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Liu C, Tang J, Liang K, Liu P, Li Z. Ready for renascence in mosquito: The regulation of gene expression in Plasmodium sexual development. Acta Trop 2024; 254:107191. [PMID: 38554994 DOI: 10.1016/j.actatropica.2024.107191] [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: 12/21/2023] [Revised: 02/21/2024] [Accepted: 03/18/2024] [Indexed: 04/02/2024]
Abstract
Malaria remains one of the most perilous vector-borne infectious diseases for humans globally. Sexual gametocyte represents the exclusive stage at which malaria parasites are transmitted from the vertebrate to the Anopheles host. The feasible and effective approach to prevent malaria transmission is by addressing the sexual developmental processes, that is, gametocytogenesis and gametogenesis. Thus, this review will comprehensively cover advances in the regulation of gene expression surrounding the transmissible stages, including epigenetic, transcriptional, and post-transcriptional control.
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Affiliation(s)
- Cong Liu
- Institute of Pathogenic Biology and Key Laboratory of Special Pathogen Prevention and Control of Hunan Province, School of Basic Medical Sciences, Hengyang Medical School, University of South China, Hengyang, Hunan, 421001, China; School of Public Health, Hengyang Medical School, University of South China, Hengyang, Hunan, 421001, China
| | - Jingjing Tang
- Institute of Pathogenic Biology and Key Laboratory of Special Pathogen Prevention and Control of Hunan Province, School of Basic Medical Sciences, Hengyang Medical School, University of South China, Hengyang, Hunan, 421001, China
| | - Kejia Liang
- Institute of Pathogenic Biology and Key Laboratory of Special Pathogen Prevention and Control of Hunan Province, School of Basic Medical Sciences, Hengyang Medical School, University of South China, Hengyang, Hunan, 421001, China
| | - Peng Liu
- Institute of Pathogenic Biology and Key Laboratory of Special Pathogen Prevention and Control of Hunan Province, School of Basic Medical Sciences, Hengyang Medical School, University of South China, Hengyang, Hunan, 421001, China
| | - Zhenkui Li
- Institute of Pathogenic Biology and Key Laboratory of Special Pathogen Prevention and Control of Hunan Province, School of Basic Medical Sciences, Hengyang Medical School, University of South China, Hengyang, Hunan, 421001, China.
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2
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Liffner B, Absalon S. Expansion microscopy of apicomplexan parasites. Mol Microbiol 2024; 121:619-635. [PMID: 37571814 DOI: 10.1111/mmi.15135] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2023] [Revised: 07/15/2023] [Accepted: 07/20/2023] [Indexed: 08/13/2023]
Abstract
Apicomplexan parasites comprise significant pathogens of humans, livestock and wildlife, but also represent a diverse group of eukaryotes with interesting and unique cell biology. The study of cell biology in apicomplexan parasites is complicated by their small size, and historically this has required the application of cutting-edge microscopy techniques to investigate fundamental processes like mitosis or cell division in these organisms. Recently, a technique called expansion microscopy has been developed, which rather than increasing instrument resolution like most imaging modalities, physically expands a biological sample. In only a few years since its development, a derivative of expansion microscopy known as ultrastructure-expansion microscopy (U-ExM) has been widely adopted and proven extremely useful for studying cell biology of Apicomplexa. Here, we review the insights into apicomplexan cell biology that have been enabled through the use of U-ExM, with a specific focus on Plasmodium, Toxoplasma and Cryptosporidium. Further, we summarize emerging expansion microscopy modifications and modalities and forecast how these may influence the field of parasite cell biology in future.
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Affiliation(s)
- Benjamin Liffner
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Sabrina Absalon
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, Indiana, USA
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3
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Jia L, Zhao Q, Zhu S, Han H, Zhao H, Yu Y, Yang J, Dong H. Proteomic Analysis of Fractionated Eimeria tenella Sporulated Oocysts Reveals Involvement in Oocyst Wall Formation. Int J Mol Sci 2023; 24:17051. [PMID: 38069374 PMCID: PMC10707475 DOI: 10.3390/ijms242317051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Accepted: 11/26/2023] [Indexed: 12/18/2023] Open
Abstract
Eimeria tenella is the most pathogenic intracellular protozoan parasite of the Eimeria species. Eimeria oocyst wall biogenesis appears to play a central role in oocyst transmission. Proteome profiling offers insights into the mechanisms governing the molecular basis of oocyst wall formation and identifies targets for blocking parasite transmission. Tandem mass tags (TMT)-labeled quantitative proteomics was used to analyze the oocyst wall and sporocysts of E. tenella. A combined total of 2865 E. tenella proteins were identified in the oocyst wall and sporocyst fractions; among these, 401 DEPs were identified, of which 211 were upregulated and 190 were downregulated. The 211 up-regulated DEPs were involved in various biological processes, including DNA replication, fatty acid metabolism and biosynthesis, glutathione metabolism, and propanoate metabolism. Among these proteins, several are of interest for their likely role in oocyst wall formation, including two tyrosine-rich gametocyte proteins (EtGAM56, EtSWP1) and two cysteine-rich proteins (EtOWP2, EtOWP6). Concurrently, 96 uncharacterized proteins may also participate in oocyst wall formation. The present study significantly expands our knowledge of the proteome of the oocyst wall of E. tenella, thereby providing a theoretical basis for further understanding of the biosynthesis and resilience of the E. tenella oocyst wall.
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Affiliation(s)
| | | | | | | | | | | | | | - Hui Dong
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Minhang, Shanghai 200241, China; (L.J.); (Q.Z.); (S.Z.); (H.H.); (H.Z.); (Y.Y.); (J.Y.)
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4
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Greischar MA, Childs LM. Extraordinary parasite multiplication rates in human malaria infections. Trends Parasitol 2023; 39:626-637. [PMID: 37336700 DOI: 10.1016/j.pt.2023.05.006] [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: 03/15/2023] [Revised: 05/18/2023] [Accepted: 05/19/2023] [Indexed: 06/21/2023]
Abstract
For pathogenic organisms, faster rates of multiplication promote transmission success, the potential to harm hosts, and the evolution of drug resistance. Parasite multiplication rates (PMRs) are often quantified in malaria infections, given the relative ease of sampling. Using modern and historical human infection data, we show that established methods return extraordinarily - and implausibly - large PMRs. We illustrate how inflated PMRs arise from two facets of malaria biology that are far from unique: (i) some developmental ages are easier to sample than others; (ii) the distribution of developmental ages changes over the course of infection. The difficulty of accurately quantifying PMRs demonstrates a need for robust methods and a subsequent re-evaluation of what is known even in the well-studied system of malaria.
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Affiliation(s)
- Megan A Greischar
- Department of Ecology & Evolutionary Biology, Cornell University, Ithaca, NY, USA.
| | - Lauren M Childs
- Department of Mathematics, Virginia Tech, Blacksburg, VA, USA
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5
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Hildebrandt F, Mohammed M, Dziedziech A, Bhandage AK, Divne AM, Barrenäs F, Barragan A, Henriksson J, Ankarklev J. scDual-Seq of Toxoplasma gondii-infected mouse BMDCs reveals heterogeneity and differential infection dynamics. Front Immunol 2023; 14:1224591. [PMID: 37575232 PMCID: PMC10415529 DOI: 10.3389/fimmu.2023.1224591] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Accepted: 07/06/2023] [Indexed: 08/15/2023] Open
Abstract
Dendritic cells and macrophages are integral parts of the innate immune system and gatekeepers against infection. The protozoan pathogen, Toxoplasma gondii, is known to hijack host immune cells and modulate their immune response, making it a compelling model to study host-pathogen interactions. Here we utilize single cell Dual RNA-seq to parse out heterogeneous transcription of mouse bone marrow-derived dendritic cells (BMDCs) infected with two distinct genotypes of T. gondii parasites, over multiple time points post infection. We show that the BMDCs elicit differential responses towards T. gondii infection and that the two parasite lineages distinctly manipulate subpopulations of infected BMDCs. Co-expression networks define host and parasite genes, with implications for modulation of host immunity. Integrative analysis validates previously established immune pathways and additionally, suggests novel candidate genes involved in host-pathogen interactions. Altogether, this study provides a comprehensive resource for characterizing host-pathogen interplay at high-resolution.
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Affiliation(s)
- Franziska Hildebrandt
- Department of Molecular Biosciences, The Wenner Gren Institute, Stockholm University, Stockholm, Sweden
| | - Mubasher Mohammed
- Department of Molecular Biosciences, The Wenner Gren Institute, Stockholm University, Stockholm, Sweden
| | - Alexis Dziedziech
- Department of Molecular Biosciences, The Wenner Gren Institute, Stockholm University, Stockholm, Sweden
- Department of Global Health, Institut Pasteur, Paris, France
| | - Amol K. Bhandage
- Department of Molecular Biosciences, The Wenner Gren Institute, Stockholm University, Stockholm, Sweden
| | - Anna-Maria Divne
- Microbial Single Cell Genomics Facility, SciLifeLab, Biomedical Center (BMC) Uppsala University, Uppsala, Sweden
| | - Fredrik Barrenäs
- Department of Molecular Biosciences, The Wenner Gren Institute, Stockholm University, Stockholm, Sweden
| | - Antonio Barragan
- Department of Molecular Biosciences, The Wenner Gren Institute, Stockholm University, Stockholm, Sweden
| | - Johan Henriksson
- Laboratory of Molecular Infection Medicine Sweden (MIMS), Umeå Center for Microbial Research, Department of Molecular Biology, Umeå University, Umeå, Sweden
| | - Johan Ankarklev
- Department of Molecular Biosciences, The Wenner Gren Institute, Stockholm University, Stockholm, Sweden
- Microbial Single Cell Genomics Facility, SciLifeLab, Biomedical Center (BMC) Uppsala University, Uppsala, Sweden
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6
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Mosquera JD, Valle CA, Nieto-Claudin A, Fessl B, Lewbart GA, Deresienski D, Bouazzi L, Zapata S, Villena I, Poulle ML. Prevalence of Toxoplasma gondii in Galapagos birds: Inference of risk factors associated with diet. PLoS One 2023; 18:e0287403. [PMID: 37405972 DOI: 10.1371/journal.pone.0287403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Accepted: 06/05/2023] [Indexed: 07/07/2023] Open
Abstract
Toxoplasma gondii is a zoonotic intracellular parasite of particular concern in the conservation of wildlife due to its ability to infect all homeotherms and potentially cause acute fatal disease in naive species. In the Galapagos (Ecuador), an archipelago composed of more than a hundred islets and islands, the presence of T. gondii can be attributed to human-introduced domestic cats, but little is known about its transmission in wildlife populations. We compared the prevalence of antibodies against T. gondii in sympatric Galapagos wild bird species that differ in diet and contact with oocyst-contaminated soil to determine the relative importance of trophic habits as an exposure factor. Plasma samples were obtained from 163 land birds inhabiting Santa Cruz, one of the cat-inhabited islands, and from 187 seabirds breeding in cat-free surrounding islands (Daphne Major, North Seymour, and South Plaza). These samples were tested for the presence of T. gondii antibodies using the modified agglutination test (MAT ≥ 1:10). All seven species of land birds and 4/6 species of seabirds presented seropositive results. All great frigatebirds (Fregata minor) (N = 25) and swallow-tailed gulls (Creagrus furcatus) (N = 23) were seronegative. Prevalence ranged from 13% in Nazca boobies (Sula granti) to 100% in Galapagos mockingbirds (Mimus parvulus). It decreased from occasional carnivores (63.43%) to granivores-insectivores (26.22%), and strict piscivores (14.62%). These results indicate that the consumption of tissue cysts poses the highest risk of exposure to T. gondii for Galapagos birds, followed by the ingestion of plants and insects contaminated by oocysts as important transmission pathways.
