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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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Keroack CD, Elsworth B, Tennessen JA, Paul AS, Hua R, Ramirez-Ramirez L, Ye S, Moreira CK, Meyers MJ, Zarringhalam K, Duraisingh MT. Comparative chemical genomics in Babesia species identifies the alkaline phosphatase PhoD as a determinant of antiparasitic resistance. Proc Natl Acad Sci U S A 2024; 121:e2312987121. [PMID: 38377214 PMCID: PMC10907312 DOI: 10.1073/pnas.2312987121] [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: 08/07/2023] [Accepted: 01/09/2024] [Indexed: 02/22/2024] Open
Abstract
Babesiosis is an emerging zoonosis and widely distributed veterinary infection caused by 100+ species of Babesia parasites. The diversity of Babesia parasites and the lack of specific drugs necessitate the discovery of broadly effective antibabesials. Here, we describe a comparative chemogenomics (CCG) pipeline for the identification of conserved targets. CCG relies on parallel in vitro evolution of resistance in independent populations of Babesia spp. (B. bovis and B. divergens). We identified a potent antibabesial, MMV019266, from the Malaria Box, and selected for resistance in two species of Babesia. After sequencing of multiple independently derived lines in the two species, we identified mutations in a membrane-bound metallodependent phosphatase (phoD). In both species, the mutations were found in the phoD-like phosphatase domain. Using reverse genetics, we validated that mutations in bdphoD confer resistance to MMV019266 in B. divergens. We have also demonstrated that BdPhoD localizes to the endomembrane system and partially with the apicoplast. Finally, conditional knockdown and constitutive overexpression of BdPhoD alter the sensitivity to MMV019266 in the parasite. Overexpression of BdPhoD results in increased sensitivity to the compound, while knockdown increases resistance, suggesting BdPhoD is a pro-susceptibility factor. Together, we have generated a robust pipeline for identification of resistance loci and identified BdPhoD as a resistance mechanism in Babesia species.
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Affiliation(s)
- Caroline D. Keroack
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA02115
| | - Brendan Elsworth
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA02115
| | - Jacob A. Tennessen
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA02115
| | - Aditya S. Paul
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA02115
| | - Renee Hua
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA02115
| | - Luz Ramirez-Ramirez
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA02115
| | - Sida Ye
- Department of Mathematics, University of Massachusetts, Boston, MA02125
- Center for Personalized Cancer Therapy, University of Massachusetts, Boston, MA02125
| | - Cristina K. Moreira
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA02115
| | - Marvin J. Meyers
- Department of Chemistry, Saint Louis University, St. Louis, MO63103
| | - Kourosh Zarringhalam
- Department of Mathematics, University of Massachusetts, Boston, MA02125
- Center for Personalized Cancer Therapy, University of Massachusetts, Boston, MA02125
| | - Manoj T. Duraisingh
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA02115
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Koonyosying P, Srichairatanakool S, Tiwananthagorn S, Sthitmatee N. Inhibitory effects on bovine babesial infection by iron chelator, 1-(N-acetyl-6-aminohexyl)- 3-hydroxy-2-methylpyridin-4-one (CM1), and antimalarial drugs. Vet Parasitol 2023; 324:110055. [PMID: 37931475 DOI: 10.1016/j.vetpar.2023.110055] [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: 07/12/2023] [Revised: 10/12/2023] [Accepted: 10/17/2023] [Indexed: 11/08/2023]
Abstract
BACKGROUND Babesiosis is an infectious disease caused by protozoa of the apicomplexan phylum, genus Babesia. It is a malaria-like parasitic disease that can be transmitted via tick bites. The apicomplexan phylum of eukaryotic microbial parasites has had detrimental impacts on human and veterinary medicine. There are only a few drugs currently available to treat this disease; however, parasitic strains that are resistant to these commercial drugs are increasing in numbers. Plasmodium and Babesia are closely related as they share similar biological features including mechanisms for host cell invasion and metabolism. Therefore, antimalarial drugs may be useful in the treatment of Babesia infections. In addition to antimalarials, iron chelators also inhibit parasite growth. In this study, we aimed to evaluate the in vitro inhibitory efficacy of iron chelator and different antimalarials in the treatment of Babesia bovis. METHODS Cytotoxicity of antimalarial drugs; pyrimethamine, artefenomel, chloroquine, primaquine, dihydroarthemisinine, and the iron chelator, 1-(N-acetyl-6-aminohexyl)- 3-hydroxy-2 methylpyridin-4-one (CM1), were evaluated against Madin Darby Bovine Kidney (MDBK) cells and compared to diminazene aceturate, which is the currently available drug for animal babesiosis using an MTT solution. Afterwards, an evaluation of the in vitro growth-inhibitory effects of antimalarial drug concentrations was performed and monitored using a flow cytometer. Half maximal inhibitory concentrations (IC50) of each antimalarial and iron chelator were determined and compared to the antibabesial drug, diminazine aceturate, by interpolation using a curve-fitting technique. Subsequently, the effect of the drug combination was assessed by constructing an isobologram. Values of the sum of fractional inhibitions at 50% inhibition were then estimated. RESULTS Results indicate that all drugs tested could safely inhibit babesia parasite growth, as high as 2500 μM were non-toxic to mammalian cells. Although no drugs inhibited B. bovis more effectively than diminazine aceturate in this experiment, in vitro growth inhibition results with IC50 values of pyrimethamine 6.25 ± 2.59 μM, artefenomel 2.56 ± 0.67 μM, chloroquine 2.14 ± 0.76 μM, primaquine 22.61 ± 6.72 μM, dihydroarthemisinine 4.65 ± 0.22 μM, 1-(N-acetyl-6-aminohexyl)- 3-hydroxy-2 methylpyridin-4-one (CM1) 9.73 ± 1.90 μM, and diminazine aceturate 0.42 ± 0.01 μM, confirm that all drugs could inhibit B. bovis and could be used as alternative treatments for bovine babesial infection. Furthermore, the efficacy of a combination of the iron chelator, CM1, in combination with artefenomel dihydroarthemisinin or chloroquine, and artefenomel in combination with the iron chelator, CM1, dihydroarthemisinin or chloroquine, exhibited synergism against B. bovis in vitro. CONCLUSION Our evaluation of the inhibitory efficacy of the iron chelator CM1, antimalarial drugs, and a combination of these drugs against B. bovis could be potentially useful in the development and discovery of a novel drug for the treatment of B. bovis in the future.
