluate whether T. gondii specificity can be improved by surface display of scFv directed against dendritic cells' endocytic receptor, DEC205, and immune checkpoint PD-L1. Anti-DEC205 scFv was anchored to the T. gondii surface either directly via glycosylphosphatidylinositol (GPI) or by fusion with the SAG1 protein. Both constructs were successfully expressed, but the binding results suggested that the anti-DEC-SAG1 scFv had more reliable functionality towards recombinant DEC protein and DEC205-expressing MutuDC cells. Two anti-PD-L1 scFv constructs were developed that differed in the localization of the HA tag. Both constructs were adequately expressed, but the localization of the HA tag determined the functionality by binding to PD-L1 protein. Co-incubation of T. gondii displaying anti-PD-L1 scFv with tumor cells expressing/displaying different levels of PD-L1 showed strong binding depending on the level of available biomarker. Neutralization assays confirmed that binding was due to the specific interaction between anti-PD-L1 scFv and its ligand. A mixed-cell assay showed that T. gondii expressing anti-PD-L1 scFv predominately targets the PD-L1-positive cells, with negligible off-target binding. The recombinant RH-PD-L1-C strain showed increased killing ability on PD-L1+ tumor cell lines compared to the parental strain. Moreover, a co-culture assay of target tumor cells and effector CD8+ T cells showed that our model could inhibit PD1/PD-L1 interaction and potentiate T-cell immune response. These findings highlight surface display of antibody fragments as a promising strategy of targeting replicative T. gondii strains while minimizing nonspecific binding.
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Affiliation(s)
- Muna Aljieli
- BioMAP, UMR ISP 1282 INRAE, Université de Tours, 37200 Tours, France; (M.A.); (C.R.); (L.L.); (N.M.); (Z.L.); (A.-F.B.); (L.L.); (N.A.); (I.D.-P.); (M.-N.M.)
- Faculty of Pharmacy, University of Gezira, Wad Madani 21111, Sudan
| | - Clément Rivière
- BioMAP, UMR ISP 1282 INRAE, Université de Tours, 37200 Tours, France; (M.A.); (C.R.); (L.L.); (N.M.); (Z.L.); (A.-F.B.); (L.L.); (N.A.); (I.D.-P.); (M.-N.M.)
| | - Louis Lantier
- BioMAP, UMR ISP 1282 INRAE, Université de Tours, 37200 Tours, France; (M.A.); (C.R.); (L.L.); (N.M.); (Z.L.); (A.-F.B.); (L.L.); (N.A.); (I.D.-P.); (M.-N.M.)
| | - Nathalie Moiré
- BioMAP, UMR ISP 1282 INRAE, Université de Tours, 37200 Tours, France; (M.A.); (C.R.); (L.L.); (N.M.); (Z.L.); (A.-F.B.); (L.L.); (N.A.); (I.D.-P.); (M.-N.M.)
| | - Zineb Lakhrif
- BioMAP, UMR ISP 1282 INRAE, Université de Tours, 37200 Tours, France; (M.A.); (C.R.); (L.L.); (N.M.); (Z.L.); (A.-F.B.); (L.L.); (N.A.); (I.D.-P.); (M.-N.M.)
| | - Anne-France Boussemart
- BioMAP, UMR ISP 1282 INRAE, Université de Tours, 37200 Tours, France; (M.A.); (C.R.); (L.L.); (N.M.); (Z.L.); (A.-F.B.); (L.L.); (N.A.); (I.D.-P.); (M.-N.M.)
| | - Thomas Cnudde
- BioMAP, UMR ISP 1282 INRAE, Université de Tours, 37200 Tours, France; (M.A.); (C.R.); (L.L.); (N.M.); (Z.L.); (A.-F.B.); (L.L.); (N.A.); (I.D.-P.); (M.-N.M.)
| | - Laurie Lajoie
- BioMAP, UMR ISP 1282 INRAE, Université de Tours, 37200 Tours, France; (M.A.); (C.R.); (L.L.); (N.M.); (Z.L.); (A.-F.B.); (L.L.); (N.A.); (I.D.-P.); (M.-N.M.)
| | - Nicolas Aubrey
- BioMAP, UMR ISP 1282 INRAE, Université de Tours, 37200 Tours, France; (M.A.); (C.R.); (L.L.); (N.M.); (Z.L.); (A.-F.B.); (L.L.); (N.A.); (I.D.-P.); (M.-N.M.)
| | - Elhadi M. Ahmed
- Faculty of Pharmacy, University of Gezira, Wad Madani 21111, Sudan
| | - Isabelle Dimier-Poisson
- BioMAP, UMR ISP 1282 INRAE, Université de Tours, 37200 Tours, France; (M.A.); (C.R.); (L.L.); (N.M.); (Z.L.); (A.-F.B.); (L.L.); (N.A.); (I.D.-P.); (M.-N.M.)
| | - Anne Di-Tommaso
- BioMAP, UMR ISP 1282 INRAE, Université de Tours, 37200 Tours, France; (M.A.); (C.R.); (L.L.); (N.M.); (Z.L.); (A.-F.B.); (L.L.); (N.A.); (I.D.-P.); (M.-N.M.)
| | - Marie-Noëlle Mévélec
- BioMAP, UMR ISP 1282 INRAE, Université de Tours, 37200 Tours, France; (M.A.); (C.R.); (L.L.); (N.M.); (Z.L.); (A.-F.B.); (L.L.); (N.A.); (I.D.-P.); (M.-N.M.)
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Santos JM, Frénal K. Dominique Soldati-Favre: Bringing Toxoplasma gondii to the Molecular World. Front Cell Infect Microbiol 2022; 12:910611. [PMID: 35711657 PMCID: PMC9196188 DOI: 10.3389/fcimb.2022.910611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 04/29/2022] [Indexed: 11/25/2022] Open
Affiliation(s)
- Joana M Santos
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Karine Frénal
- Université Bordeaux, CNRS, Microbiologie Fondamentale et Pathogénicité, UMR 5234, Bordeaux, France
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Kidaka T, Sugi T, Hayashida K, Suzuki Y, Xuan X, Dubey JP, Yamagishi J. TSS-seq of Toxoplasma gondii sporozoites revealed a novel motif in stage-specific promoters. INFECTION, GENETICS AND EVOLUTION : JOURNAL OF MOLECULAR EPIDEMIOLOGY AND EVOLUTIONARY GENETICS IN INFECTIOUS DISEASES 2022; 98:105213. [PMID: 35041968 DOI: 10.1016/j.meegid.2022.105213] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 01/06/2022] [Accepted: 01/11/2022] [Indexed: 06/14/2023]
Abstract
Toxoplasma gondii is one of the most common zoonotic protozoan parasites. It has three major infectious stages: rapidly multiplying tachyzoites (Tz), slowly replicating bradyzoites (Bz) and a resting/free-living stage, sporozoites (Sz). The regulatory mechanisms governing stage-specific gene expression are not fully understood. Few transcriptional start sites (TSS) are known for Sz. In this study, we obtained TSS of Sz using an oligo-capping method and RNA-seq analysis. We identified 1,043,503 TSS in the Sz transcriptome. These defined 38,973 TSS clusters, of which, 11,925 were expressed in Sz and 1535 TSS differentially expressed in Sz. Based on these data, we defined promoter regions and novel sporozoite stage-specific motifs using MEME. TGTANNTACA was distributed around -55 to -75 regions from each TSS. Interestingly, the same motif was reported in another apicomplexan, Plasmodium berghei, as a cis-element of female-specific gametocyte genes, implying the presence of common regulatory machinery. Further comparative analysis should better define the distribution and function of these elements in other members of this important parasitic phylum.
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Affiliation(s)
- Taishi Kidaka
- Division of Collaboration and Education, International Institute for Zoonosis Control, Hokkaido University, Sapporo, Hokkaido 001-0020, Japan
| | - Tatsuki Sugi
- Division of Collaboration and Education, International Institute for Zoonosis Control, Hokkaido University, Sapporo, Hokkaido 001-0020, Japan
| | - Kyoko Hayashida
- Division of Collaboration and Education, International Institute for Zoonosis Control, Hokkaido University, Sapporo, Hokkaido 001-0020, Japan; International Collaboration Unit, International Institute for Zoonosis Control, Hokkaido University, Sapporo, Hokkaido 001-0020, Japan
| | - Yutaka Suzuki
- Department of Medical Genome Sciences, University of Tokyo, Kashiwa, Chiba 277-8562, Japan
| | - Xuenan Xuan
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido 080-8555, Japan
| | - Jitender P Dubey
- United States Department of Agriculture, Agricultural Research Service, Animal Parasitic Diseases Laboratory, Beltsville, MD, 20705-2350, USA
| | - Junya Yamagishi
- Division of Collaboration and Education, International Institute for Zoonosis Control, Hokkaido University, Sapporo, Hokkaido 001-0020, Japan; International Collaboration Unit, International Institute for Zoonosis Control, Hokkaido University, Sapporo, Hokkaido 001-0020, Japan.
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Lunghi M, Kloehn J, Krishnan A, Varesio E, Vadas O, Soldati-Favre D. Pantothenate biosynthesis is critical for chronic infection by the neurotropic parasite Toxoplasma gondii. Nat Commun 2022; 13:345. [PMID: 35039477 PMCID: PMC8764084 DOI: 10.1038/s41467-022-27996-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2021] [Accepted: 01/03/2022] [Indexed: 11/16/2022] Open
Abstract
Coenzyme A (CoA) is an essential molecule acting in metabolism, post-translational modification, and regulation of gene expression. While all organisms synthesize CoA, many, including humans, are unable to produce its precursor, pantothenate. Intriguingly, like most plants, fungi and bacteria, parasites of the coccidian subgroup of Apicomplexa, including the human pathogen Toxoplasma gondii, possess all the enzymes required for de novo synthesis of pantothenate. Here, the importance of CoA and pantothenate biosynthesis for the acute and chronic stages of T. gondii infection is dissected through genetic, biochemical and metabolomic approaches, revealing that CoA synthesis is essential for T. gondii tachyzoites, due to the parasite's inability to salvage CoA or intermediates of the pathway. In contrast, pantothenate synthesis is only partially active in T. gondii tachyzoites, making the parasite reliant on its uptake. However, pantothenate synthesis is crucial for the establishment of chronic infection, offering a promising target for intervention against the persistent stage of T. gondii.
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Affiliation(s)
- Matteo Lunghi
- Department of Microbiology and Molecular Medicine, University of Geneva, CMU, Rue Michel-Servet 1, 1211, Geneva, Switzerland
| | - Joachim Kloehn
- Department of Microbiology and Molecular Medicine, University of Geneva, CMU, Rue Michel-Servet 1, 1211, Geneva, Switzerland
| | - Aarti Krishnan
- Department of Microbiology and Molecular Medicine, University of Geneva, CMU, Rue Michel-Servet 1, 1211, Geneva, Switzerland
| | - Emmanuel Varesio
- Institute of Pharmaceutical Sciences of Western Switzerland (ISPSO), University of Geneva, CMU, Rue Michel-Servet 1, 1211, Geneva, Switzerland
- Mass Spectrometry Core Facility (MZ 2.0), University of Geneva, 1211, Geneva, Switzerland
| | - Oscar Vadas
- Department of Microbiology and Molecular Medicine, University of Geneva, CMU, Rue Michel-Servet 1, 1211, Geneva, Switzerland
- Protein and peptide purification platform, University of Geneva, CMU, Rue Michel-Servet 1, 1211, Geneva, Switzerland
| | - Dominique Soldati-Favre
- Department of Microbiology and Molecular Medicine, University of Geneva, CMU, Rue Michel-Servet 1, 1211, Geneva, Switzerland.