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Affiliation(s)
- Juan D Mosquera
- Epidémio-Surveillance et Circulation des Parasites dans les Environnements (ESCAPE), EA 7510, CAP SANTE, Université de Reims Champagne-Ardenne, Reims, France
- Instituto de Microbiología, Colegio de Ciencias Biológicas y Ambientales (COCIBA), Universidad San Francisco de Quito (USFQ), Quito, Ecuador
- Galápagos Science Center (GSC), Colegio de Ciencias Biológicas y Ambientales (COCIBA), Universidad San Francisco de Quito (USFQ), Quito, Ecuador
| | - Carlos A Valle
- Galápagos Science Center (GSC), Colegio de Ciencias Biológicas y Ambientales (COCIBA), Universidad San Francisco de Quito (USFQ), Quito, Ecuador
| | - Ainoa Nieto-Claudin
- Charles Darwin Research Station, Charles Darwin Foundation, Santa Cruz, Galapagos Islands, Ecuador
- Saint Louis Zoo Institute for Conservation Medicine, Saint Lois Zoo, Saint Louis, Missouri, United States of America
| | - Birgit Fessl
- Charles Darwin Research Station, Charles Darwin Foundation, Santa Cruz, Galapagos Islands, Ecuador
| | - Gregory A Lewbart
- Galápagos Science Center (GSC), Colegio de Ciencias Biológicas y Ambientales (COCIBA), Universidad San Francisco de Quito (USFQ), Quito, Ecuador
- College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Diane Deresienski
- Galápagos Science Center (GSC), Colegio de Ciencias Biológicas y Ambientales (COCIBA), Universidad San Francisco de Quito (USFQ), Quito, Ecuador
- College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Leïla Bouazzi
- Comité Universitaire de Ressources pour la Recherche en Santé, Université de Reims Champagne-Ardenne, Reims, France
| | - Sonia Zapata
- Instituto de Microbiología, Colegio de Ciencias Biológicas y Ambientales (COCIBA), Universidad San Francisco de Quito (USFQ), Quito, Ecuador
- Galápagos Science Center (GSC), Colegio de Ciencias Biológicas y Ambientales (COCIBA), Universidad San Francisco de Quito (USFQ), Quito, Ecuador
| | - Isabelle Villena
- Epidémio-Surveillance et Circulation des Parasites dans les Environnements (ESCAPE), EA 7510, CAP SANTE, Université de Reims Champagne-Ardenne, Reims, France
- Laboratoire de Parasitologie-Mycologie, Centre National de Référence de la Toxoplasmose, Centre de Ressources Biologiques Toxoplasma, CHU Reims, Reims, France
| | - Marie-Lazarine Poulle
- Epidémio-Surveillance et Circulation des Parasites dans les Environnements (ESCAPE), EA 7510, CAP SANTE, Université de Reims Champagne-Ardenne, Reims, France
- CERFE, Université de Reims Champagne-Ardenne, Boult-aux-Bois, France
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7
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Liu J, Shi F, Zhang Y, Tang X, Wang C, Gao Y, Suo J, Yu Y, Chen L, Zhang N, Sun P, Liu X, Suo X. Evidence of high-efficiency cross fertilization in Eimeria acervulina revealed using two lines of transgenic parasites. Int J Parasitol 2023; 53:81-89. [PMID: 36549444 DOI: 10.1016/j.ijpara.2022.10.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 10/20/2022] [Accepted: 10/22/2022] [Indexed: 12/23/2022]
Abstract
Eimeria species are apicomplexan parasites with a direct life cycle consisting of a replicative phase involving multiple rounds of asexual replication in the intestine or other organs including kidneys, liver, and gallbladder, depending on the species, followed by a sexual phase or gamogony involving the development and fertilization of gametes, an essential process for Eimeria transmission. Recent advances in the genetic manipulation of these parasites made it possible to conduct genetic crosses combined with genomic approaches to elucidate the genetic determinants of Eimeria development, virulence, drug resistance, and immune evasion. Here, we employed genetic techniques to generate two transgenic Eimeria acervulina lines, EaGAM56 and EaHAP2, each expressing two unique fluorescent proteins, with one controlled by a constitutive promotor for cross-efficiency analysis and the other by a male or female gametocyte stage-specific promoter to observe sexual development. The expression of fluorescent proteins in the transgenic lines was analyzed in different developmental stages of the E. acervulina life cycle by immunoblotting and by examination of frozen sections using fluorescence microscopy. The effect of infective doses on cross-fertilization was further investigated by conducting several genetic crosses between the two transgenic lines at different doses and ratios. Two transgenic lines expressing constitutive and gametocyte-specific fluorescence proteins were generated and characterized. These transgenic parasites display synchronous development in chickens, comparable with that of the wild type. Genetic crosses between the two transgenic parasites showed that a high rate of oocysts co-expressing the two reporters could be achieved following inoculation with high doses of infective oocysts. We further showed that the proportion of co-transfected oocysts can be modulated by altering the ratio of the transgenic parental lines. Higher infective doses and similar numbers of functional gametocytes from the parents increase the rate of cross-fertilization. Our data highlight the usefulness of genetic manipulation and fluorescently-labeled transgenic gametocytes as tools to study Eimeria development and to elucidate the factors that modulate sexual development. This work sets the stage for the implementation of novel approaches to investigate other aspects of Eimeria pathogenesis, virulence, and drug susceptibility and resistance.
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Affiliation(s)
- Jie Liu
- National Animal Protozoa Laboratory & College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
| | - Fangyun Shi
- National Animal Protozoa Laboratory & College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
| | - Yuanyuan Zhang
- Key Laboratory of Animal Genetics, Breeding and Reproduction of the Ministry of Agriculture & Beijing Key Laboratory of Animal Genetic Improvement, China Agricultural University, Beijing 100193 China
| | - Xinming Tang
- Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Chaoyue Wang
- National Animal Protozoa Laboratory & College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
| | - Yang Gao
- National Animal Protozoa Laboratory & College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
| | - Jingxia Suo
- National Animal Protozoa Laboratory & College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
| | - Ying Yu
- National Animal Protozoa Laboratory & College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
| | - Linlin Chen
- National Animal Protozoa Laboratory & College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
| | - Ning Zhang
- National Animal Protozoa Laboratory & College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
| | - Pei Sun
- National Animal Protozoa Laboratory & College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
| | - Xianyong Liu
- National Animal Protozoa Laboratory & College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
| | - Xun Suo
- National Animal Protozoa Laboratory & College of Veterinary Medicine, China Agricultural University, Beijing 100193, China.
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8
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Feix AS, Cruz-Bustos T, Ruttkowski B, Joachim A. Inhibition of sexual stage-specific proteins results in reduced numbers of sexual stages and oocysts of Cystoisospora suis (Apicomplexa: Coccidia) in vitro. Int J Parasitol 2022; 52:829-841. [PMID: 36270547 DOI: 10.1016/j.ijpara.2022.09.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 08/30/2022] [Accepted: 09/01/2022] [Indexed: 11/05/2022]
Abstract
Parasites of the order Coccidia (phylum: Alveolata, subphylum: Apicomplexa) have sophisticated life cycles that include a switch from asexual to sexual development, characterised by distinct cell types. During the development of gametes (gamogony), substantial changes occur at the cellular and subcellular levels, leading to cell fusion of micro- and microgametes, and the development of a zygote that forms a protective outer layer for environmental survival as an oocyst, the transmissible stage. Studies on the porcine coccidian Cystoisospora suis already identified changes in transcription profiles during different time points in the parasite's development and identified proteins with potential roles in the sexual development of this parasite. Here, we focus on three proteins that are possibly involved in the sexual development of C. suis. Enkurin and hapless protein 2 (HAP2) play important roles in signal transduction and gamete fusion during the fertilisation process, and oocyst wall forming protein 1 (OWP1) is a homologue of oocyst wall forming proteins of related parasites. We evaluated their locations in the different life cycle stages of C. suis and their inhibition by specific antibodies in vitro. Immunolocalization detected enkurin in merozoites and sporulated oocysts, HAP2 in merozoites and microgamonts, and OWP2 in merozoites, macrogamonts, oocysts and sporozoites. Up to 100% inhibition of the development of sexual stages and oocyst formation with purified chicken immunoglobulin IgY sera against recombinant enkurin, HAP2, and especially OWP1, were demonstrated. We conclude that the three investigated sexual stage-specific proteins constitute targets for in vivo intervention strategies to interrupt parasite development and transmission to susceptible hosts.
