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Sollelis L, Howick VM, Marti M. Revisiting the determinants of malaria transmission. Trends Parasitol 2024; 40:302-312. [PMID: 38443304 DOI: 10.1016/j.pt.2024.02.001] [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: 12/20/2023] [Revised: 02/05/2024] [Accepted: 02/05/2024] [Indexed: 03/07/2024]
Abstract
Malaria parasites have coevolved with humans over thousands of years, mirroring their migration out of Africa. They persist to this day, despite continuous elimination efforts worldwide. These parasites can adapt to changing environments during infection of human and mosquito, and when expanding the geographical range by switching vector species. Recent studies in the human malaria parasite, Plasmodium falciparum, identified determinants governing the plasticity of sexual conversion rates, sex ratio, and vector competence. Here we summarize the latest literature revealing environmental, epigenetic, and genetic determinants of malaria transmission.
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Affiliation(s)
- Lauriane Sollelis
- Wellcome Center for Integrative Parasitology, Institute of Infection and Immunity University of Glasgow, Glasgow, UK; Institute of Parasitology, Vetsuisse Faculty, University of Zürich, Zürich, Switzerland
| | - Virginia M Howick
- Institute of Parasitology, Vetsuisse Faculty, University of Zürich, Zürich, Switzerland; Institute of Biodiversity, Animal Health, and Comparative Medicine, University of Glasgow, Glasgow, UK
| | - Matthias Marti
- Wellcome Center for Integrative Parasitology, Institute of Infection and Immunity University of Glasgow, Glasgow, UK; Institute of Parasitology, Vetsuisse Faculty, University of Zürich, Zürich, Switzerland.
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2
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Saha B, McNinch CM, Lu S, Ho MCW, De Carvalho SS, Barillas-Mury C. In-depth transcriptomic analysis of Anopheles gambiae hemocytes uncovers novel genes and the oenocytoid developmental lineage. BMC Genomics 2024; 25:80. [PMID: 38243165 PMCID: PMC10799387 DOI: 10.1186/s12864-024-09986-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Accepted: 01/07/2024] [Indexed: 01/21/2024] Open
Abstract
BACKGROUND Hemocytes are immune cells that patrol the mosquito hemocoel and mediate critical cellular defense responses against pathogens. However, despite their importance, a comprehensive transcriptome of these cells was lacking because they constitute a very small fraction of the total cells in the insect, limiting the study of hemocyte differentiation and immune function. RESULTS In this study, an in-depth hemocyte transcriptome was built by extensive bulk RNA sequencing and assembly of hemocyte RNAs from adult A. gambiae female mosquitoes, based on approximately 2.4 billion short Illumina and about 9.4 million long PacBio high-quality reads that mapped to the A. gambiae PEST genome (P4.14 version). A total of 34,939 transcripts were annotated including 4,020 transcripts from novel genes and 20,008 novel isoforms that result from extensive differential splicing of transcripts from previously annotated genes. Most hemocyte transcripts identified (89.8%) are protein-coding while 10.2% are non-coding RNAs. The number of transcripts identified in the novel hemocyte transcriptome is twice the number in the current annotation of the A. gambiae genome (P4.14 version). Furthermore, we were able to refine the analysis of a previously published single-cell transcriptome (scRNAseq) data set by using the novel hemocyte transcriptome as a reference to re-define the hemocyte clusters and determine the path of hemocyte differentiation. Unsupervised pseudo-temporal ordering using the Tools for Single Cell Analysis software uncovered a novel putative prohemocyte precursor cell type that gives rise to prohemocytes. Pseudo-temporal ordering with the Monocle 3 software, which analyses changes in gene expression during dynamic biological processes, determined that oenocytoids derive from prohemocytes, a cell population that also gives rise to the granulocyte lineage. CONCLUSION A high number of mRNA splice variants are expressed in hemocytes, and they may account for the plasticity required to mount efficient responses to many different pathogens. This study highlights the importance of a comprehensive set of reference transcripts to perform robust single-cell transcriptomic data analysis of cells present in low abundance. The detailed annotation of the hemocyte transcriptome will uncover new facets of hemocyte development and function in adult dipterans and is a valuable community resource for future studies on mosquito cellular immunity.
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Affiliation(s)
- Banhisikha Saha
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, USA
| | - Colton M McNinch
- Bioinformatics and Computational Biosciences Branch, Office of Cyber Infrastructure and Computational Biology, National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health, 20892, Bethesda, MD, USA
| | - Stephen Lu
- Vector Biology Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, Bethesda, MD, USA
| | - Margaret C W Ho
- Bioinformatics and Computational Biosciences Branch, Office of Cyber Infrastructure and Computational Biology, National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health, 20892, Bethesda, MD, USA
| | - Stephanie Serafim De Carvalho
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, USA
| | - Carolina Barillas-Mury
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, USA.
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3
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Ukegbu CV, Gomes AR, Giorgalli M, Campos M, Bailey AJ, Besson TRB, Billker O, Vlachou D, Christophides GK. Identification of genes required for Plasmodium gametocyte-to-sporozoite development in the mosquito vector. Cell Host Microbe 2023; 31:1539-1551.e6. [PMID: 37708854 DOI: 10.1016/j.chom.2023.08.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Revised: 06/03/2023] [Accepted: 08/14/2023] [Indexed: 09/16/2023]
Abstract
Malaria remains one of the most devastating infectious diseases. Reverse genetic screens offer a powerful approach to identify genes and molecular processes governing malaria parasite biology. However, the complex regulation of gene expression and genotype-phenotype associations in the mosquito vector, along with sexual reproduction, have hindered the development of screens in this critical part of the parasite life cycle. To address this, we developed a genetic approach in the rodent parasite Plasmodium berghei that, in combination with barcode sequencing, circumvents the fertilization roadblock and enables screening for gametocyte-expressed genes required for parasite infection of the mosquito Anopheles coluzzii. Our results confirm previous findings, validating our approach for scaling up, and identify genes necessary for mosquito midgut infection, oocyst development, and salivary gland infection. These findings can aid efforts to study malaria transmission biology and to develop interventions for controlling disease transmission.
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Affiliation(s)
| | - Ana Rita Gomes
- Department of Life Sciences, Imperial College London, London SW7 2AZ, UK; Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton CB10 1SA, UK
| | - Maria Giorgalli
- Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | - Melina Campos
- Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | - Alexander J Bailey
- Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | | | - Oliver Billker
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton CB10 1SA, UK
| | - Dina Vlachou
- Department of Life Sciences, Imperial College London, London SW7 2AZ, UK.
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4
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Andrade AO, Santos NAC, Bastos AS, Pontual JDC, Araújo JE, Silva AMV, Martinez LN, Lima AA, Aguiar ACC, G. Teles CB, Medeiros JF, Pereira DB, Vinetz JM, Gazzinelli RT, Araújo MS. Transmission-blocking activity of antimalarials for Plasmodium vivax malaria in Anopheles darlingi. PLoS Negl Trop Dis 2023; 17:e0011425. [PMID: 37327209 PMCID: PMC10310017 DOI: 10.1371/journal.pntd.0011425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Revised: 06/29/2023] [Accepted: 05/30/2023] [Indexed: 06/18/2023] Open
Abstract
Malaria is caused by parasite of the genus Plasmodium and is still one of the most important infectious diseases in the world. Several biological characteristics of Plasmodium vivax contribute to the resilience of this species, including early gametocyte production, both of which lead to efficient malaria transmission to mosquitoes. This study evaluated the impact of currently used drugs on the transmission of P. vivax. Participants received one of the following treatments for malaria: i) chloroquine [10 mg/kg on day 1 and 7.5 mg/kg on day 2 and 3] co-administered with Primaquine [0.5 mg/kg/day for 7 days]; ii) Chloroquine [10 mg/kg on day 1 and 7.5 mg/kg on day 2 and 3] co-administered with one-dose of Tafenoquine [300 mg on day 1]; and iii) Artesunate and Mefloquine [100 mg and 200 mg on day 1, 2 and 3] co-administered with Primaquine [0.5 mg/kg/day for 14 days]. Patient blood was collected before treatment and 4 h, 24 h, 48 h and 72 h after treatment. The blood was used to perform a direct membrane feeding assay (DMFA) using Anopheles darlingi mosquitoes. The results showed 100% inhibition of the mosquito infection after 4 h using ASMQ+PQ, after 24 h for the combination of CQ+PQ and 48 h using CQ+TQ. The density of gametocytes declined over time in all treatment groups, although the decline was more rapid in the ASMQ+PQ group. In conclusion, it was possible to demonstrate the transmission-blocking efficacy of the malaria vivax treatment and that ASMQ+PQ acts faster than the two other treatments.
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Affiliation(s)
- Alice O. Andrade
- Plataforma de Produção e Infecção de Vetores da Malária (PIVEM), Laboratório de Entomologia, Fiocruz Rondônia, Porto Velho, Rondônia, Brazil
| | - Najara A. C. Santos
- Plataforma de Produção e Infecção de Vetores da Malária (PIVEM), Laboratório de Entomologia, Fiocruz Rondônia, Porto Velho, Rondônia, Brazil
- Programa de Pós-Graduação em Biologia Experimental, Fundação Universidade Federal de Rondônia, FIOCRUZ Rondônia, Porto Velho, Rondônia, Brazil
| | - Alessandra S. Bastos
- Plataforma de Produção e Infecção de Vetores da Malária (PIVEM), Laboratório de Entomologia, Fiocruz Rondônia, Porto Velho, Rondônia, Brazil
| | - José D. C. Pontual
- Plataforma de Produção e Infecção de Vetores da Malária (PIVEM), Laboratório de Entomologia, Fiocruz Rondônia, Porto Velho, Rondônia, Brazil
| | - Jéssica E. Araújo
- Plataforma de Produção e Infecção de Vetores da Malária (PIVEM), Laboratório de Entomologia, Fiocruz Rondônia, Porto Velho, Rondônia, Brazil
- Programa de Pós-Graduação em Biologia Experimental, Fundação Universidade Federal de Rondônia, FIOCRUZ Rondônia, Porto Velho, Rondônia, Brazil
| | - Alexia M. V. Silva
- Ambulatório de Malária, Centro de Pesquisa em Medicina Tropical, Porto Velho, Rondônia, Brazil
| | - Leandro N. Martinez
- Programa de Pós-Graduação em Biologia Experimental, Fundação Universidade Federal de Rondônia, FIOCRUZ Rondônia, Porto Velho, Rondônia, Brazil
- Plataforma de Bioensaios de Malária e Leishmaniose da Fiocruz (PBML), Fiocruz Rondônia, Porto Velho, Rondônia, Brazil
| | - Alzemar A. Lima
- Ambulatório de Malária, Centro de Pesquisa em Medicina Tropical, Porto Velho, Rondônia, Brazil
| | | | - Carolina B. G. Teles
- Programa de Pós-Graduação em Biologia Experimental, Fundação Universidade Federal de Rondônia, FIOCRUZ Rondônia, Porto Velho, Rondônia, Brazil
- Plataforma de Bioensaios de Malária e Leishmaniose da Fiocruz (PBML), Fiocruz Rondônia, Porto Velho, Rondônia, Brazil
| | - Jansen F. Medeiros
- Plataforma de Produção e Infecção de Vetores da Malária (PIVEM), Laboratório de Entomologia, Fiocruz Rondônia, Porto Velho, Rondônia, Brazil
- Programa de Pós-Graduação em Biologia Experimental, Fundação Universidade Federal de Rondônia, FIOCRUZ Rondônia, Porto Velho, Rondônia, Brazil
| | - Dhelio B. Pereira
- Ambulatório de Malária, Centro de Pesquisa em Medicina Tropical, Porto Velho, Rondônia, Brazil
| | - Joseph M. Vinetz
- Section of Infectious Diseases, Department of Internal Medicine, Yale School of Medicine, New Haven, Connecticut, United States of America
| | - Ricardo T. Gazzinelli
- Laboratório de Imunopatologia, Instituto René Rachou, Fundação Oswaldo Cruz, Belo Horizonte, Minas Gerais, Brazil
- Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Maisa S. Araújo
- Plataforma de Produção e Infecção de Vetores da Malária (PIVEM), Laboratório de Entomologia, Fiocruz Rondônia, Porto Velho, Rondônia, Brazil
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Grogan C, Bennett M, Lampe DJ. An evaluation of fusion partner proteins for paratransgenesis in Asaia bogorensis. PLoS One 2022; 17:e0273568. [PMID: 36048823 PMCID: PMC9436115 DOI: 10.1371/journal.pone.0273568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 08/10/2022] [Indexed: 11/18/2022] Open
Abstract
Mosquitoes transmit many pathogens responsible for human diseases, such as malaria which is caused by parasites in the genus Plasmodium. Current strategies to control vector-transmitted diseases are increasingly undermined by mosquito and pathogen resistance, so additional methods of control are required. Paratransgenesis is a method whereby symbiotic bacteria are genetically modified to affect the mosquito’s phenotype by engineering them to deliver effector molecules into the midgut to kill parasites. One paratransgenesis candidate is Asaia bogorensis, a Gram-negative bacterium colonizing the midgut, ovaries, and salivary glands of Anopheles sp. mosquitoes. Previously, engineered Asaia strains using native signals to drive the release of the antimicrobial peptide, scorpine, fused to alkaline phosphatase were successful in significantly suppressing the number of oocysts formed after a blood meal containing P. berghei. However, these strains saw high fitness costs associated with the production of the recombinant protein. Here, we report evaluation of five different partner proteins fused to scorpine that were evaluated for effects on the growth and fitness of the transgenic bacteria. Three of the new partner proteins resulted in significant levels of protein released from the Asaia bacterium while also significantly reducing the prevalence of mosquitoes infected with P. berghei. Two partners performed as well as the previously tested Asaia strain that used alkaline phosphatase in the fitness analyses, but neither exceeded it. It may be that there is a maximum level of fitness and parasite inhibition that can be achieved with scorpine being driven constitutively, and that use of a Plasmodium specific effector molecule in place of scorpine would help to mitigate the stress on the symbionts.