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Affiliation(s)
- Pongpisid Koonyosying
- Laboratory of Veterinary Vaccine and Biological Products, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai 50100, Thailand; Office of Research Administration, Chiang Mai University, Chiang Mai 50200, Thailand
| | - Somdet Srichairatanakool
- Department of Biochemistry, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand
| | - Saruda Tiwananthagorn
- Laboratory of Veterinary Vaccine and Biological Products, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai 50100, Thailand
| | - Nattawooti Sthitmatee
- Laboratory of Veterinary Vaccine and Biological Products, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai 50100, Thailand.
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Shor SM, Schweig SK. The Use of Natural Bioactive Nutraceuticals in the Management of Tick-Borne Illnesses. Microorganisms 2023; 11:1759. [PMID: 37512931 PMCID: PMC10384908 DOI: 10.3390/microorganisms11071759] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2023] [Revised: 06/29/2023] [Accepted: 06/29/2023] [Indexed: 07/30/2023] Open
Abstract
The primary objective of this paper is to provide an evidence-based update of the literature on the use of bioactive phytochemicals, nutraceuticals, and micronutrients (dietary supplements that provide health benefits beyond their nutritional value) in the management of persistent cases of Borrelia burgdorferi infection (Lyme disease) and two other tick-borne pathogens, Babesia and Bartonella species. Recent studies have advanced our understanding of the pathophysiology and mechanisms of persistent infections. These advances have increasingly enabled clinicians and patients to utilize a wider set of options to manage these frequently disabling conditions. This broader toolkit holds the promise of simultaneously improving treatment outcomes and helping to decrease our reliance on the long-term use of pharmaceutical antimicrobials and antibiotics in the treatment of tick-borne pathogens such as Borrelia burgdorferi, Babesia, and Bartonella.
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Affiliation(s)
- Samuel M Shor
- Internal Medicine of Northern Virginia, George Washington University Health Care Sciences, Reston, VA 20190, USA
| | - Sunjya K Schweig
- California Center for Functional Medicine, Oakland, CA 94619, USA
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5
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Keroack CD, Elsworth B, Tennessen JA, Paul AS, Hua R, Ramirez-Ramirez L, Ye S, Moreira CM, Meyers MJ, Zarringhalam K, Duraisingh MT. Comparative chemical genomics in Babesia species identifies the alkaline phosphatase phoD as a novel determinant of resistance. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.13.544849. [PMID: 37398106 PMCID: PMC10312741 DOI: 10.1101/2023.06.13.544849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Babesiosis is an emerging zoonosis and widely distributed veterinary infection caused by 100+ species of Babesia parasites. The diversity of Babesia parasites, coupled with the lack of potent inhibitors necessitates the discovery of novel conserved druggable targets for the generation of broadly effective antibabesials. Here, we describe a comparative chemogenomics (CCG) pipeline for the identification of novel and conserved targets. CCG relies on parallel in vitro evolution of resistance in independent populations of evolutionarily-related Babesia spp. ( B. bovis and B. divergens ). We identified a potent antibabesial inhibitor from the Malaria Box, MMV019266. We were able to select for resistance to this compound in two species of Babesia, achieving 10-fold or greater resistance after ten weeks of intermittent selection. After sequencing of multiple independently derived lines in the two species, we identified mutations in a single conserved gene in both species: a membrane-bound metallodependent phosphatase (putatively named PhoD). In both species, the mutations were found in the phoD-like phosphatase domain, proximal to the predicted ligand binding site. Using reverse genetics, we validated that mutations in PhoD confer resistance to MMV019266. We have also demonstrated that PhoD localizes to the endomembrane system and partially with the apicoplast. Finally, conditional knockdown and constitutive overexpression of PhoD alter the sensitivity to MMV019266 in the parasite: overexpression of PhoD results in increased sensitivity to the compound, while knockdown increases resistance, suggesting PhoD is a resistance mechanism. Together, we have generated a robust pipeline for identification of resistance loci, and identified PhoD as a novel determinant of resistance in Babesia species. Highlights Use of two species for in vitro evolution identifies a high confidence locus associated with resistance Resistance mutation in phoD was validated using reverse genetics in B. divergens Perturbation of phoD using function genetics results in changes in the level of resistance to MMV019266Epitope tagging reveals localization to the ER/apicoplast, a conserved localization with a similar protein in diatoms Together, phoD is a novel resistance determinant in multiple Babesia spp .