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Markus BM, Boydston EA, Lourido S. CRISPR-Mediated Transcriptional Repression in Toxoplasma gondii. mSphere 2021; 6:e0047421. [PMID: 34643425 PMCID: PMC8513686 DOI: 10.1128/msphere.00474-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2021] [Accepted: 09/23/2021] [Indexed: 11/20/2022] Open
Abstract
Tools for tuning endogenous gene expression are key to determining the genetic basis of diverse cellular phenotypes. Although synthetic regulatable promoters are available in Toxoplasma, scalable methods for targeted and combinatorial downregulation of gene expression-like RNA interference-have yet to be developed. To investigate the feasibility of CRISPR-mediated transcriptional regulation, we examined the function of two catalytically inactive Cas9 (dCas9) orthologs, from Streptococcus pyogenes and Streptococcus thermophilus, in Toxoplasma. Following the addition of single-guide RNAs (sgRNAs) targeting the promoter and 5' untranslated region (UTR) of the surface antigen gene SAG1, we profiled changes in protein abundance of targeted genes by flow cytometry for transcriptional reporters and immunoblotting. We found that the dCas9 orthologs generated a range of target gene expression levels, and the degree of repression was durable and stably inherited. Therefore, S. pyogenes and S. thermophilus dCas9 can effectively produce intermediate levels of gene expression in Toxoplasma. The distinct sgRNA scaffold requirements of the two dCas9s permit their orthogonal use for simultaneous examination of two distinct loci through transcriptional modulation, labeling for microscopy-based studies, or other dCas9-based approaches. Taking advantage of newly available genomic transcription start site data, these tools will aid in the development of new loss-of-function screening approaches in Toxoplasma. IMPORTANCE Toxoplasma gondii is a ubiquitous intracellular parasite of humans and animals that causes life-threatening disease in immunocompromised patients, fetal abnormalities when contracted during gestation, and recurrent eye lesions in some patients. Despite its health implications, about half of the Toxoplasma genome still lacks functional annotation. A particularly powerful tool for the investigation of an organism's cell biology is the modulation of gene expression, which can produce the subtle phenotypes often required for informing gene function. In Toxoplasma, such tools have limited throughput and versatility. Here, we detail the adaptation of a new set of tools based on CRISPR-Cas9, which allows the targeted downregulation of gene expression in Toxoplasma. With its scalability and adaptability to diverse genomic loci, this approach has the potential to greatly accelerate the functional characterization of the Toxoplasma genome.
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Affiliation(s)
- Benedikt M. Markus
- Whitehead Institute for Biomedical Research, Cambridge, Massachusetts, USA
- Faculty of Biology, University of Freiburg, Freiburg, Germany
| | | | - Sebastian Lourido
- Whitehead Institute for Biomedical Research, Cambridge, Massachusetts, USA
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
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Sharifpour MF, Khadiv S, Meissner M, McAllister MM. A GRA2 minimal promoter improves the efficiency of TATi / Tet-Off conditional regulation of gene expression in Toxoplasma gondii. Mol Biochem Parasitol 2021; 244:111384. [PMID: 34051228 DOI: 10.1016/j.molbiopara.2021.111384] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 05/23/2021] [Accepted: 05/24/2021] [Indexed: 11/18/2022]
Abstract
A tetracycline-responsive transcription system (Tet-Off) adapted for use in Toxoplasma gondii (nicknamed TATi) is useful for molecular biological studies of this organism. Previous studies using TATi incorporated minimal promoters derived from the gene promoters for TgSAG1 or TgSAG4. The present study achieves improved activation and suppression of an integrated reporter gene in the absence and presence of anhydrotetracycline, respectively (p < 0.0001), by use of a newly derived minimal promoter based on the core promoter of TgGRA2. In comparison with the SAG1 minimal promoter, use of the GRA2 minimal promoter in stable transfectants has a 23-fold higher Signal to Noise Ratio for EYFP fluorescence in the absence or presence of anhydrotetracycline. We conclude that the performance of TATi for both activation and suppression of transcription can be markedly enhanced by incorporating a GRA2 minimal promoter.
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Affiliation(s)
- Mohammad Farouq Sharifpour
- School of Animal and Veterinary Sciences, The University of Adelaide, Adelaide, South Australia, Australia
| | - Shadi Khadiv
- School of Animal and Veterinary Sciences, The University of Adelaide, Adelaide, South Australia, Australia
| | - Markus Meissner
- Institute for Experimental Parasitology, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität Munich, Bavaria, Germany
| | - Milton M McAllister
- School of Animal and Veterinary Sciences, The University of Adelaide, Adelaide, South Australia, Australia.
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7
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Lantier L, Poupée-Beaugé A, di Tommaso A, Ducournau C, Epardaud M, Lakhrif Z, Germon S, Debierre-Grockiego F, Mévélec MN, Battistoni A, Coënon L, Deluce-Kakwata-Nkor N, Velge-Roussel F, Beauvillain C, Baranek T, Lee GS, Kervarrec T, Touzé A, Moiré N, Dimier-Poisson I. Neospora caninum: a new class of biopharmaceuticals in the therapeutic arsenal against cancer. J Immunother Cancer 2020; 8:e001242. [PMID: 33257408 PMCID: PMC7705568 DOI: 10.1136/jitc-2020-001242] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/02/2020] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND Microorganisms that can be used for their lytic activity against tumor cells as well as inducing or reactivating antitumor immune responses are a relevant part of the available immunotherapy strategies. Viruses, bacteria and even protozoa have been largely explored with success as effective human antitumor agents. To date, only one oncolytic virus-T-VEC-has been approved by the US Food and Drug Administration for use in biological cancer therapy in clinical trials. The goal of our study is to evaluate the potential of a livestock pathogen, the protozoan Neospora caninum, non-pathogenic in humans, as an effective and safe antitumorous agent. METHODS/RESULTS We demonstrated that the treatment of murine thymoma EG7 by subcutaneous injection of N. caninum tachyzoites either in or remotely from the tumor strongly inhibits tumor development, and often causes their complete eradication. Analysis of immune responses showed that N. caninum had the ability to 1) lyze infected cancer cells, 2) reactivate the immunosuppressed immune cells and 3) activate the systemic immune system by generating a protective antitumor response dependent on natural killer cells, CD8-T cells and associated with a strong interferon (IFN)-γ secretion in the tumor microenvironment. Most importantly, we observed a total clearance of the injected agent in the treated animals: N. caninum exhibited strong anticancer effects without persisting in the organism of treated mice. We also established in vitro and an in vivo non-obese diabetic/severe combined immunodeficiency mouse model that N. caninum infected and induced a strong regression of human Merkel cell carcinoma. Finally, we engineered a N. caninum strain to secrete human interleukin (IL)-15, associated with the alpha-subunit of the IL-15 receptor thus strengthening the immuno-stimulatory properties of N. caninum. Indeed, this NC1-IL15hRec strain induced both proliferation of and IFN-γ secretion by human peripheral blood mononuclear cells, as well as improved efficacy in vivo in the EG7 tumor model. CONCLUSION These results highlight N. caninum as a potential, extremely effective and non-toxic anticancer agent, capable of being engineered to either express at its surface or to secrete biodrugs. Our work has identified the broad clinical possibilities of using N. caninum as an oncolytic protozoan in human medicine.
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Affiliation(s)
- Louis Lantier
- Université de Tours, INRAE, ISP, F-37000, Tours, France
| | | | | | | | | | - Zineb Lakhrif
- Université de Tours, INRAE, ISP, F-37000, Tours, France
| | | | | | | | | | - Loïs Coënon
- Université de Tours, INRAE, ISP, F-37000, Tours, France
| | - Nora Deluce-Kakwata-Nkor
- EA 4245 Cellules Dendritiques, Immuno-Modulation et Greffes, F-37000, Universite de Tours, Tours, France
| | - Florence Velge-Roussel
- EA 4245 Cellules Dendritiques, Immuno-Modulation et Greffes, F-37000, Universite de Tours, Tours, France
| | - Céline Beauvillain
- Inserm U1232, Faculté des Sciences, CRCINA, CHU d'Angers, Université Angers, Angers, France
| | - Thomas Baranek
- INSERM, Centre d'Etude des Pathologies Respiratoires (CEPR), UMR, 1100, Université de Tours, Tours, France
| | | | - Thibault Kervarrec
- Université de Tours, INRAE, ISP, F-37000, Tours, France
- Department of Pathology, Université de Tours, CHU de Tours, Tours, France
| | - Antoine Touzé
- Université de Tours, INRAE, ISP, F-37000, Tours, France
| | - Nathalie Moiré
- INRAE, Université de Tours, ISP, F-37380, Nouzilly, France
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Characterization of natural antisense transcripts arisen from the locus encoding Toxoplasma gondii ubiquitin-like protease. Mol Biochem Parasitol 2020; 240:111334. [PMID: 33011210 DOI: 10.1016/j.molbiopara.2020.111334] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 09/16/2020] [Accepted: 09/28/2020] [Indexed: 11/22/2022]
Abstract
Natural antisense transcripts (NATs) are non-protein coding RNAs that could play an important role in regulating the expression of their counterpart protein encoding sense transcript. Although NATs are widespread in most eukaryotic genomes, very little is known about their functions. This study focuses on gaining a better understanding of the function of NATs in Toxoplasma gondii, a pathogenic unicellular eukaryote. Previously, we characterized the gene encoding the first committed enzyme in sumoylation, named ubiquitin-like protease 1 (TgUlp1), and showed that the expression of TgUlp1 is vital to the life cycle of T. gondii. Interestingly, the locus of TgUlp1 also transcribes a NAT species. Using a dual luciferase assay, we identified the promoter of TgUlp1 NAT to be located within the 3'-region of its counterpart coding sequence. While TgUlp1 mRNA level was detected at a lower level throughout the life cycle of T. gondii, its NAT level was upregulated when the parasite converts from actively replicating tachyzoite form to slowly growing bradyzoite form. To investigate the effect of TgUlp1 NAT on the expression of its counterpart mRNA, we used a reporter system bearing TgUlp1 mRNA sequences and showed that the single-stranded TgUlp1 NAT and its in vitro RNase III processed products have the ability to lower the expression of the reporter system. Using a transgenic Dicer-knockout (TgDicer-KO) strain, we showed that TgDicer is required for the function of TgUlp1 NAT in vivo. The findings strongly suggest that the RNA interference pathway is necessary for the function of TgUlp1 NAT.
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Periz J, Del Rosario M, McStea A, Gras S, Loney C, Wang L, Martin-Fernandez ML, Meissner M. A highly dynamic F-actin network regulates transport and recycling of micronemes in Toxoplasma gondii vacuoles. Nat Commun 2019; 10:4183. [PMID: 31519913 PMCID: PMC6744512 DOI: 10.1038/s41467-019-12136-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Accepted: 08/19/2019] [Indexed: 01/03/2023] Open
Abstract
The obligate intracellular parasite Toxoplasma gondii replicates in an unusual process, described as internal budding. Multiple dausghter parasites are formed sequentially within a single mother cell, requiring replication and distribution of essential organelles such as micronemes. These organelles are thought to be formed de novo in the developing daughter cells. Using dual labelling of a microneme protein MIC2 and super-resolution microscopy, we show that micronemes are recycled from the mother to the forming daughter parasites using a highly dynamic F-actin network. While this recycling pathway is F-actin dependent, de novo synthesis of micronemes appears to be F-actin independent. The F-actin network connects individual parasites, supports long, multidirectional vesicular transport, and regulates transport, density and localisation of micronemal vesicles. The residual body acts as a storage and sorting station for these organelles. Our data describe an F-actin dependent mechanism in apicomplexans for transport and recycling of maternal organelles during intracellular development. Replication of Toxoplasma gondii requires replication and distribution of essential organelles such as micronemes. Here, Periz et al. show that micronemes are recycled from the mother to the forming daughter cells using a highly dynamic F-actin network that supports multidirectional vesicle transport.
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Affiliation(s)
- Javier Periz
- Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity & Inflammation, University of Glasgow, Glasgow, UK.
| | - Mario Del Rosario
- Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity & Inflammation, University of Glasgow, Glasgow, UK
| | - Alexandra McStea
- Central Laser Facility, Research Complex at Harwell Science & Technology Facilities Council, Harwell Campus, Didcot, UK
| | - Simon Gras
- Experimental Parasitology, Department for Veterinary Sciences, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Colin Loney
- MRC-University of Glasgow Centre for Virus Research, Sir Michael Stoker Building, Garscube Campus, Glasgow, UK
| | - Lin Wang
- Central Laser Facility, Research Complex at Harwell Science & Technology Facilities Council, Harwell Campus, Didcot, UK
| | - Marisa L Martin-Fernandez
- Central Laser Facility, Research Complex at Harwell Science & Technology Facilities Council, Harwell Campus, Didcot, UK
| | - Markus Meissner
- Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity & Inflammation, University of Glasgow, Glasgow, UK. .,Experimental Parasitology, Department for Veterinary Sciences, Ludwig-Maximilians-University Munich, Munich, Germany.