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Affiliation(s)
- Anna Sophia Feix
- Institute of Parasitology, Department of Pathobiology, University of Veterinary Medicine Vienna, Veterinärplatz 1, Vienna A-1210, Austria.
| | - Teresa Cruz-Bustos
- Institute of Parasitology, Department of Pathobiology, University of Veterinary Medicine Vienna, Veterinärplatz 1, Vienna A-1210, Austria
| | - Bärbel Ruttkowski
- Institute of Parasitology, Department of Pathobiology, University of Veterinary Medicine Vienna, Veterinärplatz 1, Vienna A-1210, Austria
| | - Anja Joachim
- Institute of Parasitology, Department of Pathobiology, University of Veterinary Medicine Vienna, Veterinärplatz 1, Vienna A-1210, Austria
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9
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In vitro cultivation methods for coccidian parasite research. Int J Parasitol 2022:S0020-7519(22)00153-9. [DOI: 10.1016/j.ijpara.2022.10.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 09/29/2022] [Accepted: 10/09/2022] [Indexed: 11/17/2022]
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10
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Epigenetic and Epitranscriptomic Gene Regulation in Plasmodium falciparum and How We Can Use It against Malaria. Genes (Basel) 2022; 13:genes13101734. [PMID: 36292619 PMCID: PMC9601349 DOI: 10.3390/genes13101734] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 09/15/2022] [Accepted: 09/21/2022] [Indexed: 11/16/2022] Open
Abstract
Malaria, caused by Plasmodium parasites, is still one of the biggest global health challenges. P. falciparum is the deadliest species to humans. In this review, we discuss how this parasite develops and adapts to the complex and heterogenous environments of its two hosts thanks to varied chromatin-associated and epigenetic mechanisms. First, one small family of transcription factors, the ApiAP2 proteins, functions as master regulators of spatio-temporal patterns of gene expression through the parasite life cycle. In addition, chromatin plasticity determines variable parasite cell phenotypes that link to parasite growth, virulence and transmission, enabling parasite adaptation within host conditions. In recent years, epitranscriptomics is emerging as a new regulatory layer of gene expression. We present evidence of the variety of tRNA and mRNA modifications that are being characterized in Plasmodium spp., and the dynamic changes in their abundance during parasite development and cell fate. We end up outlining that new biological systems, like the mosquito model, to decipher the unknowns about epigenetic mechanisms in vivo; and novel methodologies, to study the function of RNA modifications; are needed to discover the Achilles heel of the parasite. With this new knowledge, future strategies manipulating the epigenetics and epitranscriptomic machinery of the parasite have the potential of providing new weapons against malaria.
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11
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English ED, Guérin A, Tandel J, Striepen B. Live imaging of the Cryptosporidium parvum life cycle reveals direct development of male and female gametes from type I meronts. PLoS Biol 2022; 20:e3001604. [PMID: 35436284 PMCID: PMC9015140 DOI: 10.1371/journal.pbio.3001604] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Accepted: 03/11/2022] [Indexed: 01/08/2023] Open
Abstract
Cryptosporidium is a leading infectious cause of diarrhea around the world associated with waterborne outbreaks, community spread, or zoonotic transmission. The parasite has significant impact on early childhood mortality, and infection is both a consequence and cause of malnutrition and stunting. There is currently no vaccine, and treatment options are very limited. Cryptosporidium is a member of the Apicomplexa, and, as typical for this, protist phylum relies on asexual and sexual reproduction. In contrast to other Apicomplexa, including the malaria parasite Plasmodium, the entire Cryptosporidium life cycle unfolds in a single host in less than 3 days. Here, we establish a model to image life cycle progression in living cells and observe, track, and compare nuclear division of asexual and sexual stage parasites. We establish the length and sequence of the cell cycles of all stages and map the developmental fate of parasites across multiple rounds of invasion and egress. We propose that the parasite executes an intrinsic program of 3 generations of asexual replication, followed by a single generation of sexual stages that is independent of environmental stimuli. We find no evidence for a morphologically distinct intermediate stage (the tetraploid type II meront) but demonstrate direct development of gametes from 8N type I meronts. The progeny of each meront is collectively committed to either asexual or sexual fate, but, importantly, meronts committed to sexual fate give rise to both males and females. We define a Cryptosporidium life cycle matching Tyzzer’s original description and inconsistent with the coccidian life cycle now shown in many textbooks.
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Affiliation(s)
- Elizabeth D. English
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Amandine Guérin
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Jayesh Tandel
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Boris Striepen
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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12
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Birkholtz LM, Alano P, Leroy D. Transmission-blocking drugs for malaria elimination. Trends Parasitol 2022; 38:390-403. [DOI: 10.1016/j.pt.2022.01.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2021] [Revised: 01/19/2022] [Accepted: 01/24/2022] [Indexed: 12/24/2022]
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13
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Cruz-Bustos T, Feix AS, Ruttkowski B, Joachim A. Sexual Development in Non-Human Parasitic Apicomplexa: Just Biology or Targets for Control? Animals (Basel) 2021; 11:ani11102891. [PMID: 34679913 PMCID: PMC8532714 DOI: 10.3390/ani11102891] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Revised: 09/30/2021] [Accepted: 10/01/2021] [Indexed: 12/17/2022] Open
Abstract
Simple Summary Cellular reproduction is a key part of the apicomplexan life cycle, and both mitotic (asexual) and meiotic (sexual) cell divisions produce new individual cells. Sexual reproduction in most eukaryotic taxa indicates that it has had considerable success during evolution, and it must confer profound benefits, considering its significant costs. The phylum Apicomplexa consists of almost exclusively parasitic single-celled eukaryotic organisms that can affect a wide host range of animals from invertebrates to mammals. Their development is characterized by complex steps in which asexual and sexual replication alternate and the fertilization of a macrogamete by a microgamete results in the formation of a zygote that undergoes meiosis, thus forming a new generation of asexual stages. In apicomplexans, sex is assumed to be induced by the (stressful) condition of having to leave the host, and either gametes or zygotes (or stages arising from it) are transmitted to a new host. Therefore, sex and meiosis are linked to parasite transmission, and consequently dissemination, which are key to the parasitic lifestyle. We hypothesize that improved knowledge of the sexual biology of the Apicomplexa will be essential to design and implement effective transmission-blocking strategies for the control of the major parasites of this group. Abstract The phylum Apicomplexa is a major group of protozoan parasites including gregarines, coccidia, haemogregarines, haemosporidia and piroplasms, with more than 6000 named species. Three of these subgroups, the coccidia, hemosporidia, and piroplasms, contain parasites that cause important diseases of humans and animals worldwide. All of them have complex life cycles involving a switch between asexual and sexual reproduction, which is key to their development. Fertilization (i.e., fusion of female and male cells) results in the formation of a zygote that undergoes meiosis, forming a new generation of asexual stages. In eukaryotes, sexual reproduction is the predominant mode of recombination and segregation of DNA. Sex is well documented in many protist groups, and together with meiosis, is frequently linked with transmission to new hosts. Apicomplexan sexual stages constitute a bottleneck in the life cycle of these parasites, as they are obligatory for the development of new transmissible stages. Consequently, the sexual stages represent attractive targets for vaccination. Detailed understanding of apicomplexan sexual biology will pave the way for the design and implementation of effective transmission-blocking strategies for parasite control. This article reviews the current knowledge on the sexual development of Apicomplexa and the progress in transmission-blocking vaccines for their control, their advantages and limitations and outstanding questions for the future.
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Wakeman KC, Hiruta S, Kondo Y, Ohtsuka S. Evidence for Host Jumping and Diversification of Marine Cephaloidophorid Gregarines (Apicomplexa) Between Two Distantly Related Animals, viz., Crustaceans and Salps. Protist 2021; 172:125822. [PMID: 34521034 DOI: 10.1016/j.protis.2021.125822] [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: 11/15/2020] [Revised: 06/04/2021] [Accepted: 06/15/2021] [Indexed: 11/18/2022]
Abstract
This study examined the evolutionary history and diversity of marine gregarine parasites of pelagic zooplankton, and highlighted a unique example of a host-jumping event of cephaloidophorid gregarines between two distantly related host groups, crustaceans and chordates. Candacia bipinnata Giesbrecht, 1889, a free-living calanoid copepod, and a salp, Salpa fusiformis Cuvier, 1804, were collected on oceanic research cruises in 2018 and 2019, in the West Pacific aboard TRV SEISUI MARU and TOYOSHIO MARU, respectively. A molecular phylogeny based on 18S rDNA nested the gregarine parasite from S. fusiformis among cephaloidophorids, within a clade exclusively comprised of gregarines from crustaceans. The relationship between these groups was underpinned with ultrastructural data including the presence of a septum, and similarities in the apices of the epicytic folds. Subsequently, it was concluded to establish a new combination, Cephaloidophora cf. flava n. comb (Ex. Thalicola flava) and transfer the other two members of the Thalicola (also parasites of salps) to the Cephaloidophora. This study also attempted to ascertain the origin of cephaloidophorids in S. fusiformis. However, the relationship between Cephaloidophora bipinnatae n. sp., and C. cf. flava n. comb. had only modest support.
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Affiliation(s)
- Kevin C Wakeman
- Institute for the Advancement of High Education, Hokkaido University, Japan.
| | - Shimpei Hiruta
- Center for Molecular Biodiversity Research, National Museum of Nature and Science, Amakubo 4-1-1, Tsukuba, Ibaraki 305-0005, Japan
| | - Yusuke Kondo
- Takehara Station, Setouchi Field Science Center, Graduate School of Integrated Sciences for Life, Hiroshima University, 5-8-1 Minato-machi, Takehara, Hiroshima 725-0024, Japan
| | - Susumu Ohtsuka
- Takehara Station, Setouchi Field Science Center, Graduate School of Integrated Sciences for Life, Hiroshima University, 5-8-1 Minato-machi, Takehara, Hiroshima 725-0024, Japan
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15
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Progression of asexual to sexual stages of Cystoisospora suis in a host cell-free environment as a model for Coccidia. Parasitology 2021; 148:1475-1481. [PMID: 34193323 PMCID: PMC8426156 DOI: 10.1017/s0031182021001074] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Abstract
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16
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Chawla J, Oberstaller J, Adams JH. Targeting Gametocytes of the Malaria Parasite Plasmodium falciparum in a Functional Genomics Era: Next Steps. Pathogens 2021; 10:346. [PMID: 33809464 PMCID: PMC7999360 DOI: 10.3390/pathogens10030346] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 02/25/2021] [Accepted: 03/03/2021] [Indexed: 02/04/2023] Open
Abstract
Mosquito transmission of the deadly malaria parasite Plasmodium falciparum is mediated by mature sexual forms (gametocytes). Circulating in the vertebrate host, relatively few intraerythrocytic gametocytes are picked up during a bloodmeal to continue sexual development in the mosquito vector. Human-to-vector transmission thus represents an infection bottleneck in the parasite's life cycle for therapeutic interventions to prevent malaria. Even though recent progress has been made in the identification of genetic factors linked to gametocytogenesis, a plethora of genes essential for sexual-stage development are yet to be unraveled. In this review, we revisit P. falciparum transmission biology by discussing targetable features of gametocytes and provide a perspective on a forward-genetic approach for identification of novel transmission-blocking candidates in the future.
