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Abstract
While disease and outbreaks are mainly clonal for bacteria and other asexually reproducing organisms, sexual reproduction in schistosomes and other helminths usually results in unique individuals. For sexually reproducing organisms, the traits conserved in clones will instead be conserved in the group of organisms that tends to breed together, the population. While the same tools are applied to characterize DNA, how results are interpreted can be quite different at times (see another article in this collection, http://www.asmscience.org/content/journal/microbiolspec/10.1128/microbiolspec.AME-0002-2018). It is difficult to know what the real effect any control program has on the parasite population without assessing the health of this population, how they respond to the control measure, and how they recover, if they do. This review, part of the Microbiology Spectrum Curated Collection: Advances in Molecular Epidemiology of Infectious Diseases, concentrates on one approach using pooled samples to study schistosome populations and shows how this and other approaches have contributed to our understanding of this parasite family's biology and epidemiology. *This article is part of a curated collection.
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Praziquantel for Schistosomiasis: Single-Drug Metabolism Revisited, Mode of Action, and Resistance. Antimicrob Agents Chemother 2017; 61:AAC.02582-16. [PMID: 28264841 DOI: 10.1128/aac.02582-16] [Citation(s) in RCA: 207] [Impact Index Per Article: 29.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Schistosomiasis, a major neglected tropical disease, affects more than 250 million people worldwide. Treatment of schistosomiasis has relied on the anthelmintic drug praziquantel (PZQ) for more than a generation. PZQ is the drug of choice for the treatment of schistosomiasis; it is effective against all major forms of schistosomiasis, although it is less active against juvenile than mature parasites. A pyrazino-isoquinoline derivative, PZQ is not considered to be toxic and generally causes few or transient, mild side effects. Increasingly, mass drug administration targeting populations in sub-Saharan Africa where schistosomiasis is endemic has led to the appearance of reduced efficacy of PZQ, which portends the selection of drug-resistant forms of these pathogens. The synthesis of improved derivatives of PZQ is attracting attention, e.g., in the (i) synthesis of drug analogues, (ii) rational design of pharmacophores, and (iii) discovery of new compounds from large-scale screening programs. This article reviews reports from the 1970s to the present on the metabolism and mechanism of action of PZQ and its derivatives against schistosomes.
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Roquis D, Lepesant JMJ, Villafan E, Boissier J, Vieira C, Cosseau C, Grunau C. Exposure to hycanthone alters chromatin structure around specific gene functions and specific repeats in Schistosoma mansoni. Front Genet 2014; 5:207. [PMID: 25076965 PMCID: PMC4099960 DOI: 10.3389/fgene.2014.00207] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Accepted: 06/18/2014] [Indexed: 11/23/2022] Open
Abstract
Schistosoma mansoni is a parasitic plathyhelminth responsible for intestinal schistosomiasis (or bilharzia), a disease affecting 67 million people worldwide and causing an important economic burden. The schistosomicides hycanthone, and its later proxy oxamniquine, were widely used for treatments in endemic areas during the twentieth century. Recently, the mechanism of action, as well as the genetic origin of a stably and Mendelian inherited resistance for both drugs was elucidated in two strains. However, several observations suggested early on that alternative mechanisms might exist, by which resistance could be induced for these two drugs in sensitive lines of schistosomes. This induced resistance appeared rapidly, within the first generation, but was metastable (not stably inherited). Epigenetic inheritance could explain such a phenomenon and we therefore re-analyzed the historical data with our current knowledge of epigenetics. In addition, we performed new experiments such as ChIP-seq on hycanthone treated worms. We found distinct chromatin structure changes between sensitive worms and induced resistant worms from the same strain. No specific pathway was discovered, but genes in which chromatin structure modifications were observed are mostly associated with transport and catabolism, which makes sense in the context of the elimination of the drug. Specific differences were observed in the repetitive compartment of the genome. We finally describe what types of experiments are needed to understand the complexity of heritability that can be based on genetic and/or epigenetic mechanisms for drug resistance in schistosomes.
