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Groomes PV, Paul AS, Duraisingh MT. Inhibition of malaria and babesiosis parasites by putative red blood cell targeting small molecules. Front Cell Infect Microbiol 2024; 14:1304839. [PMID: 38572319 PMCID: PMC10988762 DOI: 10.3389/fcimb.2024.1304839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Accepted: 02/15/2024] [Indexed: 04/05/2024] Open
Abstract
Background Chemotherapies for malaria and babesiosis frequently succumb to the emergence of pathogen-related drug-resistance. Host-targeted therapies are thought to be less susceptible to resistance but are seldom considered for treatment of these diseases. Methods Our overall objective was to systematically assess small molecules for host cell-targeting activity to restrict proliferation of intracellular parasites. We carried out a literature survey to identify small molecules annotated for host factors implicated in Plasmodium falciparum infection. Alongside P. falciparum, we implemented in vitro parasite susceptibility assays also in the zoonotic parasite Plasmodium knowlesi and the veterinary parasite Babesia divergens. We additionally carried out assays to test directly for action on RBCs apart from the parasites. To distinguish specific host-targeting antiparasitic activity from erythrotoxicity, we measured phosphatidylserine exposure and hemolysis stimulated by small molecules in uninfected RBCs. Results We identified diverse RBC target-annotated inhibitors with Plasmodium-specific, Babesia-specific, and broad-spectrum antiparasitic activity. The anticancer MEK-targeting drug trametinib is shown here to act with submicromolar activity to block proliferation of Plasmodium spp. in RBCs. Some inhibitors exhibit antimalarial activity with transient exposure to RBCs prior to infection with parasites, providing evidence for host-targeting activity distinct from direct inhibition of the parasite. Conclusions We report here characterization of small molecules for antiproliferative and host cell-targeting activity for malaria and babesiosis parasites. This resource is relevant for assessment of physiological RBC-parasite interactions and may inform drug development and repurposing efforts.
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Affiliation(s)
| | | | - Manoj T. Duraisingh
- Department of Immunology & Infectious Diseases, Harvard T. H. Chan School of Public Health, Boston, MA, United States
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van Schalkwyk DA, Pratt S, Nolder D, Stewart LB, Liddy H, Muwanguzi-Karugaba J, Beshir KB, Britten D, Victory E, Rogers C, Millard J, Brown M, Nabarro LE, Taylor A, Young BC, Chiodini PL, Sutherland CJ. Treatment Failure in a UK Malaria Patient Harboring Genetically Variant Plasmodium falciparum From Uganda With Reduced In Vitro Susceptibility to Artemisinin and Lumefantrine. Clin Infect Dis 2024; 78:445-452. [PMID: 38019958 PMCID: PMC10874266 DOI: 10.1093/cid/ciad724] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Revised: 11/20/2023] [Accepted: 11/27/2023] [Indexed: 12/01/2023] Open
Abstract
BACKGROUND Recent cases of clinical failure in malaria patients in the United Kingdom (UK) treated with artemether-lumefantrine have implications for malaria chemotherapy worldwide. METHODS Parasites were isolated from an index case of confirmed Plasmodium falciparum treatment failure after standard treatment, and from comparable travel-acquired UK malaria cases. Drug susceptibility in vitro and genotypes at 6 resistance-associated loci were determined for all parasite isolates and compared with clinical outcomes for each parasite donor. RESULTS A traveler, who returned to the UK from Uganda in 2022 with Plasmodium falciparum malaria, twice failed treatment with full courses of artemether-lumefantrine. Parasites from the patient exhibited significantly reduced susceptibility to artemisinin (ring-stage survival, 17.3% [95% confidence interval {CI}, 13.6%-21.1%]; P < .0001) and lumefantrine (effective concentration preventing 50% of growth = 259.4 nM [95% CI, 130.6-388.2 nM]; P = .001). Parasite genotyping identified an allele of pfk13 encoding both the A675V variant in the Pfk13 propeller domain and a novel L145V nonpropeller variant. In vitro susceptibility testing of 6 other P. falciparum lines of Ugandan origin identified reduced susceptibility to artemisinin and lumefantrine in 1 additional line, also from a 2022 treatment failure case. These parasites did not harbor a pfk13 propeller domain variant but rather the novel nonpropeller variant T349I. Variant alleles of pfubp1, pfap2mu, and pfcoronin were also identified among the 7 parasite lines. CONCLUSIONS We confirm, in a documented case of artemether-lumefantrine treatment failure imported from Uganda, the presence of pfk13 mutations encoding L145V and A675V. Parasites with reduced susceptibility to both artemisinin and lumefantrine may be emerging in Uganda.
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Affiliation(s)
- Donelly A van Schalkwyk
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Sade Pratt
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Debbie Nolder
- UK Health Security Agency Malaria Reference Laboratory, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Lindsay B Stewart
- UK Health Security Agency Malaria Reference Laboratory, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Helen Liddy
- UK Health Security Agency Malaria Reference Laboratory, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Julian Muwanguzi-Karugaba
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Khalid B Beshir
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Dawn Britten
- UK Health Security Agency Malaria Reference Laboratory, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Emma Victory
- UK Health Security Agency Malaria Reference Laboratory, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Claire Rogers
- UK Health Security Agency Malaria Reference Laboratory, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - James Millard
- Hospital for Tropical Diseases, University College London Hospitals NHS Foundation Trust, London, United Kingdom
| | - Michael Brown
- Hospital for Tropical Diseases, University College London Hospitals NHS Foundation Trust, London, United Kingdom
| | - Laura E Nabarro
- Hospital for Tropical Diseases, University College London Hospitals NHS Foundation Trust, London, United Kingdom
| | - Andrew Taylor
- Department of Infectious Diseases, Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom
| | - Bernadette C Young
- Department of Infectious Diseases, Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom
| | - Peter L Chiodini
- UK Health Security Agency Malaria Reference Laboratory, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Colin J Sutherland
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
- UK Health Security Agency Malaria Reference Laboratory, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
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Craven HM, Nettesheim G, Cicuta P, Blagborough AM, Merrick CJ. Effects of the G-quadruplex-binding drugs quarfloxin and CX-5461 on the malaria parasite Plasmodium falciparum. Int J Parasitol Drugs Drug Resist 2023; 23:106-119. [PMID: 38041930 PMCID: PMC10711401 DOI: 10.1016/j.ijpddr.2023.11.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 11/15/2023] [Accepted: 11/20/2023] [Indexed: 12/04/2023]
Abstract
Plasmodium falciparum is the deadliest causative agent of human malaria. This parasite has historically developed resistance to most drugs, including the current frontline treatments, so new therapeutic targets are needed. Our previous work on guanine quadruplexes (G4s) in the parasite's DNA and RNA has highlighted their influence on parasite biology, and revealed G4 stabilising compounds as promising candidates for repositioning. In particular, quarfloxin, a former anticancer agent, kills blood-stage parasites at all developmental stages, with fast rates of kill and nanomolar potency. Here we explored the molecular mechanism of quarfloxin and its related derivative CX-5461. In vitro, both compounds bound to P. falciparum-encoded G4 sequences. In cellulo, quarfloxin was more potent than CX-5461, and could prevent establishment of blood-stage malaria in vivo in a murine model. CX-5461 showed clear DNA damaging activity, as reported in human cells, while quarfloxin caused weaker signatures of DNA damage. Both compounds caused transcriptional dysregulation in the parasite, but the affected genes were largely different, again suggesting different modes of action. Therefore, CX-5461 may act primarily as a DNA damaging agent in both Plasmodium parasites and mammalian cells, whereas the complete antimalarial mode of action of quarfloxin may be parasite-specific and remains somewhat elusive.
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Affiliation(s)
- Holly M Craven
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QP, UK
| | - Guilherme Nettesheim
- Department of Physics, Cavendish Laboratory University of Cambridge, J.J. Thomson Avenue, Cambridge, CB3 0HE, UK
| | - Pietro Cicuta
- Department of Physics, Cavendish Laboratory University of Cambridge, J.J. Thomson Avenue, Cambridge, CB3 0HE, UK
| | - Andrew M Blagborough
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QP, UK
| | - Catherine J Merrick
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QP, UK.
