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Imhof D, Hänggeli KPA, De Sousa MCF, Vigneswaran A, Hofmann L, Amdouni Y, Boubaker G, Müller J, Hemphill A. Working towards the development of vaccines and chemotherapeutics against neosporosis-With all of its ups and downs-Looking ahead. ADVANCES IN PARASITOLOGY 2024; 124:91-154. [PMID: 38754928 DOI: 10.1016/bs.apar.2024.01.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2024]
Abstract
Neospora caninum is an apicomplexan and obligatory intracellular parasite, which is the leading cause of reproductive failure in cattle and affects other farm and domestic animals, but also induces neuromuscular disease in dogs of all ages. In cattle, neosporosis is an important health problem, and has a considerable economic impact. To date there is no protective vaccine or chemotherapeutic treatment on the market. Immuno-prophylaxis has long been considered as the best control measure. Proteins involved in host cell interaction and invasion, as well as antigens mediating inflammatory responses have been the most frequently assessed vaccine targets. However, despite considerable efforts no effective vaccine has been introduced to the market to date. The development of effective compounds to limit the effects of vertical transmission of N. caninum tachyzoites has emerged as an alternative or addition to vaccination, provided suitable targets and safe and efficacious drugs can be identified. Additionally, the combination of both treatment strategies might be interesting to further increase protectivity against N. caninum infections and to decrease the duration of treatment and the risk of potential drug resistance. Well-established and standardized animal infection models are key factors for the evaluation of promising vaccine and compound candidates. The vast majority of experimental animal experiments concerning neosporosis have been performed in mice, although in recent years the numbers of experimental studies in cattle and sheep have increased. In this review, we discuss the recent findings concerning the progress in drug and vaccine development against N. caninum infections in mice and ruminants.
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Affiliation(s)
- Dennis Imhof
- Institute of Parasitology, Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, University of Bern, Bern, Switzerland.
| | - Kai Pascal Alexander Hänggeli
- Institute of Parasitology, Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, University of Bern, Bern, Switzerland; Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - Maria Cristina Ferreira De Sousa
- Institute of Parasitology, Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, University of Bern, Bern, Switzerland; Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - Anitha Vigneswaran
- Institute of Parasitology, Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Larissa Hofmann
- Institute of Parasitology, Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Yosra Amdouni
- Institute of Parasitology, Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Ghalia Boubaker
- Institute of Parasitology, Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Joachim Müller
- Institute of Parasitology, Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Andrew Hemphill
- Institute of Parasitology, Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, University of Bern, Bern, Switzerland.
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Müller J, Hemphill A. In vitro screening technologies for the discovery and development of novel drugs against Toxoplasma gondii. Expert Opin Drug Discov 2024; 19:97-109. [PMID: 37921660 DOI: 10.1080/17460441.2023.2276349] [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: 08/31/2023] [Accepted: 10/24/2023] [Indexed: 11/04/2023]
Abstract
INTRODUCTION Toxoplasmosis constitutes a challenge for public health, animal production and welfare. Since more than 60 years, only a limited panel of drugs has been in use for clinical applications. AREAS COVERED Herein, the authors describe the methodology and the results of library screening approaches to identify inhibitors of Toxoplasma gondii and related strains. The authors then provide the reader with their expert perspectives for the future. EXPERT OPINION Various library screening projects, in particular those using reporter strains, have led to the identification of numerous compounds with good efficacy and specificity in vitro. However, only few compounds are effective in suitable animal models such as rodents. Whereas no novel compound has cleared the hurdle to applications in humans, the few compounds with known indication and application profiles in human patients are of interest for further investigations. Taken together, drug repurposing as well as high-throughput screening of novel compound libraries may shorten the way to novel drugs against toxoplasmosis.