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Chen H, Guo Y, Qiu Y, Huang H, Lin C, Liu M, Chen X, Yang P, Wu K. Efficient genome engineering of Toxoplasma gondii using the TALEN technique. Parasit Vectors 2019; 12:112. [PMID: 30876436 PMCID: PMC6419828 DOI: 10.1186/s13071-019-3378-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 03/05/2019] [Indexed: 01/12/2023] Open
Abstract
Background Aromatic amino acid hydroxylase 2 (AAH2) is a bradyzoite-specific upregulated protein that may alter host behaviour by altering the host dopaminergic pathway. To better understand the role of the parasite’s AAH2 in host-parasite interactions, we generated an AAH2 fluorescent marker strain of T. gondii using the TALEN technique. Methods We generated an AAH2 fluorescent marker strain of T. gondii, which was designated PRU/AAH2-eGFP, using the TALEN technique. This strain stably expressed pyrimethamine resistance for screening and expressed enhanced green fluorescent protein (eGFP)-tagged AAH2 in the bradyzoite stage. The bradyzoite conversion of PRU/AAH2-eGFP was observed both in vitro and in vivo. The fluorescence localization of AAH2 in mouse models of chronic infection was observed by a Bruker in vivo imaging system. Results Transgenic T. gondii was successfully generated by the TALEN system. The eGFP-tagged AAH2 could be detected by in vivo imaging. Conclusions This study verified the feasibility of using TALEN technology for T. gondii research and provided an in vivo imaging method for in vivo research of bradyzoite-stage proteins. Electronic supplementary material The online version of this article (10.1186/s13071-019-3378-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Hongmei Chen
- Department of Pathogen Biology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou, 510515, China
| | - Yijia Guo
- Department of Pathogen Biology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou, 510515, China
| | - Yushu Qiu
- Department of Pathogen Biology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou, 510515, China
| | - Huanbin Huang
- Department of Pathogen Biology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou, 510515, China
| | - Changqing Lin
- Department of Pathogen Biology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou, 510515, China
| | - Min Liu
- Department of Pathogen Biology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou, 510515, China
| | - Xiaoguang Chen
- Department of Pathogen Biology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou, 510515, China
| | - Peiliang Yang
- Experimental Animal Center, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China.
| | - Kun Wu
- Department of Pathogen Biology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou, 510515, China.
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11
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Crater AK, Roscoe S, Fahim A, Ananvoranich S. Toxoplasma ubiquitin-like protease 1, a key enzyme in sumoylation and desumoylation pathways, is under the control of non-coding RNAs. Int J Parasitol 2018; 48:867-880. [PMID: 30005881 DOI: 10.1016/j.ijpara.2018.05.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 05/15/2018] [Accepted: 05/17/2018] [Indexed: 11/17/2022]
Abstract
Sumoylation and desumoylation are reversible pathways responsible for modification of protein structures and functions by the reversible covalent attachment of a small ubiquitin-like modifier (SUMO) peptide. These pathways are important for a wide range of cellular processes and require a steady supply of SUMO, which is generated by an enzymatic reaction catalysed by the ubiquitin-like protease (Ulp) family. Here we show by functional complementation analysis that the Ulp1 of Toxoplasma gondii (TgUlp1) can rescue a growth-deficient phenotype of a yeast-Ulp1 knockout. Recombinant TgUlp1 is an active enzyme capable of removing SUMO from a sumoylated substrate. Using a clonal transgenic strain of T. gondii expressing an epitope-tagged version of TgUlp1, we detected that the expression of TgUlp1 is modulated by Tg-miR-60, the most abundant species of micro RNA found in the T. gondii type 1 strain. The introduction of Tg-miR-60 inhibitor caused an increase in TgUlp1 expression and its enzymatic activity, as well as affecting the parasite's growth fitness. Moreover, we discovered a polyadenylated antisense RNA transcribed from the TgUlp1 locus, referred to as TgUlp1-NAT1 (TgUlp1-natural antisense transcript 1). Both Tg-miR-60 and TgUlp1-NAT1 confer a regulatory function by down-regulating the expression of TgUlp1 and affecting the sumoylation and desumoylation pathways in T. gondii.
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Affiliation(s)
- Anna K Crater
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario N9B3P4, Canada
| | - Scott Roscoe
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario N9B3P4, Canada
| | - Ambreen Fahim
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario N9B3P4, Canada
| | - Sirinart Ananvoranich
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario N9B3P4, Canada.
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12
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Whitelaw JA, Latorre-Barragan F, Gras S, Pall GS, Leung JM, Heaslip A, Egarter S, Andenmatten N, Nelson SR, Warshaw DM, Ward GE, Meissner M. Surface attachment, promoted by the actomyosin system of Toxoplasma gondii is important for efficient gliding motility and invasion. BMC Biol 2017; 15:1. [PMID: 28100223 PMCID: PMC5242020 DOI: 10.1186/s12915-016-0343-5] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2016] [Accepted: 12/10/2016] [Indexed: 12/17/2022] Open
Abstract
Background Apicomplexan parasites employ a unique form of movement, termed gliding motility, in order to invade the host cell. This movement depends on the parasite’s actomyosin system, which is thought to generate the force during gliding. However, recent evidence questions the exact molecular role of this system, since mutants for core components of the gliding machinery, such as parasite actin or subunits of the MyoA-motor complex (the glideosome), remain motile and invasive, albeit at significantly reduced efficiencies. While compensatory mechanisms and unusual polymerisation kinetics of parasite actin have been evoked to explain these findings, the actomyosin system could also play a role distinct from force production during parasite movement. Results In this study, we compared the phenotypes of different mutants for core components of the actomyosin system in Toxoplasma gondii to decipher their exact role during gliding motility and invasion. We found that, while some phenotypes (apicoplast segregation, host cell egress, dense granule motility) appeared early after induction of the act1 knockout and went to completion, a small percentage of the parasites remained capable of motility and invasion well past the point at which actin levels were undetectable. Those act1 conditional knockout (cKO) and mlc1 cKO that continue to move in 3D do so at speeds similar to wildtype parasites. However, these mutants are virtually unable to attach to a collagen-coated substrate under flow conditions, indicating an important role for the actomyosin system of T. gondii in the formation of attachment sites. Conclusion We demonstrate that parasite actin is essential during the lytic cycle and cannot be compensated by other molecules. Our data suggest a conventional polymerisation mechanism in vivo that depends on a critical concentration of G-actin. Importantly, we demonstrate that the actomyosin system of the parasite functions in attachment to the surface substrate, and not necessarily as force generator. Electronic supplementary material The online version of this article (doi:10.1186/s12915-016-0343-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jamie A Whitelaw
- Wellcome Trust Centre For Molecular Parasitology, Institute of Infection, Immunity & Inflammation, Glasgow Biomedical Research Centre, University of Glasgow, 120 University Place, Glasgow, G12 8TA, UK
| | - Fernanda Latorre-Barragan
- Wellcome Trust Centre For Molecular Parasitology, Institute of Infection, Immunity & Inflammation, Glasgow Biomedical Research Centre, University of Glasgow, 120 University Place, Glasgow, G12 8TA, UK
| | - Simon Gras
- Wellcome Trust Centre For Molecular Parasitology, Institute of Infection, Immunity & Inflammation, Glasgow Biomedical Research Centre, University of Glasgow, 120 University Place, Glasgow, G12 8TA, UK
| | - Gurman S Pall
- Wellcome Trust Centre For Molecular Parasitology, Institute of Infection, Immunity & Inflammation, Glasgow Biomedical Research Centre, University of Glasgow, 120 University Place, Glasgow, G12 8TA, UK
| | - Jacqueline M Leung
- Department of Biology, Indiana University, Bloomington, Myers Hall 240, 915 E 3rd St Bloomington, Bloomington, IN, 47405, USA.,University of Vermont, Department of Microbiology and Molecular Genetics, College of Medicine, Burlington, VT, 05405, USA
| | - Aoife Heaslip
- University of Vermont, Department of Molecular Physiology and Biophysics Burlington, Vermont, 05405, USA
| | - Saskia Egarter
- Wellcome Trust Centre For Molecular Parasitology, Institute of Infection, Immunity & Inflammation, Glasgow Biomedical Research Centre, University of Glasgow, 120 University Place, Glasgow, G12 8TA, UK
| | - Nicole Andenmatten
- Wellcome Trust Centre For Molecular Parasitology, Institute of Infection, Immunity & Inflammation, Glasgow Biomedical Research Centre, University of Glasgow, 120 University Place, Glasgow, G12 8TA, UK
| | - Shane R Nelson
- University of Vermont, Department of Molecular Physiology and Biophysics Burlington, Vermont, 05405, USA
| | - David M Warshaw
- University of Vermont, Department of Molecular Physiology and Biophysics Burlington, Vermont, 05405, USA
| | - Gary E Ward
- University of Vermont, Department of Microbiology and Molecular Genetics, College of Medicine, Burlington, VT, 05405, USA
| | - Markus Meissner
- Wellcome Trust Centre For Molecular Parasitology, Institute of Infection, Immunity & Inflammation, Glasgow Biomedical Research Centre, University of Glasgow, 120 University Place, Glasgow, G12 8TA, UK.
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13
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Deshmukh AS, Mitra P, Maruthi M. Cdk7 mediates RPB1-driven mRNA synthesis in Toxoplasma gondii. Sci Rep 2016; 6:35288. [PMID: 27759017 PMCID: PMC5069487 DOI: 10.1038/srep35288] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 09/28/2016] [Indexed: 11/16/2022] Open
Abstract
Cyclin-dependent kinase 7 in conjunction with CyclinH and Mat1 activates cell cycle CDKs and is a part of the general transcription factor TFIIH. Role of Cdk7 is well characterized in model eukaryotes however its relevance in protozoan parasites has not been investigated. This important regulator of key processes warrants closer examination particularly in this parasite given its unique cell cycle progression and flexible mode of replication. We report functional characterization of TgCdk7 and its partners TgCyclinH and TgMat1. Recombinant Cdk7 displays kinase activity upon binding its cyclin partner and this activity is further enhanced in presence of Mat1. The activated kinase phosphorylates C-terminal domain of TgRPB1 suggesting its role in parasite transcription. Therefore, the function of Cdk7 in CTD phosphorylation and RPB1 mediated transcription was investigated using Cdk7 inhibitor. Unphosphorylated CTD binds promoter DNA while phosphorylation by Cdk7 triggers its dissociation from DNA with implications for transcription initiation. Inhibition of Cdk7 in the parasite led to strong reduction in Serine 5 phosphorylation of TgRPB1-CTD at the promoters of constitutively expressed actin1 and sag1 genes with concomitant reduction of both nascent RNA synthesis and 5′-capped transcripts. Therefore, we provide compelling evidence for crucial role of TgCdk7 kinase activity in mRNA synthesis.
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Affiliation(s)
| | - Pallabi Mitra
- International Centre for Genetic Engineering and Biotechnology, New Delhi, India
| | - Mulaka Maruthi
- Department of Animal Biology, School of Life Sciences, University of Hyderabad, Hyderabad, India
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14
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Sidik SM, Hortua Triana MA, Paul AS, El Bakkouri M, Hackett CG, Tran F, Westwood NJ, Hui R, Zuercher WJ, Duraisingh MT, Moreno SNJ, Lourido S. Using a Genetically Encoded Sensor to Identify Inhibitors of Toxoplasma gondii Ca2+ Signaling. J Biol Chem 2016; 291:9566-80. [PMID: 26933036 PMCID: PMC4850295 DOI: 10.1074/jbc.m115.703546] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Indexed: 11/27/2022] Open
Abstract
The life cycles of apicomplexan parasites progress in accordance with fluxes in cytosolic Ca2+. Such fluxes are necessary for events like motility and egress from host cells. We used genetically encoded Ca2+ indicators (GCaMPs) to develop a cell-based phenotypic screen for compounds that modulate Ca2+ signaling in the model apicomplexan Toxoplasma gondii. In doing so, we took advantage of the phosphodiesterase inhibitor zaprinast, which we show acts in part through cGMP-dependent protein kinase (protein kinase G; PKG) to raise levels of cytosolic Ca2+. We define the pool of Ca2+ regulated by PKG to be a neutral store distinct from the endoplasmic reticulum. Screening a library of 823 ATP mimetics, we identify both inhibitors and enhancers of Ca2+ signaling. Two such compounds constitute novel PKG inhibitors and prevent zaprinast from increasing cytosolic Ca2+. The enhancers identified are capable of releasing intracellular Ca2+ stores independently of zaprinast or PKG. One of these enhancers blocks parasite egress and invasion and shows strong antiparasitic activity against T. gondii. The same compound inhibits invasion of the most lethal malaria parasite, Plasmodium falciparum. Inhibition of Ca2+-related phenotypes in these two apicomplexan parasites suggests that depletion of intracellular Ca2+ stores by the enhancer may be an effective antiparasitic strategy. These results establish a powerful new strategy for identifying compounds that modulate the essential parasite signaling pathways regulated by Ca2+, underscoring the importance of these pathways and the therapeutic potential of their inhibition.