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Affiliation(s)
- Christina Grogan
- Department of Biological Sciences, Bayer School of Natural and Environmental Sciences, Duquesne University, Pittsburgh, PA, United States of America
| | - Marissa Bennett
- Department of Biological Sciences, Bayer School of Natural and Environmental Sciences, Duquesne University, Pittsburgh, PA, United States of America
| | - David J. Lampe
- Department of Biological Sciences, Bayer School of Natural and Environmental Sciences, Duquesne University, Pittsburgh, PA, United States of America
- * E-mail:
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6
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Dash M, Sachdeva S, Bansal A, Sinha A. Gametogenesis in Plasmodium: Delving Deeper to Connect the Dots. Front Cell Infect Microbiol 2022; 12:877907. [PMID: 35782151 PMCID: PMC9241518 DOI: 10.3389/fcimb.2022.877907] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 05/09/2022] [Indexed: 11/16/2022] Open
Abstract
In the coming decades, eliminating malaria is the foremost goal of many tropical countries. Transmission control, along with an accurate and timely diagnosis of malaria, effective treatment and prevention are the different aspects that need to be met synchronously to accomplish the goal. The current review is focused on one of these aspects i.e., transmission control, by looking deeper into the event called gametogenesis. In the Plasmodium life cycle, gametocytes are the first life forms of the sexual phase. The transmission of the parasite and the disease is critically dependent on the number, viability and sex ratio of mature gametocytes and their further development inside mosquito vectors. Gametogenesis, the process of conversion of gametocytes into viable gametes, takes place inside the mosquito midgut, and is a tightly regulated event with fast and multiple rounds of DNA replication and diverse cellular changes going on within a short period. Interrupting the gametocyte-gamete transition is ought to restrict the successful transmission and progression of the disease and hence an area worth exploring for designing transmission-blocking strategies. This review summarizes an in-depth and up-to-date understanding of the biochemical and physiological mechanism of gametogenesis in Plasmodium, which could be targeted to control parasite and malaria transmission. This review also raises certain key questions regarding gametogenesis biology in Plasmodium and brings out gaps that still accompany in understanding the spectacular process of gametogenesis.
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Affiliation(s)
- Manoswini Dash
- Parasite Host Biology, Indian Council of Medical Research (ICMR)-National Institute of Malaria Research, New Delhi, India
- Central Molecular Laboratory, Govind Ballabh (GB) Pant Institute of Postgraduate Medical Education and Research, New Delhi, India
| | - Sherry Sachdeva
- Parasite Host Biology, Indian Council of Medical Research (ICMR)-National Institute of Malaria Research, New Delhi, India
| | - Abhisheka Bansal
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Abhinav Sinha
- Parasite Host Biology, Indian Council of Medical Research (ICMR)-National Institute of Malaria Research, New Delhi, India
- *Correspondence: Abhinav Sinha,
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Kingston DGI, Cassera MB. Antimalarial Natural Products. PROGRESS IN THE CHEMISTRY OF ORGANIC NATURAL PRODUCTS 2022; 117:1-106. [PMID: 34977998 DOI: 10.1007/978-3-030-89873-1_1] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Natural products have made a crucial and unique contribution to human health, and this is especially true in the case of malaria, where the natural products quinine and artemisinin and their derivatives and analogues, have saved millions of lives. The need for new drugs to treat malaria is still urgent, since the most dangerous malaria parasite, Plasmodium falciparum, has become resistant to quinine and most of its derivatives and is becoming resistant to artemisinin and its derivatives. This volume begins with a short history of malaria and follows this with a summary of its biology. It then traces the fascinating history of the discovery of quinine for malaria treatment and then describes quinine's biosynthesis, its mechanism of action, and its clinical use, concluding with a discussion of synthetic antimalarial agents based on quinine's structure. The volume then covers the discovery of artemisinin and its development as the source of the most effective current antimalarial drug, including summaries of its synthesis and biosynthesis, its mechanism of action, and its clinical use and resistance. A short discussion of other clinically used antimalarial natural products leads to a detailed treatment of other natural products with significant antiplasmodial activity, classified by compound type. Although the search for new antimalarial natural products from Nature's combinatorial library is challenging, it is very likely to yield new antimalarial drugs. The chapter thus ends by identifying over ten natural products with development potential as clinical antimalarial agents.
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Affiliation(s)
- David G I Kingston
- Department of Chemistry and the Virginia Tech Center for Drug Discovery, Virginia Tech, Blacksburg, VA, 24061, USA.
| | - Maria Belen Cassera
- Department of Biochemistry and Molecular Biology, and Center for Tropical and Emerging Global Diseases (CTEGD), University of Georgia, Athens, GA, 30602, USA
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Sharma M, Choudhury H, Roy R, Michaels SA, Ojo KK, Bansal A. CDPKs: The critical decoders of calcium signal at various stages of malaria parasite development. Comput Struct Biotechnol J 2021; 19:5092-5107. [PMID: 34589185 PMCID: PMC8453137 DOI: 10.1016/j.csbj.2021.08.054] [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: 04/24/2021] [Revised: 08/31/2021] [Accepted: 08/31/2021] [Indexed: 12/13/2022] Open
Abstract
Calcium ions are used as important signals during various physiological processes. In malaria parasites, Plasmodium spp., calcium dependent protein kinases (CDPKs) have acquired the unique ability to sense and transduce calcium signals at various critical steps during the lifecycle, either through phosphorylation of downstream substrates or mediating formation of high molecular weight protein complexes. Calcium signaling cascades establish important crosstalk events with signaling pathways mediated by other secondary messengers such as cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP). CDPKs play critical roles at various important physiological steps during parasite development in vertebrates and mosquitoes. They are also important for transmission of the parasite between the two hosts. Combined with the fact that CDPKs are not present in humans, they continue to be pursued as important targets for development of anti-malarial drugs.
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Affiliation(s)
- Manish Sharma
- Molecular Parasitology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Himashree Choudhury
- Molecular Parasitology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Rajarshi Roy
- Molecular Parasitology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Samantha A. Michaels
- Center for Emerging and Re-emerging Infectious Diseases, Division of Allergy & Infectious Diseases, Department of Medicine, University of Washington, Seattle, WA 98109 USA
| | - Kayode K. Ojo
- Center for Emerging and Re-emerging Infectious Diseases, Division of Allergy & Infectious Diseases, Department of Medicine, University of Washington, Seattle, WA 98109 USA
| | - Abhisheka Bansal
- Molecular Parasitology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
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Kubo-Irie M, Hirai M, Irie M, Mohri H. Postulated Process of Axoneme Organization in the Male Gametogenesis of Malaria Parasite Plasmodium berghei. Zoolog Sci 2021; 38:187-192. [PMID: 33812358 DOI: 10.2108/zs200064] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2020] [Accepted: 09/13/2020] [Indexed: 11/17/2022]
Abstract
The ultrastructural features of axoneme organization within the cytoplasm and exflagellation were investigated in detail in microgametes of a malaria parasite, Plasmodium berghei, by electron and fluorescence microscopy. The kinetosomes (basal bodies) of the microgamete were characterized by an electron dense mass in which singlet microtubules (MTs) were embedded. Around the kinetosomes, several singlet and doublet MTs were recognized in transverse sections. Incomplete doublets with growing B-tubule were also observed. As precursors of the axoneme, arrays of over three doublets showed a tendency to encircle the central pair MTs. Some of the doublet MTs were already equipped with inner and outer dynein arms. In the microgamete, which lacks an intraflagellar transport (IFT) system, self-assembly of microtubular and associated components appeared to proceed stepwise from singlet MTs through arrays of one to nine doublet MTs, surrounding the central pair, to form the complete axoneme in a quite short time. At exflagellation, some extra doublets were occasionally included between the axoneme and the flagellar membrane. At high magnification, the outer dynein arm of the Plasmodium microgamete had a pistol-like shape representing a three-headed dynein molecule like that of other Alveolata.
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Affiliation(s)
- Miyoko Kubo-Irie
- Biological Laboratory, The Open University of Japan, Wakaba, Mihama-ku, Chiba 261-8506, Japan,
| | - Makoto Hirai
- Department of Tropical Medicine and Parasitology, School of Medicine, Juntendo University, Hongo, Bunkyo-ku, Tokyo 113-8421, Japan
| | - Masaru Irie
- Department of Computer Science, Waseda University, Shinjuku-ku, Tokyo 169-8555, Japan
| | - Hideo Mohri
- Department of Biological Science, Graduate School of Arts and Sciences, the University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8902, Japan
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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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11
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Grogan C, Bennett M, Moore S, Lampe D. Novel Asaia bogorensis Signal Sequences for Plasmodium Inhibition in Anopheles stephensi. Front Microbiol 2021; 12:633667. [PMID: 33664722 PMCID: PMC7921796 DOI: 10.3389/fmicb.2021.633667] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Accepted: 01/27/2021] [Indexed: 12/11/2022] Open
Abstract
Mosquitoes vector many pathogens that cause human disease, such as malaria that is caused by parasites in the genus Plasmodium. Current strategies to control vector-transmitted diseases are hindered by mosquito and pathogen resistance, so research has turned to altering the microbiota of the vectors. In this strategy, called paratransgenesis, symbiotic bacteria are genetically modified to affect the mosquito's phenotype by engineering them to deliver antiplasmodial effector molecules into the midgut to kill parasites. One paratransgenesis candidate is Asaia bogorensis, a Gram-negative, rod-shaped bacterium colonizing the midgut, ovaries, and salivary glands of Anopheles sp. mosquitoes. However, common secretion signals from E. coli and closely related species do not function in Asaia. Here, we report evaluation of 20 native Asaia N-terminal signal sequences predicted from bioinformatics for their ability to mediate increased levels of antiplasmodial effector molecules directed to the periplasm and ultimately outside the cell. We tested the hypothesis that by increasing the amount of antiplasmodials released from the cell we would also increase parasite killing power. We scanned the Asaia bogorensis SF2.1 genome to identify signal sequences from extra-cytoplasmic proteins and fused these to the reporter protein alkaline phosphatase. Six signals resulted in significant levels of protein released from the Asaia bacterium. Three signals were successfully used to drive the release of the antimicrobial peptide, scorpine. Further testing in mosquitoes demonstrated that these three Asaia strains were able to suppress the number of oocysts formed after a blood meal containing P. berghei to a significantly greater degree than wild-type Asaia, although prevalence was not decreased beyond levels obtained with a previously isolated siderophore receptor signal sequence. We interpret these results to indicate that there is a maximum level of suppression that can be achieved when the effectors are constitutively driven due to stress on the symbionts. This suggests that simply increasing the amount of antiplasmodial effector molecules in the midgut is insufficient to create superior paratransgenic bacterial strains and that symbiont fitness must be considered as well.
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Affiliation(s)
- Christina Grogan
- Department of Biological Sciences, Bayer School of Natural and Environmental Sciences, Duquesne University, Pittsburgh, PA, United States
| | - Marissa Bennett
- Department of Biological Sciences, Bayer School of Natural and Environmental Sciences, Duquesne University, Pittsburgh, PA, United States
| | - Shannon Moore
- Department of Biological Sciences, Bayer School of Natural and Environmental Sciences, Duquesne University, Pittsburgh, PA, United States
| | - David Lampe
- Department of Biological Sciences, Bayer School of Natural and Environmental Sciences, Duquesne University, Pittsburgh, PA, United States
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12
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Isaïa J, Rivero A, Glaizot O, Christe P, Pigeault R. Last-come, best served? Mosquito biting order and Plasmodium transmission. Proc Biol Sci 2020; 287:20202615. [PMID: 33234076 PMCID: PMC7739503 DOI: 10.1098/rspb.2020.2615] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
A pervasive characteristic of parasite infections is their tendency to be overdispersed. Understanding the mechanisms underlying this overdispersed distribution is of key importance as it may impact the transmission dynamics of the pathogen. Although multiple factors ranging from environmental stochasticity to inter-individual heterogeneity may explain parasite overdispersion, parasite infection is also overdispersed in an inbred host population maintained under laboratory conditions, suggesting that other mechanisms are at play. Here, we show that the aggregated distribution of malaria parasites within mosquito vectors is partially explained by a temporal heterogeneity in parasite infectivity triggered by the bites of mosquitoes. Parasite transmission tripled between the mosquito's first and last blood feed in a period of only 3 h. Surprisingly, the increase in transmission is not associated with an increase in parasite investment in production of the transmissible stage. Overall, we highlight that Plasmodium is capable of responding to the bites of mosquitoes to increase its own transmission at a much faster pace than initially thought and that this is partly responsible for overdispersed distribution of infection. We discuss the underlying mechanisms as well as the broader implications of this plastic response for the epidemiology of malaria.