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Sangsri R, Choowongkomon K, Tuntipaiboontana R, Sugaram R, Boondej P, Sudathip P, Dondorp AM, Imwong M. Limited Polymorphism in the Dihydrofolate Reductase (dhfr) and dihydropteroate synthase genes (dhps) of Plasmodium knowlesi isolate from Thailand. Acta Trop 2023; 248:107016. [PMID: 37683820 PMCID: PMC10632683 DOI: 10.1016/j.actatropica.2023.107016] [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: 06/20/2023] [Revised: 08/27/2023] [Accepted: 08/31/2023] [Indexed: 09/10/2023]
Abstract
BACKGROUND The 2022 malaria WHO reported around 4000 P. knowlesi infections in the South-East Asia region. In the same period, 72 positive cases were reported by the Department of Disease Control in Thailand, suggesting a persistent infection. Little is known about dihydrofolate reductase (pkdhfr) and dihydropteroate synthase (pkdhps), putative antimalarial resistance markers for P. knowlesi. The relevant amplification and sequencing protocol are presently unavailable. In this study, we developed a protocol for amplifying and evaluating pkdhps mutations. The haplotype pattern of pkdhfr-pkdhps in Thai isolates was analyzed, and the effects of these pkdhps mutations were predicted by using a computer program. METHODS Pkdhps were amplified and sequenced from 28 P. knowlesi samples collected in 2008 and 2020 from nine provinces across Thailand. Combining pkdhfr sequencing data from previous work with pkdhps data to analyze polymorphisms of pkdhfr and pkdhps haplotype. Protein modeling and molecular docking were constructed using two inhibitors, sulfadoxine and sulfamethoxazole, and further details were obtained through analyses of protein-ligand interactions by using the Genetic Optimisation for Ligand Docking program. A phylogenetic tree cluster analysis was reconstructed to compare the P. knowlesi Malaysia isolates. RESULTS Five nonsynonymous mutations in the pkdhps were detected outside the equivalence of the binding pocket sites to sulfadoxine and sulfamethoxazole, which are at N391S, E421G, I425R, A449S, and N517S. Based on the modeling and molecular docking analyses, the N391S and N517S mutations located close to the enzyme-binding pocket demonstrated a different docking score and protein-ligand interaction in loop 2 of the enzyme. These findings indicated that it was less likely to induce drug resistance. Of the four haplotypes of pkdhfr-pkdhps, the most common one is the R34L pkdhfr mutation and the pkdhps quadruple mutation (GRSS) at E421G, I425R, A449S, and N517S, which were observed in P. knowlesi in southern Thailand (53.57%). Based on the results of neighbor-joining analysis for pkdhfr and pkdhps, the samples isolated from eastern Thailand displayed a close relationship with Cambodia isolates, while southern Thailand isolates showed a long branch separated from the Malaysian isolates. CONCLUSIONS A new PCR protocol amplification and evaluation of dihydropteroate synthase mutations in Knowlesi (pkdhps) has been developed. The most prevalent pkdhfr-pkdhps haplotypes (53.57%) in southern Thailand are R34L pkdhfr mutation and pkdhps quadruple mutation. Further investigation requires additional phenotypic data from clinical isolates, transgenic lines expressing mutant alleles, or recombinant proteins.
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Affiliation(s)
- Raweewan Sangsri
- Department of Molecular Tropical Medicine and Genetics, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand
| | - Kiattawee Choowongkomon
- Department of Biochemistry, Faculty of Science, Kasetsart University, Bangkok 10903, Thailand
| | - Runch Tuntipaiboontana
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand
| | - Rungniran Sugaram
- Division of Vector Borne Diseases, Department of Disease Control, Ministry of Public Health, Nonthaburi 11000, Thailand
| | - Patcharida Boondej
- Division of Vector Borne Diseases, Department of Disease Control, Ministry of Public Health, Nonthaburi 11000, Thailand
| | - Prayuth Sudathip
- Division of Vector Borne Diseases, Department of Disease Control, Ministry of Public Health, Nonthaburi 11000, Thailand
| | - Arjen M Dondorp
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand; Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Mallika Imwong
- Department of Molecular Tropical Medicine and Genetics, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand; Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand.
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5
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Wong ML, Zulzahrin Z, Vythilingam I, Lau YL, Sam IC, Fong MY, Lee WC. Perspectives of vector management in the control and elimination of vector-borne zoonoses. Front Microbiol 2023; 14:1135977. [PMID: 37025644 PMCID: PMC10070879 DOI: 10.3389/fmicb.2023.1135977] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Accepted: 02/28/2023] [Indexed: 04/08/2023] Open
Abstract
The complex transmission profiles of vector-borne zoonoses (VZB) and vector-borne infections with animal reservoirs (VBIAR) complicate efforts to break the transmission circuit of these infections. To control and eliminate VZB and VBIAR, insecticide application may not be conducted easily in all circumstances, particularly for infections with sylvatic transmission cycle. As a result, alternative approaches have been considered in the vector management against these infections. In this review, we highlighted differences among the environmental, chemical, and biological control approaches in vector management, from the perspectives of VZB and VBIAR. Concerns and knowledge gaps pertaining to the available control approaches were discussed to better understand the prospects of integrating these vector control approaches to synergistically break the transmission of VZB and VBIAR in humans, in line with the integrated vector management (IVM) developed by the World Health Organization (WHO) since 2004.
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Affiliation(s)
- Meng Li Wong
- Department of Parasitology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur, Malaysia
| | - Zulhisham Zulzahrin
- Department of Parasitology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur, Malaysia
| | - Indra Vythilingam
- Department of Parasitology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur, Malaysia
| | - Yee Ling Lau
- Department of Parasitology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur, Malaysia
| | - I-Ching Sam
- Department of Medical Microbiology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur, Malaysia
- Department of Medical Microbiology, University Malaya Medical Centre (UMMC), Kuala Lumpur, Malaysia
| | - Mun Yik Fong
- Department of Parasitology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur, Malaysia
| | - Wenn-Chyau Lee
- Department of Parasitology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur, Malaysia
- A*STAR Infectious Diseases Labs (A*STAR ID Labs), Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
- *Correspondence: Wenn-Chyau Lee,
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6
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Mohring F, van Schalkwyk DA, Henrici RC, Blasco B, Leroy D, Sutherland CJ, Moon RW. Cation ATPase (ATP4) Orthologue Replacement in the Malaria Parasite Plasmodium knowlesi Reveals Species-Specific Responses to ATP4-Targeting Drugs. mBio 2022; 13:e0117822. [PMID: 36190127 PMCID: PMC9600963 DOI: 10.1128/mbio.01178-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Accepted: 08/31/2022] [Indexed: 11/30/2022] Open
Abstract
Several unrelated classes of antimalarial compounds developed against Plasmodium falciparum target a parasite-specific P-type ATP-dependent Na+ pump, PfATP4. We have previously shown that other malaria parasite species infecting humans are less susceptible to these compounds. Here, we generated a series of transgenic Plasmodium knowlesi orthologue replacement (OR) lines in which the endogenous pkatp4 locus was replaced by a recodonized P. knowlesi atp4 (pkatp4) coding region or the orthologous coding region from P. falciparum, Plasmodium malariae, Plasmodium ovale subsp. curtisi, or Plasmodium vivax. Each OR transgenic line displayed a similar growth pattern to the parental P. knowlesi line. We found significant orthologue-specific differences in parasite susceptibility to three chemically unrelated ATP4 inhibitors, but not to comparator drugs, among the P. knowlesi OR lines. The PfATP4OR transgenic line of P. knowlesi was significantly more susceptible than our control PkATP4OR line to three ATP4 inhibitors: cipargamin, PA21A092, and SJ733. The PvATP4OR and PmATP4OR lines were similarly susceptible to the control PkATP4OR line, but the PocATP4OR line was significantly less susceptible to all ATP4 inhibitors than the PkATP4OR line. Cipargamin-induced inhibition of Na+ efflux was also significantly greater with the P. falciparum orthologue of ATP4. This confirms that species-specific susceptibility differences previously observed in ex vivo studies of human isolates are partly or wholly enshrined in the primary amino acid sequences of the respective ATP4 orthologues and highlights the need to monitor efficacy of investigational malaria drugs against multiple species. P. knowlesi is now established as an important in vitro model for studying drug susceptibility in non-falciparum malaria parasites. IMPORTANCE Effective drugs are vital to minimize the illness and death caused by malaria. Development of new drugs becomes ever more urgent as drug resistance emerges. Among promising compounds now being developed to treat malaria are several unrelated molecules that each inhibit the same protein in the malaria parasite-ATP4. Here, we exploited the genetic tractability of P. knowlesi to replace its own ATP4 genes with orthologues from five human-infective species to understand the drug susceptibility differences among these parasites. We previously estimated the susceptibility to ATP4-targeting drugs of each species using clinical samples from malaria patients. These estimates closely matched those of the corresponding "hybrid" P. knowlesi parasites carrying introduced ATP4 genes. Thus, species-specific ATP4 inhibitor efficacy is directly determined by the sequence of the gene. Our novel approach to understanding cross-species susceptibility/resistance can strongly support the effort to develop antimalarials that effectively target all human malaria parasite species.