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Affiliation(s)
- David Roquis
- Département de Biologie, Université de Perpignan Via DomitiaPerpignan, France
- CNRS, UMR 5244, Écologie et Évolution des Interactions (2EI)Perpignan, France
| | - Julie M. J. Lepesant
- Département de Biologie, Université de Perpignan Via DomitiaPerpignan, France
- CNRS, UMR 5244, Écologie et Évolution des Interactions (2EI)Perpignan, France
| | - Emanuel Villafan
- CNRS, UMR 5558, Laboratoire de Biométrie et Biologie Évolutive, Département de Biologie, Université Lyon 1Villeurbane, France
- Red de Estudios Moleculares Avanzados, Instituto de Ecología A.C.Xalapa, México
| | - Jérôme Boissier
- Département de Biologie, Université de Perpignan Via DomitiaPerpignan, France
- Red de Estudios Moleculares Avanzados, Instituto de Ecología A.C.Xalapa, México
| | - Cristina Vieira
- CNRS, UMR 5558, Laboratoire de Biométrie et Biologie Évolutive, Département de Biologie, Université Lyon 1Villeurbane, France
- Département de Biologie, Institut Universitaire de FranceParis, France
| | - Céline Cosseau
- Département de Biologie, Université de Perpignan Via DomitiaPerpignan, France
- CNRS, UMR 5244, Écologie et Évolution des Interactions (2EI)Perpignan, France
| | - Christoph Grunau
- Département de Biologie, Université de Perpignan Via DomitiaPerpignan, France
- CNRS, UMR 5244, Écologie et Évolution des Interactions (2EI)Perpignan, France
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Wang W, Wang L, Liang YS. Susceptibility or resistance of praziquantel in human schistosomiasis: a review. Parasitol Res 2012; 111:1871-7. [PMID: 23052781 DOI: 10.1007/s00436-012-3151-z] [Citation(s) in RCA: 257] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Accepted: 09/26/2012] [Indexed: 01/07/2023]
Abstract
Since praziquantel was developed in 1970s, it has replaced other antischistosomal drugs to become the only drug of choice for treatment of human schistosomiases, due to high efficacy, excellent tolerability, few and transient side effects, simple administration, and competitive cost. Praziquantel-based chemotherapy has been involved in the global control strategy of the disease and led to the control strategy shifting from disease control to morbidity control, which has greatly reduced the prevalence and intensity of infections. Given that the drug has been widely used for morbidity control in endemic areas for more than three decades, the emergence of resistance of Schistosoma to praziquantel under drug selection pressure has been paid much attention. It is possible to induce resistance of Schistosoma mansoni and Schistosoma japonicum to praziquantel in mice under laboratorial conditions, and a reduced susceptibility to praziquantel in the field isolates of S. mansoni has been found in many foci. In addition, there are several schistosomiasis cases caused by Schistosoma haematobium infections in which repeated standard treatment fails to clear the infection. However, in the absence of exact mechanisms of action of praziquantel, the mechanisms of drug resistance in schistosomes remain unclear. The present review mainly demonstrates the evidence of drug resistance in the laboratory and field and the mechanism of praziquantel resistance and proposes some strategies for control of praziquantel resistance in schistosomes.
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Affiliation(s)
- Wei Wang
- Jiangsu Institute of Parasitic Diseases, 117 Yangxiang, Meiyuan, Wuxi City, Jiangsu Province 214064, People's Republic of China.
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Fallon PG. Schistosome resistance to praziquantel. Drug Resist Updat 1998; 1:236-41. [PMID: 16904406 DOI: 10.1016/s1368-7646(98)80004-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/1998] [Revised: 04/22/1998] [Accepted: 04/22/1998] [Indexed: 10/25/2022]
Abstract
Praziquantel (PZQ) is the drug of choice for the treatment of human schistosomiasis. In 1994, it was first demonstrated that by sustained drug pressure on a Schistosoma mansoni strain in laboratory conditions resistance to PZQ can develop. Studies in Senegal and Egypt, both schistosomiasis endemic areas, have found that there are schistosome strain(s) that are tolerant to PZQ. In this article evidence from laboratory and field studies regarding the existence of PZQ resistance or tolerant schistosome strain(s) will be examined.
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Affiliation(s)
- P G Fallon
- Department of Pathology, University of Cambridge, Cambridge, UK.
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Fallon PG, Tao LF, Ismail MM, Bennett JL. Schistosome resistance to praziquantel: Fact or artifact? ACTA ACUST UNITED AC 1996; 12:316-20. [PMID: 15275183 DOI: 10.1016/0169-4758(96)10029-6] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Praziquantel is the current drug of choice for human schistosomiasis. Recent reports from laboratory and field studies concerning reduced praziquantel efficacy against Schistosoma mansoni have generated some controversy. The prevailing question is whether the emergence of strains of schistosome resistant to praziquantel is a fact, or an artifact resulting from erroneous field or laboratory experimentation. In this article, Padraic Fallon, Liang-feng Tao, Magdi Ismail and James Bennett examine the available evidence for schistosome resistance to praziquantel. Contributory factors to the schistosomicidal activity of praziquantel, which may interfere with evaluation of drug efficacy or resistance, are also considered.
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Affiliation(s)
- P G Fallon
- Department of Pathology, University of Cambridge. Tennis Court Road, Cambride, UK.
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Abstract
The major antischistosomal drugs that have been or still are in use against infections with schistosomes are considered here together with some compounds that have not been in clinical use, but show interesting characteristics. Each individual compound presents aspects that may be enlightening about parasite biochemistry, parasite biology, and host-parasite relationships. Special attention is given to the mechanisms of action, an understanding of which is seen here as a major factor of progress in chemotherapy. Three compounds are currently in use, i.e., metrifonate, oxamniquine, and praziquantel, and all three are included in the World Health Organization list of essential drugs. They are analyzed in some detail, as each one presents advantages and disadvantages in antischistosomal therapy. The reported occurrence of drug-resistant schistosomes after treatment with oxamniquine and praziquantel suggests strict monitoring of such phenomena and encourages renewed efforts toward the development of multiple drugs against this human parasite.
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Affiliation(s)
- D Cioli
- Institute of Cell Biology, Rome, Italy
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