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Affiliation(s)
- Saima M Sidik
- From the Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142
| | - Miryam A Hortua Triana
- the Center for Tropical and Emerging Global Diseases, Department of Cellular Biology, University of Georgia, Athens, Georgia 30602
| | - Aditya S Paul
- the Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Boston, Massachusetts 02115
| | - Majida El Bakkouri
- the Structural Genomics Consortium, University of Toronto, Toronto, Ontario M5G 1L7, Canada
| | - Caroline G Hackett
- From the Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142
| | - Fanny Tran
- the School of Chemistry and Biomedical Sciences Research Complex, University of St. Andrews and EaStCHEM, North Haugh, St. Andrews, Fife KY16 9ST, Scotland, United Kingdom, and
| | - Nicholas J Westwood
- the School of Chemistry and Biomedical Sciences Research Complex, University of St. Andrews and EaStCHEM, North Haugh, St. Andrews, Fife KY16 9ST, Scotland, United Kingdom, and
| | - Raymond Hui
- the Structural Genomics Consortium, University of Toronto, Toronto, Ontario M5G 1L7, Canada
| | - William J Zuercher
- the Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Manoj T Duraisingh
- the Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Boston, Massachusetts 02115
| | - Silvia N J Moreno
- the Center for Tropical and Emerging Global Diseases, Department of Cellular Biology, University of Georgia, Athens, Georgia 30602
| | - Sebastian Lourido
- From the Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142,
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15
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Rugarabamu G, Marq JB, Guérin A, Lebrun M, Soldati-Favre D. Distinct contribution of Toxoplasma gondii rhomboid proteases 4 and 5 to micronemal protein protease 1 activity during invasion. Mol Microbiol 2015; 97:244-62. [PMID: 25846828 DOI: 10.1111/mmi.13021] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/31/2015] [Indexed: 10/23/2022]
Abstract
Host cell entry by the Apicomplexa is associated with the sequential secretion of invasion factors from specialized apical organelles. Secretion of micronemal proteins (MICs) complexes by Toxoplasma gondii facilitates parasite gliding motility, host cell attachment and entry, as well as egress from infected cells. The shedding of MICs during these steps is mediated by micronemal protein proteases MPP1, MPP2 and MPP3. The constitutive activity of MPP1 leads to the cleavage of transmembrane MICs and is linked to the surface rhomboid protease 4 (ROM4) and possibly to rhomboid protease 5 (ROM5). To determine their importance and respective contribution to MPP1 activity, in this study ROM4 and ROM5 genes were abrogated using Cre-recombinase and CRISPR-Cas9 nuclease, respectively, and shown to be dispensable for parasite survival. Parasites lacking ROM4 predominantly engage in twirling motility and exhibit enhanced attachment and impaired invasion, whereas intracellular growth and egress is not affected. The substrates MIC2 and MIC6 are not cleaved in rom4-ko parasites, in contrast, intramembrane cleavage of AMA1 is reduced but not completely abolished. Shedding of MICs and invasion are not altered in the absence of ROM5; however, this protease responsible for the residual cleavage of AMA1 is able to cleave other AMA family members and exhibits a detectable contribution to invasion in the absence of ROM4.
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Affiliation(s)
- George Rugarabamu
- Department of Microbiology and Molecular Medicine, CMU, University of Geneva, 1 Rue Michel-Servet, 1211, Geneva 4, Switzerland
| | - Jean-Baptiste Marq
- Department of Microbiology and Molecular Medicine, CMU, University of Geneva, 1 Rue Michel-Servet, 1211, Geneva 4, Switzerland
| | - Amandine Guérin
- UMR 5235 CNRS, Université de Montpellier 2, 34095, Montpellier, France
| | - Maryse Lebrun
- UMR 5235 CNRS, Université de Montpellier 2, 34095, Montpellier, France
| | - Dominique Soldati-Favre
- Department of Microbiology and Molecular Medicine, CMU, University of Geneva, 1 Rue Michel-Servet, 1211, Geneva 4, Switzerland
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16
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Lunghi M, Galizi R, Magini A, Carruthers VB, Di Cristina M. Expression of the glycolytic enzymes enolase and lactate dehydrogenase during the early phase ofToxoplasmadifferentiation is regulated by an intron retention mechanism. Mol Microbiol 2015; 96:1159-75. [DOI: 10.1111/mmi.12999] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/11/2015] [Indexed: 01/12/2023]
Affiliation(s)
- Matteo Lunghi
- Department of Chemistry, Biology and Biotechnology; University of Perugia; Perugia Italy
| | - Roberto Galizi
- Department of Experimental Medicine; University of Perugia; Perugia Italy
| | - Alessandro Magini
- Department of Chemistry, Biology and Biotechnology; University of Perugia; Perugia Italy
| | - Vern B. Carruthers
- Department of Microbiology and Immunology; University of Michigan Medical School; Ann Arbor MI USA
| | - Manlio Di Cristina
- Department of Chemistry, Biology and Biotechnology; University of Perugia; Perugia Italy
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17
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Mouveaux T, Oria G, Werkmeister E, Slomianny C, Fox BA, Bzik DJ, Tomavo S. Nuclear glycolytic enzyme enolase of Toxoplasma gondii functions as a transcriptional regulator. PLoS One 2014; 9:e105820. [PMID: 25153525 PMCID: PMC4143315 DOI: 10.1371/journal.pone.0105820] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Accepted: 07/28/2014] [Indexed: 01/07/2023] Open
Abstract
Apicomplexan parasites including Toxoplasma gondii have complex life cycles within different hosts and their infectivity relies on their capacity to regulate gene expression. However, little is known about the nuclear factors that regulate gene expression in these pathogens. Here, we report that T. gondii enolase TgENO2 is targeted to the nucleus of actively replicating parasites, where it specifically binds to nuclear chromatin in vivo. Using a ChIP-Seq technique, we provide evidence for TgENO2 enrichment at the 5′ untranslated gene regions containing the putative promoters of 241 nuclear genes. Ectopic expression of HA-tagged TgENO1 or TgENO2 led to changes in transcript levels of numerous gene targets. Targeted disruption of TgENO1 gene results in a decrease in brain cyst burden of chronically infected mice and in changes in transcript levels of several nuclear genes. Complementation of this knockout mutant with ectopic TgENO1-HA fully restored normal transcript levels. Our findings reveal that enolase functions extend beyond glycolytic activity and include a direct role in coordinating gene regulation in T. gondii.
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Affiliation(s)
- Thomas Mouveaux
- Center for Infection and Immunity of Lille, CNRS UMR 8204, INSERM U 1019, Institut Pasteur de Lille, Université Lille Nord de France, Lille, France
| | - Gabrielle Oria
- Center for Infection and Immunity of Lille, CNRS UMR 8204, INSERM U 1019, Institut Pasteur de Lille, Université Lille Nord de France, Lille, France
| | - Elisabeth Werkmeister
- Center for Infection and Immunity of Lille, CNRS UMR 8204, INSERM U 1019, Institut Pasteur de Lille, Université Lille Nord de France, Lille, France
| | - Christian Slomianny
- Laboratory of Cell Physiology, INSERM U 1003, Université Lille Nord de France, Villeneuve d'Ascq, France
| | - Barbara A. Fox
- Department of Microbiology and Immunology, The Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire, United States of America
| | - David J. Bzik
- Department of Microbiology and Immunology, The Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire, United States of America
| | - Stanislas Tomavo
- Center for Infection and Immunity of Lille, CNRS UMR 8204, INSERM U 1019, Institut Pasteur de Lille, Université Lille Nord de France, Lille, France
- * E-mail:
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18
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Research progress on surface antigen 1 (SAG1) of Toxoplasma gondii. Parasit Vectors 2014; 7:180. [PMID: 24726014 PMCID: PMC3989796 DOI: 10.1186/1756-3305-7-180] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 04/04/2014] [Indexed: 11/20/2022] Open
Abstract
Toxoplasma gondii is an obligate intracellular parasitic protozoan that has a wide host range and causes a zoonotic parasitosis called toxoplasmosis. This infection causes significant morbidity, costs for care and loss of productivity and suffering. The most effective measures to minimize this parasite’s harm to patients are prompt diagnosis and treatment and preventing infection. A parasite surface antigen, SAG1, is considered an important antigen for the development of effective diagnostic tests or subunit vaccines. This review covers several aspects of this antigen, including its gene structure, contribution to host invasion, mechanisms of the immune responses and its applications for diagnosis and vaccine development. This significant progress on this antigen provides foundations for further development of more effective and precise approaches to diagnose toxoplasmosis in the clinic, and also have important implications for exploring novel measures to control toxoplasmosis in the near future.
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19
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Andenmatten N, Egarter S, Jackson AJ, Jullien N, Herman JP, Meissner M. Conditional genome engineering in Toxoplasma gondii uncovers alternative invasion mechanisms. Nat Methods 2013; 10:125-7. [PMID: 23263690 PMCID: PMC3605914 DOI: 10.1038/nmeth.2301] [Citation(s) in RCA: 192] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2012] [Accepted: 11/27/2012] [Indexed: 12/02/2022]
Abstract
We established a conditional site-specific recombination system based on dimerizable Cre recombinase-mediated recombination in the apicomplexan parasite Toxoplasma gondii. Using a new single-vector strategy that allows ligand-dependent, efficient removal of a gene of interest, we generated three knockouts of apicomplexan genes considered essential for host-cell invasion. Our findings uncovered the existence of an alternative invasion pathway in apicomplexan parasites.
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Affiliation(s)
- Nicole Andenmatten
- Division of Infection and Immunity, Institute of Biomedical Life Sciences, Wellcome Centre for Molecular Parasitology, Glasgow Biomedical Research Centre, University of Glasgow, 120 University Place, Glasgow G12 8TA, UK
| | - Saskia Egarter
- Division of Infection and Immunity, Institute of Biomedical Life Sciences, Wellcome Centre for Molecular Parasitology, Glasgow Biomedical Research Centre, University of Glasgow, 120 University Place, Glasgow G12 8TA, UK
| | - Allison J Jackson
- Division of Infection and Immunity, Institute of Biomedical Life Sciences, Wellcome Centre for Molecular Parasitology, Glasgow Biomedical Research Centre, University of Glasgow, 120 University Place, Glasgow G12 8TA, UK
| | - Nicolas Jullien
- ICNE-UMR 6544 Centre National de Recherche Scientifique (CNRS), Université de Méditerranée, Marseille, France
| | - Jean-Paul Herman
- ICNE-UMR 6544 Centre National de Recherche Scientifique (CNRS), Université de Méditerranée, Marseille, France
| | - Markus Meissner
- Division of Infection and Immunity, Institute of Biomedical Life Sciences, Wellcome Centre for Molecular Parasitology, Glasgow Biomedical Research Centre, University of Glasgow, 120 University Place, Glasgow G12 8TA, UK
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20
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Hao Y, Yang J, Li X, Ding J, Zhang W, Liu Q. Optimized expression of dual reporter genes in transient transfection of purified Toxoplasma gondii using different promoters. Can J Microbiol 2012; 58:483-9. [PMID: 22455755 DOI: 10.1139/w2012-017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Fluorescent protein and luciferase genes are valuable reporter genes and have been widely used for noninvasive monitoring of gene expression in living tissues and cells. We tested expression of the dual reporter genes in transient transfection of purified Toxoplasma gondii tachyzoites. Two copies of the enhanced yellow fluorescent protein (EYFP) gene were put under the control of 3 representative T. gondii promoters (GRA1, SAG1, and DHFR). Fluorescence from each EYFP reporter was significantly higher than that from a green fluorescent protein (GFP) reporter. The GRA1-EYFP reporter gave the highest fluorescence. Although both fluorescence and luciferase were expressed in the dual reporter system, the luciferase reporter was more efficient than either the EYFP or GFP reporters, and it required fewer parasites to be successfully used.