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Affiliation(s)
- Franziska Mohring
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Donelly A. van Schalkwyk
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Ryan C. Henrici
- Center for Global Health, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
| | | | - Didier Leroy
- Medicines for Malaria Venture, Geneva, Switzerland
| | - Colin J. Sutherland
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
- UK Health Security Agency Malaria Reference Laboratory, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Robert W. Moon
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
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Catalytic Properties of Caseinolytic Protease Subunit of Plasmodium knowlesi and Its Inhibition by a Member of δ-Lactone, Hyptolide. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27123787. [PMID: 35744912 PMCID: PMC9228282 DOI: 10.3390/molecules27123787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 06/05/2022] [Accepted: 06/08/2022] [Indexed: 11/17/2022]
Abstract
The caseinolytic protease (Clp) system plays an essential role in the protein homeostasis of the malaria parasite, particularly at the stage of apicoplast development. The inhibition of this protein is known to have a lethal effect on the parasite and is therefore considered an interesting avenue for antimalaria drugs discovery. The catalytic activity of the Clp system is modulated by its proteolytic subunit (ClpP), which belongs to the serine protease family member and is therefore extensively studied for further inhibitors development. Among many inhibitors, the group of β-lactone is known to be a specific inhibitor for ClpP. Nevertheless, other groups of lactones have never been studied. This study aims to characterize the catalytic properties of ClpP of Plasmodium knowlesi (Pk-ClpP) and the inhibition properties of a δ-lactone hyptolide against this protein. Accordingly, a codon-optimized synthetic gene encoding Pk-ClpP was expressed in Escherichia coli BL21(DE3) and purified under a single step of Ni2+-affinity chromatography, yielding a 2.20 mg from 1 L culture. Meanwhile, size-exclusion chromatography indicated that Pk-ClpP migrated primarily as homoheptameric with a size of 205 kDa. The specific activity of pure Pk-ClpP was 0.73 U µg-1, with a catalytic efficiency kcat/KM of 0.05 µM-1 s-1, with optimum temperature and pH of 50 °C and 7.0-7.5, respectively. Interestingly, hyptolide, a member of δ-lactone, was shown to inhibit Pk-ClpP with an IC50 value of 17.36 ± 1.44 nM. Structural homology modelling, secondary structure prediction, and far-UV CD spectra revealed that helical structures dominate this protein. In addition, the structural homology modeling showed that this protein forms a barrel-shaped homoheptamer. Docking simulation revealed that the inhibition was found to be a competitive inhibition in which hyptolide was able to dock into the catalytic site and block the substrate. The competitiveness of hyptolide is due to the higher binding affinity of this molecule than the substrate.
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Lee WC, Cheong FW, Amir A, Lai MY, Tan JH, Phang WK, Shahari S, Lau YL. Plasmodium knowlesi: the game changer for malaria eradication. Malar J 2022; 21:140. [PMID: 35505339 PMCID: PMC9066973 DOI: 10.1186/s12936-022-04131-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Accepted: 03/18/2022] [Indexed: 11/12/2022] Open
Abstract
Plasmodium knowlesi is a zoonotic malaria parasite that has gained increasing medical interest over the past two decades. This zoonotic parasitic infection is prevalent in Southeast Asia and causes many cases with fulminant pathology. Despite several biogeographical restrictions that limit its distribution, knowlesi malaria cases have been reported in different parts of the world due to travelling and tourism activities. Here, breakthroughs and key information generated from recent (over the past five years, but not limited to) studies conducted on P. knowlesi were reviewed, and the knowledge gap in various research aspects that need to be filled was discussed. Besides, challenges and strategies required to control and eradicate human malaria with this emerging and potentially fatal zoonosis were described.
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Affiliation(s)
- Wenn-Chyau Lee
- Department of Parasitology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur, Malaysia
| | - Fei Wen Cheong
- Department of Parasitology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur, Malaysia
| | - Amirah Amir
- Department of Parasitology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur, Malaysia
| | - Meng Yee Lai
- Department of Parasitology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur, Malaysia
| | - Jia Hui Tan
- Department of Parasitology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur, Malaysia
| | - Wei Kit Phang
- Department of Parasitology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur, Malaysia
| | - Shahhaziq Shahari
- Department of Parasitology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur, Malaysia
| | - Yee-Ling Lau
- Department of Parasitology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur, Malaysia.
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9
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Abacha YZ, Forkuo AD, Gbedema SY, Mittal N, Ottilie S, Rocamora F, Winzeler EA, van Schalkwyk DA, Kelly JM, Taylor MC, Reader J, Birkholtz LM, Lisgarten DR, Cockcroft JK, Lisgarten JN, Palmer RA, Talbert RC, Shnyder SD, Wright CW. Semi-Synthetic Analogues of Cryptolepine as a Potential Source of Sustainable Drugs for the Treatment of Malaria, Human African Trypanosomiasis, and Cancer. Front Pharmacol 2022; 13:875647. [PMID: 35600849 PMCID: PMC9119314 DOI: 10.3389/fphar.2022.875647] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Accepted: 03/08/2022] [Indexed: 12/11/2022] Open
Abstract
The prospect of eradicating malaria continues to be challenging in the face of increasing parasite resistance to antimalarial drugs so that novel antimalarials active against asexual, sexual, and liver-stage malaria parasites are urgently needed. In addition, new antimalarials need to be affordable and available to those most in need and, bearing in mind climate change, should ideally be sustainable. The West African climbing shrub Cryptolepis sanguinolenta is used traditionally for the treatment of malaria; its principal alkaloid, cryptolepine (1), has been shown to have antimalarial properties, and the synthetic analogue 2,7-dibromocryptolepine (2) is of interest as a lead toward new antimalarial agents. Cryptolepine (1) was isolated using a two-step Soxhlet extraction of C. sanguinolenta roots, followed by crystallization (yield 0.8% calculated as a base with respect to the dried roots). Semi-synthetic 7-bromo- (3), 7, 9-dibromo- (4), 7-iodo- (5), and 7, 9-dibromocryptolepine (6) were obtained in excellent yields by reaction of 1 with N-bromo- or N-iodosuccinimide in trifluoroacetic acid as a solvent. All compounds were active against Plasmodia in vitro, but 6 showed the most selective profile with respect to Hep G2 cells: P. falciparum (chloroquine-resistant strain K1), IC50 = 0.25 µM, SI = 113; late stage, gametocytes, IC50 = 2.2 µM, SI = 13; liver stage, P. berghei sporozoites IC50 = 6.13 µM, SI = 4.6. Compounds 3-6 were also active against the emerging zoonotic species P. knowlesi with 5 being the most potent (IC50 = 0.11 µM). In addition, 3-6 potently inhibited T. brucei in vitro at nM concentrations and good selectivity with 6 again being the most selective (IC50 = 59 nM, SI = 478). These compounds were also cytotoxic to wild-type ovarian cancer cells as well as adriamycin-resistant and, except for 5, cisplatin-resistant ovarian cancer cells. In an acute oral toxicity test in mice, 3-6 did not exhibit toxic effects at doses of up to 100 mg/kg/dose × 3 consecutive days. This study demonstrates that C. sanguinolenta may be utilized as a sustainable source of novel compounds that may lead to the development of novel agents for the treatment of malaria, African trypanosomiasis, and cancer.