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Affiliation(s)
- J Isaïa
- Department of Ecology and Evolution, University of Lausanne, CH-1015 Lausanne, Switzerland
| | - A Rivero
- MIVEGEC (UMR CNRS 5290), Montpellier, France.,CREES (Centre de Recherche en Ecologie et Evolution de la Santé), Montpellier, France
| | - O Glaizot
- Department of Ecology and Evolution, University of Lausanne, CH-1015 Lausanne, Switzerland.,Musée Cantonal de Zoologie, Lausanne, Switzerland
| | - P Christe
- Department of Ecology and Evolution, University of Lausanne, CH-1015 Lausanne, Switzerland
| | - R Pigeault
- Department of Ecology and Evolution, University of Lausanne, CH-1015 Lausanne, Switzerland
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13
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Zheng W, Liu F, Du F, Yang F, Kou X, He Y, Feng H, Fan Q, Luo E, Min H, Miao J, Cui L, Cao Y. Characterization of a Sulfhydryl Oxidase From Plasmodium berghei as a Target for Blocking Parasite Transmission. Front Cell Infect Microbiol 2020; 10:311. [PMID: 32670896 PMCID: PMC7332561 DOI: 10.3389/fcimb.2020.00311] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 05/22/2020] [Indexed: 11/13/2022] Open
Abstract
Quiescin sulfhydryl oxidase (QSOX), present in a wide variety of eukaryotic species, catalyzes the insertion of disulfide bonds into unfolded, reduced proteins. Here we characterized the QSOX protein from the rodent malaria parasite Plasmodium berghei (PbQSOX), which is conserved in all sequenced malaria parasite species. The PbQSOX protein was not expressed in asexual erythrocytic stages, but was most abundantly expressed in ookinetes. Indirect immunofluorescence assays revealed PbQSOX was not only localized in cytoplasm of gametocytes, gametes and ookinetes, but also expressed on the surface of gametes and ookinetes. Western blot identified extracellular presence of PbQSOX in the culture medium of ookinetes suggestive of secretion. Pbqsox deletion (Δpbqsox) did not affect asexual intraerythrocytic development, but reduced exflagellation of male gametocytes as well as formation and maturation of ookinetes. Pbqsox deletion also led to a significant increase in the reduced thiol groups of ookinete surface proteins, suggesting that it may play a role in maintaining the integrity of disulfide bonds of surface proteins, which might be needed for ookinete development. Mosquitoes that fed on Δpbqsox-infected mice showed a significant reduction in ookinete and oocyst numbers compared to those fed on wild-type parasite-infected mice. Further, both polyclonal mouse antisera and a monoclonal antibody against the recombinant PbQSOX exhibited substantial transmission-blocking activities in in vitro and mosquito feeding assays, suggesting QSOX is a potential target for blocking parasite transmission.
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Affiliation(s)
- Wenqi Zheng
- Department of Immunology, College of Basic Medical Sciences, China Medical University, Shenyang, China
- Department of Clinical Laboratory, Affiliated Hospital of Inner Mongolian Medical University, Hohhot, China
| | - Fei Liu
- Department of Immunology, College of Basic Medical Sciences, China Medical University, Shenyang, China
| | - Feng Du
- Department of Pathogen Biology, College of Basic Medical Sciences, China Medical University, Shenyang, China
| | - Fan Yang
- Department of Immunology, College of Basic Medical Sciences, China Medical University, Shenyang, China
| | - Xu Kou
- Department of Immunology, College of Basic Medical Sciences, China Medical University, Shenyang, China
- Department of Animal Quarantine, College of Animal Husbandry and Veterinary Sciences, Liaoning Medical University, Jinzhou, China
| | - Yiwen He
- Department of Immunology, College of Basic Medical Sciences, China Medical University, Shenyang, China
| | - Hui Feng
- Department of Immunology, College of Basic Medical Sciences, China Medical University, Shenyang, China
| | - Qi Fan
- Dalian Institute of Biotechnology, Dalian, China
| | - Enjie Luo
- Department of Pathogen Biology, College of Basic Medical Sciences, China Medical University, Shenyang, China
| | - Hui Min
- Department of Immunology, College of Basic Medical Sciences, China Medical University, Shenyang, China
- Department of Internal Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL, United States
| | - Jun Miao
- Department of Internal Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL, United States
| | - Liwang Cui
- Department of Internal Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL, United States
| | - Yaming Cao
- Department of Immunology, College of Basic Medical Sciences, China Medical University, Shenyang, China
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14
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Jiang Y, Wei J, Cui H, Liu C, Zhi Y, Jiang Z, Li Z, Li S, Yang Z, Wang X, Qian P, Zhang C, Zhong C, Su XZ, Yuan J. An intracellular membrane protein GEP1 regulates xanthurenic acid induced gametogenesis of malaria parasites. Nat Commun 2020; 11:1764. [PMID: 32273496 PMCID: PMC7145802 DOI: 10.1038/s41467-020-15479-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 03/14/2020] [Indexed: 11/09/2022] Open
Abstract
Gametocytes differentiation to gametes (gametogenesis) within mosquitos is essential for malaria parasite transmission. Both reduction in temperature and mosquito-derived XA or elevated pH are required for triggering cGMP/PKG dependent gametogenesis. However, the parasite molecule for sensing or transducing these environmental signals to initiate gametogenesis remains unknown. Here we perform a CRISPR/Cas9-based functional screening of 59 membrane proteins expressed in the gametocytes of Plasmodium yoelii and identify that GEP1 is required for XA-stimulated gametogenesis. GEP1 disruption abolishes XA-stimulated cGMP synthesis and the subsequent signaling and cellular events, such as Ca2+ mobilization, gamete formation, and gametes egress out of erythrocytes. GEP1 interacts with GCα, a cGMP synthesizing enzyme in gametocytes. Both GEP1 and GCα are expressed in cytoplasmic puncta of both male and female gametocytes. Depletion of GCα impairs XA-stimulated gametogenesis, mimicking the defect of GEP1 disruption. The identification of GEP1 being essential for gametogenesis provides a potential new target for intervention of parasite transmission.
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Affiliation(s)
- Yuanyuan Jiang
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, 361102, Xiamen, Fujian, China
| | - Jun Wei
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, 361102, Xiamen, Fujian, China
| | - Huiting Cui
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, 361102, Xiamen, Fujian, China
| | - Chuanyuan Liu
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, 361102, Xiamen, Fujian, China
| | - Yuan Zhi
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, 361102, Xiamen, Fujian, China
| | - ZhengZheng Jiang
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, 361102, Xiamen, Fujian, China
| | - Zhenkui Li
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, 361102, Xiamen, Fujian, China
| | - Shaoneng Li
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, 361102, Xiamen, Fujian, China
| | - Zhenke Yang
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, 361102, Xiamen, Fujian, China
| | - Xu Wang
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, 361102, Xiamen, Fujian, China
| | - Pengge Qian
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, 361102, Xiamen, Fujian, China
| | - Cui Zhang
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, 361102, Xiamen, Fujian, China
| | - Chuanqi Zhong
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, 361102, Xiamen, Fujian, China
| | - Xin-Zhuan Su
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Jing Yuan
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, 361102, Xiamen, Fujian, China.
- Lingnan Guangdong Laboratory of Modern Agriculture, 510642, Guangzhou, China.
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15
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Azevedo R, Mendes AM, Prudêncio M. Inhibition of Plasmodium sporogonic stages by ivermectin and other avermectins. Parasit Vectors 2019; 12:549. [PMID: 31752986 PMCID: PMC6873674 DOI: 10.1186/s13071-019-3805-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Accepted: 11/12/2019] [Indexed: 12/15/2022] Open
Abstract
Background The transmissible forms of Plasmodium parasites result from a process of sporogony that takes place inside their obligatory mosquito vector and culminates in the formation of mammalian-infective parasite forms. Ivermectin is a member of the avermectin family of endectocides, which has been proposed to inhibit malaria transmission due its insecticidal effect. However, it remains unclear whether ivermectin also exerts a direct action on the parasite’s blood and transmission stages. Methods We employed a rodent model of infection to assess the impact of ivermectin treatment on P. berghei asexual and sexual blood forms in vivo. We then made use of a newly established luminescence-based methodology to evaluate the activity of ivermectin and other avermectins against the sporogonic stages of P. berghei parasites in vitro independent of their role on mosquito physiology. Results Our results show that whereas ivermectin does not affect the parasite’s parasitemia, gametocytemia or exflagellation in the mammalian host, several members of the avermectin family of compounds exert a strong inhibitory effect on the generation and development of P. berghei oocysts. Conclusions Our results shed light on the action of avermectins against Plasmodium transmission stages and highlight the potential of these compounds to help prevent the spread of malaria.
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Affiliation(s)
- Raquel Azevedo
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Avenida Professor Egas Moniz, 1649-028, Lisbon, Portugal
| | - António M Mendes
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Avenida Professor Egas Moniz, 1649-028, Lisbon, Portugal.
| | - Miguel Prudêncio
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Avenida Professor Egas Moniz, 1649-028, Lisbon, Portugal.
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16
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Moreno M, Tong-Rios C, Orjuela-Sanchez P, Carrasco-Escobar G, Campo B, Gamboa D, Winzeler EA, Vinetz JM. Continuous Supply of Plasmodium vivax Sporozoites from Colonized Anopheles darlingi in the Peruvian Amazon. ACS Infect Dis 2018; 4:541-548. [PMID: 29465219 PMCID: PMC5902790 DOI: 10.1021/acsinfecdis.7b00195] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
In vitro culture of Plasmodium vivax liver stages underlies key understandings of the fundamental biology of this parasite, particularly the latent, hyponozoite stage, toward drug and vaccine development. Here, we report systematic production of Plasmodium vivax sporozoites in colonized Anopheles darlingi mosquitoes in the Peruvian Amazon. Human subject-derived P. vivax-infected blood was fed to Anopheles darlingi females using standard membrane feedings assays. Optimizing A. darlingi infection and sporozoite production included replacement of infected patient donor serum with naïve donor serum, comparing anticoagulants in processing blood samples, and addition of penicillin-streptomycin and ATP to infectious blood meals. Replacement of donor serum by naïve serum in the P. vivax donor blood increased oocysts in the mosquito midgut, and heparin, as anticoagulant, was associated with the highest sporozoite yields. Maintaining blood-fed mosquitoes on penicillin-streptomycin in sugar significantly extended mosquito survival which enabled greater sporozoite yield. In this study, we have shown that a robust P. vivax sporozoite production is feasible in a malaria-endemic setting where infected subjects and a stable A. darlingi colony are brought together, with optimized laboratory conditions.
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Affiliation(s)
- Marta Moreno
- Division of Infectious Diseases, Department of Medicine, School of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States
| | - Carlos Tong-Rios
- Laboratorio ICEMR-Amazonia, Laboratorios de Investigacion y Desarrollo, Facultad de Ciencias y Filosofia, Universidad Peruana Cayetano Heredia, Av. Honorio Delgado 430, San Martín de Porres, Lima, 15102, Peru
| | - Pamela Orjuela-Sanchez
- Department of Pediatrics, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States
| | - Gabriel Carrasco-Escobar
- Laboratorio ICEMR-Amazonia, Laboratorios de Investigacion y Desarrollo, Facultad de Ciencias y Filosofia, Universidad Peruana Cayetano Heredia, Av. Honorio Delgado 430, San Martín de Porres, Lima, 15102, Peru
| | - Brice Campo
- Medicines for Malaria Venture, Route de Pré-Bois 20, Meyrin, 1215, Switzerland
| | - Dionicia Gamboa
- Laboratorio ICEMR-Amazonia, Laboratorios de Investigacion y Desarrollo, Facultad de Ciencias y Filosofia, Universidad Peruana Cayetano Heredia, Av. Honorio Delgado 430, San Martín de Porres, Lima, 15102, Peru
- Instituto de Medicina Tropical “Alexander von Humboldt”, Universidad Peruana Cayetano Heredia, Lima, 15102, Peru
| | - Elizabeth A. Winzeler
- Department of Pediatrics, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States
| | - Joseph M. Vinetz
- Division of Infectious Diseases, Department of Medicine, School of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States
- Laboratorio ICEMR-Amazonia, Laboratorios de Investigacion y Desarrollo, Facultad de Ciencias y Filosofia, Universidad Peruana Cayetano Heredia, Av. Honorio Delgado 430, San Martín de Porres, Lima, 15102, Peru
- Instituto de Medicina Tropical “Alexander von Humboldt”, Universidad Peruana Cayetano Heredia, Lima, 15102, Peru
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17
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Orjuela-Sanchez P, Villa ZH, Moreno M, Tong-Rios C, Meister S, LaMonte GM, Campo B, Vinetz JM, Winzeler EA. Developing Plasmodium vivax Resources for Liver Stage Study in the Peruvian Amazon Region. ACS Infect Dis 2018. [PMID: 29542317 DOI: 10.1021/acsinfecdis.7b00198] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
To develop new drugs and vaccines for malaria elimination, it will be necessary to discover biological interventions, including small molecules that act against Plasmodium vivax exoerythrocytic forms. However, a robust in vitro culture system for P. vivax is still lacking. Thus, to study exoerythrocytic forms, researchers must have simultaneous access to fresh, temperature-controlled patient blood samples, as well as an anopheline mosquito colony. In addition, researchers must rely on native mosquito species to avoid introducing a potentially dangerous invasive species into a malaria-endemic region. Here, we report an in vitro culture system carried out on site in a malaria-endemic region for liver stage parasites of P. vivax sporozoites obtained from An. darlingi, the main malaria vector in the Americas. P. vivax sporozoites were obtained by dissection of salivary glands from infected An. darlingi mosquitoes and purified by Accudenz density gradient centrifugation. HC04 liver cells were exposed to P. vivax sporozoites and cultured up to 9 days. To overcome low P. vivax patient parasitemias, potentially lower mosquito vectorial capacity, and humid, nonsterile environmental conditions, a new antibiotic cocktail was included in tissue culture to prevent contamination. Culturing conditions supported exoerythrocytic (EEF) P. vivax liver stage growth up to 9 days and allowed for maturation into intrahepatocyte merosomes. Some of the identified small forms were resistant to atovaquone (1 μM) but sensitive to the phosphatidylinositol 4-kinase inhibitor, KDU691 (1 μM). This study reports a field-accessible EEF production process for drug discovery in a malaria-endemic site in which viable P. vivax sporozoites are used for drug studies using hepatocyte infection. Our data demonstrate that the development of meaningful, field-based resources for P. vivax liver stage drug screening and liver stage human malaria experimentation in the Amazon region is feasible.