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Affiliation(s)
- Yongxin Hao
- Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100193, People's Republic of China
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21
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Payne TM, Payne AJ, Knoll LJ. A Toxoplasma gondii mutant highlights the importance of translational regulation in the apicoplast during animal infection. Mol Microbiol 2011; 82:1204-16. [PMID: 22059956 DOI: 10.1111/j.1365-2958.2011.07879.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Toxoplasma gondii is an obligate intracellular parasite of all warm-blooded animals. We previously described a forward genetic screen to identify T. gondii mutants defective in the establishment of a chronic infection. One of the mutants isolated was disrupted in the 3' untranslated region (3'UTR) of an orthologue of bacterial translation elongation factor G (EFG). The mutant does not have a growth defect in tissue culture. Genetic complementation of this mutant with the genomic locus of TgEFG restores virulence in an acute infection mouse model. Epitope tagged TgEFG localized to the apicoplast, via a non-canonical targeting signal, where it functions as an elongation factor for translation in the apicoplast. Comparisons of TgEFG expression constructs with wild-type or mutant 3'UTRs showed that a wild-type 3'UTR is necessary for translation of TgEFG. In tissue culture, the TgEFG transcript is equally abundant in wild-type and mutant parasites; however, during an animal infection, the TgEFG transcript is increased more than threefold in the mutant. These results highlight that in tissue culture, translation in the apicoplast can be diminished, but during an animal infection, translation in the apicoplast must be fully functional.
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Affiliation(s)
- T Matthew Payne
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI 53706, USA
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A patatin-like protein protects Toxoplasma gondii from degradation in a nitric oxide-dependent manner. Infect Immun 2011; 80:55-61. [PMID: 22006568 DOI: 10.1128/iai.05543-11] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Toxoplasma gondii is an obligate intracellular parasite that uses immune cells to disseminate throughout its host. T. gondii can persist and even slowly replicate in activated host macrophages by reducing the antimicrobial effects of molecules such as nitric oxide (NO). A T. gondii patatin-like protein called TgPL1 was previously shown to be important for survival in activated macrophages. Here we show that a T. gondii mutant with a deletion of the TgPL1 gene (ΔTgPL1) is degraded in activated macrophages. This degradation phenotype is abolished by the removal of NO by the use of an inducible NO synthase (iNOS) inhibitor or iNOS-deficient macrophages. The exogenous addition of NO to macrophages results in reduced parasite growth but not the degradation of ΔTgPL1 parasites. These results suggest that NO is necessary but not sufficient for the degradation of ΔTgPL1 parasites in activated macrophages. While some patatin-like proteins have phospholipase A2 (PLA2) activity, recombinant TgPL1 purified from Escherichia coli does not have phospholipase activity. This result was not surprising, as TgPL1 contains a G-to-S change at the predicted catalytic serine residue. An epitope-tagged version of TgPL1 partially colocalized with a dense granule protein in the parasitophorous vacuole space. These results may suggest that TgPL1 moves to the parasitophorous vacuole to protect parasites from nitric oxide by an undetermined mechanism.
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Olguin-Lamas A, Madec E, Hovasse A, Werkmeister E, Callebaut I, Slomianny C, Delhaye S, Mouveaux T, Schaeffer-Reiss C, Van Dorsselaer A, Tomavo S. A novel Toxoplasma gondii nuclear factor TgNF3 is a dynamic chromatin-associated component, modulator of nucleolar architecture and parasite virulence. PLoS Pathog 2011; 7:e1001328. [PMID: 21483487 PMCID: PMC3068996 DOI: 10.1371/journal.ppat.1001328] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2010] [Accepted: 03/01/2011] [Indexed: 01/13/2023] Open
Abstract
In Toxoplasma gondii, cis-acting elements present in promoter sequences of genes that are stage-specifically regulated have been described. However, the nuclear factors that bind to these cis-acting elements and regulate promoter activities have not been identified. In the present study, we performed affinity purification, followed by proteomic analysis, to identify nuclear factors that bind to a stage-specific promoter in T. gondii. This led to the identification of several nuclear factors in T. gondii including a novel factor, designated herein as TgNF3. The N-terminal domain of TgNF3 shares similarities with the N-terminus of yeast nuclear FK506-binding protein (FKBP), known as a histone chaperone regulating gene silencing. Using anti-TgNF3 antibodies, HA-FLAG and YFP-tagged TgNF3, we show that TgNF3 is predominantly a parasite nucleolar, chromatin-associated protein that binds specifically to T. gondii gene promoters in vivo. Genome-wide analysis using chromatin immunoprecipitation followed by high-throughput sequencing (ChIP-seq) identified promoter occupancies by TgNF3. In addition, TgNF3 has a direct role in transcriptional control of genes involved in parasite metabolism, transcription and translation. The ectopic expression of TgNF3 in the tachyzoites revealed dynamic changes in the size of the nucleolus, leading to a severe attenuation of virulence in vivo. We demonstrate that TgNF3 physically interacts with H3, H4 and H2A/H2B assembled into bona fide core and nucleosome-associated histones. Furthermore, TgNF3 interacts specifically to histones in the context of stage-specific gene silencing of a promoter that lacks active epigenetic acetylated histone marks. In contrast to virulent tachyzoites, which express the majority of TgNF3 in the nucleolus, the protein is exclusively located in the cytoplasm of the avirulent bradyzoites. We propose a model where TgNF3 acts essentially to coordinate nucleolus and nuclear functions by modulating nucleosome activities during the intracellular proliferation of the virulent tachyzoites of T. gondii. Apicomplexa including Toxoplasma gondii are responsible for a variety of deadly infections. These intracellular parasites have complex life cycles within different hosts and their infectivity relies on their capacity to regulate gene expression in response to different environments. However, to date, little is known about nuclear factors that regulate their gene expression. Here, we have characterized parasite nuclear factors that bind to a stage-specific promoter. We identified several nuclear factors including a novel factor, designated herein as TgNF3. The N-terminal domain of TgNF3 shares similarities with the N-terminus of yeast nuclear FK506-binding protein (FKBP), known as a histone chaperone regulating gene silencing. We show that TgNF3 is predominantly a nucleolar, chromatin-associated protein that specifically binds to T. gondii nucleosome-associated histones and promoters. Genome-wide analysis identified promoter occupancies by TgNF3 and we demonstrated a direct role for this factor in transcriptional control of genes involved in parasite metabolism, transcription and translation. Ectopic expression of TgNF3 induces dynamic changes in the size of the nucleolus, and a severe attenuation of parasite virulence in vivo. In avirulent bradyzoites, TgNF3 is found exclusively in the cytoplasm, suggesting a potential role in regulating nucleolar and nuclear functions in the virulent tachyzoites of T. gondii.
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Affiliation(s)
- Alejandro Olguin-Lamas
- Center for Infection and Immunity of Lille, CNRS UMR 8204, INSERM U 1019, Institut Pasteur de Lille, Université Lille Nord de France, Lille, France
- Centre National de la Recherche Scientifique, CNRS UMR 8576, UGSF, Université de Lille 1, Villeneuve d'Ascq, France
| | - Edwige Madec
- Centre National de la Recherche Scientifique, CNRS UMR 8576, UGSF, Université de Lille 1, Villeneuve d'Ascq, France
| | - Agnes Hovasse
- Laboratoire de Spectrométrie de Masse Bioorganique, IPHC, CNRS UMR 7178, Université de Strasbourg, Strasbourg, France
| | - Elisabeth Werkmeister
- Center for Infection and Immunity of Lille, CNRS UMR 8204, INSERM U 1019, Institut Pasteur de Lille, Université Lille Nord de France, Lille, France
| | - Isabelle Callebaut
- Centre National de la Recherche Scientifique, Universités Pierre et Marie Curie-Paris 6 et Denis Diderot-Paris 7, UMR7590, Paris, France
| | - Christian Slomianny
- Laboratoire de Physiologie Cellulaire, INSERM U1003, Université de Lille 1, Villeneuve d'Ascq, France
| | - Stephane Delhaye
- Center for Infection and Immunity of Lille, CNRS UMR 8204, INSERM U 1019, Institut Pasteur de Lille, Université Lille Nord de France, Lille, France
- Centre National de la Recherche Scientifique, CNRS UMR 8576, UGSF, Université de Lille 1, Villeneuve d'Ascq, France
| | - Thomas Mouveaux
- Center for Infection and Immunity of Lille, CNRS UMR 8204, INSERM U 1019, Institut Pasteur de Lille, Université Lille Nord de France, Lille, France
- Centre National de la Recherche Scientifique, CNRS UMR 8576, UGSF, Université de Lille 1, Villeneuve d'Ascq, France
| | - Christine Schaeffer-Reiss
- Laboratoire de Spectrométrie de Masse Bioorganique, IPHC, CNRS UMR 7178, Université de Strasbourg, Strasbourg, France
| | - Alain Van Dorsselaer
- Laboratoire de Spectrométrie de Masse Bioorganique, IPHC, CNRS UMR 7178, Université de Strasbourg, Strasbourg, France
| | - Stanislas Tomavo
- Center for Infection and Immunity of Lille, CNRS UMR 8204, INSERM U 1019, Institut Pasteur de Lille, Université Lille Nord de France, Lille, France
- Centre National de la Recherche Scientifique, CNRS UMR 8576, UGSF, Université de Lille 1, Villeneuve d'Ascq, France
- * E-mail:
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Yamagishi J, Wakaguri H, Ueno A, Goo YK, Tolba M, Igarashi M, Nishikawa Y, Sugimoto C, Sugano S, Suzuki Y, Watanabe J, Xuan X. High-resolution characterization of Toxoplasma gondii transcriptome with a massive parallel sequencing method. DNA Res 2010; 17:233-43. [PMID: 20522451 PMCID: PMC2920756 DOI: 10.1093/dnares/dsq013] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
For the last couple of years, a method that permits the collection of precise positional information of transcriptional start sites (TSSs) together with digital information of the gene-expression levels in a high-throughput manner was established. We applied this novel method, ‘tss-seq’, to elucidate the transcriptome of tachyzoites of the Toxoplasma gondii, which resulted in the identification of 124 000 TSSs, and they were clustered into 10 000 transcription regions (TRs) with a statistics-based analysis. The TRs and annotated ORFs were paired, resulting in the identification of 30% of the TRs and 40% of the ORFs without their counterparts, which predicted undiscovered genes and stage-specific transcriptions, respectively. The massive data for TSSs make it possible to execute the first systematic analysis of the T. gondii core promoter structure, and the information showed that T. gondii utilized an initiator-like motif for their transcription in the major and novel motif, the downstream thymidine cluster, which was similar to the Y patch observed in plants. This encyclopaedic analysis also suggested that the TATA box, and the other well-known core promoter elements were hardly utilized.
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Affiliation(s)
- Junya Yamagishi
- 1National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Japan
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25
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Dixon SE, Stilger KL, Elias EV, Naguleswaran A, Sullivan WJ. A decade of epigenetic research in Toxoplasma gondii. Mol Biochem Parasitol 2010; 173:1-9. [PMID: 20470832 DOI: 10.1016/j.molbiopara.2010.05.001] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2010] [Revised: 04/30/2010] [Accepted: 05/04/2010] [Indexed: 11/25/2022]
Abstract
In the past 10 years, the field of parasitology has witnessed an explosion of studies investigating gene regulation. In this review, we will describe recent advances largely stemming from the study of Toxoplasma gondii, a significant opportunistic pathogen and useful model for other apicomplexan protozoa. Surprising findings have emerged, including the discovery of a wealth of epigenetic machinery in these primitive eukaryotes, unusual histone variants, and a battery of plant-like transcription factors. We will elaborate on how these unusual features impact parasite physiology and potential therapeutics as we summarize some of the key discoveries from the last decade. We will close by proposing a few questions to address in the next 10 years.