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Affiliation(s)
- Joachim Müller
- Institute of Parasitology, Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Andrew Hemphill
- Institute of Parasitology, Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
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Müller J, Hemphill A. Toxoplasma gondii infection: novel emerging therapeutic targets. Expert Opin Ther Targets 2023; 27:293-304. [PMID: 37212443 PMCID: PMC10330558 DOI: 10.1080/14728222.2023.2217353] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2023] [Accepted: 04/24/2023] [Indexed: 05/23/2023]
Abstract
INTRODUCTION Toxoplasmosis constitutes a challenge for public health, animal production, and welfare. So far, only a limited panel of drugs has been marketed for clinical applications. In addition to classical screening, the investigation of unique targets of the parasite may lead to the identification of novel drugs. AREAS COVERED Herein, the authors describe the methodology to identify novel drug targets in Toxoplasma gondii and review the literature with a focus on the last two decades. EXPERT OPINION Over the last two decades, the investigation of essential proteins of T. gondii as potential drug targets has fostered the hope of identifying novel compounds for the treatment of toxoplasmosis. Despite good efficacies in vitro, only a few classes of these compounds are effective in suitable rodent models, and none has cleared the hurdle to applications in humans. This shows that target-based drug discovery is in no way better than classical screening approaches. In both cases, off-target effects and adverse side effects in the hosts must be considered. Proteomics-driven analyses of parasite- and host-derived proteins that physically bind drug candidates may constitute a suitable tool to characterize drug targets, irrespectively of the drug discovery methods.
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Affiliation(s)
- Joachim Müller
- Department of Infectious Diseases and Pathobiology, Institute of Parasitology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Andrew Hemphill
- Department of Infectious Diseases and Pathobiology, Institute of Parasitology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
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Imhof D, Pownall WR, Schlange C, Monney C, Ortega-Mora LM, Ojo KK, Van Voorhis WC, Oevermann A, Hemphill A. Vaccine-Linked Chemotherapy Approach: Additive Effects of Combining the Listeria monocytogenes-Based Vaccine Lm3Dx_NcSAG1 With the Bumped Kinase Inhibitor BKI-1748 Against Neospora caninum Infection in Mice. Front Vet Sci 2022; 9:901056. [PMID: 35832325 PMCID: PMC9272043 DOI: 10.3389/fvets.2022.901056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 06/03/2022] [Indexed: 12/30/2022] Open
Abstract
The apicomplexan parasite Neospora (N.) caninum causes neosporosis in numerous host species. There is no marketed vaccine and no licensed drug for the prevention and/or treatment of neosporosis. Vaccine development against this parasite has encountered significant obstacles, probably due to pregnancy-induced immunomodulation hampering efficacy, which has stimulated the search for potential drug therapies that could be applied to limit the effects of neosporosis in dams as well as in offspring. We here investigated, in a pregnant neosporosis mouse model, the safety and efficacy of a combined vaccination-drug treatment approach. Mice were vaccinated intramuscularly with 1 × 107 CFU of our recently generated Listeria (L.) monocytogenes vaccine vector expressing the major N. caninum tachyzoite surface antigen NcSAG1 (Lm3Dx_SAG1). Following mating and experimental subcutaneous infection with 1 × 105 N. caninum (NcSpain-7) tachyzoites on day 7 of pregnancy, drug treatments were initiated using the bumped kinase inhibitor BKI-1748 at 20 mg/kg/day for 5 days. In parallel, other experimental groups were either just vaccinated or only treated. Dams and offspring were followed-up until day 25 post-partum, after which all mice were euthanized. None of the treatments induced adverse effects and neither of the treatments affected fertility or litter sizes. Cerebral infection in dams as assessed by real-time PCR was significantly reduced in the vaccinated and BKI-1748 treated groups, but was not reduced significantly in the group receiving the combination. However, in non-pregnant mice, all three treatment groups exhibited significantly reduced parasite burdens. Both, vaccination as well BKI-1748 as single treatment increased pup survival to 44 and 48%, respectively, while the combination treatment led to survival of 86% of all pups. Vertical transmission in the combination group was 23% compared to 46 and 50% in the groups receiving only BKI-treatment or the vaccine, respectively. In the dams, IgG titers were significantly reduced in all treatment groups compared to the untreated control, while in non-pregnant mice, IgG titers were reduced only in the group receiving the vaccine. Overall, vaccine-linked chemotherapy was more efficacious than vaccination or drug treatment alone and should be considered for further evaluation in a more relevant experimental model.