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Affiliation(s)
- Pamela Orjuela-Sanchez
- Division of Host-Microbe Systems and Therapeutics, Health Sciences Center for Immunology, Infection and Inflammation, Department of Pediatrics, School of Medicine, University of California, San Diego, 9500 Gilman Drive #0760, La Jolla, California 92093-0760, United States
| | - Zaira Hellen Villa
- Laboratorio ICEMR-Amazonia, Laboratorios de Investigacion y Desarrollo, Facultad de Ciencias y Filosofia, Universidad Peruana Cayetano Heredia, Av. Honorio Delgado 430, San Martín de Porres, Lima, 15102, Peru
| | - Marta Moreno
- Division of Infectious Diseases, Department of Medicine, University of California, San Diego, 9500 Gilman Drive #0760, La Jolla, California 92093-0760, United States
| | - Carlos Tong-Rios
- Laboratorio ICEMR-Amazonia, Laboratorios de Investigacion y Desarrollo, Facultad de Ciencias y Filosofia, Universidad Peruana Cayetano Heredia, Av. Honorio Delgado 430, San Martín de Porres, Lima, 15102, Peru
| | - Stephan Meister
- Division of Host-Microbe Systems and Therapeutics, Health Sciences Center for Immunology, Infection and Inflammation, Department of Pediatrics, School of Medicine, University of California, San Diego, 9500 Gilman Drive #0760, La Jolla, California 92093-0760, United States
| | - Gregory M. LaMonte
- Division of Host-Microbe Systems and Therapeutics, Health Sciences Center for Immunology, Infection and Inflammation, Department of Pediatrics, School of Medicine, University of California, San Diego, 9500 Gilman Drive #0760, La Jolla, California 92093-0760, United States
| | - Brice Campo
- Medicines for Malaria Venture (MMV), International Center Cointrin, Block G, 20 Route de Pre-Bois, POB 1826, Geneva, CH-1215, Switzerland
| | - Joseph M. Vinetz
- Laboratorio ICEMR-Amazonia, Laboratorios de Investigacion y Desarrollo, Facultad de Ciencias y Filosofia, Universidad Peruana Cayetano Heredia, Av. Honorio Delgado 430, San Martín de Porres, Lima, 15102, Peru
- Division of Infectious Diseases, Department of Medicine, University of California, San Diego, 9500 Gilman Drive #0760, La Jolla, California 92093-0760, United States
- Instituto de Medicina Tropical “Alexander von Humboldt”, Universidad Peruana Cayetano Heredia, Lima, 15102, Peru
| | - Elizabeth A. Winzeler
- Division of Host-Microbe Systems and Therapeutics, Health Sciences Center for Immunology, Infection and Inflammation, Department of Pediatrics, School of Medicine, University of California, San Diego, 9500 Gilman Drive #0760, La Jolla, California 92093-0760, United States
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18
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Yamamoto DS, Sumitani M, Hatakeyama M, Matsuoka H. Malaria infectivity of xanthurenic acid-deficient anopheline mosquitoes produced by TALEN-mediated targeted mutagenesis. Transgenic Res 2018; 27:51-60. [DOI: 10.1007/s11248-018-0057-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Accepted: 01/11/2018] [Indexed: 12/15/2022]
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19
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Brancucci NMB, Gerdt JP, Wang C, De Niz M, Philip N, Adapa SR, Zhang M, Hitz E, Niederwieser I, Boltryk SD, Laffitte MC, Clark MA, Grüring C, Ravel D, Blancke Soares A, Demas A, Bopp S, Rubio-Ruiz B, Conejo-Garcia A, Wirth DF, Gendaszewska-Darmach E, Duraisingh MT, Adams JH, Voss TS, Waters AP, Jiang RHY, Clardy J, Marti M. Lysophosphatidylcholine Regulates Sexual Stage Differentiation in the Human Malaria Parasite Plasmodium falciparum. Cell 2017; 171:1532-1544.e15. [PMID: 29129376 PMCID: PMC5733390 DOI: 10.1016/j.cell.2017.10.020] [Citation(s) in RCA: 192] [Impact Index Per Article: 27.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Revised: 07/17/2017] [Accepted: 10/12/2017] [Indexed: 01/11/2023]
Abstract
Transmission represents a population bottleneck in the Plasmodium life cycle and a key intervention target of ongoing efforts to eradicate malaria. Sexual differentiation is essential for this process, as only sexual parasites, called gametocytes, are infective to the mosquito vector. Gametocyte production rates vary depending on environmental conditions, but external stimuli remain obscure. Here, we show that the host-derived lipid lysophosphatidylcholine (LysoPC) controls P. falciparum cell fate by repressing parasite sexual differentiation. We demonstrate that exogenous LysoPC drives biosynthesis of the essential membrane component phosphatidylcholine. LysoPC restriction induces a compensatory response, linking parasite metabolism to the activation of sexual-stage-specific transcription and gametocyte formation. Our results reveal that malaria parasites can sense and process host-derived physiological signals to regulate differentiation. These data close a critical knowledge gap in parasite biology and introduce a major component of the sexual differentiation pathway in Plasmodium that may provide new approaches for blocking malaria transmission.
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Affiliation(s)
- Nicolas M B Brancucci
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK; Harvard T.H. Chan School of Public Health, Department of Immunology and Infectious Diseases, Boston, MA 02155, USA
| | - Joseph P Gerdt
- Harvard Medical School, Department of Biological Chemistry and Molecular Pharmacology, Boston, MA 02155, USA
| | - ChengQi Wang
- Center for Global Health & Infectious Diseases Research, Department of Global Health, College of Public Health, University of South Florida, Tampa, FL 33620, USA
| | - Mariana De Niz
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK; Harvard T.H. Chan School of Public Health, Department of Immunology and Infectious Diseases, Boston, MA 02155, USA
| | - Nisha Philip
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK; Centre for Immunity, Infection and Evolution, Institute for Immunology and Infection Research, University of Edinburgh, Edinburgh EH9 3FL, UK
| | - Swamy R Adapa
- Center for Global Health & Infectious Diseases Research, Department of Global Health, College of Public Health, University of South Florida, Tampa, FL 33620, USA
| | - Min Zhang
- Center for Global Health & Infectious Diseases Research, Department of Global Health, College of Public Health, University of South Florida, Tampa, FL 33620, USA
| | - Eva Hitz
- Swiss Tropical and Public Health Institute, 4051 Basel, Switzerland; University of Basel, 4001 Basel, Switzerland
| | - Igor Niederwieser
- Swiss Tropical and Public Health Institute, 4051 Basel, Switzerland; University of Basel, 4001 Basel, Switzerland
| | - Sylwia D Boltryk
- Swiss Tropical and Public Health Institute, 4051 Basel, Switzerland; University of Basel, 4001 Basel, Switzerland
| | - Marie-Claude Laffitte
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Martha A Clark
- Harvard T.H. Chan School of Public Health, Department of Immunology and Infectious Diseases, Boston, MA 02155, USA
| | - Christof Grüring
- Harvard T.H. Chan School of Public Health, Department of Immunology and Infectious Diseases, Boston, MA 02155, USA
| | - Deepali Ravel
- Harvard T.H. Chan School of Public Health, Department of Immunology and Infectious Diseases, Boston, MA 02155, USA
| | - Alexandra Blancke Soares
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Allison Demas
- Harvard T.H. Chan School of Public Health, Department of Immunology and Infectious Diseases, Boston, MA 02155, USA
| | - Selina Bopp
- Harvard T.H. Chan School of Public Health, Department of Immunology and Infectious Diseases, Boston, MA 02155, USA
| | - Belén Rubio-Ruiz
- Department of Pharmaceutical and Organic Chemistry, Faculty of Pharmacy, University of Granada, 18010 Granada, Spain
| | - Ana Conejo-Garcia
- Department of Pharmaceutical and Organic Chemistry, Faculty of Pharmacy, University of Granada, 18010 Granada, Spain
| | - Dyann F Wirth
- Harvard T.H. Chan School of Public Health, Department of Immunology and Infectious Diseases, Boston, MA 02155, USA
| | - Edyta Gendaszewska-Darmach
- Institute of Technical Biochemistry, Faculty of Biotechnology and Food Sciences, Lodz University of Technology, 90-924 Lodz, Poland
| | - Manoj T Duraisingh
- Harvard T.H. Chan School of Public Health, Department of Immunology and Infectious Diseases, Boston, MA 02155, USA
| | - John H Adams
- Center for Global Health & Infectious Diseases Research, Department of Global Health, College of Public Health, University of South Florida, Tampa, FL 33620, USA
| | - Till S Voss
- Swiss Tropical and Public Health Institute, 4051 Basel, Switzerland; University of Basel, 4001 Basel, Switzerland
| | - Andrew P Waters
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Rays H Y Jiang
- Center for Global Health & Infectious Diseases Research, Department of Global Health, College of Public Health, University of South Florida, Tampa, FL 33620, USA
| | - Jon Clardy
- Harvard Medical School, Department of Biological Chemistry and Molecular Pharmacology, Boston, MA 02155, USA.
| | - Matthias Marti
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK; Harvard T.H. Chan School of Public Health, Department of Immunology and Infectious Diseases, Boston, MA 02155, USA.
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20
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Modulation of transmission success of Plasmodium falciparum gametocytes (sexual stages) in various species of Anopheles by erythrocytic asexual stage parasites. Acta Trop 2017; 176:263-269. [PMID: 28859956 DOI: 10.1016/j.actatropica.2017.08.027] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Revised: 08/23/2017] [Accepted: 08/26/2017] [Indexed: 12/15/2022]
Abstract
During malaria infection, a small proportion of erythrocytic asexual stages undergo sexual differentiation. Male and female gametocytes ingested in the blood meal initiate the sexual development of malaria parasites in the mosquito midgut. During blood feeding on a host, a mosquito ingests, in addition to mature gametocytes, host immune factors present in the blood, as well as large excess of erythrocytic asexual stages. In the current study we addressed the impact of the presence of large excess of asexual stages, hitherto not known or even suspected to influence, on the infectivity of gametocytes in the mosquito. Asexual stages resulted in a dose-dependent inhibition of infectiousness of gametocytes, and some of this could be explained by the presumed effect of hemozoin and other unknown asexual-stage components on the mosquito immune system, affecting survival and maturation of parasites in the mosquito midgut. Interactions between asexual and sexual stages, maturity and ratio of male and female gametocytes, host immune factors and mosquito innate immune factors are some of the variables that determine the infectiousness of gametocytes in the mosquitoes and ultimately malaria transmission success. Understanding of determinants affecting malaria transmission will be critical to approaches directly targeting the transmission process for malaria elimination.
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21
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Plasmodium berghei P47 is essential for ookinete protection from the Anopheles gambiae complement-like response. Sci Rep 2017; 7:6026. [PMID: 28729672 PMCID: PMC5519742 DOI: 10.1038/s41598-017-05917-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 06/06/2017] [Indexed: 11/26/2022] Open
Abstract
Malaria is a mosquito-borne disease affecting millions of people every year. The rodent parasite Plasmodium berghei has served as a model for human malaria transmission studies and played a pivotal role in dissecting the mosquito immune response against infection. The 6-cysteine protein P47, known to be important for P. berghei female gamete fertility, is shown to serve a different function in Plasmodium falciparum, protecting ookinetes from the mosquito immune response. Here, we investigate the function of P. berghei P47 in Anopheles gambiae mosquito infections. We show that P47 is expressed on the surface of both female gametocytes and ookinetes where it serves distinct functions in promoting gametocyte-to-ookinete development and protecting ookinetes from the mosquito complement-like response, respectively. The latter function is essential, as ookinetes lacking P47 are targeted for killing while traversing the mosquito midgut cells and eliminated upon exposure to hemolymph proteins of the complement-like system. Silencing key factors of the complement-like system restores oocyst development and disease transmission to rodent hosts. Our data establish a dual role of P. berghei P47 in vivo and reinforce the use of this parasite to study the impact of the mosquito immune response on human malaria transmission.