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Affiliation(s)
- Yabalu Z. Abacha
- School of Pharmacy and Medical Sciences, University of Bradford, Bradford, United Kingdom,Department of Pharmacognosy, Faculty of Pharmacy, University of Maiduguri, Maiduguri, Nigeria
| | - Arnold Donkor Forkuo
- Department of Pharmacology, Faculty of Pharmacy and Pharmaceutical Sciences, College of Health Sciences, Kwame Nkrumah University of Science and Technology (KNUST), Kumasi, Ghana
| | - Stephen Y. Gbedema
- Department of Pharmaceutics, Faculty of Pharmacy and Pharmaceutical Sciences, College of Health Sciences, KNUST, Kumasi, Ghana
| | - Nimisha Mittal
- Malaria Drug Accelerator (MalDA) Consortium, School of Medicine, University of California, San Diego, La Jolla, CA, United States
| | - Sabine Ottilie
- Malaria Drug Accelerator (MalDA) Consortium, School of Medicine, University of California, San Diego, La Jolla, CA, United States
| | - Frances Rocamora
- Malaria Drug Accelerator (MalDA) Consortium, School of Medicine, University of California, San Diego, La Jolla, CA, United States
| | - Elizabeth A. Winzeler
- Malaria Drug Accelerator (MalDA) Consortium, School of Medicine, University of California, San Diego, La Jolla, CA, United States
| | - Donelly A. van Schalkwyk
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - John M. Kelly
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Martin C. Taylor
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Janette Reader
- Department of Biochemistry, Genetics and Microbiology, Faculty of Natural and Agricultural Sciences, Institute for Sustainable Malaria Control, University of Pretoria, Hatfield, South Africa
| | - Lyn-Marie Birkholtz
- Department of Biochemistry, Genetics and Microbiology, Faculty of Natural and Agricultural Sciences, Institute for Sustainable Malaria Control, University of Pretoria, Hatfield, South Africa
| | - David R. Lisgarten
- Biomolecular Research Group, School of Psychology and Life Sciences, Canterbury Christ Church University, Canterbury, United Kingdom
| | - Jeremy K. Cockcroft
- Department of Chemistry, Christopher Ingold Laboratories, University College London, London, United Kingdom
| | | | - Rex A. Palmer
- Department of Crystallography, Biochemical Sciences, Birkbeck College, University of London, London, United Kingdom
| | - Rosemary C. Talbert
- Biomolecular Research Group, School of Psychology and Life Sciences, Canterbury Christ Church University, Canterbury, United Kingdom
| | - Steven D. Shnyder
- School of Pharmacy and Medical Sciences, Institute of Cancer Therapeutics, University of Bradford, Bradford, United Kingdom
| | - Colin W. Wright
- School of Pharmacy and Medical Sciences, University of Bradford, Bradford, United Kingdom,*Correspondence: Colin W. Wright,
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10
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de Carvalho LP, Groeger-Otero S, Kreidenweiss A, Kremsner PG, Mordmüller B, Held J. Boromycin has Rapid-Onset Antibiotic Activity Against Asexual and Sexual Blood Stages of Plasmodium falciparum. Front Cell Infect Microbiol 2022; 11:802294. [PMID: 35096650 PMCID: PMC8795978 DOI: 10.3389/fcimb.2021.802294] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Accepted: 12/27/2021] [Indexed: 11/25/2022] Open
Abstract
Boromycin is a boron-containing macrolide antibiotic produced by Streptomyces antibioticus with potent activity against certain viruses, Gram-positive bacteria and protozoan parasites. Most antimalarial antibiotics affect plasmodial organelles of prokaryotic origin and have a relatively slow onset of action. They are used for malaria prophylaxis and for the treatment of malaria when combined to a fast-acting drug. Despite the success of artemisinin combination therapies, the current gold standard treatment, new alternatives are constantly needed due to the ability of malaria parasites to become resistant to almost all drugs that are in heavy clinical use. In vitro antiplasmodial activity screens of tetracyclines (omadacycline, sarecycline, methacycline, demeclocycline, lymecycline, meclocycline), macrolides (oleandomycin, boromycin, josamycin, troleandomycin), and control drugs (chloroquine, clindamycin, doxycycline, minocycline, eravacycline) revealed boromycin as highly potent against Plasmodium falciparum and the zoonotic Plasmodium knowlesi. In contrast to tetracyclines, boromycin rapidly killed asexual stages of both Plasmodium species already at low concentrations (~ 1 nM) including multidrug resistant P. falciparum strains (Dd2, K1, 7G8). In addition, boromycin was active against P. falciparum stage V gametocytes at a low nanomolar range (IC50: 8.5 ± 3.6 nM). Assessment of the mode of action excluded the apicoplast as the main target. Although there was an ionophoric activity on potassium channels, the effect was too low to explain the drug´s antiplasmodial activity. Boromycin is a promising antimalarial candidate with activity against multiple life cycle stages of the parasite.
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Affiliation(s)
| | - Sara Groeger-Otero
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany
| | - Andrea Kreidenweiss
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany
- Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon
- German Center for Infection Research (DZIF), partner site Tübingen, Tübingen, Germany
| | - Peter G. Kremsner
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany
- Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon
- German Center for Infection Research (DZIF), partner site Tübingen, Tübingen, Germany
| | - Benjamin Mordmüller
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany
- Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon
- German Center for Infection Research (DZIF), partner site Tübingen, Tübingen, Germany
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, Netherlands
| | - Jana Held
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany
- Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon
- German Center for Infection Research (DZIF), partner site Tübingen, Tübingen, Germany
- *Correspondence: Jana Held, ;
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11
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Ressurreição M, Moon RW, Baker DA, van Ooij C. Synchronisation of Plasmodium falciparum and P. knowlesi In Vitro Cultures Using a Highly Specific Protein Kinase Inhibitor. Methods Mol Biol 2022; 2470:101-120. [PMID: 35881342 DOI: 10.1007/978-1-0716-2189-9_10] [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] [Indexed: 10/16/2022]
Abstract
Synchronisation of Plasmodium cultures is essential to investigate the complexities of time-dependent events associated with the asexual blood stage of the malaria parasite life cycle. Here we describe a procedure using ML10, a highly specific inhibitor of the parasite cyclic GMP-dependent protein kinase (PKG), to attain high synchronicity of Plasmodium falciparum and P. knowlesi asexual blood-stage cultures and to obtain high levels of arrested mature schizonts as well as viable released merozoites. Additionally, we describe how to use ML10 to improve the transfection efficiency of P. falciparum parasites and also how to derive the half maximal effective concentration (EC50) of ML10 in other P. falciparum laboratory lines and clinical isolates.
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Affiliation(s)
- Margarida Ressurreição
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK
| | - Robert William Moon
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK
| | - David Andrew Baker
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK
| | - Christiaan van Ooij
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK.
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12
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van Schalkwyk DA, Moon RW, Duffey M, Leroy D, Sutherland CJ. Ex vivo susceptibility to new antimalarial agents differs among human-infecting Plasmodium species. Int J Parasitol Drugs Drug Resist 2021; 17:5-11. [PMID: 34315108 PMCID: PMC8327131 DOI: 10.1016/j.ijpddr.2021.07.002] [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: 05/11/2021] [Revised: 07/19/2021] [Accepted: 07/21/2021] [Indexed: 11/16/2022]
Abstract
Several promising antimalarial drugs are currently being tested in human trials, such as artefenomel, cipargamin, ferroquine and ganaplacide. Many of these compounds were identified using high throughput screens against a single species of human malaria, Plasmodium falciparum, under the assumption that effectiveness against all malaria species will be similar, as has been observed for other antimalarial drugs. However, using our in vitro adapted line, we demonstrated recently that P. knowlesi is significantly less susceptible than P. falciparum to some new antimalarial drugs (e.g., cipargamin and DSM265), and more susceptible to others (e.g., ganaplacide). There is, therefore, an urgent need to determine the susceptibility profile of all human malaria species to the current generation of antimalarial compounds. We obtained ex vivo malaria samples from travellers returning to the United Kingdom and, using the [3H]hypoxanthine incorporation method, compared susceptibility to select established and experimental antimalarial agents among all major human infective Plasmodium species. We demonstrate that P. malariae and P. ovale spp. are significantly less susceptible than P. falciparum to cipargamin, DSM265 and AN13762, but are more susceptible to ganaplacide. Preliminary ex vivo data from single isolates of P. knowlesi and P. vivax demonstrate a similar profile. Our findings highlight the need to ensure cross species susceptibility profiles are determined early in the drug development pipeline. Our data can also be used to inform further drug development, and illustrate the utility of the P. knowlesi in vitro model as a scalable approach for predicting the drug susceptibility of non-falciparum malaria species in general.
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Affiliation(s)
- Donelly A van Schalkwyk
- Department of Infection Biology, Faculty of Infectious & Tropical Diseases, London School of Hygiene & Tropical Medicine, Keppel Street, London, WC1E 7HT, UK.
| | - Robert W Moon
- Department of Infection Biology, Faculty of Infectious & Tropical Diseases, London School of Hygiene & Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Maëlle Duffey
- Medicines for Malaria Venture, 20 rte de Pré Bois, Geneva, CH 1215, Switzerland
| | - Didier Leroy
- Medicines for Malaria Venture, 20 rte de Pré Bois, Geneva, CH 1215, Switzerland
| | - Colin J Sutherland
- Department of Infection Biology, Faculty of Infectious & Tropical Diseases, London School of Hygiene & Tropical Medicine, Keppel Street, London, WC1E 7HT, UK; Department of Clinical Parasitology, Hospital for Tropical Diseases, Mortimer Market Centre, Capper Street, London, WC1E 6JB, UK
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13
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Barber BE, Grigg MJ, Cooper DJ, van Schalkwyk DA, William T, Rajahram GS, Anstey NM. Clinical management of Plasmodium knowlesi malaria. ADVANCES IN PARASITOLOGY 2021; 113:45-76. [PMID: 34620385 DOI: 10.1016/bs.apar.2021.08.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
The zoonotic parasite Plasmodium knowlesi has emerged as an important cause of human malaria in parts of Southeast Asia. The parasite is indistinguishable by microscopy from the more benign P. malariae, but can result in high parasitaemias with multiorgan failure, and deaths have been reported. Recognition of severe knowlesi malaria, and prompt initiation of effective therapy is therefore essential to prevent adverse outcomes. Here we review all studies reporting treatment of uncomplicated and severe knowlesi malaria. We report that although chloroquine is effective for the treatment of uncomplicated knowlesi malaria, artemisinin combination treatment is associated with faster parasite clearance times and lower rates of anaemia during follow-up, and should be considered the treatment of choice, particularly given the risk of administering chloroquine to drug-resistant P. vivax or P. falciparum misdiagnosed as P. knowlesi malaria in co-endemic areas. For severe knowlesi malaria, intravenous artesunate has been shown to be highly effective and associated with reduced case-fatality rates, and should be commenced without delay. Regular paracetamol may also be considered for patients with severe knowlesi malaria or for those with acute kidney injury, to attenuate the renal damage resulting from haemolysis-induced lipid peroxidation.