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Affiliation(s)
- Dennis Imhof
- Department of Infectious Diseases and Pathobiology, Institute of Parasitology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - William Robert Pownall
- Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
- Division of Small Animal Surgery, Department of Clinical Veterinary Science, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Carling Schlange
- Department of Infectious Diseases and Pathobiology, Institute of Parasitology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Camille Monney
- Department of Clinical Research and Veterinary Public Health, Division of Neurological Sciences, DCR-VPH, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Luis-Miguel Ortega-Mora
- SALUVET, Animal Health Department, Faculty of Veterinary Sciences, Complutense University of Madrid, Madrid, Spain
| | - Kayode K. Ojo
- Center for Emerging and Re-Emerging Infectious Diseases (CERID), Division of Allergy and Infectious Diseases, Department of Medicine, University of Washington, Seattle, WA, United States
| | - Wesley C. Van Voorhis
- Center for Emerging and Re-Emerging Infectious Diseases (CERID), Division of Allergy and Infectious Diseases, Department of Medicine, University of Washington, Seattle, WA, United States
| | - Anna Oevermann
- Department of Clinical Research and Veterinary Public Health, Division of Neurological Sciences, DCR-VPH, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Andrew Hemphill
- Department of Infectious Diseases and Pathobiology, Institute of Parasitology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
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Anghel N, Imhof D, Winzer P, Balmer V, Ramseier J, Haenggeli K, Choi R, Hulverson MA, Whitman GR, Arnold SL, Ojo KK, Van Voorhis WC, Doggett JS, Ortega-Mora LM, Hemphill A. Endochin-like quinolones (ELQs) and bumped kinase inhibitors (BKIs): Synergistic and additive effects of combined treatments against Neospora caninum infection in vitro and in vivo. Int J Parasitol Drugs Drug Resist 2021; 17:92-106. [PMID: 34482255 PMCID: PMC8416643 DOI: 10.1016/j.ijpddr.2021.08.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 08/19/2021] [Accepted: 08/26/2021] [Indexed: 12/30/2022]
Abstract
The apicomplexan parasite Neospora caninum is an important causative agent of congenital neosporosis, resulting in abortion, birth of weak offspring and neuromuscular disorders in cattle, sheep, and many other species. Among several compound classes that are currently being developed, two have been reported to limit the effects of congenital neosporosis: (i) bumped kinase inhibitors (BKIs) target calcium dependent protein kinase 1 (CDPK1), an enzyme that is encoded by an apicoplast-derived gene and found only in apicomplexans and plants. CDPK1 is essential for host cell invasion and egress; (ii) endochin-like quinolones (ELQs) are inhibitors of the cytochrome bc1 complex of the mitochondrial electron transport chain and thus inhibit oxidative phosphorylation. We here report on the in vitro and in vivo activities of BKI-1748, and of ELQ-316 and its respective prodrugs ELQ-334 and ELQ-422, applied either as single-compounds or ELQ-BKI-combinations. In vitro, BKI-1748 and ELQ-316, as well as BKI-1748 and ELQ-334, acted synergistically, while this was not observed for the BKI-1748/ELQ-422 combination treatment. In a N. caninum-infected pregnant BALB/c mouse model, the synergistic effects observed in vitro were not entirely reproduced, but 100% postnatal survival and 100% inhibition of vertical transmission was noted in the group treated with the BKI-1748/ELQ-334 combination. In addition, the combined drug applications resulted in lower neonatal mortality compared to treatments with single drugs.
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Affiliation(s)
- Nicoleta Anghel
- Institute of Parasitology, Vetsuisse Faculty, University of Bern, Switzerland,Graduate School for Cellular and Biomedical Sciences (GCB), University of Bern, Switzerland,Corresponding author. Institute of Parasitology, Vetsuisse Faculty, University of Bern, Switzerland.