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Affiliation(s)
- Stacy E Dixon
- Department of Pharmacology & Toxicology, Indiana University School of Medicine, Indianapolis, 46202, United States
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26
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Holmes M, Liwak U, Pricop I, Wang X, Tomavo S, Ananvoranich S. Silencing of tachyzoite enolase 2 alters nuclear targeting of bradyzoite enolase 1 in Toxoplasma gondii. Microbes Infect 2010; 12:19-27. [DOI: 10.1016/j.micinf.2009.09.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2009] [Revised: 08/14/2009] [Accepted: 09/05/2009] [Indexed: 11/30/2022]
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27
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Isolation of Toxoplasma gondii development mutants identifies a potential proteophosphogylcan that enhances cyst wall formation. Mol Biochem Parasitol 2009; 169:120-3. [PMID: 19879901 DOI: 10.1016/j.molbiopara.2009.10.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2009] [Revised: 10/13/2009] [Accepted: 10/20/2009] [Indexed: 11/20/2022]
Abstract
Within warm-blooded animals, Toxoplasma gondii switches from an actively replicating form called a tachyzoite into a slow growing encysted form called a bradyzoite. To uncover the genes involved in bradyzoite development, we screened over 8000 T. gondii insertional mutants by immunofluorescence microscopy. We identified nine bradyzoite development mutants that were defective in both cyst wall formation and expression of a bradyzoite specific heat shock protein. One of these mutants, named 42F5, contained an insertion into the predicted gene TGME49_097520. The disrupted protein is serine/proline-rich with homology to proteophosphoglycans from Leishmania. T. gondii proteophosphoglycan (GU182879) expressed from the native promoter was undetectable in tachyzoites, but bradyzoites show punctate spots within the parasite and staining around the parasitophorous vacuole. Complementation of the 42F5 mutant with GU182879 expressed from either the alpha-tubulin or native promoter restores cyst wall formation. Overall, GU182879 is upregulated in bradyzoites and enhances cyst wall component expression and assembly.
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28
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A transmembrane domain-containing surface protein from Toxoplasma gondii augments replication in activated immune cells and establishment of a chronic infection. Infect Immun 2009; 77:3731-9. [PMID: 19581395 DOI: 10.1128/iai.00450-09] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Toxoplasma gondii mutants identified as defective in the establishment of chronic infection were screened to isolate those specifically impaired in their ability to replicate within activated macrophages. One of the identified mutants contains an insertion in the hypothetical gene TGME49_111670. Genetic complementation restores the ability of the mutant to replicate in immune cells and produce cysts in the brains of mice. While the mutant is more sensitive to nitric oxide than is its parental strain, it is not defective in its ability to suppress nitric oxide. The disrupted protein has no significant homology to proteins with known functions, but is predicted to have one transmembrane domain. Immunofluorescence shows the protein on the parasite surface, even in activated macrophages, colocalizing with a tachyzoite surface antigen, SAG1, and oriented with its C-terminal end external. Western analysis reveals that the protein is downregulated in bradyzoites. Despite the tachyzoite specificity of this protein, mice infected with the mutant succumb to acute infection similarly to those infected with the parent strain. Serum samples from mice with chronic T. gondii infection react to a polypeptide from TGME49_11670, indicating that the protein is seen by the immune system during infection. This study is the first to characterize a T. gondii surface protein that contains a transmembrane domain and show that the protein contributes to parasite replication in activated immune cells and the establishment of chronic infection.
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29
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Mullapudi N, Joseph SJ, Kissinger JC. Identification and functional characterization of cis-regulatory elements in the apicomplexan parasite Toxoplasma gondii. Genome Biol 2009; 10:R34. [PMID: 19351398 PMCID: PMC2688925 DOI: 10.1186/gb-2009-10-4-r34] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2008] [Revised: 01/11/2009] [Accepted: 04/07/2009] [Indexed: 11/17/2022] Open
Abstract
Mining of genomic sequence data of the apicomplexan parasite Toxoplasma gondii identifies putative cis-regulatory elements using a de novo approach. Background Toxoplasma gondii is a member of the phylum Apicomplexa, which consists entirely of parasitic organisms that cause several diseases of veterinary and human importance. Fundamental mechanisms of gene regulation in this group of protistan parasites remain largely uncharacterized. Owing to their medical and veterinary importance, genome sequences are available for several apicomplexan parasites. Their genome sequences reveal an apparent paucity of known transcription factors and the absence of canonical cis-regulatory elements. We have approached the question of gene regulation from a sequence perspective by mining the genomic sequence data to identify putative cis-regulatory elements using a de novo approach. Results We have identified putative cis-regulatory elements present upstream of functionally related groups of genes and subsequently characterized the function of some of these conserved elements using reporter assays in the parasite. We show a sequence-specific role in gene-expression for seven out of eight identified elements. Conclusions This work demonstrates the power of pure sequence analysis in the absence of expression data or a priori knowledge of regulatory elements in eukaryotic organisms with compact genomes.
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Affiliation(s)
- Nandita Mullapudi
- Department of Genetics, University of Georgia, East Green Street, Athens, Georgia 30602, USA.
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30
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The heptanucleotide motif GAGACGC is a key component of a cis-acting promoter element that is critical for SnSAG1 expression in Sarcocystis neurona. Mol Biochem Parasitol 2009; 166:85-8. [PMID: 19428678 DOI: 10.1016/j.molbiopara.2009.02.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2008] [Revised: 02/09/2009] [Accepted: 02/12/2009] [Indexed: 11/23/2022]
Abstract
The apicomplexan parasite Sarcocystis neurona undergoes a complex process of intracellular development, during which many genes are temporally regulated. The described study was undertaken to begin identifying the basic promoter elements that control gene expression in S. neurona. Sequence analysis of the 5'-flanking region of five S. neurona genes revealed a conserved heptanucleotide motif GAGACGC that is similar to the WGAGACG motif described upstream of multiple genes in Toxoplasma gondii. The promoter region for the major surface antigen gene SnSAG1, which contains three heptanucleotide motifs within 135 bases of the transcription start site, was dissected by functional analysis using a dual luciferase reporter assay. These analyses revealed that a minimal promoter fragment containing all three motifs was sufficient to drive reporter molecule expression, with the presence and orientation of the 5'-most heptanucleotide motif being absolutely critical for promoter function. Further studies should help to identify additional sequence elements important for promoter function and for controlling gene expression during intracellular development by this apicomplexan pathogen.
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31
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Haraldsen JD, Liu G, Botting CH, Walton JGA, Storm J, Phalen TJ, Kwok LY, Soldati-Favre D, Heintz NH, Müller S, Westwood NJ, Ward GE. IDENTIFICATION OF CONOIDIN A AS A COVALENT INHIBITOR OF PEROXIREDOXIN II. Org Biomol Chem 2009; 7:3040-3048. [PMID: 21359112 DOI: 10.1039/b901735f] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Conoidin A (1) is an inhibitor of host cell invasion by the protozoan parasite Toxoplasma gondii. In the course of studies aimed at identifying potential targets of this compound, we determined that it binds to the T. gondii enzyme peroxiredoxin II (TgPrxII). Peroxiredoxins are a widely conserved family of enzymes that function in antioxidant defense and signal transduction, and changes in PrxII expression are associated with a variety of human diseases, including cancer. Disruption of the TgPrxII gene by homologous recombination had no effect on the sensitivity of the parasites to 1, suggesting that TgPrxII is not the invasion-relevant target of 1. However, we showed that 1 binds covalently to the peroxidatic cysteine of TgPrxII, inhibiting its enzymatic activity in vitro. Studies with human epithelial cells showed that 1 also inhibits hyperoxidation of human PrxII. These data identify Conoidin A as a novel inhibitor of this important class of antioxidant and redox signaling enzymes.
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Affiliation(s)
- Jeralyn D Haraldsen
- Department of Microbiology and Molecular Genetics, 316 Stafford Hall, University of Vermont, 95 Carrigan Drive, Burlington VT 05405, USA
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Gissot M, Kim K, Schaap D, Ajioka JW. New eukaryotic systematics: a phylogenetic perspective of developmental gene expression in the Apicomplexa. Int J Parasitol 2008; 39:145-51. [PMID: 18983845 DOI: 10.1016/j.ijpara.2008.10.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2008] [Revised: 10/01/2008] [Accepted: 10/14/2008] [Indexed: 12/14/2022]
Abstract
The phylum Apicomplexa consists of obligate intracellular protistan parasites, some of which are responsible for global disease causing serious morbidity and mortality in humans and animals. Understanding the mechanisms of gene expression that drive the cellular changes required to complete their life cycles will be critical in combating infection and disease. Plasmodium spp. and Toxoplasma gondii have served as good models for growth and development in the Apicomplexa. Elucidating developmental gene expression relies on comparisons with known mechanisms and their DNA, RNA and protein components. Transcriptional profiling across asexual development suggests a model where a cascade of gene expression results in a "just-in-time" production process that makes products only when needed. Some mechanisms that control transcription such as chromatin/histone modification are highly conserved in the phylum compared with the traditional model organisms, yeast, worms, flies and mammals. Studies exploiting this phenomenon show great potential for both investigating the effects of chromatin structure on developmental gene expression, and helping to identify genes that are expressed in a stage-specific manner. Transcription factors and their cognate cis-acting binding sites have been difficult to identify. This may be because the DNA binding motifs that have evolved to act as transcription factors in the Apicomplexa, e.g. the AP2 family, may be more like plants than the traditional model organisms. A new eukaryotic phylogenetic model comprised of six super-groups divides the traditional model organisms, plants and the Apicomplexa into separate super-groups. This phylogenetic model helps explain why basic functions such as transcriptional regulation appear be a composite of mechanisms in the Apicomplexa compared with what is known from other eukaryotes.
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Affiliation(s)
- Mathieu Gissot
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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33
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Expression quantitative trait locus mapping of toxoplasma genes reveals multiple mechanisms for strain-specific differences in gene expression. EUKARYOTIC CELL 2008; 7:1403-14. [PMID: 18552283 PMCID: PMC2519772 DOI: 10.1128/ec.00073-08] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Toxoplasma gondii is an intracellular parasite with a significant impact on human health, especially in cases where individuals are immunocompromised (e.g., due to human immunodeficiency virus/AIDS). In Europe and North America, only a few clonal genotypes appear to be responsible for the vast majority of Toxoplasma infections, and these clonotypes have been intensely studied to identify strain-specific phenotypes that may play a role in the manifestation of more-severe disease. To identify and genetically map strain-specific differences in gene expression, we have carried out expression quantitative trait locus analysis on Toxoplasma gene expression phenotypes by using spotted cDNA microarrays. This led to the identification of 16 Toxoplasma genes that had significant and mappable strain-specific variation in hybridization intensity. While the analysis should identify both cis- and trans-mapping hybridization profiles, we identified only loci with strain-specific hybridization differences that are most likely due to differences in the locus itself (i.e., cis mapping). Interestingly, a larger number of these cis-mapping genes than would be expected by chance encode either confirmed or predicted secreted proteins, many of which are known to localize to the specialized secretory organelles characteristic of members of the phylum Apicomplexa. For six of the cis-mapping loci, we determined if the strain-specific hybridization differences were due to true transcriptional differences or rather to strain-specific differences in hybridization efficiency because of extreme polymorphism and/or deletion, and we found examples of both scenarios.