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Rizk MA, El-Sayed SAES, Igarashi I. In vivo activity and atom pair fingerprint analysis of MMV665941 against the apicomplexan parasite Babesia microti, the causative agent of babesiosis in humans and rodents. Pathog Glob Health 2023; 117:315-321. [PMID: 36172647 PMCID: PMC10081058 DOI: 10.1080/20477724.2022.2128571] [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] [Indexed: 10/14/2022] Open
Abstract
The effect of MMV665941 on the growth of Babesia microti (B. microti) in mice, was investigated in this study using a fluorescence-based SYBR Green I test. Using atom Pair signatures, we investigated the structural similarity between MMV665941 and the commonly used antibabesial medicines diminazene aceturate (DA), imidocarb dipropionate (ID), or atovaquone (AV). In vitro cultures of Babesia bovis (B. bovis) and, Theileria equi (T. equi) were utilized to determine the MMV665941 and AV interaction using combination ratios ranged from 0.75 IC50 MMV665941:0.75 IC50 AV to 0.50 IC50 MMV665941:0.50 IC50 AV. The used combinations were prepared depending on the IC50 of each drug against the in vitro growth of the tested parasite. Every 96 h, the hemolytic anemia in the treated mice was monitored using a Celltac MEK-6450 computerized hematology analyzer. A single dose of 5 mg/kg MMV665941 exhibited inhibition in the B. microti growth from day 4 post-inoculation (p.i.) till day 12 p.i. MMV665941 caused 62.10%, 49.88%, and 74.23% inhibitions in parasite growth at days 4, 6 and 8 p.i., respectively. Of note, 5 mg/kg MMV665941 resulted in quick recovery of hemolytic anemia caused by babesiosis. The atom pair fingerprint (APfp) analysis revealed that MMV665941 and atovaquone (AV) showed maximum structural similarity. Of note, high concentrations (0.75 IC50) of MMV665941 and AV caused synergistic inhibition on B. bovis growth. These findings suggest that MMV665941 might be a promising drug for babesiosis treatment, particularly when combined with the commonly used antibabesial drug, AV.
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Affiliation(s)
- Mohamed Abdo Rizk
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido, Japan
- Department of Internal Medicine and Infectious Diseases, Faculty of Veterinary Medicine, Mansoura University, Mansoura, Egypt
| | - Shimaa Abd El-Salam El-Sayed
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido, Japan
- Department of Biochemistry and Chemistry of Nutrition, Faculty of Veterinary Medicine, Mansoura University, Mansoura, Egypt
| | - Ikuo Igarashi
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido, Japan
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Compounds from the Medicines for Malaria Venture Box Inhibit In Vitro Growth of Babesia divergens, a Blood-Borne Parasite of Veterinary and Zoonotic Importance. Molecules 2021; 26:molecules26237118. [PMID: 34885700 PMCID: PMC8658764 DOI: 10.3390/molecules26237118] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 11/18/2021] [Accepted: 11/23/2021] [Indexed: 11/17/2022] Open
Abstract
Babesiosis is an infectious disease with an empty drug pipeline. A search inside chemical libraries for novel potent antibabesial candidates may help fill such an empty drug pipeline. A total of 400 compounds (200 drug-like and 200 probe-like) from the Malaria Box were evaluated in the current study against the in vitro growth of Babesia divergens (B. divergens), a parasite of veterinary and zoonotic importance. Novel and more effective anti-B. divergens drugs than the traditionally used ones were identified. Seven compounds (four drug-like and three probe-like) revealed a highly inhibitory effect against the in vitro growth of B. divergens, with IC50s ≤ 10 nanomolar. Among these hits, MMV006913 exhibited an IC50 value of 1 nM IC50 and the highest selectivity index of 32,000. The atom pair fingerprint (APfp) analysis revealed that MMV006913 and MMV019124 showed maximum structural similarity (MSS) with atovaquone and diminazene aceturate (DA), and with DA and imidocarb dipropionate (ID), respectively. MMV665807 and MMV665850 showed MMS with each other and with ID. Of note, a high concentration (0.75 IC50) of MMV006913 caused additive inhibition of B. divergens growth when combined with DA at 0.75 or 0.50 IC50. The Medicines for Malaria Venture box is a treasure trove of anti-B. divergens candidates according to the obtained results.
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Renard I, Ben Mamoun C. Treatment of Human Babesiosis: Then and Now. Pathogens 2021; 10:pathogens10091120. [PMID: 34578153 PMCID: PMC8469882 DOI: 10.3390/pathogens10091120] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 08/23/2021] [Accepted: 08/27/2021] [Indexed: 12/26/2022] Open
Abstract
Babesiosis is an emerging tick-borne disease caused by apicomplexan parasites of the genus Babesia. With its increasing incidence worldwide and the risk of human-to-human transmission through blood transfusion, babesiosis is becoming a rising public health concern. The current arsenal for the treatment of human babesiosis is limited and consists of combinations of atovaquone and azithromycin or clindamycin and quinine. These combination therapies were not designed based on biological criteria unique to Babesia parasites, but were rather repurposed based on their well-established efficacy against other apicomplexan parasites. However, these compounds are associated with mild or severe adverse events and a rapid emergence of drug resistance, thus highlighting the need for new therapeutic strategies that are specifically tailored to Babesia parasites. Herein, we review ongoing babesiosis therapeutic and management strategies and their limitations, and further review current efforts to develop new, effective, and safer therapies for the treatment of this disease.