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Affiliation(s)
- Jyotsna Chawla
- Molecular Medicine, Morsani College of Medicine, University of South Florida, 12901 Bruce B Downs Blvd, MDC 7, Tampa, FL 33612, USA;
| | - Jenna Oberstaller
- Center for Global Health and Infectious Diseases Research and USF Genomics Program, College of Public Health, University of South Florida, 3720 Spectrum Blvd, Suite 404, Tampa, FL 33612, USA;
| | - John H. Adams
- Center for Global Health and Infectious Diseases Research and USF Genomics Program, College of Public Health, University of South Florida, 3720 Spectrum Blvd, Suite 404, Tampa, FL 33612, USA;
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Martorelli Di Genova B, Knoll LJ. Comparisons of the Sexual Cycles for the Coccidian Parasites Eimeria and Toxoplasma. Front Cell Infect Microbiol 2020; 10:604897. [PMID: 33381466 PMCID: PMC7768002 DOI: 10.3389/fcimb.2020.604897] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 11/12/2020] [Indexed: 12/11/2022] Open
Abstract
Toxoplasma gondii and Eimeria spp. are widely prevalent Coccidian parasites that undergo sexual reproduction during their life cycle. T. gondii can infect any warm-blooded animal in its asexual cycle; however, its sexual cycle is restricted to felines. Eimeria spp. are usually restricted to one host species, and their whole life cycle is completed within this same host. The literature reviewed in this article comprises the recent findings regarding the unique biology of the sexual development of T. gondii and Eimeria spp. The molecular basis of sex in these pathogens has been significantly unraveled by new findings in parasite differentiation along with transcriptional analysis of T. gondii and Eimeria spp. pre-sexual and sexual stages. Focusing on the metabolic networks, analysis of these transcriptome datasets shows enrichment for several different metabolic pathways. Transcripts for glycolysis enzymes are consistently more abundant in T. gondii cat infection stages than the asexual tachyzoite stage and Eimeria spp. merozoite and gamete stages compared to sporozoites. Recent breakthroughs in host-pathogen interaction and host restriction have significantly expanded the understating of the unique biology of these pathogens. This review aims to critically explore advances in the sexual cycle of Coccidia parasites with the ultimate goal of comparing and analyzing the sexual cycle of Eimeria spp. and T. gondii.
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Affiliation(s)
| | - Laura J. Knoll
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI, United States
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18
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Feix AS, Cruz-Bustos T, Ruttkowski B, Joachim A. Characterization of Cystoisospora suis sexual stages in vitro. Parasit Vectors 2020; 13:143. [PMID: 32188507 PMCID: PMC7079422 DOI: 10.1186/s13071-020-04014-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 03/10/2020] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND The porcine coccidium Cystoisospora suis is characterized by a complex life-cycle during which asexual multiplication is followed by sexual development with two morphologically distinct cell types, the micro- and macrogametes. Genes related to the sexual stages and cell cycle progression were previously identified in related Apicomplexa. Dynein light chain type 1 and male gamete fusion factor HAP2 are restricted to microgametes. Tyrosine-rich proteins and oocyst wall proteins are a part of the oocyst wall. The Rad51/Dmc1-like protein and Nima-related protein kinases are associated with the cell cycle and fertilization process. Here, the sexual stages of C. suis were characterized in vitro morphologically and for temporal expression changes of the mentioned genes to gain insight into this poorly known phase of coccidian development. METHODS Sexual stages of C. suis developing in vitro in porcine intestinal epithelial cells were examined by light and electron microscopy. The transcriptional levels of genes related to merozoite multiplication and sexual development were evaluated by quantitative real-time PCR at different time points of cultivation. Transcription levels were compared for parasites in culture supernatants at 6-9 days of cultivation (doc) and intracellular parasites at 6-15 doc. RESULTS Sexual stage of C. suis was detected during 8-11 doc in vitro. Microgamonts (16.8 ± 0.9 µm) and macrogamonts (16.6 ± 1.1 µm) are very similar in shape and size. Microgametes had a round body (3.5 ± 0.5 µm) and two flagella (11.2 ± 0.5 µm). Macrogametes were spherical with a diameter of 12.1 ± 0.5 µm. Merozoite gene transcription peaked on 10 doc and then declined. Genes related to the sexual stages and cell cycle showed an upregulation with a peak on 13 doc, after which they declined. CONCLUSIONS The present study linked gene expression changes to the detailed morphological description of C. suis sexual development in vitro, including fertilization, meiosis and oocyst formation in this unique model for coccidian parasites. Following this process at the cellular and molecular level will elucidate details on potential bottlenecks of C. suis development (applicable for coccidian parasites in general) which could be exploited as a novel target for control.
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Affiliation(s)
- Anna Sophia Feix
- Institute for Parasitology, Department of Pathobiology, University of Veterinary Medicine Vienna, Veterinaerplatz 1, Vienna, 1210 Austria
| | - Teresa Cruz-Bustos
- Institute for Parasitology, Department of Pathobiology, University of Veterinary Medicine Vienna, Veterinaerplatz 1, Vienna, 1210 Austria
| | - Bärbel Ruttkowski
- Institute for Parasitology, Department of Pathobiology, University of Veterinary Medicine Vienna, Veterinaerplatz 1, Vienna, 1210 Austria
| | - Anja Joachim
- Institute for Parasitology, Department of Pathobiology, University of Veterinary Medicine Vienna, Veterinaerplatz 1, Vienna, 1210 Austria
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19
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Su S, Hou Z, Wang L, Liu D, Hu J, Xu J, Tao J. Further confirmation of second- and third-generation Eimeria necatrix merozoite DEGs using suppression subtractive hybridization. Parasitol Res 2019; 118:1159-1169. [PMID: 30747293 DOI: 10.1007/s00436-019-06242-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2018] [Accepted: 01/31/2019] [Indexed: 11/28/2022]
Abstract
In our previous study, we obtained a large number of differentially expressed genes (DEGs) between second-generation merozoites (MZ-2) and third-generation merozoites (MZ-3) of Eimeria necatrix using RNA sequencing (RNA-seq). Here, we report two subtractive cDNA libraries for MZ2 (forward library) and MZ3 (reverse library) that were constructed using suppression subtractive hybridization (SSH). PCR amplification revealed that the MZ2 and MZ3 libraries contained approximately 96.7% and 95% recombinant clones, respectively, and the length of the inserted fragments ranged from 0.5 to 1.5 kb. A total of 106 and 111 unique sequences were obtained from the MZ2 and MZ3 libraries, respectively, and were assembled into 13 specific consensus sequences (contigs or genes) (5 from MZ2 and 8 from MZ3). The qRT-PCR results revealed that 11 out of 13 genes were differentially expressed between MZ-2 and MZ-3. Of 13 genes, 11 genes were found in both SSH and our RNA-seq data and displayed a similar expression trend between SSH and RNA-seq data, and the remaining 2 genes have not been reported in both E. necatrix genome and our RNA-seq data. Among the 11 genes, the expression trends of 8 genes were highly consistent between SSH and our RNA-seq data. These DEGs may provide specialized functions related to the life-cycle transitions of Eimeria species.
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Affiliation(s)
- Shijie Su
- College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, People's Republic of China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, 225009, People's Republic of China.,Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, 225009, People's Republic of China.,Joint International Research Laboratory of Agriculture and Agri-Product Safety, the Ministry of Education of China, Yangzhou University, Yangzhou, 225009, People's Republic of China
| | - Zhaofeng Hou
- College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, People's Republic of China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, 225009, People's Republic of China.,Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, 225009, People's Republic of China.,Joint International Research Laboratory of Agriculture and Agri-Product Safety, the Ministry of Education of China, Yangzhou University, Yangzhou, 225009, People's Republic of China
| | - Lele Wang
- College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, People's Republic of China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, 225009, People's Republic of China.,Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, 225009, People's Republic of China.,Joint International Research Laboratory of Agriculture and Agri-Product Safety, the Ministry of Education of China, Yangzhou University, Yangzhou, 225009, People's Republic of China
| | - Dandan Liu
- College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, People's Republic of China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, 225009, People's Republic of China.,Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, 225009, People's Republic of China.,Joint International Research Laboratory of Agriculture and Agri-Product Safety, the Ministry of Education of China, Yangzhou University, Yangzhou, 225009, People's Republic of China
| | - Junjie Hu
- Biology Department, Yunnan University, Kunming, 650500, People's Republic of China
| | - Jinjun Xu
- College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, People's Republic of China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, 225009, People's Republic of China.,Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, 225009, People's Republic of China.,Joint International Research Laboratory of Agriculture and Agri-Product Safety, the Ministry of Education of China, Yangzhou University, Yangzhou, 225009, People's Republic of China
| | - Jianping Tao
- College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, People's Republic of China. .,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, 225009, People's Republic of China. .,Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, 225009, People's Republic of China. .,Joint International Research Laboratory of Agriculture and Agri-Product Safety, the Ministry of Education of China, Yangzhou University, Yangzhou, 225009, People's Republic of China.
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20
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Tadesse FG, Meerstein-Kessel L, Gonçalves BP, Drakeley C, Ranford-Cartwright L, Bousema T. Gametocyte Sex Ratio: The Key to Understanding Plasmodium falciparum Transmission? Trends Parasitol 2018; 35:226-238. [PMID: 30594415 PMCID: PMC6396025 DOI: 10.1016/j.pt.2018.12.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 11/30/2018] [Accepted: 12/03/2018] [Indexed: 11/25/2022]
Abstract
A mosquito needs to ingest at least one male and one female gametocyte to become infected with malaria. The sex of Plasmodium falciparum gametocytes can be determined microscopically but recent transcriptomics studies paved the way for the development of molecular methods that allow sex-ratio assessments at much lower gametocyte densities. These sex-specific gametocyte diagnostics were recently used to examine gametocyte dynamics in controlled and natural infections as well as the impact of different antimalarial drugs. It is currently unclear to what extent sex-specific gametocyte diagnostics obviate the need for mosquito feeding assays to formally assess transmission potential. Here, we review recent and historic assessments of gametocyte sex ratio in relation to host and parasite characteristics, treatment, and transmission potential. Recent RNA sequencing studies have uncovered a number of P. falciparum gametocyte sex-specific targets and provided new insights in gametocyte biology. After decades when gametocyte sex-ratio research was restricted to nonhuman malarias or in vitro experiments, molecular tools for assessing gametocyte sex ratio are now increasingly available for use in natural P. falciparum infections. Evidence that gametocyte sex ratio is influenced by total gametocyte density and antimalarial treatment, and improves predictions of transmission potential, highlight the relevance of understanding the gametocyte sex ratio during natural infections. The finding that the most widely used P. falciparum gametocyte marker Pfs25 is expressed predominantly by female gametocytes and has non-negligible levels of background expression in asexual parasites necessitates a re-evaluation of existing gametocyte data.