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Affiliation(s)
- Bridget E Barber
- QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia; Menzies School of Health Research, Charles Darwin University, Darwin, NT, Australia.
| | - Matthew J Grigg
- Menzies School of Health Research, Charles Darwin University, Darwin, NT, Australia
| | - Daniel J Cooper
- Menzies School of Health Research, Charles Darwin University, Darwin, NT, Australia; Department of Medicine, University of Cambridge School of Medicine, Cambridge, United Kingdom
| | | | - Timothy William
- Gleneagles Medical Centre, Kota Kinabalu, Malaysia; Clinical Research Centre, Queen Elizabeth Hospital 1, Kota Kinabalu, Malaysia
| | - Giri S Rajahram
- Clinical Research Centre, Queen Elizabeth Hospital 1, Kota Kinabalu, Malaysia; Queen Elizabeth Hospital 2, Kota Kinabalu, Malaysia
| | - Nicholas M Anstey
- Menzies School of Health Research, Charles Darwin University, Darwin, NT, Australia
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14
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Vieira TB, Astro TP, de Moraes Barros RR. Genetic Manipulation of Non-Falciparum Human Malaria Parasites. Front Cell Infect Microbiol 2021; 11:680460. [PMID: 34527600 PMCID: PMC8435838 DOI: 10.3389/fcimb.2021.680460] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Accepted: 08/11/2021] [Indexed: 11/13/2022] Open
Abstract
The development of genetic manipulation of Plasmodium falciparum in the 1980s was key to study malaria biology. Genetically modified parasites have been used to study several aspects of the disease, such as red blood cell invasion, drug resistance mechanisms, gametocyte development and mosquito transmission. However, biological and genetic differences between P. falciparum and the other human malaria parasites make P. falciparum a poor model to study different species. The lack of robust systems of long-term in vitro culture of P. vivax and the other human malaria parasites lagged the genetic manipulation of these species. Here we review the efforts to generate genetically modified non-falciparum human malaria parasites, in vivo and in vitro. Using in vivo models – infection of non-human primates such as rhesus macaques and saimiri monkeys – researchers were able to generate transgenic lines of P. knowlesi, P. cynomolgi, and P. vivax. The development of long-term in vitro culture of P. knowlesi in the 2000’s, using rhesus and human red blood cells, created a platform to genetically manipulate non-falciparum malaria parasites. Recently, the use of CRISPR/Cas9 technology to genome edit P. knowlesi provides another tool to non-falciparum malaria research, extending the possibilities and allowing researchers to study different aspects of the biology of these parasites and understand the differences between these species and P. falciparum.
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Affiliation(s)
- Taís Baruel Vieira
- Department of Microbiology, Immunology and Parasitology, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Thafne Plastina Astro
- Department of Microbiology, Immunology and Parasitology, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Roberto Rudge de Moraes Barros
- Department of Microbiology, Immunology and Parasitology, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
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15
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Synthesis and Antiplasmodial Activity of Bisindolylcyclobutenediones. Molecules 2021; 26:molecules26164739. [PMID: 34443327 PMCID: PMC8402075 DOI: 10.3390/molecules26164739] [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: 06/09/2021] [Revised: 07/12/2021] [Accepted: 07/15/2021] [Indexed: 12/02/2022] Open
Abstract
Malaria is one of the most dangerous infectious diseases. Because the causative Plasmodium parasites have developed resistances against virtually all established antimalarial drugs, novel antiplasmodial agents are required. In order to target plasmodial kinases, novel N-unsubstituted bisindolylcyclobutenediones were designed as analogs to the kinase inhibitory bisindolylmaleimides. Molecular docking experiments produced favorable poses of the unsubstituted bisindolylcyclobutenedione in the ATP binding pocket of various plasmodial protein kinases. The synthesis of the title compounds was accomplished by sequential Friedel-Crafts acylation procedures. In vitro screening of the new compounds against transgenic NF54-luc P. falciparum parasites revealed a set of derivatives with submicromolar activity, of which some displayed a reasonable selectivity profile against a human cell line. Although the molecular docking studies suggested the plasmodial protein kinase PfGSK-3 as the putative biological target, the title compounds failed to inhibit the isolated enzyme in vitro. As selective submicromolar antiplasmodial agents, the N-unsubstituted bisindolylcyclobutenediones are promising starting structures in the search for antimalarial drugs, albeit for a rational development, the biological target addressed by these compounds has yet to be identified.
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16
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Duffey M, Blasco B, Burrows JN, Wells TNC, Fidock DA, Leroy D. Assessing risks of Plasmodium falciparum resistance to select next-generation antimalarials. Trends Parasitol 2021; 37:709-721. [PMID: 34001441 DOI: 10.1016/j.pt.2021.04.006] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 04/01/2021] [Accepted: 04/08/2021] [Indexed: 02/07/2023]
Abstract
Strategies to counteract or prevent emerging drug resistance are crucial for the design of next-generation antimalarials. In the past, resistant parasites were generally identified following treatment failures in patients, and compounds would have to be abandoned late in development. An early understanding of how candidate therapeutics lose efficacy as parasites evolve resistance is important to facilitate drug design and improve resistance detection and monitoring up to the postregistration phase. We describe a new strategy to assess resistance to antimalarial compounds as early as possible in preclinical development by leveraging tools to define the Plasmodium falciparum resistome, predict potential resistance risks of clinical failure for candidate therapeutics, and inform decisions to guide antimalarial drug development.
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Affiliation(s)
| | - Benjamin Blasco
- Medicines for Malaria Venture, Geneva, Switzerland; Global Antibiotic Research and Development Partnership, Geneva, Switzerland
| | | | | | - David A Fidock
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, NY, USA; Division of Infectious Diseases, Department of Medicine, Columbia University Irving Medical Center, New York, NY, USA
| | - Didier Leroy
- Medicines for Malaria Venture, Geneva, Switzerland.
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17
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Guan J, Spry C, Tjhin ET, Yang P, Kittikool T, Howieson VM, Ling H, Starrs L, Duncan D, Burgio G, Saliba KJ, Auclair K. Exploring Heteroaromatic Rings as a Replacement for the Labile Amide of Antiplasmodial Pantothenamides. J Med Chem 2021; 64:4478-4497. [PMID: 33792339 DOI: 10.1021/acs.jmedchem.0c01755] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Malaria-causing Plasmodium parasites are developing resistance to antimalarial drugs, providing the impetus for new antiplasmodials. Although pantothenamides show potent antiplasmodial activity, hydrolysis by pantetheinases/vanins present in blood rapidly inactivates them. We herein report the facile synthesis and biological activity of a small library of pantothenamide analogues in which the labile amide group is replaced with a heteroaromatic ring. Several of these analogues display nanomolar antiplasmodial activity against Plasmodium falciparum and/or Plasmodium knowlesi, and are stable in the presence of pantetheinase. Both a known triazole and a novel isoxazole derivative were further characterized and found to possess high selectivity indices, medium or high Caco-2 permeability, and medium or low microsomal clearance in vitro. Although they fail to suppress Plasmodium berghei proliferation in vivo, the pharmacokinetic and contact time data presented provide a benchmark for the compound profile likely required to achieve antiplasmodial activity in mice and should facilitate lead optimization.