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Ji S, Liu M, Galon EM, Rizk MA, Li J, Li Y, Zafar I, Igarashi I, Xuan X. In vitro screening of novel anti-Babesia gibsoni drugs from natural products. Parasitol Int 2021; 85:102437. [PMID: 34389492 DOI: 10.1016/j.parint.2021.102437] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 07/26/2021] [Accepted: 08/07/2021] [Indexed: 11/17/2022]
Abstract
Babesia gibsoni is a tick-transmitted intraerythrocytic apicomplexan parasite that causes babesiosis in dogs. Due to the strong side effects and lack of efficacy of current drugs, novel drugs against B. gibsoni are urgently needed. Natural products as a source for new drugs is a good choice for screening drugs against B. gibsoni. The current study focuses on identifying novel potential drugs from natural products against B. gibsoniin vitro. Parasite inhibition was verified using a SYBR green I-based fluorescence assay. A total of 502 natural product compounds were screened for anti-B. gibsoni activity in vitro. Twenty-four compounds showed high growth inhibition (>80%) on B. gibsoni and 5 plant-derived compounds were selected for further study. The half-maximal inhibitory concentration (IC50) values of lycorine (LY), vincristine sulfate (VS), emetine·2HCl (EME), harringtonine (HT) and cephaeline·HBr (CEP) were 784.4 ± 3.3, 643.0 ± 2.8, 253.1 ± 1.4, 23.4 ± 1.2, and 108.1 ± 4.3 nM, respectively. The Madin-Darby canine kidney (MDCK) cell line was used to assess cytotoxicity of hit compounds. All compounds showed minimal toxicity to the MDCK cells. The effects of hit compounds combined with diminazene aceturate (DA) on B. gibsoni were further evaluated in vitro. VS, EME, HT or CEP combined with DA showed synergistic effects against B. gibsoni, whereas LY combined with DA showed an antagonistic effect against B. gibsoni. The results obtained in this study indicate that LY, VS, EME, HT and CEP are promising compounds for B. gibsoni treatment.
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Affiliation(s)
- Shengwei Ji
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada-cho, Obihiro, Hokkaido 080-8555, Japan
| | - Mingming Liu
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada-cho, Obihiro, Hokkaido 080-8555, Japan; Department of Microbiology and Immunology, School of Basic Medicine, Hubei University of Arts and Science, Xiangyang 441053, China
| | - Eloiza May Galon
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada-cho, Obihiro, Hokkaido 080-8555, Japan
| | - Mohamed Abdo Rizk
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada-cho, Obihiro, Hokkaido 080-8555, Japan; Department of Internal Medicine and Infectious Diseases, Faculty of Veterinary Medicine, Mansoura University, Mansoura 35516, Egypt
| | - Jixu Li
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada-cho, Obihiro, Hokkaido 080-8555, Japan; College of Agriculture and Animal Science, Qinghai University, Xining 810016, China
| | - Yongchang Li
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada-cho, Obihiro, Hokkaido 080-8555, Japan; Parasitology Laboratory, Veterinary College, Xinjiang Agricultural University, Urumqi 830011, China
| | - Iqra Zafar
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada-cho, Obihiro, Hokkaido 080-8555, Japan
| | - Ikuo Igarashi
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada-cho, Obihiro, Hokkaido 080-8555, Japan
| | - Xuenan Xuan
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada-cho, Obihiro, Hokkaido 080-8555, Japan.
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Elsworth B, Duraisingh MT. A framework for signaling throughout the life cycle of Babesia species. Mol Microbiol 2020; 115:882-890. [PMID: 33274587 DOI: 10.1111/mmi.14650] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 11/16/2020] [Accepted: 11/17/2020] [Indexed: 01/28/2023]
Abstract
Babesia species are tick-borne intracellular parasites that infect the red blood cells of their mammalian host, leading to severe or fatal disease. Babesia spp. infect a wide range of mammalian species and cause a significant economic burden globally, predominantly through disease in cattle. Several Babesia spp. are increasingly being recognized as zoonotic pathogens of humans. Babesia spp. have complex life cycles involving multiple stages in the tick and the mammalian host. The parasite utilizes complex signaling pathways during replication, egress, and invasion in each of these stages. They must also rapidly respond to their environment when switching between the mammalian and tick stages. This review will focus on the signaling pathways and environmental stimuli that Babesia spp. utilize in the bloodstream and for transmission to the tick, with an emphasis on the role of phosphorylation- and calcium-based signaling during egress and invasion. The expanding availability of in vitro and in vivo culture systems, genomes, transcriptomes, and transgenic systems available for a range of Babesia spp. should encourage further biological and translational studies of these ubiquitous parasites.