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Affiliation(s)
- Fitsum G Tadesse
- Radboud Institute for Health Sciences, Radboud University Medical Centre, Nijmegen, The Netherlands; Armauer Hansen Research Institute (AHRI), Addis Ababa, Ethiopia; Institute of Biotechnology, Addis Ababa University, Addis Ababa, Ethiopia; These authors contributed equally
| | - Lisette Meerstein-Kessel
- Radboud Institute for Health Sciences, Radboud University Medical Centre, Nijmegen, The Netherlands; These authors contributed equally
| | - Bronner P Gonçalves
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
| | - Chris Drakeley
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
| | - Lisa Ranford-Cartwright
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Teun Bousema
- Radboud Institute for Health Sciences, Radboud University Medical Centre, Nijmegen, The Netherlands; Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK.
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21
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Josling GA, Williamson KC, Llinás M. Regulation of Sexual Commitment and Gametocytogenesis in Malaria Parasites. Annu Rev Microbiol 2018; 72:501-519. [PMID: 29975590 DOI: 10.1146/annurev-micro-090817-062712] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Sexual differentiation of malaria parasites from the asexual blood stage into gametocytes is an essential part of the life cycle, as gametocytes are the form that is taken up by the mosquito host. Because of the essentiality of this process for transmission to the mosquito, gametocytogenesis is an extremely attractive target for therapeutic interventions. The subject of this review is the considerable progress that has been made in recent years in elucidating the molecular mechanisms governing this important differentiation process. In particular, a number of critical transcription factors and epigenetic regulators have emerged as crucial elements in the regulation of commitment. The identification of these factors has allowed us to understand better than ever before the events occurring prior to and during commitment to sexual development and offers potential for new therapeutic interventions.
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Affiliation(s)
- Gabrielle A Josling
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania 16802, USA; .,Huck Center for Malaria Research, Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Kim C Williamson
- Microbiology and Immunology Department, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814, USA
| | - Manuel Llinás
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania 16802, USA; .,Huck Center for Malaria Research, Pennsylvania State University, University Park, Pennsylvania 16802, USA.,Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802, USA
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22
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Su S, Hou Z, Liu D, Jia C, Wang L, Xu J, Tao J. Comparative transcriptome analysis of Eimeria necatrix third-generation merozoites and gametocytes reveals genes involved in sexual differentiation and gametocyte development. Vet Parasitol 2018; 252:35-46. [PMID: 29559148 DOI: 10.1016/j.vetpar.2018.01.019] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 01/20/2018] [Accepted: 01/22/2018] [Indexed: 11/17/2022]
Abstract
Eimeria necatrix is one of the most pathogenic parasites causing high mortality in chicken older than 8 weeks. Eimeria spp. possess a coccidian lifecycle including both sexual and asexual stages. Sexual differentiation and development occupies a central place in the life cycle of the Eimeria parasite. However, our knowledge of the sexual differentiation and gametocyte development of Eimeria is very limited. Here using RNA sequencing, we conducted a comparative transcriptome analysis between third-generation merozoites (MZ-3) and gametocytes (GAM) of E. necatrix to identify genes with functions related to sexual differentiation and gametocyte development. Approximately 4267 genes were differentially expressed between MZ-3 and GAM. Compared with MZ-3, 2789 genes were upregulated and 1478 genes were downregulated in GAM. Approximately 329 genes in MZ-3 and 1289 genes in GAM were further analyzed in the evaluation of stage-specific genes. Gene Ontology (GO) classification and KEGG analysis revealed that 953 upregulated gametocyte genes were annotated with 170 GO assignments, and 405 upregulated genes were associated with 231 signaling pathways. We also predicted a further 83 upregulated gametocyte genes, of which 53 were involved in the biosynthesis of the oocyst wall, and 30 were involved in microgametocyte development. This information offers insights into the mechanisms governing the sexual development of E. necatrix and may potentially allow the identification of targets for blocking parasite transmission.
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Affiliation(s)
- Shijie Su
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou 225009, China; Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou 225009, China
| | - Zhaofeng Hou
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou 225009, China; Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou 225009, China
| | - Dandan Liu
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou 225009, China; Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou 225009, China
| | - Chuanli Jia
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou 225009, China; Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou 225009, China
| | - Lele Wang
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou 225009, China; Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou 225009, China
| | - Jinjun Xu
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou 225009, China; Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou 225009, China
| | - Jianping Tao
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou 225009, China; Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou 225009, China.
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Suarez CE, Bishop RP, Alzan HF, Poole WA, Cooke BM. Advances in the application of genetic manipulation methods to apicomplexan parasites. Int J Parasitol 2017; 47:701-710. [PMID: 28893636 DOI: 10.1016/j.ijpara.2017.08.002] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2017] [Revised: 08/24/2017] [Accepted: 08/24/2017] [Indexed: 12/13/2022]
Abstract
Apicomplexan parasites such as Babesia, Theileria, Eimeria, Cryptosporidium and Toxoplasma greatly impact animal health globally, and improved, cost-effective measures to control them are urgently required. These parasites have complex multi-stage life cycles including obligate intracellular stages. Major gaps in our understanding of the biology of these relatively poorly characterised parasites and the diseases they cause severely limit options for designing novel control methods. Here we review potentially important shared aspects of the biology of these parasites, such as cell invasion, host cell modification, and asexual and sexual reproduction, and explore the potential of the application of relatively well-established or newly emerging genetic manipulation methods, such as classical transfection or gene editing, respectively, for closing important gaps in our knowledge of the function of specific genes and proteins, and the biology of these parasites. In addition, genetic manipulation methods impact the development of novel methods of control of the diseases caused by these economically important parasites. Transient and stable transfection methods, in conjunction with whole and deep genome sequencing, were initially instrumental in improving our understanding of the molecular biology of apicomplexan parasites and paved the way for the application of the more recently developed gene editing methods. The increasingly efficient and more recently developed gene editing methods, in particular those based on the CRISPR/Cas9 system and previous conceptually similar techniques, are already contributing to additional gene function discovery using reverse genetics and related approaches. However, gene editing methods are only possible due to the increasing availability of in vitro culture, transfection, and genome sequencing and analysis techniques. We envisage that rapid progress in the development of novel gene editing techniques applied to apicomplexan parasites of veterinary interest will ultimately lead to the development of novel and more efficient methods for disease control.
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Affiliation(s)
- C E Suarez
- Animal Disease Research Unit, USDA-ARS, Washington State University, 3003 ADBF, P.O. Box 646630, Pullman, WA 99164, USA; Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WA 99164, USA.
| | - R P Bishop
- Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WA 99164, USA; The Paul G. Allen School for Global Animal Health, Washington State University, Pullman, WA, USA
| | - H F Alzan
- Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WA 99164, USA; Parasitology and Animal Diseases Department, National Research Center, Dokki, Giza, Egypt
| | - W A Poole
- Biomedicine Discovery Institute and Department of Microbiology, Monash University, Victoria 3800, Australia
| | - B M Cooke
- Biomedicine Discovery Institute and Department of Microbiology, Monash University, Victoria 3800, Australia.
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Ren B, Gupta N. Taming Parasites by Tailoring Them. Front Cell Infect Microbiol 2017; 7:292. [PMID: 28730142 PMCID: PMC5498469 DOI: 10.3389/fcimb.2017.00292] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Accepted: 06/14/2017] [Indexed: 12/17/2022] Open
Abstract
The next-generation gene editing based on CRISPR (clustered regularly interspaced short palindromic repeats) has been successfully implemented in a wide range of organisms including some protozoan parasites. However, application of such a versatile game-changing technology in molecular parasitology remains fairly underexplored. Here, we briefly introduce state-of-the-art in human and mouse research and usher new directions to drive the parasitology research in the years to come. In precise, we outline contemporary ways to embolden existing apicomplexan and kinetoplastid parasite models by commissioning front-line gene-tailoring methods, and illustrate how we can break the enduring gridlock of gene manipulation in non-model parasitic protists to tackle intriguing questions that remain long unresolved otherwise. We show how a judicious solicitation of the CRISPR technology can eventually balance out the two facets of pathogen-host interplay.
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Affiliation(s)
- Bingjian Ren
- Faculty of Life Sciences, Institute of Biology, Humboldt UniversityBerlin, Germany
| | - Nishith Gupta
- Faculty of Life Sciences, Institute of Biology, Humboldt UniversityBerlin, Germany
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Jalovecka M, Bonsergent C, Hajdusek O, Kopacek P, Malandrin L. Stimulation and quantification of Babesia divergens gametocytogenesis. Parasit Vectors 2016; 9:439. [PMID: 27502772 PMCID: PMC4977898 DOI: 10.1186/s13071-016-1731-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 07/27/2016] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Babesia divergens is the most common blood parasite in Europe causing babesiosis, a tick-borne malaria-like disease. Despite an increasing focus on B. divergens, especially regarding veterinary and human medicine, the sexual development of Babesia is poorly understood. Development of Babesia sexual stages in the host blood (gametocytes) plays a decisive role in parasite acquisition by the tick vector. However, the exact mechanism of gametocytogenesis is still unexplained. METHODS Babesia divergens gametocytes are characterized by expression of bdccp1, bdccp2 and bdccp3 genes. Using previously described sequences of bdccp1, bdccp2 and bdccp3, we have established a quantitative real-time PCR (qRT-PCR) assay for detection and assessment of the efficiency of B. divergens gametocytes production in bovine blood. We analysed fluctuations in expression of bdccp genes during cultivation in vitro, as well as in cultures treated with different drugs and stimuli. RESULTS We demonstrated that all B. divergens clonal lines tested, originally derived from naturally infected cows, exhibited sexual stages. Furthermore, sexual commitment was stimulated during continuous growth of the cultures, by addition of specific stress-inducing drugs or by alternating cultivation conditions. Expression of bdccp genes was greatly reduced or even lost after long-term cultivation, suggesting possible problems in the artificial infections of ticks in feeding assays in vitro. CONCLUSIONS Our research provides insight into sexual development of B. divergens and may facilitate the development of transmission models in vitro, enabling a more detailed understanding of Babesia-tick interactions.