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Affiliation(s)
- Jinming Guan
- Department of Chemistry, McGill University, Montreal, QC H3A 0B8, Canada
| | - Christina Spry
- Research School of Biology, The Australian National University, Acton, ACT 2601, Australia
| | - Erick T Tjhin
- Research School of Biology, The Australian National University, Acton, ACT 2601, Australia
| | - Penghui Yang
- Department of Chemistry, McGill University, Montreal, QC H3A 0B8, Canada.,College of Chemistry and Chemical Engineering, Xi'an Shiyou University, Xi'an 710065, China
| | - Tanakorn Kittikool
- Department of Chemistry, McGill University, Montreal, QC H3A 0B8, Canada
| | - Vanessa M Howieson
- Research School of Biology, The Australian National University, Acton, ACT 2601, Australia
| | - Harriet Ling
- Research School of Biology, The Australian National University, Acton, ACT 2601, Australia
| | - Lora Starrs
- John Curtin School of Medical Research, The Australian National University, Acton, ACT 2601, Australia
| | - Dustin Duncan
- Department of Chemistry, McGill University, Montreal, QC H3A 0B8, Canada
| | - Gaetan Burgio
- John Curtin School of Medical Research, The Australian National University, Acton, ACT 2601, Australia
| | - Kevin J Saliba
- Research School of Biology, The Australian National University, Acton, ACT 2601, Australia.,Medical School, The Australian National University, Acton, ACT 2601, Australia
| | - Karine Auclair
- Department of Chemistry, McGill University, Montreal, QC H3A 0B8, Canada
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18
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Clark MA, Kanjee U, Rangel GW, Chery L, Mascarenhas A, Gomes E, Rathod PK, Brugnara C, Ferreira MU, Duraisingh MT. Plasmodium vivax infection compromises reticulocyte stability. Nat Commun 2021; 12:1629. [PMID: 33712609 PMCID: PMC7955053 DOI: 10.1038/s41467-021-21886-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 02/17/2021] [Indexed: 12/21/2022] Open
Abstract
The structural integrity of the host red blood cell (RBC) is crucial for propagation of Plasmodium spp. during the disease-causing blood stage of malaria infection. To assess the stability of Plasmodium vivax-infected reticulocytes, we developed a flow cytometry-based assay to measure osmotic stability within characteristically heterogeneous reticulocyte and P. vivax-infected samples. We find that erythroid osmotic stability decreases during erythropoiesis and reticulocyte maturation. Of enucleated RBCs, young reticulocytes which are preferentially infected by P. vivax, are the most osmotically stable. P. vivax infection however decreases reticulocyte stability to levels close to those of RBC disorders that cause hemolytic anemia, and to a significantly greater degree than P. falciparum destabilizes normocytes. Finally, we find that P. vivax new permeability pathways contribute to the decreased osmotic stability of infected-reticulocytes. These results reveal a vulnerability of P. vivax-infected reticulocytes that could be manipulated to allow in vitro culture and develop novel therapeutics. During Plasmodium intra-erythrocytic developmental, parasites compromise the structural integrity of host red-blood cells. Here, Clark et al. develop a flow cytometric osmotic stability assay to show that P. vivax infection destabilizes host reticulocytes, which are less stable than P. falciparum-infected normocytes.
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Affiliation(s)
- Martha A Clark
- Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Boston, MA, USA
| | - Usheer Kanjee
- Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Boston, MA, USA
| | - Gabriel W Rangel
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA, USA
| | - Laura Chery
- Department of Chemistry, University of Washington, Seattle, WA, USA
| | - Anjali Mascarenhas
- Malaria Evolution in South Asia (MESA)-International Centers of Excellence in Malaria Research (ICEMR), Goa Medical College, Bambolim, Goa, India
| | - Edwin Gomes
- Malaria Evolution in South Asia (MESA)-International Centers of Excellence in Malaria Research (ICEMR), Goa Medical College, Bambolim, Goa, India
| | | | - Carlo Brugnara
- Department of Laboratory Medicine, Boston Children's Hospital, Boston, MA, USA
| | - Marcelo U Ferreira
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
| | - Manoj T Duraisingh
- Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Boston, MA, USA.
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19
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Burns AL, Sleebs BE, Siddiqui G, De Paoli AE, Anderson D, Liffner B, Harvey R, Beeson JG, Creek DJ, Goodman CD, McFadden GI, Wilson DW. Retargeting azithromycin analogues to have dual-modality antimalarial activity. BMC Biol 2020; 18:133. [PMID: 32993629 PMCID: PMC7526119 DOI: 10.1186/s12915-020-00859-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Accepted: 08/28/2020] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND Resistance to front-line antimalarials (artemisinin combination therapies) is spreading, and development of new drug treatment strategies to rapidly kill Plasmodium spp. malaria parasites is urgently needed. Azithromycin is a clinically used macrolide antibiotic proposed as a partner drug for combination therapy in malaria, which has also been tested as monotherapy. However, its slow-killing 'delayed-death' activity against the parasite's apicoplast organelle and suboptimal activity as monotherapy limit its application as a potential malaria treatment. Here, we explore a panel of azithromycin analogues and demonstrate that chemical modifications can be used to greatly improve the speed and potency of antimalarial action. RESULTS Investigation of 84 azithromycin analogues revealed nanomolar quick-killing potency directed against the very earliest stage of parasite development within red blood cells. Indeed, the best analogue exhibited 1600-fold higher potency than azithromycin with less than 48 hrs treatment in vitro. Analogues were effective against zoonotic Plasmodium knowlesi malaria parasites and against both multi-drug and artemisinin-resistant Plasmodium falciparum lines. Metabolomic profiles of azithromycin analogue-treated parasites suggested activity in the parasite food vacuole and mitochondria were disrupted. Moreover, unlike the food vacuole-targeting drug chloroquine, azithromycin and analogues were active across blood-stage development, including merozoite invasion, suggesting that these macrolides have a multi-factorial mechanism of quick-killing activity. The positioning of functional groups added to azithromycin and its quick-killing analogues altered their activity against bacterial-like ribosomes but had minimal change on 'quick-killing' activity. Apicoplast minus parasites remained susceptible to both azithromycin and its analogues, further demonstrating that quick-killing is independent of apicoplast-targeting, delayed-death activity. CONCLUSION We show that azithromycin and analogues can rapidly kill malaria parasite asexual blood stages via a fast action mechanism. Development of azithromycin and analogues as antimalarials offers the possibility of targeting parasites through both a quick-killing and delayed-death mechanism of action in a single, multifactorial chemotype.
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Affiliation(s)
- Amy L Burns
- Research Centre for Infectious Diseases, School of Biological Sciences, The University of Adelaide, Adelaide, 5005, Australia
| | - Brad E Sleebs
- Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria, 3050, Australia
- Department of Medical Biology, University of Melbourne, Melbourne, Victoria, 3050, Australia
| | - Ghizal Siddiqui
- Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne, Victoria, 3052, Australia
| | - Amanda E De Paoli
- Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne, Victoria, 3052, Australia
| | - Dovile Anderson
- Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne, Victoria, 3052, Australia
| | - Benjamin Liffner
- Research Centre for Infectious Diseases, School of Biological Sciences, The University of Adelaide, Adelaide, 5005, Australia
| | - Richard Harvey
- Research Centre for Infectious Diseases, School of Biological Sciences, The University of Adelaide, Adelaide, 5005, Australia
| | - James G Beeson
- Burnet Institute, Melbourne, Victoria, 3004, Australia
- Department of Medicine, University of Melbourne, Melbourne, Australia
- Central Clinical School and Department of Microbiology, Monash University, Melbourne, Australia
| | - Darren J Creek
- Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne, Victoria, 3052, Australia
| | - Christopher D Goodman
- School of Biosciences, University of Melbourne, Melbourne, Victoria, 3010, Australia
| | - Geoffrey I McFadden
- School of Biosciences, University of Melbourne, Melbourne, Victoria, 3010, Australia
| | - Danny W Wilson
- Research Centre for Infectious Diseases, School of Biological Sciences, The University of Adelaide, Adelaide, 5005, Australia.
- Burnet Institute, Melbourne, Victoria, 3004, Australia.
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20
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Ressurreição M, Thomas JA, Nofal SD, Flueck C, Moon RW, Baker DA, van Ooij C. Use of a highly specific kinase inhibitor for rapid, simple and precise synchronization of Plasmodium falciparum and Plasmodium knowlesi asexual blood-stage parasites. PLoS One 2020; 15:e0235798. [PMID: 32673324 PMCID: PMC7365400 DOI: 10.1371/journal.pone.0235798] [Citation(s) in RCA: 18] [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: 04/28/2020] [Accepted: 06/22/2020] [Indexed: 12/15/2022] Open
Abstract
During the course of the asexual erythrocytic stage of development, Plasmodium spp. parasites undergo a series of morphological changes and induce alterations in the host cell. At the end of this stage, the parasites egress from the infected cell, after which the progeny invade a new host cell. These processes are rapid and occur in a time-dependent manner. Of particular importance, egress and invasion of erythrocytes by the parasite are difficult to capture in an unsynchronized culture, or even a culture that has been synchronized within a window of one to several hours. Therefore, precise synchronization of parasite cultures is of paramount importance for the investigation of these processes. Here we describe a method for synchronizing Plasmodium falciparum and Plasmodium knowlesi asexual blood stage parasites with ML10, a highly specific inhibitor of the cGMP-dependent protein kinase (PKG) that arrests parasite growth approximately 15 minutes prior to egress. This inhibitor allows parasite cultures to be synchronized so that all parasites are within a window of development of several minutes, with a simple wash step. Furthermore, we show that parasites remain viable for several hours after becoming arrested by the compound and that ML10 has advantages, owing to its high specificity and low EC50, over the previously used PKG inhibitor Compound 2. Here, we demonstrate that ML10 is an invaluable tool for the study of Plasmodium spp. asexual blood stage biology and for the routine synchronization of P. falciparum and P. knowlesi cultures.