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Behnke MS, Radke JB, Smith AT, Sullivan WJ, White MW. The transcription of bradyzoite genes in Toxoplasma gondii is controlled by autonomous promoter elements. Mol Microbiol 2008; 68:1502-18. [PMID: 18433450 PMCID: PMC2440561 DOI: 10.1111/j.1365-2958.2008.06249.x] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/06/2008] [Indexed: 11/28/2022]
Abstract
Experimental evidence suggests that apicomplexan parasites possess bipartite promoters with basal and regulated cis-elements similar to other eukaryotes. Using a dual luciferase model adapted for recombinational cloning and use in Toxoplasma gondii, we show that genomic regions flanking 16 parasite genes, which encompass examples of constitutive and tachyzoite- and bradyzoite-specific genes, are able to reproduce the appropriate developmental stage expression in a transient luciferase assay. Mapping of cis-acting elements in several bradyzoite promoters led to the identification of short sequence spans that are involved in control of bradyzoite gene expression in multiple strains and under different bradyzoite induction conditions. Promoters that regulate the heat shock protein BAG1 and a novel bradyzoite-specific NTPase during bradyzoite development were fine mapped to a 6-8 bp resolution and these minimal cis-elements were capable of converting a constitutive promoter to one that is induced by bradyzoite conditions. Gel-shift experiments show that mapped cis-elements are bound by parasite protein factors with the appropriate functional sequence specificity. These studies are the first to identify the minimal sequence elements that are required and sufficient for bradyzoite gene expression and to show that bradyzoite promoters are maintained in a 'poised' chromatin state throughout the intermediate host life cycle in low passage strains. Together, these data demonstrate that conventional eukaryotic promoter mechanisms work with epigenetic processes to regulate developmental gene expression during tissue cyst formation.
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Affiliation(s)
- Michael S Behnke
- Department of Veterinary Molecular Biology, Montana State University BozemanMT 59717, USA
| | - Josh B Radke
- Department of Veterinary Molecular Biology, Montana State University BozemanMT 59717, USA
| | - Aaron T Smith
- Department Pharmacology and Toxicology, Indiana University School of MedicineIndianapolis, IN 46202, USA
| | - William J Sullivan
- Department Pharmacology and Toxicology, Indiana University School of MedicineIndianapolis, IN 46202, USA
| | - Michael W White
- Department of Veterinary Molecular Biology, Montana State University BozemanMT 59717, USA
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Kessler H, Herm-Götz A, Hegge S, Rauch M, Soldati-Favre D, Frischknecht F, Meissner M. Microneme protein 8 – a new essential invasion factor inToxoplasma gondii. J Cell Sci 2008; 121:947-56. [PMID: 18319299 DOI: 10.1242/jcs.022350] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Apicomplexan parasites rely on sequential secretion of specialised secretory organelles for the invasion of the host cell. First, micronemes release their content upon contact with the host cell. Second, rhoptries are discharged, leading to the formation of a tight interaction (moving junction) with the host cell, through which the parasite invades. The functional characterisation of several micronemal proteins in Toxoplasma gondii suggests the occurrence of a stepwise process. Here, we show that the micronemal protein MIC8 of T. gondii is essential for the parasite to invade the host cell. When MIC8 is not present, a block in invasion is caused by the incapability of the parasite to form a moving junction with the host cell. We furthermore demonstrate that the cytosolic domain is crucial for the function of MIC8 and can not be functionally complemented by any other micronemal protein characterised so far, suggesting that MIC8 represents a novel, functionally distinct invasion factor in this apicomplexan parasite.
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Affiliation(s)
- Henning Kessler
- Hygieneinstitute, Department of Parasitology, University Hospital Heidelberg, Im Neuenheimer Feld 324, D-69120 Heidelberg, Germany
| | - Angelika Herm-Götz
- Hygieneinstitute, Department of Parasitology, University Hospital Heidelberg, Im Neuenheimer Feld 324, D-69120 Heidelberg, Germany
| | - Stephan Hegge
- Hygieneinstitute, Department of Parasitology, University Hospital Heidelberg, Im Neuenheimer Feld 324, D-69120 Heidelberg, Germany
| | - Manuel Rauch
- Hygieneinstitute, Department of Parasitology, University Hospital Heidelberg, Im Neuenheimer Feld 324, D-69120 Heidelberg, Germany
| | - Dominique Soldati-Favre
- Department of Microbiology and Molecular Medicine, University of Geneva, CMU, 1, rue Michel-Servet 1211, Geneva 4, Switzerland
| | - Friedrich Frischknecht
- Hygieneinstitute, Department of Parasitology, University Hospital Heidelberg, Im Neuenheimer Feld 324, D-69120 Heidelberg, Germany
| | - Markus Meissner
- Hygieneinstitute, Department of Parasitology, University Hospital Heidelberg, Im Neuenheimer Feld 324, D-69120 Heidelberg, Germany
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36
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A cluster of four surface antigen genes specifically expressed in bradyzoites, SAG2CDXY, plays an important role in Toxoplasma gondii persistence. Infect Immun 2008; 76:2402-10. [PMID: 18347037 DOI: 10.1128/iai.01494-07] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Toxoplasma gondii is one of the most successful protozoan parasites of warm-blooded animals. Stage-specific expression of its surface molecules is thought to be key to its ability to establish chronic infection in immunocompetent animals. The rapidly dividing tachyzoite stage displays a different subset of family of surface antigen 1 (SAG1)-related sequences (SRSs) from that displayed by the encysted bradyzoite stage. It is possible that this switch is necessary to protect the bradyzoites against an immune response raised against the tachyzoite stage. Alternatively, it might be that bradyzoite SRSs evolved to facilitate invasion of different cell types, such as those found in the brain, where cysts develop, or the small intestine, where bradyzoites must enter after oral infection. Here we studied the function of a cluster of four tandem genes, encoding bradyzoite SRSs called SAG2C, -D, -X, and -Y. Using bioluminescence imaging of mice infected with parasites expressing firefly luciferase (FLUC) driven by the SAG2D promoter, we show stage conversion for the first time in living animals. A truncated version of the SAG2D promoter (SAG2Dmin) gave efficient expression of FLUC in both tachyzoites and bradyzoites, indicating that the bradyzoite specificity of the complete SAG2D promoter is likely due to an element(s) that normally suppresses expression in tachyzoites. Comparing mice infected with the wild type or a mutant where the SAG2CDXY cluster of genes has been deleted (DeltaSAG2CDXY), we demonstrate that whereas DeltaSAG2CDXY parasites are less capable of maintaining a chronic infection in the brain, they do not show a defect in oral infectivity.
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Rapid control of protein level in the apicomplexan Toxoplasma gondii. Nat Methods 2007; 4:1003-5. [PMID: 17994029 DOI: 10.1038/nmeth1134] [Citation(s) in RCA: 169] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2007] [Accepted: 10/23/2007] [Indexed: 11/08/2022]
Abstract
Analysis of gene function in apicomplexan parasites is limited by the absence of reverse genetic tools that allow easy and rapid modulation of protein levels. The fusion of a ligand-controlled destabilization domain (ddFKBP) to a protein of interest enables rapid and reversible protein stabilization in T. gondii. This allows an efficient functional analysis of proteins that have a dual role during host cell invasion and/or intracellular growth of the parasite.
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Highly polymorphic family of glycosylphosphatidylinositol-anchored surface antigens with evidence of developmental regulation in Toxoplasma gondii. Infect Immun 2007; 76:103-10. [PMID: 17938221 DOI: 10.1128/iai.01170-07] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The life cycle of the apicomplexan parasite Toxoplasma gondii requires that an infectious cyst develop and be maintained throughout the life of the host. The molecules displayed on the parasite surface are important in controlling the immune response to the parasite. T. gondii has a superfamily of glycosylphosphatidylinositol (GPI)-anchored surface antigens, termed the surface antigen (SAG) and SAG-related surface antigens, that are developmentally regulated during infection. Using a clustering algorithm, we identified a new family of 31 surface proteins that are predicted to be GPI anchored but are unrelated to the SAG proteins, and thus we named these proteins SAG-unrelated surface antigens (SUSA). Analysis of the single nucleotide polymorphism density showed that the members of this family are the most polymorphic genes within the T. gondii genome. Immunofluorescence of SUSA1 and SUSA2, two members of the family, revealed that they are found on the parasite surface. We confirmed that SUSA1 and SUSA2 are GPI anchored by phospholipase cleavage. Analysis of expressed sequence tags (ESTs) revealed that SUSA1 had 22 of 23 ESTs from chronic infection. Analysis of mRNA and protein confirmed that SUSA1 is highly expressed in the chronic form of the parasite. Sera from mice with chronic T. gondii infection reacted to SUSA1, indicating that SUSA1 interacts with the host immune system during infection. This group of proteins likely represents a new family of polymorphic GPI-anchored surface antigens that are recognized by the host's immune system and whose expression is regulated during infection.
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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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Zhang J, Gu Q, Hou X, Zhou H, Cong H, Li Y, Zhao Q, Li S. Identification of a necessary element for Toxoplasma gondii SAG1 gene expression. Exp Parasitol 2007; 116:175-81. [PMID: 17258203 DOI: 10.1016/j.exppara.2006.11.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2006] [Revised: 11/26/2006] [Accepted: 11/29/2006] [Indexed: 10/23/2022]
Abstract
SAG1 codes for the stage-specific major surface antigen P30 of Toxoplasma gondii (T. gondii) tachyzoites. Six tandemly repeated, conserved 27 bp cassettes in the region from -231 to -70 bp were previously confirmed to be essential for high-level expression of SAG1 and serve as a positioning element directing the initiation of transcription. We demonstrate here that an element located between +19 and +28 bp is necessary for SAG1 gene expression by using deletion mutagenesis analysis and electrophoresis mobility shift assay (EMSA). This will provide an insight into the regulatory mechanisms of SAG1 gene expression.
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Affiliation(s)
- Jiaqin Zhang
- Department of Parasitology, School of Medicine, Shandong University, and Nephrology Department, The Second Hospital of Shandong University, PR China
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Mordue DG, Scott-Weathers CF, Tobin CM, Knoll LJ. A patatin-like protein protects Toxoplasma gondii from degradation in activated macrophages. Mol Microbiol 2006; 63:482-96. [PMID: 17166175 PMCID: PMC3392091 DOI: 10.1111/j.1365-2958.2006.05538.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The apicomplexan parasite Toxoplasma gondii is able to suppress nitric oxide production in activated macrophages. A screen of over 6000 T. gondii insertional mutants identified two clones, which were consistently unable to suppress nitric oxide production from activated macrophages. One strain, called 89B7, grew at the same rate as wild-type parasites in naïve macrophages, but unlike wild type, the mutant was degraded in activated macrophages. This degradation was marked by a reduction in the number of parasites within vacuoles over time, the loss of GRA4 and SAG1 protein staining by immunofluorescence assay, and the vesiculation and breakdown of the internal parasite ultrastructure by electron microscopy. The mutagenesis plasmid in the 89B7 clone disrupts the promoter of a 3.4 kb mRNA that encodes a predicted 68 kDa protein with a cleavable signal peptide and a patatin-like phospholipase domain. Genetic complementation with the genomic locus of this patatin-like protein restores the parasites ability to suppress nitric oxide and replicate in activated macrophages. A haemagglutinin-tagged version of this patatin-like protein shows punctate localization into atypical T. gondii structures within the parasite. This is the first study that defines a specific gene product that is needed for parasite survival in activated but not naïve macrophages.
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Affiliation(s)
| | | | | | - Laura J. Knoll
- For correspondence. ; Tel. (+1) 608 262 3161; Fax (+1) 608 262 8418
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Gaji RY, Zhang D, Breathnach CC, Vaishnava S, Striepen B, Howe DK. Molecular genetic transfection of the coccidian parasite Sarcocystis neurona. Mol Biochem Parasitol 2006; 150:1-9. [PMID: 16844242 DOI: 10.1016/j.molbiopara.2006.06.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2006] [Revised: 05/12/2006] [Accepted: 06/07/2006] [Indexed: 10/24/2022]
Abstract
Sarcocystis neurona is an apicomplexan parasite that is the major cause of equine protozoal myeloencephalitis (EPM). The biology of this pathogen remains poorly understood in part due to unavailability of molecular genetic tools. Hence, with an objective to develop DNA transfection capabilities for S. neurona, the 5' flanking region of the SnSAG1 gene was isolated from a genomic library and used to construct expression plasmids. In transient assays, the reporter molecules beta-galactosidase (beta-gal) and yellow fluorescent protein (YFP) could be detected in electroporated S. neurona, thereby confirming the feasibility of transgene expression in this organism. Stable transformation of S. neurona was achieved using a mutant dihydrofolate reductase thymidylate synthase (DHFR-TS) gene of Toxoplasma gondii that confers resistance to pyrimethamine. This selection system was used to create transgenic S. neurona that stably express beta-gal and YFP. As shown in this study, these transgenic clones can be useful for analyzing growth rate of parasites in vitro and for assessing drug sensitivities. More importantly, the DNA transfection methods described herein should greatly facilitate studies examining intracellular parasitism by this important coccidian pathogen.