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22
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Bioluminescence Method for In Vitro Screening of Plasmodium Transmission-Blocking Compounds. Antimicrob Agents Chemother 2017; 61:AAC.02699-16. [PMID: 28348156 PMCID: PMC5444155 DOI: 10.1128/aac.02699-16] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 03/23/2017] [Indexed: 12/12/2022] Open
Abstract
The sporogonic stage of the life cycle of Plasmodium spp., the causative agents of malaria, occurs inside the parasite's mosquito vector, where a process of fertilization, meiosis, and mitotic divisions culminates in the generation of large numbers of mammalian-infective sporozoites. Efforts to cultivate Plasmodium mosquito stages in vitro have proved challenging and yielded only moderate success. Here, we describe a methodology that simplifies the in vitro screening of much-needed transmission-blocking (TB) compounds employing a bioluminescence-based method to monitor the in vitro development of sporogonic stages of the rodent malaria parasite Plasmodium berghei. Our proof-of-principle assessment of the in vitro TB activity of several commonly used antimalarial compounds identified cycloheximide, thiostrepton, and atovaquone as the most active compounds against the parasite's sporogonic stages. The TB activity of these compounds was further confirmed by in vivo studies that validated our newly developed in vitro approach to TB compound screening.
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23
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Abstract
This article attempts to draw together current knowledge on the biology of Plasmodium and experience gained from past control campaigns to interpret and guide current efforts to discover and develop exciting new strategies targeting the parasite with the objective of interrupting transmission. Particular note is made of the advantages of targeting often unappreciated small, yet vital, bottleneck populations to enhance both the impact and the useful lifetime of hard-won interventions. A case is made for the standardization of methods to measure transmission blockade to permit the rational comparison of how diverse interventions (drugs, vaccines, insecticides, Genetically Modified technologies) targeting disparate aspects of parasite biology may impact upon the commonly used parameter of parasite prevalence in the human population.
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Affiliation(s)
- R E Sinden
- The Jenner Institute, Oxford, United Kingdom.
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24
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Carter LM, Pollitt LC, Wilson LG, Reece SE. Ecological influences on the behaviour and fertility of malaria parasites. Malar J 2016; 15:220. [PMID: 27091194 PMCID: PMC4835847 DOI: 10.1186/s12936-016-1271-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2015] [Accepted: 04/01/2016] [Indexed: 12/26/2022] Open
Abstract
Background Sexual reproduction in the mosquito is essential for the transmission of malaria parasites and a major target for transmission-blocking interventions. Male gametes need to locate and fertilize females in the challenging environment of the mosquito blood meal, but remarkably little is known about the ecology and behaviour of male gametes. Methods Here, a series of experiments explores how some aspects of the chemical and physical environment experienced during mating impacts upon the production, motility, and fertility of male gametes. Results and conclusions Specifically, the data confirm that: (a) rates of male gametogenesis vary when induced by the family of compounds (tryptophan metabolites) thought to trigger gamete differentiation in nature; and (b) complex relationships between gametogenesis and mating success exist across parasite species. In addition, the data reveal that (c) microparticles of the same size as red blood cells negatively affect mating success; and (d) instead of swimming in random directions, male gametes may be attracted by female gametes. Understanding the mating ecology of malaria parasites, may offer novel approaches for blocking transmission and explain adaptation to different species of mosquito vectors. Electronic supplementary material The online version of this article (doi:10.1186/s12936-016-1271-0) contains supplementary material, which is available to authorized users.
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25
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Zheng W, Kou X, Du Y, Liu F, Yu C, Tsuboi T, Fan Q, Luo E, Cao Y, Cui L. Identification of three ookinete-specific genes and evaluation of their transmission-blocking potentials in Plasmodium berghei. Vaccine 2016; 34:2570-8. [PMID: 27083421 DOI: 10.1016/j.vaccine.2016.04.011] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 03/12/2016] [Accepted: 04/05/2016] [Indexed: 12/31/2022]
Abstract
With a renewed hope for malaria elimination, interventions that prevent transmission of parasites from humans to mosquitoes have received elevated attention. Transmission-blocking vaccines (TBVs) targeting the sexual stages are well suited for this task. Here, through bioinformatic analysis, we selected two putative Plasmodium berghei ookinete-stage proteins (PBANKA_111920, and PBANKA_145770) and a previously characterized ookinete protein PBANKA_135340 (PSOP7) for evaluation of their transmission-blocking potentials. Fragments of these predicted proteins were expressed in bacteria and purified recombinant proteins were used to immunize mice. Antisera against these recombinant proteins recognized proteins of predicted sizes from ookinete lysates and localized their expression on the surface of ookinetes. Inclusion of these antisera in in vitro ookinete culture significantly inhibited ookinete formation. Mosquitoes fed on mice immunized with the recombinant proteins also showed significantly reduced oocyst densities (60.0-70.7%) and modest reductions of oocyst prevalence (10.7-37.4%). These data, together with the conservation of these genes in Plasmodium, suggest that these three ookinete proteins could be new promising targets for TBVs and are worth of future investigations in the human malaria parasites.
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Affiliation(s)
- Wenqi Zheng
- Department of Pathogen Biology, College of Basic Medical Sciences, China Medical University, Shenyang, Liaoning 110001, China
| | - Xu Kou
- Department of Pathogen Biology, College of Basic Medical Sciences, China Medical University, Shenyang, Liaoning 110001, China; College of Animal Husbandry and Veterinary, Liaoning Medical University, Jinzhou, Liaoning 121001, China
| | - Yunting Du
- Department of Immunology, College of Basic Medical Sciences, China Medical University, Shenyang, Liaoning 110001, China
| | - Fei Liu
- Department of Immunology, College of Basic Medical Sciences, China Medical University, Shenyang, Liaoning 110001, China
| | - Chunyun Yu
- Department of Immunology, College of Basic Medical Sciences, China Medical University, Shenyang, Liaoning 110001, China
| | - Takafumi Tsuboi
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Ehime 790-8577, Japan
| | - Qi Fan
- Dalian Institute of Biotechnology, Dalian, Liaoning, China
| | - Enjie Luo
- Department of Pathogen Biology, College of Basic Medical Sciences, China Medical University, Shenyang, Liaoning 110001, China.
| | - Yaming Cao
- Department of Immunology, College of Basic Medical Sciences, China Medical University, Shenyang, Liaoning 110001, China.
| | - Liwang Cui
- Department of Entomology, Pennsylvania State University, University Park, PA 16802, USA
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26
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Inhibition of Plasmodium berghei Development in Mosquitoes by Effector Proteins Secreted from Asaia sp. Bacteria Using a Novel Native Secretion Signal. PLoS One 2015; 10:e0143541. [PMID: 26636338 PMCID: PMC4670117 DOI: 10.1371/journal.pone.0143541] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Accepted: 11/05/2015] [Indexed: 11/25/2022] Open
Abstract
Novel interventions are needed to prevent the transmission of the Plasmodium parasites that cause malaria. One possible method is to supply mosquitoes with antiplasmodial effector proteins from bacteria by paratransgenesis. Mosquitoes have a diverse complement of midgut microbiota including the Gram-negative bacteria Asaia bogorensis. This study presents the first use of Asaia sp. bacteria for paratransgenesis against P. berghei. We identified putative secreted proteins from A. bogorensis by a genetic screen using alkaline phosphatase gene fusions. Two were secreted efficiently: a siderophore receptor protein and a YVTN beta-propeller repeat protein. The siderophore receptor gene was fused with antiplasmodial effector genes including the scorpine antimicrobial peptide and an anti-Pbs21 scFv-Shiva1 immunotoxin. Asaia SF2.1 secreting these fusion proteins were fed to mosquitoes and challenged with Plasmodium berghei-infected blood. With each of these effector constructs, significant inhibition of parasite development was observed. These results provide a novel and promising intervention against malaria transmission.
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27
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Ning J, Otto TD, Pfander C, Schwach F, Brochet M, Bushell E, Goulding D, Sanders M, Lefebvre PA, Pei J, Grishin NV, Vanderlaan G, Billker O, Snell WJ. Comparative genomics in Chlamydomonas and Plasmodium identifies an ancient nuclear envelope protein family essential for sexual reproduction in protists, fungi, plants, and vertebrates. Genes Dev 2013; 27:1198-215. [DOI: 10.1101/gad.212746.112] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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28
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Johnston GL, Smith DL, Fidock DA. Malaria's missing number: calculating the human component of R0 by a within-host mechanistic model of Plasmodium falciparum infection and transmission. PLoS Comput Biol 2013; 9:e1003025. [PMID: 23637586 PMCID: PMC3630126 DOI: 10.1371/journal.pcbi.1003025] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2012] [Accepted: 02/25/2013] [Indexed: 11/18/2022] Open
Abstract
Human infection by malarial parasites of the genus Plasmodium begins with the bite of an infected Anopheles mosquito. Current estimates place malaria mortality at over 650,000 individuals each year, mostly in African children. Efforts to reduce disease burden can benefit from the development of mathematical models of disease transmission. To date, however, comprehensive modeling of the parameters defining human infectivity to mosquitoes has remained elusive. Here, we describe a mechanistic within-host model of Plasmodium falciparum infection in humans and pathogen transmission to the mosquito vector. Our model incorporates the entire parasite lifecycle, including the intra-erythrocytic asexual forms responsible for disease, the onset of symptoms, the development and maturation of intra-erythrocytic gametocytes that are transmissible to Anopheles mosquitoes, and human-to-mosquito infectivity. These model components were parameterized from malaria therapy data and other studies to simulate individual infections, and the ensemble of outputs was found to reproduce the full range of patient responses to infection. Using this model, we assessed human infectivity over the course of untreated infections and examined the effects in relation to transmission intensity, expressed by the basic reproduction number R0 (defined as the number of secondary cases produced by a single typical infection in a completely susceptible population). Our studies predict that net human-to-mosquito infectivity from a single non-immune individual is on average equal to 32 fully infectious days. This estimate of mean infectivity is equivalent to calculating the human component of malarial R0. We also predict that mean daily infectivity exceeds five percent for approximately 138 days. The mechanistic framework described herein, made available as stand-alone software, will enable investigators to conduct detailed studies into theories of malaria control, including the effects of drug treatment and drug resistance on transmission. We report a new mathematical model of the progression, within a human host, of a malaria infection caused by the parasite Plasmodium falciparum. This model incorporates probability distributions for the key parameters of infection and transmission so that model outputs match the entire range of observed responses in patients, without the requirement for fitting individual data. Further, we simulate the daily densities of both the disease-causing and transmissible forms of the parasite within an individual, as well as the onset of fever and the probability of parasite transmission to mosquitoes. This model allows us to reproduce aspects of infection that are critical for malaria control modeling. As a first application, we calculate the net infectiousness of humans to mosquitoes and predict that net human infectivity from a single infection is on average equal to approximately 32 fully infectious days. This value has been used to help map the worldwide intensity of malaria transmission. We also predict that mean daily infectivity is greater than five percent for approximately 138 days. Our modeling framework, available as downloadable software, will allow researchers to probe the effects of treatment and drug resistance on malaria transmission in unprecedented detail, helping to improve malaria control efforts.
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Affiliation(s)
- Geoffrey L. Johnston
- Department of Microbiology and Immunology, Columbia University College of Physicians and Surgeons, New York, New York, United States of America
- School of International and Public Affairs, Columbia University, New York, New York, United States of America
- Bloomberg School of Public Health, John Hopkins University, Baltimore, Maryland, United States of America
| | - David L. Smith
- Bloomberg School of Public Health, John Hopkins University, Baltimore, Maryland, United States of America
- * E-mail: (DLS); (DAF)
| | - David A. Fidock
- Department of Microbiology and Immunology, Columbia University College of Physicians and Surgeons, New York, New York, United States of America
- Division of Infectious Diseases, Department of Medicine, Columbia University College of Physicians and Surgeons, New York, New York, United States of America
- * E-mail: (DLS); (DAF)
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29
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Wenger EA, Eckhoff PA. A mathematical model of the impact of present and future malaria vaccines. Malar J 2013; 12:126. [PMID: 23587051 PMCID: PMC3658952 DOI: 10.1186/1475-2875-12-126] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Accepted: 03/20/2013] [Indexed: 11/30/2022] Open
Abstract
Background With the encouraging advent of new malaria vaccine candidates, mathematical modelling of expected impacts of present and future vaccines as part of multi-intervention strategies is especially relevant. Methods The impact of potential malaria vaccines is presented utilizing the EMOD model, a comprehensive model of the vector life cycle coupled to a detailed mechanistic representation of intra-host parasite and immune dynamics. Values of baseline transmission and vector feeding behaviour parameters are identified, for which local elimination is enabled by layering pre-erythrocytic vaccines of various efficacies on top of high and sustained insecticide-treated net coverage. The expected reduction in clinical cases is further explored in a scenario that targets children by adding a pre-erythrocytic vaccine to the EPI programme for newborns. Results At high transmission, there is a minimal reduction in clinical disease cases, as the time to infection is only slightly delayed. At lower transmission, there is an accelerating community-level protection that has subtle dependences on heterogeneities in vector behaviour, ecology, and intervention coverage. At very low transmission, the trend reverses as many children are vaccinated to prevent few cases. Conclusions The maximum-impact setting is one in which the impact of increasing bed net coverage has saturated, vector feeding is primarily outdoors, and transmission is just above the threshold where small perturbations from a vaccine intervention result in large community benefits.