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Affiliation(s)
- Margarida Ressurreição
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - James A. Thomas
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Stephanie D. Nofal
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Christian Flueck
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Robert W. Moon
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - David A. Baker
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Christiaan van Ooij
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, United Kingdom
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21
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Novel Endochin-Like Quinolones Exhibit Potent In Vitro Activity against Plasmodium knowlesi but Do Not Synergize with Proguanil. Antimicrob Agents Chemother 2020; 64:AAC.02549-19. [PMID: 32094134 DOI: 10.1128/aac.02549-19] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 02/21/2020] [Indexed: 12/16/2022] Open
Abstract
Quinolones, such as the antimalarial atovaquone, are inhibitors of the malarial mitochondrial cytochrome bc 1 complex, a target critical to the survival of both liver- and blood-stage parasites, making these drugs useful as both prophylaxis and treatment. Recently, several derivatives of endochin have been optimized to produce novel quinolones that are active in vitro and in animal models. While these quinolones exhibit potent ex vivo activity against Plasmodium falciparum and Plasmodium vivax, their activity against the zoonotic agent Plasmodium knowlesi is unknown. We screened several of these novel endochin-like quinolones (ELQs) for their activity against P. knowlesi in vitro and compared this with their activity against P. falciparum tested under identical conditions. We demonstrated that ELQs are potent against P. knowlesi (50% effective concentration, <117 nM) and equally effective against P. falciparum We then screened selected quinolones and partner drugs using a longer exposure (2.5 life cycles) and found that proguanil is 10-fold less potent against P. knowlesi than P. falciparum, while the quinolones demonstrate similar potency. Finally, we used isobologram analysis to compare combinations of the ELQs with either proguanil or atovaquone. We show that all quinolone combinations with proguanil are synergistic against P. falciparum However, against P. knowlesi, no evidence of synergy between proguanil and the quinolones was found. Importantly, the combination of the novel quinolone ELQ-300 with atovaquone was synergistic against both species. Our data identify potentially important species differences in proguanil susceptibility and in the interaction of proguanil with quinolones and support the ongoing development of novel quinolones as potent antimalarials that target multiple species.
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Modification of pfap2μ and pfubp1 Markedly Reduces Ring-Stage Susceptibility of Plasmodium falciparum to Artemisinin In Vitro. Antimicrob Agents Chemother 2019; 64:AAC.01542-19. [PMID: 31636063 DOI: 10.1128/aac.01542-19] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Accepted: 10/10/2019] [Indexed: 12/26/2022] Open
Abstract
Management of uncomplicated malaria worldwide is threatened by the emergence in Asia of Plasmodium falciparum carrying variants of the pfk13 locus and exhibiting reduced susceptibility to artemisinin. Mutations in two other genes, ubp1 and ap2μ, are associated with artemisinin resistance in rodent malaria and with clinical failure of combination therapy in African malaria patients. Transgenic P. falciparum clones, each carrying orthologues of mutations in pfap2μ and pfubp1 associated with artemisinin resistance in Plasmodium chabaudi, were derived by Cas9 gene editing. Susceptibility to artemisinin and other antimalarial drugs was determined. Following exposure to 700 nM dihydroartemisinin in the ring-stage survival assay, we found strong evidence that transgenic parasites expressing the I592T variant (11% survival), but not the S160N variant (1% survival), of the AP2μ adaptin subunit were significantly less susceptible than the parental wild-type parasite population. The V3275F variant of UBP1, but not the V3306F variant, also displayed reduced susceptibility to dihydroartemisinin (8.5% survival versus 0.5% survival). AP2μ and UBP1 variants did not elicit reduced susceptibility to 48 h of exposure to artemisinin or to other antimalarial drugs. Therefore, variants of the AP2 adaptor complex μ-subunit and of the ubiquitin hydrolase UBP1 reduce in vitro artemisinin susceptibility at the early ring stage in P. falciparum These findings confirm the existence of multiple pathways to perturbation of either the mode of action of artemisinin, the parasite's adaptive mechanisms of resistance, or both. The cellular role of UBP1 and AP2μ in Plasmodium parasites should now be elucidated.
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Verzier LH, Coyle R, Singh S, Sanderson T, Rayner JC. Plasmodium knowlesi as a model system for characterising Plasmodium vivax drug resistance candidate genes. PLoS Negl Trop Dis 2019; 13:e0007470. [PMID: 31158222 PMCID: PMC6564043 DOI: 10.1371/journal.pntd.0007470] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Revised: 06/13/2019] [Accepted: 05/15/2019] [Indexed: 12/29/2022] Open
Abstract
Plasmodium vivax causes the majority of malaria outside Africa, but is poorly understood at a cellular level partly due to technical difficulties in maintaining it in in vitro culture conditions. In the past decades, drug resistant P. vivax parasites have emerged, mainly in Southeast Asia, but while some molecular markers of resistance have been identified, none have so far been confirmed experimentally, which limits interpretation of the markers, and hence our ability to monitor and control the spread of resistance. Some of these potential markers have been identified through P. vivax genome-wide population genetic analyses, which highlighted genes under recent evolutionary selection in Southeast Asia, where chloroquine resistance is most prevalent. These genes could be involved in drug resistance, but no experimental proof currently exists to support this hypothesis. In this study, we used Plasmodium knowlesi, the most closely related species to P. vivax that can be cultured in human erythrocytes, as a model system to express P. vivax genes and test for their role in drug resistance. We adopted a strategy of episomal expression, and were able to express fourteen P. vivax genes, including two allelic variants of several hypothetical resistance genes. Their expression level and localisation were assessed, confirming cellular locations conjectured from orthologous species, and suggesting locations for several previously unlocalised proteins, including an apical location for PVX_101445. These findings establish P. knowlesi as a suitable model for P. vivax protein expression. We performed chloroquine and mefloquine drug assays, finding no significant differences in drug sensitivity: these results could be due to technical issues, or could indicate that these genes are not actually involved in drug resistance, despite being under positive selection pressure in Southeast Asia. These data confirm that in vitro P. knowlesi is a useful tool for studying P. vivax biology. Its close evolutionary relationship to P. vivax, high transfection efficiency, and the availability of markers for colocalisation, all make it a powerful model system. Our study is the first of its kind using P. knowlesi to study unknown P. vivax proteins and investigate drug resistance mechanisms.
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Affiliation(s)
- Lisa H. Verzier
- Parasites and Microbes Programme, Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridgeshire, United Kingdom
| | - Rachael Coyle
- Parasites and Microbes Programme, Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridgeshire, United Kingdom
| | - Shivani Singh
- Parasites and Microbes Programme, Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridgeshire, United Kingdom
| | - Theo Sanderson
- Parasites and Microbes Programme, Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridgeshire, United Kingdom
| | - Julian C. Rayner
- Parasites and Microbes Programme, Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridgeshire, United Kingdom
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Ngernna S, Chim-Ong A, Roobsoong W, Sattabongkot J, Cui L, Nguitragool W. Efficient synchronization of Plasmodium knowlesi in vitro cultures using guanidine hydrochloride. Malar J 2019; 18:148. [PMID: 31023359 PMCID: PMC6482532 DOI: 10.1186/s12936-019-2783-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Accepted: 04/16/2019] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Long-term in vitro culture of blood stage Plasmodium parasites invariably leads to asynchronous parasite development. The most often used technique to synchronize Plasmodium falciparum culture is sorbitol treatment, which differentially induces osmotic lysis of trophozoite- and schizont-infected red blood cells due to presence of the new permeation pathways in the membranes of these cells. However, sorbitol treatment does not work well when used to synchronize the culture-adapted Plasmodium knowlesi A1-H.1 line. METHODS A number of common solutes were tested in lieu of sorbitol for synchronization of P. knowlesi A1-H.1 ring stage. RESULTS Guanidine hydrochloride was found to selectively lyse trophozoite- and schizont-infected red blood cells, yielding highly synchronous and viable rings. CONCLUSIONS A method for synchronization of P. knowlesi in human red blood cells was developed. Requiring only common laboratory reagents, this method is simple and should be applicable to most laboratory settings.
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Affiliation(s)
- Sutharinee Ngernna
- Department of Molecular Tropical Medicine, Faculty of Tropical Medicine, Mahidol University, 420/6 Ratchawithi Road, Ratchathewi, Bangkok, 10400, Thailand
| | - Anongruk Chim-Ong
- Department of Molecular Tropical Medicine, Faculty of Tropical Medicine, Mahidol University, 420/6 Ratchawithi Road, Ratchathewi, Bangkok, 10400, Thailand
| | - Wanlapa Roobsoong
- Mahidol Vivax Research Unit, Faculty of Tropical Medicine, Mahidol University, 420/6 Ratchawithi Road, Ratchathewi, Bangkok, 10400, Thailand
| | - Jetsumon Sattabongkot
- Mahidol Vivax Research Unit, Faculty of Tropical Medicine, Mahidol University, 420/6 Ratchawithi Road, Ratchathewi, Bangkok, 10400, Thailand
| | - Liwang Cui
- Department of Internal Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL, USA
| | - Wang Nguitragool
- Department of Molecular Tropical Medicine, Faculty of Tropical Medicine, Mahidol University, 420/6 Ratchawithi Road, Ratchathewi, Bangkok, 10400, Thailand.