| | - Dennis Imhof
- Institute of Parasitology, Vetsuisse Faculty, University of Bern, Switzerland,Graduate School for Cellular and Biomedical Sciences (GCB), University of Bern, Switzerland
| | - Pablo Winzer
- Institute of Parasitology, Vetsuisse Faculty, University of Bern, Switzerland,Graduate School for Cellular and Biomedical Sciences (GCB), University of Bern, Switzerland
| | - Vreni Balmer
- Institute of Parasitology, Vetsuisse Faculty, University of Bern, Switzerland
| | - Jessica Ramseier
- Institute of Parasitology, Vetsuisse Faculty, University of Bern, Switzerland
| | - Kai Haenggeli
- Institute of Parasitology, Vetsuisse Faculty, University of Bern, Switzerland,Graduate School for Cellular and Biomedical Sciences (GCB), University of Bern, Switzerland
| | - Ryan Choi
- Center for Emerging and Re-emerging Infectious Diseases (CERID), Division of Allergy and Infectious Diseases, Department of Medicine, University of Washington School of Medicine, Seattle, WA, USA
| | - Matthew A. Hulverson
- Center for Emerging and Re-emerging Infectious Diseases (CERID), Division of Allergy and Infectious Diseases, Department of Medicine, University of Washington School of Medicine, Seattle, WA, USA
| | - Grant R. Whitman
- Center for Emerging and Re-emerging Infectious Diseases (CERID), Division of Allergy and Infectious Diseases, Department of Medicine, University of Washington School of Medicine, Seattle, WA, USA
| | - Samuel L.M. Arnold
- Center for Emerging and Re-emerging Infectious Diseases (CERID), Division of Allergy and Infectious Diseases, Department of Medicine, University of Washington School of Medicine, Seattle, WA, USA,Department of Pharmaceutics, University of Washington, Seattle, WA, USA
| | - Kayode K. Ojo
- Center for Emerging and Re-emerging Infectious Diseases (CERID), Division of Allergy and Infectious Diseases, Department of Medicine, University of Washington School of Medicine, Seattle, WA, USA
| | - Wesley C. Van Voorhis
- Center for Emerging and Re-emerging Infectious Diseases (CERID), Division of Allergy and Infectious Diseases, Department of Medicine, University of Washington School of Medicine, Seattle, WA, USA,Departments of Global Health and Microbiology, University of Washington, Seattle, WA, USA
| | - J. Stone Doggett
- VA Portland Health Care System, Research and Development Service, Portland, OR, USA
| | - Luis M. Ortega-Mora
- SALUVET, Animal Health Department, Faculty of Veterinary Sciences, Complutense University of Madrid, Ciudad Universitaria s/n, Madrid, Spain
| | - Andrew Hemphill
- Institute of Parasitology, Vetsuisse Faculty, University of Bern, Switzerland,Corresponding author.
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Wang C, Yang C, Liu J, Liu Q. NcPuf1 Is a Key Virulence Factor in Neospora caninum. Pathogens 2020; 9:pathogens9121019. [PMID: 33276672 PMCID: PMC7761618 DOI: 10.3390/pathogens9121019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 11/28/2020] [Accepted: 11/28/2020] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Neospora caninum is an apicomplexan parasite that infects many mammals and particularly causes abortion in cattle. The key factors in its wide distribution are its virulence and ability to transform between tachyzoite and bradyzoite forms. However, the factors are not well understood. Although Puf protein (named after Pumilio from Drosophila melanogaster and fem-3 binding factor from Caenorhabditis elegans) have a functionally conserved role in promoting proliferation and inhibiting differentiation in many eukaryotes, the function of the Puf proteins in N. caninum is poorly understood. METHODS The CRISPR/CAS9 system was used to identify and study the function of the Puf protein in N. caninum. RESULTS We showed that N. caninum encodes a Puf protein, which was designated NcPuf1. NcPuf1 is found in the cytoplasm in intracellular parasites and in processing bodies (P-bodies), which are reported for the first time in N. caninum in extracellular parasites. NcPuf1 is not needed for the formation of P-bodies in N. caninum. The deletion of NcPuf1 (ΔNcPuf1) does not affect the differentiation in vitro and tissue cysts formation in the mouse brain. However, ΔNcPuf1 resulted in decreases in the proliferative capacity of N. caninum in vitro and virulence in mice. CONCLUSIONS Altogether, the disruption of NcPuf1 does not affect bradyzoites differentiation, but seriously impairs tachyzoite proliferation in vitro and virulence in mice. These results can provide a theoretical basis for the development of attenuated vaccines to prevent the infection of N. caninum.