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Affiliation(s)
- Brendan Elsworth
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Manoj T Duraisingh
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA, USA
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11
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Carvalho LJM, Tuvshintulga B, Nugraha AB, Sivakumar T, Yokoyama N. Activities of artesunate-based combinations and tafenoquine against Babesia bovis in vitro and Babesia microti in vivo. Parasit Vectors 2020; 13:362. [PMID: 32690081 PMCID: PMC7372749 DOI: 10.1186/s13071-020-04235-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Accepted: 07/15/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Babesiosis represents a veterinary and medical threat, with a need for novel drugs. Artemisinin-based combination therapies (ACT) have been successfully implemented for malaria, a human disease caused by related parasites, Plasmodium spp. The aim of this study was to investigate whether ACT is active against Babesia in vitro and in vivo. METHODS Mefloquine, tafenoquine, primaquine, methylene blue and lumefantrine, alone or in combination with artesunate, were tested in vitro against Babesia bovis. Parasite growth was verified using a SYBR green I-based fluorescence assay. Mice infected with Babesia microti were treated with mefloquine or tafenoquine, alone or in combination with artesunate, and parasitemia was verified by microscopy and PCR. RESULTS All drugs, except lumefantrine, showed in vitro activity against B. bovis, with methylene blue showing the most potent activity (concentration 0.2 μM). Combination with artesunate led to improved activity, with mefloquine showing a striking 20-fold increase in activity. Tafenoquine (10 mg/kg, base), combined or not with artesunate, but not mefloquine, induced rapid clearance of B. microti in vivo by microscopy, but mice remained PCR-positive. Blood from mice treated with tafenoquine alone, but not with tafenoquine-artesunate, was infective for naive mice upon sub-inoculation. CONCLUSIONS Tafenoquine, and most likely other 8-aminoquinoline compounds, are promising compounds for the development of ACT for babesiosis.
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Affiliation(s)
- Leonardo J M Carvalho
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Hokkaido, Japan. .,Research Center for Global Agromedicine, Obihiro University of Agriculture and Veterinary Medicine, Hokkaido, Japan. .,Laboratory of Malaria Research, Oswaldo Cruz Institute, Fiocruz, Rio de Janeiro, Brazil.
| | - Bunduurem Tuvshintulga
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Hokkaido, Japan
| | - Arifin B Nugraha
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Hokkaido, Japan
| | - Thillaiampalam Sivakumar
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Hokkaido, Japan
| | - Naoaki Yokoyama
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Hokkaido, Japan.,Research Center for Global Agromedicine, Obihiro University of Agriculture and Veterinary Medicine, Hokkaido, Japan.,OIE Reference Laboratory for Bovine Babesiosis and Equine Piroplasmosis, National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Hokkaido, Japan
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12
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Zhang Y, Bai C, Shi W, Alvarez-Manzo H, Zhang Y. Identification of Essential Oils Including Garlic Oil and Black Pepper Oil with High Activity against Babesia duncani. Pathogens 2020; 9:pathogens9060466. [PMID: 32545549 PMCID: PMC7350376 DOI: 10.3390/pathogens9060466] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2020] [Revised: 06/08/2020] [Accepted: 06/09/2020] [Indexed: 12/16/2022] Open
Abstract
Some evidence indicated that human babesiosis caused by Babesia duncani has spread widely in North America. However, current therapeutic regimens (atovaquone + azithromycin) for human babesiosis are suboptimal with frequent recrudescence and side effects, and furthermore, there is no specific treatment for human babesiosis caused by B. duncani. Here, we screened 97 essential oils and identified 10 essential oils (garlic, black pepper, tarragon, palo santo, coconut, pine, meditation, cajeput, moringa, and stress relief) at a low concentration (0.001%; v/v) that showed good inhibitory activity against B. duncani in the hamster red blood cell culture model. Among them, garlic oil and black pepper oil performed best, as well as their potential active ingredients diallyl disulfide (DADS) and β-caryophyllene (BCP), respectively. Interestingly, further subculture study indicated that B. duncani could relapse after treatment with current therapeutic drugs atovaquone or azithromycin even at high concentrations. In contrast, the combination of garlic oil or DADS and azithromycin showed eradication of B. duncani at low concentrations without regrowth. These results are encouraging and suggest that the garlic-derived sulfur compound DADS and β-caryophyllene (BCP) may be promising drug candidates for evaluation of their ability to cure persistent B. duncani infections in the future.
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13
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Gubbels MJ, Keroack CD, Dangoudoubiyam S, Worliczek HL, Paul AS, Bauwens C, Elsworth B, Engelberg K, Howe DK, Coppens I, Duraisingh MT. Fussing About Fission: Defining Variety Among Mainstream and Exotic Apicomplexan Cell Division Modes. Front Cell Infect Microbiol 2020; 10:269. [PMID: 32582569 PMCID: PMC7289922 DOI: 10.3389/fcimb.2020.00269] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2020] [Accepted: 05/06/2020] [Indexed: 12/17/2022] Open
Abstract
Cellular reproduction defines life, yet our textbook-level understanding of cell division is limited to a small number of model organisms centered around humans. The horizon on cell division variants is expanded here by advancing insights on the fascinating cell division modes found in the Apicomplexa, a key group of protozoan parasites. The Apicomplexa display remarkable variation in offspring number, whether karyokinesis follows each S/M-phase or not, and whether daughter cells bud in the cytoplasm or bud from the cortex. We find that the terminology used to describe the various manifestations of asexual apicomplexan cell division emphasizes either the number of offspring or site of budding, which are not directly comparable features and has led to confusion in the literature. Division modes have been primarily studied in two human pathogenic Apicomplexa, malaria-causing Plasmodium spp. and Toxoplasma gondii, a major cause of opportunistic infections. Plasmodium spp. divide asexually by schizogony, producing multiple daughters per division round through a cortical budding process, though at several life-cycle nuclear amplifications stages, are not followed by karyokinesis. T. gondii divides by endodyogeny producing two internally budding daughters per division round. Here we add to this diversity in replication mechanisms by considering the cattle parasite Babesia bigemina and the pig parasite Cystoisospora suis. B. bigemina produces two daughters per division round by a “binary fission” mechanism whereas C. suis produces daughters through both endodyogeny and multiple internal budding known as endopolygeny. In addition, we provide new data from the causative agent of equine protozoal myeloencephalitis (EPM), Sarcocystis neurona, which also undergoes endopolygeny but differs from C. suis by maintaining a single multiploid nucleus. Overall, we operationally define two principally different division modes: internal budding found in cyst-forming Coccidia (comprising endodyogeny and two forms of endopolygeny) and external budding found in the other parasites studied (comprising the two forms of schizogony, binary fission and multiple fission). Progressive insights into the principles defining the molecular and cellular requirements for internal vs. external budding, as well as variations encountered in sexual stages are discussed. The evolutionary pressures and mechanisms underlying apicomplexan cell division diversification carries relevance across Eukaryota.