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30
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Eckhoff PA. Malaria parasite diversity and transmission intensity affect development of parasitological immunity in a mathematical model. Malar J 2012; 11:419. [PMID: 23241282 PMCID: PMC3557182 DOI: 10.1186/1475-2875-11-419] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2012] [Accepted: 12/13/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The development of parasitological immunity against malaria affects the ability to detect infection, the efficiency of the local human parasite reservoir at infecting mosquitoes, and the response to reintroduction of parasites to previously cleared areas. Observations of similar age-trends in detected prevalence and mean parasitaemia across more than an order-of-magnitude of variation in baseline transmission complicate simple exposure-driven explanations. METHODS Mathematical models often employ age-dependent immune factors to match the observed trends, while the present model uses a new detailed mechanistic model of parasite transmission dynamics to explain age-trends through the mechanism of parasite diversity. Illustrative simulations are performed for multiple field sites in Tanzania and Nigeria, and observed age-trends and seasonality in parasite prevalence are recreated in silico, proffering possible mechanistic explanations of the observational data. RESULTS Observed temporal dynamics in measured parasitaemia are recreated for each location and age-prevalence outputs are studied. Increasing population-level diversity in malaria surface antigens delays development of broad parasitological immunity. A local parasite population with high diversity can recreate the observed trends in age-prevalence across more than an order of magnitude of variation in transmission intensities. CONCLUSIONS Mechanistic models of human immunity and parasite antigen diversity can recreate the observed temporal patterns for the development of parasitological immunity across a wide range of transmission intensities. This has implications for the distribution of disease burden across the population, the human transmission reservoir, design of elimination campaigns, and development and roll-out of potential vaccines.
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Affiliation(s)
- Philip A Eckhoff
- Intellectual Ventures Laboratory, 1600 132nd Ave NE, Bellevue, WA 98004, USA.
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31
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A high-throughput assay for the identification of malarial transmission-blocking drugs and vaccines. Int J Parasitol 2012; 42:999-1006. [PMID: 23023046 DOI: 10.1016/j.ijpara.2012.08.009] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Revised: 07/16/2012] [Accepted: 08/21/2012] [Indexed: 11/21/2022]
Abstract
Following the cessation of the global malaria eradication initiative in the 1970s, the prime objective of malarial intervention has been to reduce morbidity and mortality. This motivated the development of high throughput assays to determine the impact of interventions on asexual bloodstage parasites. In response to the new eradication agenda, interrupting parasite transmission from the human to the mosquito has been recognised as an important and additional target for intervention. Current assays for Plasmodium mosquito stage development are very low throughput and resource intensive, and are therefore inappropriate for high throughput screening. Using an ookinete-specific GFP reporter strain of the rodent parasite Plasmodium berghei, it has been possible to develop and validate a high biological complexity, high throughput bioassay that can rapidly, reproducibly and accurately evaluate the effect of transmission-blocking drugs or vaccines on the ability of host-derived gametocytes to undergo the essential onward steps of gamete formation, fertilisation and ookinete maturation. This assay may greatly accelerate the development of malaria transmission-blocking interventions.
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32
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Eckhoff P. P. falciparum infection durations and infectiousness are shaped by antigenic variation and innate and adaptive host immunity in a mathematical model. PLoS One 2012; 7:e44950. [PMID: 23028698 PMCID: PMC3446976 DOI: 10.1371/journal.pone.0044950] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Accepted: 08/14/2012] [Indexed: 11/29/2022] Open
Abstract
Many questions remain about P. falciparum within-host dynamics, immunity, and transmission–issues that may affect public health campaign planning. These gaps in knowledge concern the distribution of durations of malaria infections, determination of peak parasitemia during acute infection, the relationships among gametocytes and immune responses and infectiousness to mosquitoes, and the effect of antigenic structure on reinfection outcomes. The present model of intra-host dynamics of P. falciparum implements detailed representations of parasite and immune dynamics, with structures based on minimal extrapolations from first-principles biology in its foundations. The model is designed to quickly and readily accommodate gains in mechanistic understanding and to evaluate effects of alternative biological hypothesis through in silico experiments. Simulations follow the parasite from the liver-stage through the detailed asexual cycle to clearance while tracking gametocyte populations. The modeled immune system includes innate inflammatory and specific antibody responses to a repertoire of antigens. The mechanistic focus provides clear explanations for the structure of the distribution of infection durations through the interaction of antigenic variation and innate and adaptive immunity. Infectiousness to mosquitoes appears to be determined not only by the density of gametocytes but also by the level of inflammatory cytokines, which harmonizes an extensive series of study results. Finally, pre-existing immunity can either decrease or increase the duration of infections upon reinfection, depending on the degree of overlap in antigenic repertoires and the strength of the pre-existing immunity.
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Affiliation(s)
- Philip Eckhoff
- Intellectual Ventures, Bellevue, Washington, United States of America.
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33
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Sinden RE, Carter R, Drakeley C, Leroy D. The biology of sexual development of Plasmodium: the design and implementation of transmission-blocking strategies. Malar J 2012; 11:70. [PMID: 22424474 PMCID: PMC3315749 DOI: 10.1186/1475-2875-11-70] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2011] [Accepted: 03/16/2012] [Indexed: 12/15/2022] Open
Abstract
A meeting to discuss the latest developments in the biology of sexual development of Plasmodium and transmission-control was held April 5-6, 2011, in Bethesda, MD. The meeting was sponsored by the Bill & Melinda Gates Foundation and the National Institutes of Health, National Institute of Allergy and Infectious Diseases (NIH/NIAID) in response to the challenge issued at the Malaria Forum in October 2007 that the malaria community should re-engage with the objective of global eradication. The consequent rebalancing of research priorities has brought to the forefront of the research agenda the essential need to reduce parasite transmission. A key component of any transmission reduction strategy must be methods to attack the parasite as it passes from man to the mosquito (and vice versa). Such methods must be rationally based on a secure understanding of transmission from the molecular-, cellular-, population- to the evolutionary-levels. The meeting represented a first attempt to draw together scientists with expertise in these multiple layers of understanding to discuss the scientific foundations and resources that will be required to provide secure progress toward the design and successful implementation of effective interventions.
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Affiliation(s)
- Robert E Sinden
- The Jenner Institute, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford OX3 7DQ, UK.
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34
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Liu Z, Miao J, Cui L. Gametocytogenesis in malaria parasite: commitment, development and regulation. Future Microbiol 2012; 6:1351-69. [PMID: 22082293 DOI: 10.2217/fmb.11.108] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Malaria parasites have evolved a complicated life cycle alternating between two hosts. Gametocytes are produced in the vertebrate hosts and are obligatory for natural transmission of the parasites through mosquito vectors. The mechanism of sexual development in Plasmodium has been the focus of extensive studies. In the postgenomic era, the advent of genome-wide analytical tools and genetic manipulation technology has enabled rapid advancement of our knowledge in this area. Patterns of gene expression during sexual development, molecular distinction of the two sexes, and mechanisms underlying subsequent formation of gametes and their fertilization have been progressively elucidated. However, the triggers and mechanism of sexual development remain largely unknown. This article provides an update of our understanding of the molecular and cellular events associated with the decision for commitment to sexual development and regulation of gene expression during gametocytogenesis. Insights into the molecular mechanisms of gametocyte development are essential for designing proper control strategies for interruption of malaria transmission and ultimate elimination.
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Affiliation(s)
- Zhenyu Liu
- Department of Entomology, The Pennsylvania State University, 537 ASI Building University Park, PA 16802, USA
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35
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Eckhoff PA. A malaria transmission-directed model of mosquito life cycle and ecology. Malar J 2011; 10:303. [PMID: 21999664 PMCID: PMC3224385 DOI: 10.1186/1475-2875-10-303] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Accepted: 10/17/2011] [Indexed: 01/21/2023] Open
Abstract
Background Malaria is a major public health issue in much of the world, and the mosquito vectors which drive transmission are key targets for interventions. Mathematical models for planning malaria eradication benefit from detailed representations of local mosquito populations, their natural dynamics and their response to campaign pressures. Methods A new model is presented for mosquito population dynamics, effects of weather, and impacts of multiple simultaneous interventions. This model is then embedded in a large-scale individual-based simulation and results for local elimination of malaria are discussed. Mosquito population behaviours, such as anthropophily and indoor feeding, are included to study their effect upon the efficacy of vector control-based elimination campaigns. Results Results for vector control tools, such as bed nets, indoor spraying, larval control and space spraying, both alone and in combination, are displayed for a single-location simulation with vector species and seasonality characteristic of central Tanzania, varying baseline transmission intensity and vector bionomics. The sensitivities to habitat type, anthropophily, indoor feeding, and baseline transmission intensity are explored. Conclusions The ability to model a spectrum of local vector species with different ecologies and behaviours allows local customization of packages of interventions and exploration of the effect of proposed new tools.
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Affiliation(s)
- Philip A Eckhoff
- Intellectual Ventures Laboratory, 1600 132nd Ave NE, Bellevue, WA 98004, USA.
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Shahabuddin M, Cociancich S, Zieler H. The Search for Novel Malaria Transmission-blocking Targets in the Mosquito Midgut. ACTA ACUST UNITED AC 2011; 14:493-7. [PMID: 17040863 DOI: 10.1016/s0169-4758(98)01348-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The need for new malaria control strategies has led to increased efforts to understand more clearly the mosquito stages of Plasmodium. The absolute requirement of gamete maturation and fertilization, transformation of sedentary zygote to motile ookinete, ookinete interaction and invasion of gut epithelium, and the survival of the mosquito against immune attack suggest that numerous unidentified targets exist, which could be modified to achieve transmission-blocking of malaria. In the search for new transmission-blocking targets in the mosquito gut, Mohammed Shahabuddin, Stéphane Cociancich and Helge Zieler here summarize recent studies to identify the cellular and biochemical factors that affect the malaria parasite's development; in particular, factors influencing the early development of Plasmodium, receptor-mediated interactions between the parasite and the mosquito midgut, and the gut-associated immune responses directed against Plasmodium.
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Affiliation(s)
- M Shahabuddin
- Medical Entomology Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892-0425, USA
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Raabe AC, Wengelnik K, Billker O, Vial HJ. Multiple roles for Plasmodium berghei phosphoinositide-specific phospholipase C in regulating gametocyte activation and differentiation. Cell Microbiol 2011; 13:955-66. [PMID: 21518218 PMCID: PMC3132445 DOI: 10.1111/j.1462-5822.2011.01591.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Critical events in the life cycle of malaria parasites are controlled by calcium-dependent signalling cascades, yet the molecular mechanisms of calcium release remain poorly understood. The synchronized development of Plasmodium berghei gametocytes relies on rapid calcium release from internal stores within 10 s of gametocytes being exposed to mosquito-derived xanthurenic acid (XA). Here we addressed the function of phosphoinositide-specific phospholipase C (PI-PLC) for regulating gametocyte activation. XA triggered the hydrolysis of PIP2 and the production of the secondary messenger IP3 in gametocytes. Both processes were selectively blocked by a PI-PLC inhibitor, which also reduced the early Ca2+ signal. However, microgametocyte differentiation into microgametes was blocked even when the inhibitor was added up to 5 min after activation, suggesting a requirement for PI-PLC beyond the early mobilization of calcium. In contrast, inhibitors of calcium release through ryanodine receptor channels were active only during the first minute of gametocyte activation. Biochemical determination of PI-PLC activity was confirmed using transgenic parasites expressing a fluorescent PIP2/IP3 probe that translocates from the parasite plasmalemma to the cytosol upon cell activation. Our study revealed a complex interdependency of Ca2+ and PI-PLC activity, with PI-PLC being essential throughout gamete formation, possibly explaining the irreversibility of this process.
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Affiliation(s)
- Andreas C Raabe
- UMR5235, CNRS-Université Montpellier 2, Place Eugène Bataillon, Montpellier cedex 5, France
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Sologub L, Kuehn A, Kern S, Przyborski J, Schillig R, Pradel G. Malaria proteases mediate inside-out egress of gametocytes from red blood cells following parasite transmission to the mosquito. Cell Microbiol 2011; 13:897-912. [DOI: 10.1111/j.1462-5822.2011.01588.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Bousema T, Drakeley C. Epidemiology and infectivity of Plasmodium falciparum and Plasmodium vivax gametocytes in relation to malaria control and elimination. Clin Microbiol Rev 2011; 24:377-410. [PMID: 21482730 PMCID: PMC3122489 DOI: 10.1128/cmr.00051-10] [Citation(s) in RCA: 508] [Impact Index Per Article: 39.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Malaria remains a major cause of morbidity and mortality in the tropics, with Plasmodium falciparum responsible for the majority of the disease burden and P. vivax being the geographically most widely distributed cause of malaria. Gametocytes are the sexual-stage parasites that infect Anopheles mosquitoes and mediate the onward transmission of the disease. Gametocytes are poorly studied despite this crucial role, but with a recent resurgence of interest in malaria elimination, the study of gametocytes is in vogue. This review highlights the current state of knowledge with regard to the development and longevity of P. falciparum and P. vivax gametocytes in the human host and the factors influencing their distribution within endemic populations. The evidence for immune responses, antimalarial drugs, and drug resistance influencing infectiousness to mosquitoes is reviewed. We discuss how the application of molecular techniques has led to the identification of submicroscopic gametocyte carriage and to a reassessment of the human infectious reservoir. These components are drawn together to show how control measures that aim to reduce malaria transmission, such as mass drug administration and a transmission-blocking vaccine, might better be deployed.