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Affiliation(s)
- Rajshekhar Y Gaji
- 108 M.H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, KY 40546, USA
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The VIIIth International Congress on Toxoplasmosis. Microbes Infect 2006. [DOI: 10.1016/j.micinf.2006.01.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Mercier C, Adjogble KDZ, Däubener W, Delauw MFC. Dense granules: are they key organelles to help understand the parasitophorous vacuole of all apicomplexa parasites? Int J Parasitol 2006; 35:829-49. [PMID: 15978597 DOI: 10.1016/j.ijpara.2005.03.011] [Citation(s) in RCA: 155] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2004] [Revised: 03/07/2005] [Accepted: 03/18/2005] [Indexed: 02/06/2023]
Abstract
Together with micronemes and rhoptries, dense granules are specialised secretory organelles of Apicomplexa parasites. Among Apicomplexa, Plasmodium represents a model of parasites propagated by way of an insect vector, whereas Toxoplasma is a model of food borne protozoa forming cysts. Through comparison of both models, this review summarises data accumulated over recent years on alternative strategies chosen by these parasites to develop within a parasitophorous vacuole and explores the role of dense granules in this process. One of the characteristics of the Plasmodium erythrocyte stages is to export numerous parasite proteins into both the host cell cytoplasm and/or plasma membrane via the vacuole used as a step trafficking compartment. Whether this feature can be correlated to few storage granules and a restricted number of dense granule proteins, is not yet clear. By contrast, the Toxoplasma developing vacuole is decorated by abundantly expressed dense granule proteins and is characterised by a network of membranous nanotubes. Although the exact function of most of these proteins remains currently unknown, recent data suggest that some of these dense granule proteins could be involved in building the intravacuolar membranous network. Conserved expression of the Toxoplasma dense granule proteins throughout most of the parasite stages suggests that they could also be key elements of the cyst formation.
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Affiliation(s)
- Corinne Mercier
- Institut Jean Roget, Université Joseph Fourier, CNRS UMR 5163, Place du Commandant Nal., 38700 La Tronche, France.
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Radke JR, Behnke MS, Mackey AJ, Radke JB, Roos DS, White MW. The transcriptome of Toxoplasma gondii. BMC Biol 2005; 3:26. [PMID: 16324218 PMCID: PMC1325263 DOI: 10.1186/1741-7007-3-26] [Citation(s) in RCA: 136] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2005] [Accepted: 12/02/2005] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Toxoplasma gondii gives rise to toxoplasmosis, among the most prevalent parasitic diseases of animals and man. Transformation of the tachzyoite stage into the latent bradyzoite-cyst form underlies chronic disease and leads to a lifetime risk of recrudescence in individuals whose immune system becomes compromised. Given the importance of tissue cyst formation, there has been intensive focus on the development of methods to study bradyzoite differentiation, although the molecular basis for the developmental switch is still largely unknown. RESULTS We have used serial analysis of gene expression (SAGE) to define the Toxoplasma gondii transcriptome of the intermediate-host life cycle that leads to the formation of the bradyzoite/tissue cyst. A broad view of gene expression is provided by >4-fold coverage from nine distinct libraries (approximately 300,000 SAGE tags) representing key developmental transitions in primary parasite populations and in laboratory strains representing the three canonical genotypes. SAGE tags, and their corresponding mRNAs, were analyzed with respect to abundance, uniqueness, and antisense/sense polarity and chromosome distribution and developmental specificity. CONCLUSION This study demonstrates that phenotypic transitions during parasite development were marked by unique stage-specific mRNAs that accounted for 18% of the total SAGE tags and varied from 1-5% of the tags in each developmental stage. We have also found that Toxoplasma mRNA pools have a unique parasite-specific composition with 1 in 5 transcripts encoding Apicomplexa-specific genes functioning in parasite invasion and transmission. Developmentally co-regulated genes were dispersed across all Toxoplasma chromosomes, as were tags representing each abundance class, and a variety of biochemical pathways indicating that trans-acting mechanisms likely control gene expression in this parasite. We observed distinct similarities in the specificity and expression levels of mRNAs in primary populations (Day-6 post-sporozoite infection) that occur prior to the onset of bradyzoite development that were uniquely shared with the virulent Type I-RH laboratory strain suggesting that development of RH may be arrested. By contrast, strains from Type II-Me49B7 and Type III-VEGmsj contain SAGE tags corresponding to bradyzoite genes, which suggests that priming of developmental expression likely plays a role in the greater capacity of these strains to complete bradyzoite development.
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Affiliation(s)
- Jay R Radke
- Department of Veterinary Molecular Biology, Montana State University Bozeman, MT 59717, USA
| | - Michael S Behnke
- Department of Veterinary Molecular Biology, Montana State University Bozeman, MT 59717, USA
| | - Aaron J Mackey
- Department of Biology and Penn Genomics Institute, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Josh B Radke
- Department of Veterinary Molecular Biology, Montana State University Bozeman, MT 59717, USA
| | - David S Roos
- Department of Biology and Penn Genomics Institute, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Michael W White
- Department of Veterinary Molecular Biology, Montana State University Bozeman, MT 59717, USA
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Meissner M, Soldati D. The transcription machinery and the molecular toolbox to control gene expression in Toxoplasma gondii and other protozoan parasites. Microbes Infect 2005; 7:1376-84. [PMID: 16087378 DOI: 10.1016/j.micinf.2005.04.019] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2005] [Revised: 04/28/2005] [Accepted: 04/29/2005] [Indexed: 02/06/2023]
Abstract
The phylum of Apicomplexa groups a large variety of obligate intracellular protozoan parasites that exhibit complicated life cycles, involving transmission and differentiation within and between different hosts. Little is known about the level of regulation and the nature of the factors controlling gene expression throughout their life stages. Unravelling the mechanisms that govern gene regulation is critical for the development of adequate tools to manipulate these parasites and modulate gene expression, in order to study their function in molecular terms in vivo. A comparative analysis of the transcriptional machinery of several apicomplexan genomes and other protozoan parasites has revealed the existence of a primitive eukaryotic transcription apparatus consisting only of a subset of the general transcription factors found in higher eukaryotes. These findings have some direct implications on development of tools.
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Affiliation(s)
- Markus Meissner
- Hygieneinstitut, abteilung parasitologie, universitätsklinikum Heidelberg, Im Neuenheimer Feld 324, D-69120 Heidelberg, Germany
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Matrajt M, Platt CD, Sagar AD, Lindsay A, Moulton C, Roos DS. Transcript initiation, polyadenylation, and functional promoter mapping for the dihydrofolate reductase-thymidylate synthase gene of Toxoplasma gondii. Mol Biochem Parasitol 2005; 137:229-38. [PMID: 15383293 DOI: 10.1016/j.molbiopara.2003.12.015] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2003] [Revised: 11/03/2003] [Accepted: 12/19/2003] [Indexed: 01/21/2023]
Abstract
The fused dihydrofolate reductase/thymidylate synthase gene of Toxoplasma gondii contains ten exons spanning approximately 8 kb of genomic DNA. We have examined the ends of DHFR-TS transcripts within this gene, and find a complex pattern including two discrete 5' termini and multiple polyadenylation sites. No TATAA box or other classical promoter motif is evident in 1.4 kb of genomic DNA upstream of the coding region, but transcript mapping by RNase protection and primer extension reveals two prominent 5' ends at positions -369 and -341 nt relative to the ATG initiation codon. Upstream genomic sequences include GC-rich regions and the (opposite strand) WGAGACG motif previously identified in other T. gondii promoters. Mutagenesis of recombinant reporter plasmids demonstrates that this region is essential for efficient transgene expression. Sequencing the 3' ends from multiple independent mRNA clones demonstrates numerous polyadenylation sites, distributed over >650 nt of genomic sequence beginning approximately 250 nt downstream of the stop codon. Within this region, certain sites seem to be preferred: 14 different positions were found among the 32 polyadenylated transcripts examined, but approximately 40% of the transcripts map to two loci. The 3' noncoding region is rich in A and T nucleotides, and contains an imperfect 50 nt direct repeat, but no obvious poly(A) addition signal was identified.
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Affiliation(s)
- Mariana Matrajt
- Department of Biology, University of Pennsylvania, 415 South University Avenue, Philadelphia, PA 19104-6018, USA
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48
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Gross U, Bohne W, Soête M, Dubremetz JF. Developmental differentiation between tachyzoites and bradyzoites of Toxoplasma gondii. ACTA ACUST UNITED AC 2005; 12:30-3. [PMID: 15275305 DOI: 10.1016/0169-4758(96)80642-9] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
An important event in the pathogenesis of toxoplasmosis is the interconversion between the bradyzoite and the tachyzoite stage of Toxoplasma gondii within the intermediate host. The factors that influence either cyst formation (bradyzoites) or reactivation (tachyzoites) are unknown. Uwe Gross, Wolfgang Bohne, Martine Soête and Jean François Dubremetz here describe current knowledge about the mechanisms that might lead to the induction of stage differentiation of this protozoan parasite.
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Affiliation(s)
- U Gross
- Institute of Hygiene and Microbiology, University of Würzburg, Josef-Schneider-Strasse 2, D-97080 Würzburg, Germany
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Kibe MK, Coppin A, Dendouga N, Oria G, Meurice E, Mortuaire M, Madec E, Tomavo S. Transcriptional regulation of two stage-specifically expressed genes in the protozoan parasite Toxoplasma gondii. Nucleic Acids Res 2005; 33:1722-36. [PMID: 15784612 PMCID: PMC1903550 DOI: 10.1093/nar/gki314] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
The protozoan parasite Toxoplasma gondii differentially expresses two distinct enolase isoenzymes known as ENO1 and ENO2, respectively. To understand differential gene expression during tachyzoite to bradyzoite conversion, we have characterized the two T.gondii enolase promoters. No homology could be found between these sequences and no TATA or CCAAT boxes were evident. The differential activation of the ENO1 and ENO2 promoters during tachyzoite to bradyzoite differentiation was investigated by deletion analysis of 5′-flanking regions fused to the chloramphenicol acetyltransferase reporter followed by transient transfection. Our data indicate that in proliferating tachyzoites, the repression of ENO1 involves a negative distal regulatory region (nucleotides −1245 to −625) in the promoter whereas a proximal regulatory region in the ENO2 promoter directs expression at a low level. In contrast, the promoter activity of ENO1 is highly induced following the conversion of tachyzoites into resting bradyzoites. The ENO2 promoter analysis in bradyzoites showed that there are two upstream repression sites (nucleotides −1929 to −1067 and −456 to −222). Furthermore, electrophoresis mobility shift assays demonstrated the presence of DNA-binding proteins in tachyzoite and bradyzoite nuclear lysates that bound to stress response elements (STRE), heat shock-like elements (HSE) and other cis-regulatory elements in the upstream regulatory regions of ENO1 and ENO2. Mutation of the consensus AGGGG sequence, completely abolished protein binding to an oligonucleotide containing this element. This study defines the first characterization of cis-regulatory elements and putative transcription factors involved in gene regulation of the important pathogen T.gondii.
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Affiliation(s)
| | | | | | | | | | | | | | - Stanislas Tomavo
- To whom correspondence should be addressed at Equipe de Parasitologie Moléculaire, Laboratoire de Chimie Biologique, CNRS UMR 8576, Bâtiment C9, Université des Sciences et Technologies de Lille, 59650 Villeneuve d'Ascq, France. Tel: +33 03 20 43 69 41; Fax: +33 03 20 65 55;
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Duncan R. DNA microarray analysis of protozoan parasite gene expression: outcomes correlate with mechanisms of regulation. Trends Parasitol 2004; 20:211-5. [PMID: 15105020 DOI: 10.1016/j.pt.2004.02.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Robert Duncan
- Division of Emerging and Transfusion Transmitted Diseases, Center for Biologics Evaluation and Research (CBER), Food and Drug Administration (FDA), 1401 Rockville Pike, Rockville, MD 20852, USA.
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