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Affiliation(s)
- Marc-Jan Gubbels
- Department of Biology, Boston College, Chestnut Hill, MA, United States
| | - Caroline D Keroack
- Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Harvard University, Boston, MA, United States
| | - Sriveny Dangoudoubiyam
- Department of Veterinary Science, Gluck Equine Research Center, University of Kentucky, Lexington, KY, United States
| | - Hanna L Worliczek
- Department of Biology, Boston College, Chestnut Hill, MA, United States.,Institute of Parasitology, University of Veterinary Medicine, Vienna, Austria
| | - Aditya S Paul
- Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Harvard University, Boston, MA, United States
| | - Ciara Bauwens
- Department of Biology, Boston College, Chestnut Hill, MA, United States
| | - Brendan Elsworth
- Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Harvard University, Boston, MA, United States.,School of Biosciences, University of Melbourne, Melbourne, VIC, Australia
| | - Klemens Engelberg
- Department of Biology, Boston College, Chestnut Hill, MA, United States
| | - Daniel K Howe
- Department of Veterinary Science, Gluck Equine Research Center, University of Kentucky, Lexington, KY, United States
| | - Isabelle Coppens
- Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, United States
| | - Manoj T Duraisingh
- Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Harvard University, Boston, MA, United States
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14
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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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15
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To kill a piroplasm: genetic technologies to advance drug discovery and target identification in Babesia. Int J Parasitol 2019; 49:153-163. [DOI: 10.1016/j.ijpara.2018.09.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 09/07/2018] [Accepted: 09/19/2018] [Indexed: 12/26/2022]
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16
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Abraham A, Brasov I, Thekkiniath J, Kilian N, Lawres L, Gao R, DeBus K, He L, Yu X, Zhu G, Graham MM, Liu X, Molestina R, Ben Mamoun C. Establishment of a continuous in vitro culture of Babesia duncani in human erythrocytes reveals unusually high tolerance to recommended therapies. J Biol Chem 2018; 293:19974-19981. [PMID: 30463941 DOI: 10.1074/jbc.ac118.005771] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 11/18/2018] [Indexed: 11/06/2022] Open
Abstract
Human babesiosis is an emerging tick-borne disease caused by apicomplexan parasites of the genus Babesia Clinical cases caused by Babesia duncani have been associated with high parasite burden, severe pathology, and death. In both mice and hamsters, the parasite causes uncontrolled fulminant infections, which ultimately lead to death. Resolving these infections requires knowledge of B. duncani biology, virulence, and susceptibility to anti-infectives, but little is known and further research is hindered by a lack of relevant model systems. Here, we report the first continuous in vitro culture of B. duncani in human red blood cells. We show that during its asexual cycle within human erythrocytes, B. duncani develops and divides to form four daughter parasites with parasitemia doubling every ∼22 h. Using this in vitro culture assay, we found that B. duncani has low susceptibility to the four drugs recommended for treatment of human babesiosis, atovaquone, azithromycin, clindamycin, and quinine, with IC50 values ranging between 500 nm and 20 μm These data suggest that current practices are of limited effect in treating the disease. We anticipate this new disease model will set the stage for a better understanding of the biology of this parasite and will help guide better therapeutic strategies to treat B. duncani-associated babesiosis.
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Affiliation(s)
- Amanah Abraham
- From the Department of Internal Medicine, Section of Infectious Diseases, and Yale School of Medicine, New Haven, Connecticut 06520
| | - Ioana Brasov
- BEI Resources, American Type Culture Collection, Manassas, Virginia 20110-2209
| | - Jose Thekkiniath
- From the Department of Internal Medicine, Section of Infectious Diseases, and Yale School of Medicine, New Haven, Connecticut 06520
| | - Nicole Kilian
- From the Department of Internal Medicine, Section of Infectious Diseases, and Yale School of Medicine, New Haven, Connecticut 06520
| | - Lauren Lawres
- From the Department of Internal Medicine, Section of Infectious Diseases, and Yale School of Medicine, New Haven, Connecticut 06520
| | - Ruiyi Gao
- From the Department of Internal Medicine, Section of Infectious Diseases, and Yale School of Medicine, New Haven, Connecticut 06520
| | - Kai DeBus
- From the Department of Internal Medicine, Section of Infectious Diseases, and Yale School of Medicine, New Haven, Connecticut 06520
| | - Lan He
- the State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei 430079, China, and
| | - Xue Yu
- the Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas 77845
| | - Guan Zhu
- the Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas 77845
| | - Morven M Graham
- the Department of Cell Biology and CCMI Electron Microscopy Core Facility, Yale School of Medicine, New Haven, Connecticut 06520
| | - Xinran Liu
- the Department of Cell Biology and CCMI Electron Microscopy Core Facility, Yale School of Medicine, New Haven, Connecticut 06520
| | - Robert Molestina
- BEI Resources, American Type Culture Collection, Manassas, Virginia 20110-2209
| | - Choukri Ben Mamoun
- From the Department of Internal Medicine, Section of Infectious Diseases, and Yale School of Medicine, New Haven, Connecticut 06520.