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Affiliation(s)
- Teun Bousema
- Department of Immunology & Infection, London School of Hygiene and Tropical Medicine, London W1CE 7HT, United Kingdom
| | - Chris Drakeley
- Department of Immunology & Infection, London School of Hygiene and Tropical Medicine, London W1CE 7HT, United Kingdom
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Bousema T, Sutherland CJ, Churcher TS, Mulder B, Gouagna LC, Riley EM, Targett GA, Drakeley CJ. Human immune responses that reduce the transmission of Plasmodium falciparum in African populations. Int J Parasitol 2011; 41:293-300. [PMID: 20974145 PMCID: PMC3052432 DOI: 10.1016/j.ijpara.2010.09.008] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2010] [Revised: 09/20/2010] [Accepted: 09/21/2010] [Indexed: 12/04/2022]
Abstract
Malaria-infected individuals can develop antibodies which reduce the infectiousness of Plasmodium gametocytes to biting Anopheles mosquitoes. When ingested in a bloodmeal together with gametocytes, these antibodies reduce or prevent subsequent parasite maturation in the insect host. This transmission-blocking immunity is usually measured in human sera by testing its effect on the infectivity of gametocytes grown in vitro. Here we evaluate evidence of transmission-blocking immunity in eight studies conducted in three African countries. Plasmodium falciparum gametocytes isolated from each individual were fed to mosquitoes in both autologous plasma collected with the parasites, and permissive serum from non-exposed donors. Evidence of transmission reducing effects of autologous plasma was found in all countries. Experiments involving 116 Gambian children (aged 0.5-15 years) were combined to determine which factors were associated with transmission reducing immune responses. The chances of infecting at least one mosquito and the average proportion of infected mosquitoes were negatively associated with recent exposure to gametocytes and sampling late in the season. These results suggest that effective malaria transmission-reducing antibodies do not commonly circulate in African children, and that recent gametocyte carriage is required to initiate and/or boost such responses.
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Affiliation(s)
- Teun Bousema
- Department of Immunology and Infection, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
| | - Colin J. Sutherland
- Department of Immunology and Infection, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
| | - Thomas S. Churcher
- Department of Infectious Disease Epidemiology, Faculty of Medicine, Imperial College London, London, UK
| | - Bert Mulder
- Microbiology Laboratory Twente, Enschede, The Netherlands
| | | | - Eleanor M. Riley
- Department of Immunology and Infection, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
| | - Geoffrey A.T. Targett
- Department of Immunology and Infection, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
| | - Chris J. Drakeley
- Department of Immunology and Infection, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
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Influence of climate on malaria transmission depends on daily temperature variation. Proc Natl Acad Sci U S A 2010; 107:15135-9. [PMID: 20696913 DOI: 10.1073/pnas.1006422107] [Citation(s) in RCA: 310] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Malaria transmission is strongly influenced by environmental temperature, but the biological drivers remain poorly quantified. Most studies analyzing malaria-temperature relations, including those investigating malaria risk and the possible impacts of climate change, are based solely on mean temperatures and extrapolate from functions determined under unrealistic laboratory conditions. Here, we present empirical evidence to show that, in addition to mean temperatures, daily fluctuations in temperature affect parasite infection, the rate of parasite development, and the essential elements of mosquito biology that combine to determine malaria transmission intensity. In general, we find that, compared with rates at equivalent constant mean temperatures, temperature fluctuation around low mean temperatures acts to speed up rate processes, whereas fluctuation around high mean temperatures acts to slow processes down. At the extremes (conditions representative of the fringes of malaria transmission, where range expansions or contractions will occur), fluctuation makes transmission possible at lower mean temperatures than currently predicted and can potentially block transmission at higher mean temperatures. If we are to optimize control efforts and develop appropriate adaptation or mitigation strategies for future climates, we need to incorporate into predictive models the effects of daily temperature variation and how that variation is altered by climate change.
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Lawaly YR, Sakuntabhai A, Marrama L, Konate L, Phimpraphi W, Sokhna C, Tall A, Diène Sarr F, Peerapittayamongkol C, Louicharoen C, Schneider BS, Levescot A, Talman A, Casademont I, Menard D, Trape JF, Rogier C, Kaewkunwal J, Sura T, Nuchprayoon I, Ariey F, Baril L, Singhasivanon P, Mercereau-Puijalon O, Paul R. Heritability of the human infectious reservoir of malaria parasites. PLoS One 2010; 5:e11358. [PMID: 20613877 PMCID: PMC2894056 DOI: 10.1371/journal.pone.0011358] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2009] [Accepted: 05/28/2010] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Studies on human genetic factors associated with malaria have hitherto concentrated on their role in susceptibility to and protection from disease. In contrast, virtually no attention has been paid to the role of human genetics in eliciting the production of parasite transmission stages, the gametocytes, and thus enhancing the spread of disease. METHODS AND FINDINGS We analysed four longitudinal family-based cohort studies from Senegal and Thailand followed for 2-8 years and evaluated the relative impact of the human genetic and non-genetic factors on gametocyte production in infections of Plasmodium falciparum or P. vivax. Prevalence and density of gametocyte carriage were evaluated in asymptomatic and symptomatic infections by examination of Giemsa-stained blood smears and/or RT-PCR (for falciparum in one site). A significant human genetic contribution was found to be associated with gametocyte prevalence in asymptomatic P. falciparum infections. By contrast, there was no heritability associated with the production of gametocytes for P. falciparum or P. vivax symptomatic infections. Sickle cell mutation, HbS, was associated with increased gametocyte prevalence but its contribution was small. CONCLUSIONS The existence of a significant human genetic contribution to gametocyte prevalence in asymptomatic infections suggests that candidate gene and genome wide association approaches may be usefully applied to explore the underlying human genetics. Prospective epidemiological studies will provide an opportunity to generate novel and perhaps more epidemiologically pertinent gametocyte data with which similar analyses can be performed and the role of human genetics in parasite transmission ascertained.
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Affiliation(s)
| | - Anavaj Sakuntabhai
- Institut Pasteur, Laboratoire de la Génétique de la réponse aux infections chez l'homme, Paris, France
- Institut Pasteur, Unité de Pathogénie Virale, Paris, France
| | - Laurence Marrama
- Institut Pasteur de Dakar, Unité d'Epidémiologie, Dakar, Senegal
| | - Lassana Konate
- Faculté des Sciences et Techniques, UCAD, Dakar, Senegal
| | - Waraphon Phimpraphi
- Institut Pasteur, Laboratoire de la Génétique de la réponse aux infections chez l'homme, Paris, France
- Department of Tropical Hygiene, Faculty of Tropical Medicine, Mahidol University, Bangkok Thailand
| | - Cheikh Sokhna
- Institut de Recherche pour le Développement, Laboratoire de Paludologie, Dakar, Senegal
| | - Adama Tall
- Institut Pasteur de Dakar, Unité d'Epidémiologie, Dakar, Senegal
| | | | | | - Chalisa Louicharoen
- Institut Pasteur, Laboratoire de la Génétique de la réponse aux infections chez l'homme, Paris, France
- Inter-Department Program of Biomedical Science, Faculty of Graduate School, Chulalongkorn University, Bangkok, Thailand
| | | | - Anaïs Levescot
- Institut Pasteur, Laboratoire de la Génétique de la réponse aux infections chez l'homme, Paris, France
| | - Arthur Talman
- Unité d'Epidémiologie Moléculaire, Institut Pasteur, Phnom Penh, Cambodia
| | - Isabelle Casademont
- Institut Pasteur, Laboratoire de la Génétique de la réponse aux infections chez l'homme, Paris, France
- Institut Pasteur, Unité de Pathogénie Virale, Paris, France
| | - Didier Menard
- Unité d'Epidémiologie Moléculaire, Institut Pasteur, Phnom Penh, Cambodia
| | - Jean-François Trape
- Institut de Recherche pour le Développement, Laboratoire de Paludologie, Dakar, Senegal
| | - Christophe Rogier
- Institut de Médecine Tropicale du Service de Santé des Armées, Unité de Recherche en Biologie et épidémiologie parasitaires, IFR48, Le Pharo, Marseille, France
| | - Jaranit Kaewkunwal
- Department of Tropical Hygiene, Faculty of Tropical Medicine, Mahidol University, Bangkok Thailand
| | - Thanyachai Sura
- Department of Medicine, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Issarang Nuchprayoon
- Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Frederic Ariey
- Unité d'Epidémiologie Moléculaire, Institut Pasteur, Phnom Penh, Cambodia
| | - Laurence Baril
- Institut Pasteur de Dakar, Unité d'Epidémiologie, Dakar, Senegal
| | - Pratap Singhasivanon
- Department of Tropical Hygiene, Faculty of Tropical Medicine, Mahidol University, Bangkok Thailand
| | | | - Rick Paul
- Institut Pasteur de Dakar, Laboratoire d'Entomologie Médicale, Dakar, Senegal
- Institut Pasteur, Laboratoire de la Génétique de la réponse aux infections chez l'homme, Paris, France
- Institut Pasteur, Unité de Pathogénie Virale, Paris, France
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Hirai M, Mori T. Fertilization is a novel attacking site for the transmission blocking of malaria parasites. Acta Trop 2010; 114:157-61. [PMID: 19665985 DOI: 10.1016/j.actatropica.2009.08.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2009] [Revised: 07/21/2009] [Accepted: 08/04/2009] [Indexed: 01/20/2023]
Abstract
Malaria parasites perform sexual reproduction in mosquitoes where a pair of gametes fertilizes and differentiates into zygotes, and a single zygote produces several thousands of progeny infectious to next vertebrates. Although the parasite fertilization step has been considered as Achilles' heel of parasite life cycle and thus a critical target for blocking malaria transmission in the mosquito, its molecular mechanisms are largely unknown. Previously, we identified that GENERATIVE CELL SPECIFIC 1 (GCS1) is a reproduction factor in angiosperm. Subsequently, it was found that rodent malaria parasite, Plasmodium berghei and green algae, Chlamydomonas reinhardtii possess GCS1 homologues which also play essential roles in gamete interaction. Moreover, intensive database mining revealed that GCS1-like gene homologues exist in the genomes of various organisms. Thus, it appears that GCS1 is an ancient and highly conserved molecule functioning at gamete interaction. In this mini-review, we describe the mechanisms of gametogenesis and fertilization in malaria parasites, comparing with other eukaryotic reproduction, and also speculate GCS1 functions in gamete interaction. We discuss the possibility of whether malaria GCS1 is a novel type of transmission blocking vaccine, by which anti-malaria GCS1 antibody may halt parasite fertilization and subsequent developments in the mosquitoes.
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Affiliation(s)
- Makoto Hirai
- Division of Medical Zoology, Department of Infection and Immunity, Jichi Medical University, School of Medicine, Shimotsuke City, Tochigi, Japan.
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44
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Smith RC, Jacobs-Lorena M. Plasmodium-Mosquito Interactions: A Tale of Roadblocks and Detours. ADVANCES IN INSECT PHYSIOLOGY 2010; 39:119-149. [PMID: 23729903 PMCID: PMC3666160 DOI: 10.1016/b978-0-12-381387-9.00004-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Affiliation(s)
- Ryan C Smith
- Department of Molecular Microbiology and Immunology, Malaria Research Institute, The Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
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Dawes EJ, Churcher TS, Zhuang S, Sinden RE, Basáñez MG. Anopheles mortality is both age- and Plasmodium-density dependent: implications for malaria transmission. Malar J 2009; 8:228. [PMID: 19822012 PMCID: PMC2770541 DOI: 10.1186/1475-2875-8-228] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2009] [Accepted: 10/12/2009] [Indexed: 01/20/2023] Open
Abstract
Background Daily mortality is an important determinant of a vector's ability to transmit pathogens. Original simplifying assumptions in malaria transmission models presume vector mortality is independent of age, infection status and parasite load. Previous studies illustrate conflicting evidence as to the importance of Plasmodium-induced vector mortality, but very few studies to date have considered the effect of infection density on mosquito survival. Methods A series of three experiments were conducted, each consisting of four cages of 400-1,000 Anopheles stephensi mosquitoes fed on blood infected with different Plasmodium berghei ookinete densities per microlitre of blood. Twice daily the numbers of dead mosquitoes in each group were recorded, and on alternate days a sample of live mosquitoes from each group were dissected to determine parasite density in both midgut and salivary glands. Results Survival analyses indicate that mosquito mortality is both age- and infection intensity-dependent. Mosquitoes experienced an initially high, partly feeding-associated, mortality rate, which declined to a minimum before increasing with mosquito age and parasite intake. As a result, the life expectancy of a mosquito is shown to be dependent on both insect age and the density of Plasmodium infection. Conclusion These results contribute to understanding in greater detail the processes that influence sporogony in the mosquito, indicate the impact that parasite density could have on malaria transmission dynamics, and have implications for the design, development, and evaluation of transmission-blocking strategies.
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Affiliation(s)
- Emma J Dawes
- Department of Infectious Disease Epidemiology, Faculty of Medicine, Imperial College London, London, UK.