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25
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Plasmodium knowlesi exhibits distinct in vitro drug susceptibility profiles from those of Plasmodium falciparum. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2019; 9:93-99. [PMID: 30831468 PMCID: PMC6403410 DOI: 10.1016/j.ijpddr.2019.02.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 02/14/2019] [Accepted: 02/18/2019] [Indexed: 12/16/2022]
Abstract
New antimalarial agents are identified and developed after extensive testing on Plasmodium falciparum parasites that can be grown in vitro. These susceptibility studies are important to inform lead optimisation and support further drug development. Until recently, little was known about the susceptibility of non-falciparum species as these had not been adapted to in vitro culture. The recent culture adaptation of P. knowlesi has therefore offered an opportunity to routinely define the drug susceptibility of this species, which is phylogenetically closer to all other human malarias than is P. falciparum. We compared the in vitro susceptibility of P. knowlesi and P. falciparum to a range of established and novel antimalarial agents under identical assay conditions. We demonstrated that P. knowlesi is significantly less susceptible than P. falciparum to six of the compounds tested; and notably these include three ATP4 inhibitors currently under development as novel antimalarial agents, and one investigational antimalarial, AN13762, which is 67 fold less effective against P. knowlesi. For the other compounds there was a less than two-fold difference in susceptibility between species. We then compared the susceptibility of a recent P. knowlesi isolate, UM01, to that of the well-established, older A1-H.1 clone. This recent isolate showed similar in vitro drug susceptibility to the A1-H.1 clone, supporting the ongoing use of the better characterised clone to further study drug susceptibility. Lastly, we used isobologram analysis to explore the interaction of a selection of drug combinations and showed similar drug interactions across species. The species differences in drug susceptibility reported by us here and previously, support adding in vitro drug screens against P. knowlesi to those using P. falciparum strains to inform new drug discovery and lead optimisation. P. knowlesi >6-fold less susceptible to several ATP4 inhibitors than P. falciparum. P. knowlesi equally susceptible to artemisinins and synthetic endoperoxides. Isobolograms show similar drug interactions for P. knowlesi and P. falciparum. New P. knowlesi isolate (UM01) similarly susceptible to antimalarials as A1-H.1
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26
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Henrici RC, van Schalkwyk DA, Sutherland CJ. Transient temperature fluctuations severely decrease P. falciparum susceptibility to artemisinin in vitro. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2018; 9:23-26. [PMID: 30599390 PMCID: PMC6312858 DOI: 10.1016/j.ijpddr.2018.12.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/04/2018] [Revised: 12/13/2018] [Accepted: 12/14/2018] [Indexed: 12/19/2022]
Abstract
Clinical studies suggest that outcomes for hospitalised malaria patients can be improved by managed hypothermia during treatment. We examined the impact of short pulses of low temperature on ring-stage susceptibility of Plasmodium falciparum to artemisinin in vitro. The usually artemisinin-sensitive clone 3D7 exhibited substantially reduced ring-stage susceptibility to a 4-h pulse of 700 nM dihydro-artemisinin administered during a 5-h pulse of low temperature down to 17 °C. Parasite growth through the subsequent asexual cycle was not affected by the temperature pulse. Chloroquine and pyronaridine susceptibility, in a standard 48-h test, was not affected by brief exposures to low temperature. Fever-like temperature pulses up to 40 °C were also accompanied by enhanced ring-stage survival of 700 nM artemisinin pulses, but parasite growth was generally attenuated at this temperature. We discuss these findings in relation to the possible activation of parasite stress responses, including the unfolded protein response, by hypo- or hyper-thermic conditions. Physiological states may need to be considered in artemisinin-treated P. falciparum patients.
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Affiliation(s)
- Ryan C Henrici
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Donelly A van Schalkwyk
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Colin J Sutherland
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom; Hospital for Tropical Diseases, University College London Hospital, London, United Kingdom.
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27
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Lyth O, Vizcay-Barrena G, Wright KE, Haase S, Mohring F, Najer A, Henshall IG, Ashdown GW, Bannister LH, Drew DR, Beeson JG, Fleck RA, Moon RW, Wilson DW, Baum J. Cellular dissection of malaria parasite invasion of human erythrocytes using viable Plasmodium knowlesi merozoites. Sci Rep 2018; 8:10165. [PMID: 29976932 PMCID: PMC6033891 DOI: 10.1038/s41598-018-28457-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Accepted: 06/22/2018] [Indexed: 12/21/2022] Open
Abstract
Plasmodium knowlesi, a zoonotic parasite causing severe-to-lethal malaria disease in humans, has only recently been adapted to continuous culture with human red blood cells (RBCs). In comparison with the most virulent human malaria, Plasmodium falciparum, there are, however, few cellular tools available to study its biology, in particular direct investigation of RBC invasion by blood-stage P. knowlesi merozoites. This leaves our current understanding of biological differences across pathogenic Plasmodium spp. incomplete. Here, we report a robust method for isolating viable and invasive P. knowlesi merozoites to high purity and yield. Using this approach, we present detailed comparative dissection of merozoite invasion (using a variety of microscopy platforms) and direct assessment of kinetic differences between knowlesi and falciparum merozoites. We go on to assess the inhibitory potential of molecules targeting discrete steps of invasion in either species via a quantitative invasion inhibition assay, identifying a class of polysulfonate polymer able to efficiently inhibit invasion in both, providing a foundation for pan-Plasmodium merozoite inhibitor development. Given the close evolutionary relationship between P. knowlesi and P. vivax, the second leading cause of malaria-related morbidity, this study paves the way for inter-specific dissection of invasion by all three major pathogenic malaria species.
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Affiliation(s)
- Oliver Lyth
- Department of Life Sciences, Imperial College London, Sir Alexander Fleming Building, Exhibition Road, South Kensington, London, UK
| | - Gema Vizcay-Barrena
- Centre for Ultrastructural Imaging, Guy's Campus, King's College London, London, UK
| | - Katherine E Wright
- Department of Life Sciences, Imperial College London, Sir Alexander Fleming Building, Exhibition Road, South Kensington, London, UK
| | - Silvia Haase
- Department of Life Sciences, Imperial College London, Sir Alexander Fleming Building, Exhibition Road, South Kensington, London, UK
| | - Franziska Mohring
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
| | - Adrian Najer
- Department of Life Sciences, Imperial College London, Sir Alexander Fleming Building, Exhibition Road, South Kensington, London, UK
| | - Isabelle G Henshall
- Research Centre for Infectious Diseases, School of Biological Sciences, The University of Adelaide, Adelaide, Australia
| | - George W Ashdown
- Department of Life Sciences, Imperial College London, Sir Alexander Fleming Building, Exhibition Road, South Kensington, London, UK
| | - Lawrence H Bannister
- Centre for Ultrastructural Imaging, Guy's Campus, King's College London, London, UK
| | - Damien R Drew
- Burnet Institute, 85 Commercial Road, Melbourne, Victoria, Australia.,Central Clinical School, Monash University, Victoria, Australia
| | - James G Beeson
- Burnet Institute, 85 Commercial Road, Melbourne, Victoria, Australia.,Central Clinical School, Monash University, Victoria, Australia
| | - Roland A Fleck
- Centre for Ultrastructural Imaging, Guy's Campus, King's College London, London, UK
| | - Robert W Moon
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
| | - Danny W Wilson
- Research Centre for Infectious Diseases, School of Biological Sciences, The University of Adelaide, Adelaide, Australia. .,Burnet Institute, 85 Commercial Road, Melbourne, Victoria, Australia.
| | - Jake Baum
- Department of Life Sciences, Imperial College London, Sir Alexander Fleming Building, Exhibition Road, South Kensington, London, UK.
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28
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Abstract
A curious aspect of the evolution of the hypnozoite theory of malarial relapse is its transmogrification from theory into 'fact', this being of historical, linguistic, scientific and sociological interest. As far as it goes, the hypnozoite explanation for relapse is almost certainly correct. I contend, however, that many of the genotypically homologous, non-reinfection, relapse-like Plasmodium vivax recurrences that researchers ascribe to hypnozoite activation are probably hypnozoite-independent. Indeed, some malariologists are starting to recognize that homologous P. vivax recurrences have most likely been overattributed to activation of hypnozoites. Hitherto identified, non-hypnozoite, possible plasmodial sources of recurrence that must be considered, besides circulating erythrocytic stages, include parasites in splenic dendritic cells, other cells in the spleen (in addition to infected erythrocytes there), bone marrow (importantly) and the skin. I argue that we need to take into account the possibility of a dual or multiple extra-vascular origin of P. vivax non-reinfection recurrences, not arbitrarily discount it. The existence of a P. vivax reservoir(s) is a topical subject and one of practical importance for malaria eradication. Pertinent drug-associated matters are also discussed, as is the dormancy-related significance of clues provided by blood-stage-induced malarial infection.
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