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17
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van Schalkwyk DA, Moon RW, Blasco B, Sutherland CJ. Comparison of the susceptibility of Plasmodium knowlesi and Plasmodium falciparum to antimalarial agents. J Antimicrob Chemother 2018; 72:3051-3058. [PMID: 28961865 PMCID: PMC5890772 DOI: 10.1093/jac/dkx279] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Accepted: 07/11/2017] [Indexed: 01/09/2023] Open
Abstract
Background The simian malaria parasite Plasmodium knowlesi is now a well-recognized pathogen of humans in South-East Asia. Clinical infections appear adequately treated with existing drug regimens, but the evidence base for this practice remains weak. The availability of P. knowlesi cultures adapted to continuous propagation in human erythrocytes enables specific studies of in vitro susceptibility of the species to antimalarial agents, and could provide a surrogate system for testing investigational compounds against Plasmodium vivax and other non-Plasmodium falciparum infections that cannot currently be propagated in vitro. Objectives We sought to optimize protocols for in vitro susceptibility testing of P. knowlesi and to contrast outputs with those obtained for P. falciparum under comparable test conditions. Methods Growth monitoring of P. knowlesi in vitro was by DNA quantification using a SYBR Green fluorescent assay or by colorimetric detection of the lactate dehydrogenase enzyme. For comparison, P. falciparum was tested under conditions identical to those used for P. knowlesi. Results The SYBR Green I assay proved the most robust format over one (27 h) or two (54 h) P. knowlesi life cycles. Unexpectedly, P. knowlesi displays significantly greater susceptibility to the dihydrofolate reductase inhibitors pyrimethamine, cycloguanil and trimethoprim than does P. falciparum, but is less susceptible to the selective agents blasticidin and DSM1 used in parasite transfections. Inhibitors of dihydroorotate dehydrogenase also demonstrate lower activity against P. knowlesi. Conclusions The fluorescent assay system validated here identified species-specific P. knowlesi drug susceptibility profiles and can be used for testing investigational compounds for activity against non-P. falciparum malaria.
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Affiliation(s)
- Donelly A van Schalkwyk
- Department of Immunology & Infection, Faculty of Infectious & Tropical Diseases, London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT, UK
| | - Robert W Moon
- Department of Immunology & Infection, Faculty of Infectious & Tropical Diseases, London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT, UK
| | - Benjamin Blasco
- Medicines for Malaria Venture, 20 rte de Pré Bois, Geneva CH 1215, Switzerland
| | - Colin J Sutherland
- Department of Immunology & Infection, 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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18
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Asensi V, González LM, Fernández-Suárez J, Sevilla E, Navascués RÁ, Suárez ML, Lauret ME, Bernardo A, Carton JA, Montero E. A fatal case of Babesia divergens infection in Northwestern Spain. Ticks Tick Borne Dis 2018; 9:730-734. [PMID: 29496491 DOI: 10.1016/j.ttbdis.2018.02.018] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 02/15/2018] [Accepted: 02/16/2018] [Indexed: 11/26/2022]
Abstract
We describe a fatal case caused by the intra-erythrocytic Babesia divergens parasite in an elderly woman. This is the third case of fatal babesiosis reported in the last 15 years in Europe, and the only one in a patient with an intact spleen.
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Affiliation(s)
- Víctor Asensi
- Infectious Diseases Unit, Hospital Universitario Central de Asturias, Oviedo University School of Medicine, Oviedo, Spain
| | - Luis Miguel González
- Parasitology Service, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain
| | - Jonathan Fernández-Suárez
- Microbiology and Parasitology Service, Hospital Universitario Central de Asturias, Oviedo University School of Medicine, Oviedo, Spain
| | - Elena Sevilla
- Parasitology Service, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain
| | - Rafael Álvarez Navascués
- Nephrology Service, Hospital Universitario Central de Asturias, Oviedo University School of Medicine, Oviedo, Spain
| | - María Luisa Suárez
- Nephrology Service, Hospital Universitario Central de Asturias, Oviedo University School of Medicine, Oviedo, Spain
| | - María Eugenia Lauret
- Gastroenterology Service, Hospital Universitario Central de Asturias, Oviedo University School of Medicine, Oviedo, Spain
| | - Angel Bernardo
- Hematology Service, Hospital Universitario Central de Asturias, Oviedo University School of Medicine, Oviedo, Spain
| | - José Antonio Carton
- Infectious Diseases Unit, Hospital Universitario Central de Asturias, Oviedo University School of Medicine, Oviedo, Spain
| | - Estrella Montero
- Parasitology Service, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain.