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Affiliation(s)
- Marie Jalovecka
- INRA, UMR1300 Biology, Epidemiology and Risk Analysis in Animal Health, CS 40706, F-44307, Nantes, France. .,LUNAM University, Nantes-Atlantic College of Veterinary Medicine and Food Sciences and Engineering, UMR BioEpAR, F-44307, Nantes, France. .,Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, CZ-370 05, Ceske Budejovice, Czech Republic. .,Faculty of Science, University of South Bohemia, CZ-370 05, Ceske Budejovice, Czech Republic.
| | - Claire Bonsergent
- INRA, UMR1300 Biology, Epidemiology and Risk Analysis in Animal Health, CS 40706, F-44307, Nantes, France.,LUNAM University, Nantes-Atlantic College of Veterinary Medicine and Food Sciences and Engineering, UMR BioEpAR, F-44307, Nantes, France
| | - Ondrej Hajdusek
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, CZ-370 05, Ceske Budejovice, Czech Republic
| | - Petr Kopacek
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, CZ-370 05, Ceske Budejovice, Czech Republic
| | - Laurence Malandrin
- INRA, UMR1300 Biology, Epidemiology and Risk Analysis in Animal Health, CS 40706, F-44307, Nantes, France.,LUNAM University, Nantes-Atlantic College of Veterinary Medicine and Food Sciences and Engineering, UMR BioEpAR, F-44307, Nantes, France
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26
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Greischar MA, Mideo N, Read AF, Bjørnstad ON. Predicting optimal transmission investment in malaria parasites. Evolution 2016; 70:1542-58. [DOI: 10.1111/evo.12969] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Accepted: 05/07/2016] [Indexed: 01/07/2023]
Affiliation(s)
- Megan A. Greischar
- Center For Infectious Disease Dynamics, Departments of Entomology and Biology, The Pennsylvania State University; University Park; Pennsylvania 16802
- Department of Ecology and Evolutionary Biology; University of Toronto; Toronto ON M5S 3B2 Canada
| | - Nicole Mideo
- Department of Ecology and Evolutionary Biology; University of Toronto; Toronto ON M5S 3B2 Canada
| | - Andrew F. Read
- Center For Infectious Disease Dynamics, Departments of Entomology and Biology, The Pennsylvania State University; University Park; Pennsylvania 16802
- Fogarty International Center; National Institutes of Health; Bethesda Maryland 20892
| | - Ottar N. Bjørnstad
- Center For Infectious Disease Dynamics, Departments of Entomology and Biology, The Pennsylvania State University; University Park; Pennsylvania 16802
- Fogarty International Center; National Institutes of Health; Bethesda Maryland 20892
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Abstract
Mathematical modelling provides an effective way to challenge conventional wisdom about
parasite evolution and investigate why parasites ‘do what they do’ within the host. Models
can reveal when intuition cannot explain observed patterns, when more complicated biology
must be considered, and when experimental and statistical methods are likely to mislead.
We describe how models of within-host infection dynamics can refine experimental design,
and focus on the case study of malaria to highlight how integration between models and
data can guide understanding of parasite fitness in three areas: (1) the adaptive
significance of chronic infections; (2) the potential for tradeoffs between virulence and
transmission; and (3) the implications of within-vector dynamics. We emphasize that models
are often useful when they highlight unexpected patterns in parasite evolution, revealing
instead why intuition yields the wrong answer and what combination of theory and data are
needed to advance understanding.
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MARÍN JOHNALEXANDERLEÓN, GANDICA IRENEDUARTE. A MATHEMATICAL MODEL FOR THE REPRODUCTION DYNAMICS OF TOXOPLASMA GONDII. J BIOL SYST 2015. [DOI: 10.1142/s0218339015400082] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
This paper presents a mathematical model describing the reproduction dynamics of the Toxoplasma gondii parasite in the definitive host Felis catus (cat). The dynamics is described by a system of partial differential equations defined in a one-dimensional region, with boundary and initial conditions. The model considers both asexual and sexual reproduction processes of the T. gondii parasite starting from the consumption of T. gondii oocysts from the environment, by the definitive host, and describing the reproduction dynamics until the cat expels infectious oocysts to the environment through its feces. The numerical solution of the system is obtained, and some simulations are made, leaving constant of transition and loss rates, since its variation does not produce significant changes in the reproduction, propagation and creation of new populations; and varying the initial consumption of oocysts from the environment by the cat. It is concluded that, either low or high, the involved populations are always reproduced; they spread by all over epithelial cells and subsequently are expelled to the environment through the cat feces. It is corroborated that the cats are potential multipliers of the oocysts and therefore, the main disseminators of the infection.
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Affiliation(s)
- JOHN ALEXANDER LEÓN MARÍN
- Escuela de Investigación en Biomatemática, Universidad del Quindío, Cra. 15 Calle 12 Norte, Armenia, Quindío, Colombia
| | - IRENE DUARTE GANDICA
- Escuela de Investigación en Biomatemática, Universidad del Quindío, Cra. 15 Calle 12 Norte, Armenia, Quindío, Colombia
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Alano P. The sound of sexual commitment breaks the silencing of malaria parasites. Trends Parasitol 2014; 30:509-10. [PMID: 25261923 DOI: 10.1016/j.pt.2014.09.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Accepted: 09/15/2014] [Indexed: 10/24/2022]
Abstract
A fundamental binary decision is made by malaria parasites at every asexual cycle in the blood between further proliferation and differentiation into gametocytes, the mosquito transmissible stages. Recent studies on Plasmodium epigenetic regulation, transcriptional control and genetic basis of gametocyte production are merging today to unveil players and propose molecular mechanisms of this key branch point in the malaria parasite life cycle.
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Affiliation(s)
- Pietro Alano
- Dipartimento di Malattie Infettive, Parassitarie ed Immunomediate, Istituto Superiore di Sanità, viale Regina Elena n.299, 00161 Rome, Italy.
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30
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Netherlands EC, Cook CA, Smit NJ, du Preez LH. Redescription and molecular diagnosis of Hepatozoon theileri (Laveran, 1905) (Apicomplexa: Adeleorina: Hepatozoidae), infecting Amietia quecketti (Anura: Pyxicephalidae). Folia Parasitol (Praha) 2014. [DOI: 10.14411/fp.2014.046] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Ankarklev J, Brancucci N, Goldowitz I, Mantel PY, Marti M. Sex: How Malaria Parasites Get Turned On. Curr Biol 2014; 24:R368-70. [DOI: 10.1016/j.cub.2014.03.046] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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32
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Carter LM, Schneider P, Reece SE. Information use and plasticity in the reproductive decisions of malaria parasites. Malar J 2014; 13:115. [PMID: 24670151 PMCID: PMC3986881 DOI: 10.1186/1475-2875-13-115] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2013] [Accepted: 03/23/2014] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND Investment in the production of transmissible stages (gametocytes) and their sex ratio are malaria parasite traits that underpin mosquito infectivity and are therefore central to epidemiology. Malaria parasites adjust their levels of investment into gametocytes and sex ratio in response to changes in the in-host environment (including red blood cell resource availability, host immune responses, competition from con-specific genotypes in mixed infections, and drug treatment). This plasticity appears to be adaptive (strategic) because parasites prioritize investment (in sexual versus asexual stages and male versus female stages) in manners predicted to maximize fitness. However, the information, or 'cues' that parasites use to detect environmental changes and make appropriate decisions about investment into gametocytes and their sex ratio are unknown. METHODS Single genotype Plasmodium chabaudi infections were exposed to 'cue' treatments consisting of intact or lysed uninfected red blood cells, lysed parasitized RBCs of the same clone or an unrelated clone, and an unmanipulated control. Infection dynamics (proportion of reticulocytes, red blood cell and asexual stage parasite densities) were monitored, and changes in gametocyte investment and sex ratio in response to cue treatments, applied either pre- or post-peak of infection were examined. RESULTS AND CONCLUSIONS A significant reduction in gametocyte density was observed in response to the presence of lysed parasite material and a borderline significant increase in sex ratio (proportion of male gametocytes) upon exposure to lysed red blood cells (both uninfected and infected) was observed. Furthermore, the changes in gametocyte density and sex ratio in response to these cues depend on the age of infection. Demonstrating that variation in gametocyte investment and sex ratio observed during infections are a result of parasite strategies (rather than the footprint of host physiology), provides a foundation to investigate the fitness consequences of plasticity and explore whether drugs could be developed to trick parasites into making suboptimal decisions.
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Affiliation(s)
- Lucy M Carter
- Institute of Evolutionary Biology, School of Biological Sciences, Ashworth Laboratories, University of Edinburgh, Edinburgh, UK
| | - Petra Schneider
- Institute of Evolutionary Biology, School of Biological Sciences, Ashworth Laboratories, University of Edinburgh, Edinburgh, UK
| | - Sarah E Reece
- Institute of Evolutionary Biology, School of Biological Sciences, Ashworth Laboratories, University of Edinburgh, Edinburgh, UK
- Centre for Immunity, Infection & Evolution, Institutes of Evolution, Immunology and Infection Research, School of Biological Sciences, Ashworth Laboratories, University of Edinburgh, Edinburgh, UK
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Phadke SS, Paixão T, Pham T, Pham S, Zufall RA. Genetic background alters dominance relationships between mat alleles in the ciliate Tetrahymena thermophila. J Hered 2013; 105:130-5. [PMID: 24190504 DOI: 10.1093/jhered/est063] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The pattern of inheritance and mechanism of sex determination can have important evolutionary consequences. We studied probabilistic sex determination in the ciliate Tetrahymena thermophila, which was previously shown to cause evolution of skewed sex ratios. We find that the genetic background alters the sex determination patterns of mat alleles in heterozygotes and that allelic interaction can differentially influence the expression probability of the 7 sexes. We quantify the dominance relationships between several mat alleles and find that A-type alleles, which specify sex I, are indeed recessive to B-type alleles, which are unable to specify that sex. Our results provide additional support for the presence of modifier loci and raise implications for the dynamics of sex ratios in populations of T. thermophila.