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Moon RW, Taylor CJ, Bex C, Schepers R, Goulding D, Janse CJ, Waters AP, Baker DA, Billker O. A cyclic GMP signalling module that regulates gliding motility in a malaria parasite. PLoS Pathog 2009; 5:e1000599. [PMID: 19779564 PMCID: PMC2742896 DOI: 10.1371/journal.ppat.1000599] [Citation(s) in RCA: 144] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2009] [Accepted: 08/31/2009] [Indexed: 11/23/2022] Open
Abstract
The ookinete is a motile stage in the malaria life cycle which forms in the mosquito blood meal from the zygote. Ookinetes use an acto-myosin motor to glide towards and penetrate the midgut wall to establish infection in the vector. The regulation of gliding motility is poorly understood. Through genetic interaction studies we here describe a signalling module that identifies guanosine 3′, 5′-cyclic monophosphate (cGMP) as an important second messenger regulating ookinete differentiation and motility. In ookinetes lacking the cyclic nucleotide degrading phosphodiesterase δ (PDEδ), unregulated signalling through cGMP results in rounding up of the normally banana-shaped cells. This phenotype is suppressed in a double mutant additionally lacking guanylyl cyclase β (GCβ), showing that in ookinetes GCβ is an important source for cGMP, and that PDEδ is the relevant cGMP degrading enzyme. Inhibition of the cGMP-dependent protein kinase, PKG, blocks gliding, whereas enhanced signalling through cGMP restores normal gliding speed in a mutant lacking calcium dependent protein kinase 3, suggesting at least a partial overlap between calcium and cGMP dependent pathways. These data demonstrate an important function for signalling through cGMP, and most likely PKG, in dynamically regulating ookinete gliding during the transmission of malaria to the mosquito. Malaria parasites are single celled organisms, which must alternate between vertebrate and mosquito hosts to survive and spread. In both hosts, certain parasite stages can glide through tissues and invade cells. Many components of the molecular motor that powers gliding and invasion are known and we have a good idea how these may interact to generate force. It is less well understood how the motor is assembled and how its component parts are regulated to switch it on and off. We have begun to address these questions in the ookinete, a parasite stage, which forms in the blood meal of a mosquito and relies on gliding to penetrate the gut wall. Using a malaria parasite of rodents, we have examined the effect of deleting candidate genes involved in controlling levels of the intracellular signalling molecule cyclic guanosine monophosphate (cGMP). We show that the right balance between cGMP production and degradation is important for ookinetes to glide, while also maintaining their typical cell shape. Overall levels of cGMP are not much affected in the mutants, though, and we therefore believe the messenger exerts its effect either locally within the cell or only while the parasite is gliding.
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Affiliation(s)
- Robert W. Moon
- Wellcome Trust Sanger Institute, Cambridge Hinxton, United Kingdom
- Imperial College London, Department of Cell and Molecular Biology, London, United Kingdom
| | - Cathy J. Taylor
- Department of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Claudia Bex
- Wellcome Trust Sanger Institute, Cambridge Hinxton, United Kingdom
| | - Rebecca Schepers
- Imperial College London, Department of Cell and Molecular Biology, London, United Kingdom
| | - David Goulding
- Wellcome Trust Sanger Institute, Cambridge Hinxton, United Kingdom
| | - Chris J. Janse
- Department of Parasitology, Centre of Infectious Diseases, Leiden University Medical Centre, Leiden, The Netherlands
| | - Andrew P. Waters
- Wellcome Trust Centre of Molecular Parasitology and Division of Infection and Immunity, University of Glasgow, Glasgow, United Kingdom
| | - David A. Baker
- Department of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Oliver Billker
- Wellcome Trust Sanger Institute, Cambridge Hinxton, United Kingdom
- Imperial College London, Department of Cell and Molecular Biology, London, United Kingdom
- * E-mail:
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Kato K, Sudo A, Kobayashi K, Sugi T, Tohya Y, Akashi H. Characterization of Plasmodium falciparum calcium-dependent protein kinase 4. Parasitol Int 2009; 58:394-400. [PMID: 19666141 DOI: 10.1016/j.parint.2009.08.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2009] [Revised: 07/30/2009] [Accepted: 08/02/2009] [Indexed: 11/30/2022]
Abstract
In Plasmodium berghei, the orthologous gene of P. falciparum calcium-dependent protein kinase 4 (PfCDPK4) was reported to be essential for the exflagellation of male gametocytes. To elucidate the role of PfCDPK4 in P. falciparum gametogenesis, we characterized the biological function of PfCDPK4 in vitro. PfCDPK4 was purified as a fusion protein that was labeled with [gamma-(32)P]ATP; this labeling was then eliminated by phosphatase. Phosphorylation activity of PfCDPK4 was eliminated when its putative catalytic lysine residue was replaced with alanine. In biochemical analyses, PfCDPK4 was found to have characteristics that were similar to those of homologous proteins from plants. PfCDPK4 phosphorylation was activated when experimental conditions were changed from those characteristic of human blood (37 degrees C, pH 7.4) to those of the mosquito bloodmeal (at least 5 degrees C below 37 degrees C, pH 7.6, with xanthurenic acid (XA)). PfCDPK4 was overexpressed in day 15 gametocytes exposed to XA or human serum. Thus, PfCDPK4 phosphorylation is activated by an increase in Ca(2+) concentration or pH and by a decrease in temperature, and is associated with the Ca(2+) signals that facilitate P. falciparum gametogenesis.
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Affiliation(s)
- Kentaro Kato
- Department of Veterinary Microbiology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan.
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Anopheles gambiae PGRPLC-mediated defense against bacteria modulates infections with malaria parasites. PLoS Pathog 2009; 5:e1000542. [PMID: 19662170 PMCID: PMC2715215 DOI: 10.1371/journal.ppat.1000542] [Citation(s) in RCA: 184] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2009] [Accepted: 07/15/2009] [Indexed: 12/15/2022] Open
Abstract
Recognition of peptidoglycan (PGN) is paramount for insect antibacterial defenses. In the fruit fly Drosophila melanogaster, the transmembrane PGN Recognition Protein LC (PGRP-LC) is a receptor of the Imd signaling pathway that is activated after infection with bacteria, mainly Gram-negative (Gram−). Here we demonstrate that bacterial infections of the malaria mosquito Anopheles gambiae are sensed by the orthologous PGRPLC protein which then activates a signaling pathway that involves the Rel/NF-κB transcription factor REL2. PGRPLC signaling leads to transcriptional induction of antimicrobial peptides at early stages of hemolymph infections with the Gram-positive (Gram+) bacterium Staphylococcus aureus, but a different signaling pathway might be used in infections with the Gram− bacterium Escherichia coli. The size of mosquito symbiotic bacteria populations and their dramatic proliferation after a bloodmeal, as well as intestinal bacterial infections, are also controlled by PGRPLC signaling. We show that this defense response modulates mosquito infection intensities with malaria parasites, both the rodent model parasite, Plasmodium berghei, and field isolates of the human parasite, Plasmodium falciparum. We propose that the tripartite interaction between mosquito microbial communities, PGRPLC-mediated antibacterial defense and infections with Plasmodium can be exploited in future interventions aiming to control malaria transmission. Molecular analysis and structural modeling provided mechanistic insights for the function of PGRPLC. Alternative splicing of PGRPLC transcripts produces three main isoforms, of which PGRPLC3 appears to have a key role in the resistance to bacteria and modulation of Plasmodium infections. Structural modeling indicates that PGRPLC3 is capable of binding monomeric PGN muropeptides but unable to initiate dimerization with other isoforms. A dual role of this isoform is hypothesized: it sequesters monomeric PGN dampening weak signals and locks other PGRPLC isoforms in binary immunostimulatory complexes further enhancing strong signals. Recognition of peptidoglycan on the bacteria cell wall triggers insect immune responses. The fruit fly PGRPLC receptor protein senses the presence of peptidoglycan and activates a pathway that mediates resistance to bacterial infections, mainly Gram-negative. We show that the PGRPLC receptor of the malaria vector mosquito Anopheles gambiae can also sense infections of the hemolymph (the mosquito blood) or the gut with bacteria of both Gram types and thereby activate a pathway that confers resistance to these infections. PGRPLC and its downstream responses also control the numbers of symbiotic bacteria that are mostly found in the mosquito gut where they drastically proliferate after a female mosquito takes a bloodmeal. Importantly, when the bloodmeal is infected with malaria parasites, the defense reaction that the mosquito mounts against proliferating bacteria also eliminate a large number of parasites. These mechanisms are largely elucidated using a rodent malaria parasite, but we also show that they significantly affect the intensities of mosquito infections with Plasmodium falciparum parasites found in the blood of children in sub-Saharan Africa.
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Gametogenesis in malaria parasites is mediated by the cGMP-dependent protein kinase. PLoS Biol 2008; 6:e139. [PMID: 18532880 PMCID: PMC2408617 DOI: 10.1371/journal.pbio.0060139] [Citation(s) in RCA: 173] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2007] [Accepted: 04/25/2008] [Indexed: 11/19/2022] Open
Abstract
Malaria parasite transmission requires differentiation of male and female gametocytes into gametes within a mosquito following a blood meal. A mosquito-derived molecule, xanthurenic acid (XA), can trigger gametogenesis, but the signalling events controlling this process in the human malaria parasite Plasmodium falciparum remain unknown. A role for cGMP was revealed by our observation that zaprinast (an inhibitor of phosphodiesterases that hydrolyse cGMP) stimulates gametogenesis in the absence of XA. Using cGMP-dependent protein kinase (PKG) inhibitors in conjunction with transgenic parasites expressing an inhibitor-insensitive mutant PKG enzyme, we demonstrate that PKG is essential for XA- and zaprinast-induced gametogenesis. Furthermore, we show that intracellular calcium (Ca2+) is required for differentiation and acts downstream of or in parallel with PKG activation. This work defines a key role for PKG in gametogenesis, elucidates the hierarchy of signalling events governing this process in P. falciparum, and demonstrates the feasibility of selective inhibition of a crucial regulator of the malaria parasite life cycle. The protozoan parasite Plasmodium falciparum, which causes malaria in humans, is responsible for over 1 million deaths each year. Its life cycle is complex; the asexually replicating forms, which cause disease symptoms, are quite distinct from the sexual forms, which mediate transmission between individuals via the bite of a mosquito. After a period of growth in the human host, these sexual forms (gametocytes) lie dormant until taken up by a mosquito. The change in environment from human to mosquito triggers differentiation into mature gametes. In this study, we have identified a protein kinase from the parasite that is instrumental in mediating this essential differentiation step. We have also gained insight into how this protein kinase might interact with calcium to coordinate these events. By using genetically modified malaria parasites in combination with specific inhibitors of the protein kinase, we have illustrated the feasibility of blocking development of the sexual stage of the parasite's life cycle. Development of a drug that targets this parasite stage, for use in combination with a curative drug, would be an important tool for controlling the spread of drug resistance. We show that differentiation of malaria parasites in response to environmental signals encountered upon entering the mosquito following a blood meal is mediated by the parasite cGMP-dependent protein kinase.
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Habtewold T, Povelones M, Blagborough AM, Christophides GK. Transmission blocking immunity in the malaria non-vector mosquito Anopheles quadriannulatus species A. PLoS Pathog 2008; 4:e1000070. [PMID: 18497855 PMCID: PMC2374904 DOI: 10.1371/journal.ppat.1000070] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2007] [Accepted: 04/14/2008] [Indexed: 01/26/2023] Open
Abstract
Despite being phylogenetically very close to Anopheles gambiae, the major mosquito vector of human malaria in Africa, Anopheles quadriannulatus is thought to be a non-vector. Understanding the difference between vector and non-vector mosquitoes can facilitate development of novel malaria control strategies. We demonstrate that An. quadriannulatus is largely resistant to infections by the human parasite Plasmodium falciparum, as well as by the rodent parasite Plasmodium berghei. By using genetics and reverse genetics, we show that resistance is controlled by quantitative heritable traits and manifested by lysis or melanization of ookinetes in the mosquito midgut, as well as by killing of parasites at subsequent stages of their development in the mosquito. Genes encoding two leucine-rich repeat proteins, LRIM1 and LRIM2, and the thioester-containing protein, TEP1, are identified as essential in these immune reactions. Their silencing completely abolishes P. berghei melanization and dramatically increases the number of oocysts, thus transforming An. quadriannulatus into a highly permissive parasite host. We hypothesize that the mosquito immune system is an important cause of natural refractoriness to malaria and that utilization of this innate capacity of mosquitoes could lead to new methods to control transmission of the disease. Malaria is a mosquito-borne infectious disease that threatens almost half of the human population and kills 1 to 3 million people every year. In sub-Saharan Africa, where the vast majority of deaths occur, the capacity of mosquitoes to transmit malaria varies greatly even between closely related species. We compared the ability of malaria parasites to develop in two very closely related mosquitoes, one vector and one non-vector, and found that non-vector mosquitoes kill parasites at various stages, predominantly when they invade the mosquito midgut. This is achieved by parasite clearance, possibly by lysis in the midgut cells and by melanization, both of which are reactions of the mosquito immune system. This phenotype depends on heritable and dominant traits that can be passed on to vector/non-vector mosquito hybrids. We examined whether specific components of the mosquito immune system affect the resistance of these mosquitoes to infection. By silencing the activity of three immunity genes, we transformed mosquitoes of the resistant species into highly susceptible. Our results suggest that the mosquito immune system may affect refractoriness to malaria in non-vector mosquitoes. This innate capacity of mosquitoes to kill malaria parasites could be utilized in future integrated efforts to control and ultimately eradicate the disease.
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Affiliation(s)
- Tibebu Habtewold
- Immunology and Infection, Division of Cell and Molecular Biology, Faculty of Natural Sciences, Imperial College London, London, United Kingdom
| | - Michael Povelones
- Immunology and Infection, Division of Cell and Molecular Biology, Faculty of Natural Sciences, Imperial College London, London, United Kingdom
| | - Andrew M. Blagborough
- Immunology and Infection, Division of Cell and Molecular Biology, Faculty of Natural Sciences, Imperial College London, London, United Kingdom
| | - George K. Christophides
- Immunology and Infection, Division of Cell and Molecular Biology, Faculty of Natural Sciences, Imperial College London, London, United Kingdom
- * E-mail:
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