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19
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Targeted Phenotypic Screening in Plasmodium falciparum and Toxoplasma gondii Reveals Novel Modes of Action of Medicines for Malaria Venture Malaria Box Molecules. mSphere 2018; 3:mSphere00534-17. [PMID: 29359192 PMCID: PMC5770543 DOI: 10.1128/msphere.00534-17] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Accepted: 12/20/2017] [Indexed: 01/23/2023] Open
Abstract
The Malaria Box collection includes 400 chemically diverse small molecules with documented potency against malaria parasite growth, but the underlying modes of action are largely unknown. Using complementary phenotypic screens against Plasmodium falciparum and Toxoplasma gondii, we report phenotype-specific hits based on inhibition of overall parasite growth, apicoplast segregation, and egress or host invasion, providing hitherto unavailable insights into the possible mechanisms affected. First, the Malaria Box library was screened against tachyzoite stage T. gondii and the half-maximal effective concentrations (EC50s) of molecules showing ≥80% growth inhibition at 10 µM were determined. Comparison of the EC50s for T. gondii and P. falciparum identified a subset of 24 molecules with nanomolar potency against both parasites. Thirty molecules that failed to induce acute growth inhibition in T. gondii tachyzoites in a 2-day assay caused delayed parasite death upon extended exposure, with at least three molecules interfering with apicoplast segregation during daughter cell formation. Using flow cytometry and microscopy-based examinations, we prioritized 26 molecules with the potential to inhibit host cell egress/invasion during asexual developmental stages of P. falciparum. None of the inhibitors affected digestive vacuole integrity, ruling out a mechanism mediated by broadly specific protease inhibitor activity. Interestingly, five of the plasmodial egress inhibitors inhibited ionophore-induced egress of T. gondii tachyzoites. These findings highlight the advantage of comparative and targeted phenotypic screens in related species as a means to identify lead molecules with a conserved mode of action. Further work on target identification and mechanism analysis will facilitate the development of antiparasitic compounds with cross-species efficacy. IMPORTANCE The phylum Apicomplexa includes many human and animal pathogens, such as Plasmodium falciparum (human malaria) and Toxoplasma gondii (human and animal toxoplasmosis). Widespread resistance to current antimalarials and the lack of a commercial vaccine necessitate novel pharmacological interventions with distinct modes of action against malaria. For toxoplasmosis, new drugs to effectively eliminate tissue-dwelling latent cysts of the parasite are needed. The Malaria Box antimalarial collection, managed and distributed by the Medicines for Malaria Venture, includes molecules of novel chemical classes with proven antimalarial efficacy. Using targeted phenotypic assays of P. falciparum and T. gondii, we have identified a subset of the Malaria Box molecules as potent inhibitors of plastid segregation and parasite invasion and egress, thereby providing early insights into their probable mode of action. Five molecules that inhibit the egress of both parasites have been identified for further mechanistic studies. Thus, the approach we have used to identify novel molecules with defined modes of action in multiple parasites can expedite the development of pan-active antiparasitic agents.
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20
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Gisselberg JE, Herrera Z, Orchard LM, Llinás M, Yeh E. Specific Inhibition of the Bifunctional Farnesyl/Geranylgeranyl Diphosphate Synthase in Malaria Parasites via a New Small-Molecule Binding Site. Cell Chem Biol 2017; 25:185-193.e5. [PMID: 29276048 DOI: 10.1016/j.chembiol.2017.11.010] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 09/24/2017] [Accepted: 11/22/2017] [Indexed: 12/19/2022]
Abstract
The bifunctional farnesyl/geranylgeranyl diphosphate synthase (FPPS/GGPPS) is a key branchpoint enzyme in isoprenoid biosynthesis in Plasmodium falciparum (malaria) parasites. PfFPPS/GGPPS is a validated, high-priority antimalarial drug target. Unfortunately, current bisphosphonate drugs that inhibit FPPS and GGPPS enzymes by acting as a diphosphate substrate analog show poor bioavailability and selectivity for PfFPPS/GGPPS. We identified a new non-bisphosphonate compound, MMV019313, which is highly selective for PfFPPS/GGPPS and showed no activity against human FPPS or GGPPS. Inhibition of PfFPPS/GGPPS by MMV019313, but not bisphosphonates, was disrupted in an S228T variant, demonstrating that MMV019313 and bisphosphonates have distinct modes of inhibition. Molecular docking indicated that MMV019313 did not bind previously characterized substrate sites in PfFPPS/GGPPS. Our finding uncovers a new, selective small-molecule binding site in this important antimalarial drug target with superior druggability compared with the known inhibitor site and sets the stage for the development of Plasmodium-specific FPPS/GGPPS inhibitors.
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Affiliation(s)
- Jolyn E Gisselberg
- Department of Biochemistry, Stanford Medical School, Stanford University, Stanford, CA 94305, USA
| | - Zachary Herrera
- Department of Biochemistry, Stanford Medical School, Stanford University, Stanford, CA 94305, USA
| | - Lindsey M Orchard
- Department of Biochemistry & Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA; Huck Center for Malaria Research, Pennsylvania State University, University Park, PA 16802, USA
| | - Manuel Llinás
- Department of Biochemistry & Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA; Huck Center for Malaria Research, Pennsylvania State University, University Park, PA 16802, USA; Department of Chemistry, Pennsylvania State University, University Park, PA 16802, USA
| | - Ellen Yeh
- Department of Biochemistry, Stanford Medical School, Stanford University, Stanford, CA 94305, USA; Department of Pathology, Stanford Medical School, Stanford University, Stanford, CA 94305, USA; Department of Microbiology and Immunology, Stanford Medical School, Stanford University, Stanford, CA 94305, USA.
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