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Affiliation(s)
- Sujal S Phadke
- the Department of Biology and Biochemistry, University of Houston, Houston, TX 77204. Sujal S. Phadke is now at the Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109. Tiago Paixão is now at the Institute of Science and Technology Austria
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Abstract
SUMMARYEimeriais a common genus of apicomplexan parasites that infect diverse vertebrates, most notably poultry, causing serious disease and economic loss. Like all apicomplexans, eimerians have a complex life cycle characterized by asexual divisions that amplify the parasite population in preparation for sexual reproduction. This can be divided into three events: gametocytogenesis, producing gametocytes from merozoites; gametogenesis, producing microgametes and macrogametes from gametocytes; and fertilization of macrogametes by microgametes, producing diploid zygotes with ensuing meiosis completing the sexual phase. Sexual development inEimeriadepends on the differential expression of stage-specific genes, rather than presence or absence of sex chromosomes. Thus, it involves the generation of specific structures and, implicitly, storage of proteins and regulation of protein expression in macrogametes, in preparation for fertilization. InEimeria, the formation of a unique, resilient structure, the oocyst wall, is essential for completion of the sexual phase and parasite transmission. In this review, we piece together the molecular events that underpin sexual reproduction inEimeriaand use additional details from analogous events inPlasmodiumto fill current knowledge gaps. The mechanisms governing sexual stage formation and subsequent fertilization may represent targets for counteracting parasite transmission.
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Trites M, Ferguson L, Ogbuah C, Dickson C, Smith T. Factors determining the in vitro emergence of sexual stages of Hepatozoon clamatae from erythrocytes of the Green Frog (Rana clamitans). CAN J ZOOL 2013. [DOI: 10.1139/cjz-2012-0241] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Sexual reproduction of apicomplexan parasites in haematophagous arthropods requires that intracellular sexual stages of these protozoa escape vertebrate erythrocytes in the blood meal. Although cues that signal sexual stages of the human malaria parasite (Plasmodium falciparum Welch, 1897) to emerge from erythrocytes are well documented, such signals are poorly known for other blood-dwelling Apicomplexa. The objective of this comparative study was to investigate conditions required to induce in vitro emergence of sexual stages of Hepatozoon clamatae (Stebbins, 1905) from frog erythrocytes. Blood was drawn from Green Frogs (Rana clamitans Latreille in Sonnini de Manoncourt and Latreille, 1801 = Lithobates clamitans clamitans (Latreille in Sonnini de Manoncourt and Latreille, 1801)) infected with H. clamatae and treated with solutions of various concentrations of saline, pH, and xanthurenic acid at different temperatures. Hypertonic saline solutions of 200 and 222 mmol/L at pH 7.4 and 7.7 elicited emergence of nearly 100% of gamonts from frog erythrocytes, but at pH 8.0 resulted in decreased emergence. Solutions containing 1, 10, and 100 μmol/L xanthurenic acid increased gamont emergence at saline concentrations of 156, 178, and 244 mmol/L, but decreased emergence at 200 and 222 mmol/L. Gamont emergence increased as incubation temperatures increased from 18 to 26 °C. These results suggest that conditions necessary for emergence of sexual stages of bloodstream Apicomplexa from erythrocytes vary among genera.
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Affiliation(s)
- M.J. Trites
- Department of Biology, Acadia University, Wolfville, NS B4P 2R6, Canada
| | - L.V. Ferguson
- Department of Biology, University of Western Ontario, London, ON N6A 5B7, Canada
| | - C.T. Ogbuah
- Department of Biology, Acadia University, Wolfville, NS B4P 2R6, Canada
| | - C.M. Dickson
- Department of Biology, Acadia University, Wolfville, NS B4P 2R6, Canada
| | - T.G. Smith
- Department of Biology, Acadia University, Wolfville, NS B4P 2R6, Canada
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Becker CAM, Malandrin L, Larcher T, Chauvin A, Bischoff E, Bonnet SI. Validation of BdCCp2 as a marker for Babesia divergens sexual stages in ticks. Exp Parasitol 2012; 133:51-6. [PMID: 23103717 DOI: 10.1016/j.exppara.2012.10.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Revised: 10/09/2012] [Accepted: 10/12/2012] [Indexed: 11/15/2022]
Abstract
Babesiosis is a tick-transmitted disease of mammalian hosts, caused by the intraerythrocytic protozoan parasites of the genus Babesia. Transmission of Babesia parasites from the vertebrate host to the tick is mediated by sexual stages, the gametocytes which are the only intraerythrocytic stages that survive and develop inside the vector. Very few data are available concerning these parasite stages and some markers are needed in order to refine our knowledge of Babesia life cycle inside the tick and to permit the monitoring of parasite transmission from vertebrate to vector. We previously identified some potential markers of the Babesia divergens gametocytes using an in silico post-genomic approach based on sequence identity between the available genomes of Plasmodium and Babesia spp. Here, one of the identified proteins, BdCCp2, was validated as a marker of sexual stages of B. divergens, in infected ticks challenged with antisera directed against recombinant BdCCp2 protein. The BdCCp2 protein was detected by Western blot in some infected ticks, as a discrete band of approximately 171 kDa, while no signal was detected in the laboratory-reared non-infected tick. BdCCp2 was also detected, by immunohistochemical analyses, in piriform or ovoid bodies, measuring 2.5-4.5 μm in diameter, in the gut of partially engorged ticks that were experimentally infected. This molecular marker can then be used in the future to characterize and analyze the biology of B. divergens gametocytes.
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Comparison of protective immune responses to apicomplexan parasites. J Parasitol Res 2011; 2012:852591. [PMID: 21876783 PMCID: PMC3159010 DOI: 10.1155/2012/852591] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2011] [Accepted: 06/27/2011] [Indexed: 12/02/2022] Open
Abstract
Members of the phylum Apicomplexa, which includes the species Plasmodium, Eimeria, Toxoplasma, and Babesia amongst others, are the most successful intracellular pathogens known to humankind. The widespread acquisition of antimicrobial resistance to most drugs used to date has sparked a great deal of research and commercial interest in the development of vaccines as alternative control strategies. A few antigens from the asexual and sexual stages of apicomplexan development have been identified and their genes characterised; however, the fine cellular and molecular details of the effector mechanisms crucial for parasite inhibition and stimulation of protective immunity are still not entirely understood. This paper provides an overview of what is currently known about the protective immune response against the various types of apicomplexan parasites and focuses mainly on the similarities of these pathogens and their host interaction. Finally, the evolutionary relationships of these parasites and their hosts, as well as the modulation of immune functions that are critical in determining the outcome of the infection by these pathogenic organisms, are discussed.
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Becker C, Malandrin L, Depoix D, Larcher T, David P, Chauvin A, Bischoff E, Bonnet S. Identification of three CCp genes in Babesia divergens: Novel markers for sexual stages parasites. Mol Biochem Parasitol 2010; 174:36-43. [DOI: 10.1016/j.molbiopara.2010.06.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2010] [Revised: 05/25/2010] [Accepted: 06/25/2010] [Indexed: 10/19/2022]
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Teboh-Ewungkem MI, Yuster T. A within-vector mathematical model of Plasmodium falciparum and implications of incomplete fertilization on optimal gametocyte sex ratio. J Theor Biol 2010; 264:273-86. [PMID: 20122943 DOI: 10.1016/j.jtbi.2009.12.017] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2009] [Revised: 12/11/2009] [Accepted: 12/14/2009] [Indexed: 10/19/2022]
Abstract
A mathematical model that simulates the within-vector dynamics of Plasmodium falciparum in an Anopheles mosquito is developed, based on experimental data. The model takes a mosquito's blood meal as input and computes the salivary gland sporozoite load as the final output, a probable measure of mosquito infectivity. Computational model results are consistent with observed results in nature. Sensitivity analysis of the model parameters suggests that reducing the gametocyte density in the blood meal most significantly lowers sporozoite load in the salivary glands and hence mosquito infectivity, and is thus an attractive target for malaria control. The model is used to investigate the implication of incomplete fertilization on optimal gametocyte sex ratio. For a single strain, the transition from complete fertilization to increasingly incomplete fertilization shifts that ratio from 1 to N, where N is the number of viable male gametes produced by a single male gametocyte, towards 1 to 1, which is demonstrated to be the limiting ratio analytically. This ratio is then shown to be an evolutionarily stable strategy as well in the limiting case.
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Abstract
This article summarises the current knowledge of the rabbit coccidia and the disease they cause. Various aspects, such as life cycles, localisation in the host, pathology and pathogenicity, immunity and control, are discussed.
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Affiliation(s)
- Michal Pakandl
- Institute of Parasitology, Biology Centre of the Academy of Sciences of the Czech Republic, Ceské Budejovice, Czech Republic.
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Reece SE, Ramiro RS, Nussey DH. Plastic parasites: sophisticated strategies for survival and reproduction? Evol Appl 2009; 2:11-23. [PMID: 20305703 PMCID: PMC2836026 DOI: 10.1111/j.1752-4571.2008.00060.x] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2008] [Accepted: 11/26/2008] [Indexed: 11/28/2022] Open
Abstract
Adaptive phenotypic plasticity in life history traits, behaviours, and strategies is ubiquitous in biological systems. It is driven by variation in selection pressures across environmental gradients and operates under constraints imposed by trade-offs. Phenotypic plasticity has been thoroughly documented for multicellular taxa, such as insects, birds and mammals, and in many cases the underlying selective pressures are well understood. Whilst unicellular parasites face many of the same selective pressures and trade-offs, plasticity in their phenotypic traits has been largely overlooked and remains poorly understood. Here, we demonstrate that evolutionary theory, developed to explain variation observed in the life-history traits of multicellular organisms, can be applied to parasites. Though our message is general - we can expect the life-histories of all parasites to have evolved phenotypic plasticity - we focus our discussion on malaria parasites. We use an evolutionary framework to explain the trade-offs that parasites face and how plasticity in their life history traits will be expressed according to changes in their in-host environment. Testing whether variation in parasites traits is adaptive will provide new and fundamental insights into the basic biology of parasites, their epidemiology and the processes of disease during individual infections.
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Abstract
In unicellular and multicellular eukaryotes, fast cell motility and rapid movement of material over cell surfaces are often mediated by ciliary or flagellar beating. The conserved defining structure in most motile cilia and flagella is the '9+2' microtubule axoneme. Our general understanding of flagellum assembly and the regulation of flagellar motility has been led by results from seminal studies of flagellate protozoa and algae. Here we review recent work relating to various aspects of protist physiology and cell biology. In particular, we discuss energy metabolism in eukaryotic flagella, modifications to the canonical assembly pathway and flagellum function in parasite virulence.
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Abstract
Malaria is one of the leading causes of death among infectious diseases in the world, claiming over one million lives every year. By these standards, this highly complex parasite is extremely successful at generating new infections. Somewhat surprisingly, however, many malaria species seem to invest relatively little in gametocytes, converting only a small percentage of circulating asexual parasite forms into this transmissible form. In this article, we use mathematical models to explore three of the hypotheses that have been proposed to explain this apparent 'reproductive restraint' and develop a novel, fourth hypothesis. We find that only one of the previous three hypotheses we explore can explain such low gametocyte conversion rates, and this hypothesis involves a very specific form of density-dependent transmission-blocking immunity. Our fourth hypothesis also provides a potential explanation and is based on the occurrence of multiple infections and the resultant within-host competition between malaria strains that this entails. Further experimental work is needed to determine which of these two hypotheses provides the most likely explanation.
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Affiliation(s)
- Nicole Mideo
- Department of Biology, Queen's University, Kingston, ON, Canada.
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44
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Abstract
Sexual differentiation and parasite transmission are intimately linked in the life cycle of malaria parasites. The specialized cells providing this crucial link are the Plasmodium gametocytes. These are formed in the vertebrate host and are programmed to mature into gametes emerging from the erythrocytes in the midgut of a blood-feeding mosquito. The ensuing fusion into a zygote establishes parasite infection in the insect vector. Although key mechanisms of gametogenesis and fertilization are becoming progressively clear, the fundamental biology of gametocyte formation still presents open questions, some of which are specific to the human malaria parasite Plasmodium falciparum. Developmental commitment to sexual differentiation, regulation of stage-specific gene expression, the profound molecular and cellular changes accompanying gametocyte specialization, the requirement for tissue-specific sequestration in P. falciparum gametocytogenesis are proposed here as areas for future investigation. The epidemiological relevance of parasite transmission from humans to mosquito in the spread of malaria and of Plasmodium drug resistance genes indicates that understanding molecular mechanisms of gametocyte formation is highly relevant to design strategies able to interfere with the transmission of this disease.
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Affiliation(s)
- Pietro Alano
- Dipartimento di Malattie Infettive, Parassitarie ed Immunomediate, Istituto Superiore di Sanità, Viale Regina Elena n. 299, 00161 Rome, Italy.
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Baton LA, Ranford-Cartwright LC. Spreading the seeds of million-murdering death**This title and some subheadings are taken from lines in Ronald Ross' poem In Exile, Reply – What Ails the Solitude, written on 21 August 1897, the day after he made his Nobel-Prize-winning discovery of parasite stages in the mosquito. ‘This day relenting God hath placed within my hand a wondrous thing; and God be praised. At His command, seeking His secret deeds with tears and toiling breath I find thy cunning seeds, O million-murdering Death. I know this little thing a myriad men will save. O Death, where is thy sting, thy victory, O Grave!’: metamorphoses of malaria in the mosquito. Trends Parasitol 2005; 21:573-80. [PMID: 16236552 DOI: 10.1016/j.pt.2005.09.012] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2005] [Revised: 08/15/2005] [Accepted: 09/29/2005] [Indexed: 11/15/2022]
Abstract
Plasmodium spp. undergo a complex obligate developmental cycle within their invertebrate vectors that enables transmission between vertebrate hosts. This developmental cycle involves sexual reproduction and then asexual multiplication, separated by phases of invasion and colonization of distinct vector tissues. As with other stages in the Plasmodium life cycle, there is exquisite adaptation of the malaria parasite to its changing environment as it transforms within the blood of its vertebrate host, through the different tissues of its mosquito vector and onwards to infect a new vertebrate host. Despite the intricacies inherent in these successive transformations, malaria parasites remain staggeringly successful at disseminating through their vertebrate host populations.
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Affiliation(s)
- Luke A Baton
- Division of Infection and Immunity, Institute of Biomedical and Life Sciences, Joseph Black Building, University of Glasgow, Glasgow, UK, G12 8QQ.
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Trager W. What triggers the gametocyte pathway in Plasmodium falciparum? Trends Parasitol 2005; 21:262-4. [PMID: 15922244 DOI: 10.1016/j.pt.2005.04.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2005] [Revised: 02/28/2005] [Accepted: 04/11/2005] [Indexed: 11/17/2022]
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Talman AM, Domarle O, McKenzie FE, Ariey F, Robert V. Gametocytogenesis: the puberty of Plasmodium falciparum. Malar J 2004; 3:24. [PMID: 15253774 PMCID: PMC497046 DOI: 10.1186/1475-2875-3-24] [Citation(s) in RCA: 136] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2004] [Accepted: 07/14/2004] [Indexed: 11/16/2022] Open
Abstract
The protozoan Plasmodium falciparum has a complex life cycle in which asexual multiplication in the vertebrate host alternates with an obligate sexual reproduction in the anopheline mosquito. Apart from the apparent recombination advantages conferred by sex, P. falciparum has evolved a remarkable biology and adaptive phenotypes to insure its transmission despite the dangers of sex. This review mainly focuses on the current knowledge on commitment to sexual development, gametocytogenesis and the evolutionary significance of various aspects of gametocyte biology. It goes further than pure biology to look at the strategies used to improve successful transmission. Although gametocytes are inevitable stages for transmission and provide a potential target to fight malaria, they have received less attention than the pathogenic asexual stages. There is a need for research on gametocytes, which are a fascinating stage, responsible to a large extent for the success of P. falciparum.
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Affiliation(s)
- Arthur M Talman
- Groupe de Recherche sur le Paludisme, Institut Pasteur de Madagascar, B.P.1274 Antananarivo 101, Madagascar
- Department of Biological Sciences, Imperial College London, Exhibition Road, SW7 2AZ London, UK
| | - Olivier Domarle
- Groupe de Recherche sur le Paludisme, Institut Pasteur de Madagascar, B.P.1274 Antananarivo 101, Madagascar
| | - F Ellis McKenzie
- Fogarty International Centre, National Institutes of Health, Bethesda, MD 20892, USA
| | - Frédéric Ariey
- Groupe de Recherche sur le Paludisme, Institut Pasteur de Madagascar, B.P.1274 Antananarivo 101, Madagascar
| | - Vincent Robert
- Groupe de Recherche sur le Paludisme, Institut Pasteur de Madagascar, B.P.1274 Antananarivo 101, Madagascar
- UR 77 Paludisme Afro-tropical, Institut de Recherche pour le Développement, Madagascar
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Yarim M, Yildiz K, Kabakci N, Karahan S. Immunohistochemical localisation of 3beta-hydroxysteroid dehydrogenase in Sarcocystis spp. Parasitol Res 2004; 93:457-60. [PMID: 15243798 DOI: 10.1007/s00436-004-1152-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2004] [Accepted: 06/08/2004] [Indexed: 10/26/2022]
Abstract
3Beta-hydroxysteroid-dehydrogenase (3beta-HSD) is an isoenzyme that catalyses an essential step in the synthesis of all classes of active steroid hormones. The presence of steroid hormones of the vertebrate type in invertebrates is acknowledged in addition to a group of steroid-like hormones called ecdysteroids that were present in arthropods and helminths. In the present study, 3beta-HSD was detected in the bradyzoites enclosed in sarcocysts of Sarcocystis spp. with immunohistochemistry. The results suggest that self-originating steroid hormones may play important roles in the development of Sarcocystis spp., and possibly in the regulation of the reciprocal immune interaction between the host and these parasites.
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Affiliation(s)
- Murat Yarim
- Department of Pathology, Faculty of Veterinary Medicine, University of Kirikkale, Yahsihan, Turkey.
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Ferguson DJP. Use of molecular and ultrastructural markers to evaluate stage conversion of Toxoplasma gondii in both the intermediate and definitive host. Int J Parasitol 2004; 34:347-60. [PMID: 15003495 DOI: 10.1016/j.ijpara.2003.11.024] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2003] [Revised: 11/12/2003] [Accepted: 11/17/2003] [Indexed: 11/18/2022]
Abstract
Toxoplasma gondii has a complex life cycle involving definite (cat) and intermediate (all warm blooded animals) hosts. This gives rise to four infectious forms each of which has a distinctive biological role. Two (tachyzoite and merozoite) are involved in propagation within a host and two (bradyzoite and sporozoite) are involved in transmission to new hosts. The various forms can be identified by their structure, host parasite relationship and distinctive developmental processes. In the present in vivo study, the various stages have been evaluated by electron microscopy and immunocytochemistry using a panel of molecular markers relating to surface and cytoplasmic molecules, metabolic iso-enzymes and secreted proteins that can differentiate between tachyzoite, bradyzoite and coccidian development. Tachyzoites were characterised as being positive for surface antigen 1, enolase isoenzyme 2, lactic dehydrogenase isoenzyme 1 and negative for bradyzoite antigen 1. In contrast, bradyzoites were negative for SAG1 but positive for BAG1, ENO1 and LDH2. When stage conversion was followed in brain lesion at 10 and 15 days post-infection, tachyzoites were predominant but a number of single intermediate organisms displaying tachyzoite and certain bradyzoite markers were observed. At later time points, small groups of organisms displaying only bradyzoite markers were also present. A number (9) of dense granule proteins (GRA1-8, NTPase) have also been identified in both tachyzoites and bradyzoites but there were differences in their location during parasite development. All the dense granule proteins extensively label the parasitophorous vacuole during tachyzoite development. In contrast the tissue cyst wall displays variable staining for the dense granule proteins, which also expresses an additional unique cyst wall protein. The molecular differences could be identified at the single cell stage consistent with conversion occurring at the time of entry into a new cell. These molecular differences were reflected in the structural differences in the parasitophorous vacuoles observed by electron microscopy. Stage conversion to enteric (coccidian) development was limited to the enterocytes of the cat small intestine. Although no specific markers were available, this form of development can be identified by the absence of specific tachyzoite (SAG1) and bradyzoite (BAG1) markers although the isoenzymes ENO2 and LHD1 were expressed. There was also a significant difference in the expression of the dense granule proteins. The coccidian stages and merozoites only expressed two (GRA7 and NTPase) of the nine dense granule proteins and this was reflected in significant differences in the structure of the parasitophorous vacuole. The coccidian stages also undergo conversion from asexual to sexual development. The mechanism controlling this process is unknown but does not involve any change in the host cell type or parasitophorous vacuole and may be pre-programmed, since the number of asexual cycles was self-limiting. In conclusion, it was possible using a combination of molecular markers to identify tachyzoite, bradyzoite and coccidian development in tissue sections.
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Affiliation(s)
- D J P Ferguson
- Nuffield Department of Pathology, Oxford University, John Radcliffe Hospital, Oxford OX3 9DU, UK.
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