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Affiliation(s)
| | | | - Jing Liu
- Correspondence: (J.L.); (Q.L.); Tel.: +86-010-62734496 (Q.L.)
| | - Qun Liu
- Correspondence: (J.L.); (Q.L.); Tel.: +86-010-62734496 (Q.L.)
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Pereira LM, Mota CM, Baroni L, Bronzon da Costa CM, Brochi JCV, Wainwright M, Mineo TWP, Braga GÚL, Yatsuda AP. Inhibitory action of phenothiazinium dyes against Neospora caninum. Sci Rep 2020; 10:7483. [PMID: 32366934 PMCID: PMC7198568 DOI: 10.1038/s41598-020-64454-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 04/13/2020] [Indexed: 12/11/2022] Open
Abstract
Neospora caninum is an Apicomplexan parasite related to important losses in livestock, causing abortions and decreased fertility in affected cows. Several chemotherapeutic strategies have been developed for disease control; however, no commercial treatment is available. Among the candidate drugs against neosporosis, phenothiazinium dyes, offer a low cost-efficient approach to parasite control. We report the anti-parasitic effects of the phenothiaziums Methylene Blue (MB), New Methylene Blue (NMB), 1,9–Dimethyl Methylene Blue (DMMB) and Toluidine Blue O (TBO) on N. caninum, using in vitro and in vivo models. The dyes inhibited parasite proliferation at nanomolar concentrations (0.019–1.83 μM) and a synergistic effect was achieved when Methylene Blue was combined with New Methylene Blue (Combination Index = 0.84). Moreover, the phenothiazinium dyes improved parasite clearance when combined with Pyrimethamine (Pyr). Combination of Methylene Blue + 1,9–Dimethyl Methylene Blue demonstrated superior efficacy compared to Pyrimethamine based counterparts in an in vivo model of infection. We also observed that Methylene Blue, New Methylene Blue and 1,9–Dimethyl Methylene Blue increased by 5000% the reactive oxygen species (ROS) levels in N. caninum tachyzoites. Phenothiazinium dyes represent an accessible group of candidates with the potential to compound future formulations for neosporosis control.
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Affiliation(s)
- Luiz Miguel Pereira
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Av do Café, sn/n, 14040-903, Ribeirão Preto, SP, Brazil.,Núcleo de Apoio à Pesquisa em Produtos Naturais e Sintéticos, Universidade de São Paulo, Ribeirão Preto, SP, Brazil
| | - Caroline Martins Mota
- Department of Immunology, Institute of Biomedical Sciences, Federal University of Uberlândia, Uberlândia, Brazil
| | - Luciana Baroni
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Av do Café, sn/n, 14040-903, Ribeirão Preto, SP, Brazil
| | - Cássia Mariana Bronzon da Costa
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Av do Café, sn/n, 14040-903, Ribeirão Preto, SP, Brazil
| | - Jade Cabestre Venancio Brochi
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Av do Café, sn/n, 14040-903, Ribeirão Preto, SP, Brazil
| | - Mark Wainwright
- School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Liverpool, L3 3AF, United Kingdom
| | - Tiago Wilson Patriarca Mineo
- Department of Immunology, Institute of Biomedical Sciences, Federal University of Uberlândia, Uberlândia, Brazil
| | - Gilberto Úbida Leite Braga
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Av do Café, sn/n, 14040-903, Ribeirão Preto, SP, Brazil
| | - Ana Patrícia Yatsuda
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Av do Café, sn/n, 14040-903, Ribeirão Preto, SP, Brazil. .,Núcleo de Apoio à Pesquisa em Produtos Naturais e Sintéticos, Universidade de São Paulo, Ribeirão Preto, SP, Brazil.
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Sánchez-Sánchez R, Vázquez P, Ferre I, Ortega-Mora LM. Treatment of Toxoplasmosis and Neosporosis in Farm Ruminants: State of Knowledge and Future Trends. Curr Top Med Chem 2019; 18:1304-1323. [PMID: 30277158 PMCID: PMC6340160 DOI: 10.2174/1568026618666181002113617] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 08/03/2018] [Accepted: 09/13/2018] [Indexed: 12/17/2022]
Abstract
Toxoplasmosis and neosporosis are closely related protozoan diseases that lead to important economic impacts in farm ruminants. Toxoplasma gondii infection mainly causes reproductive failure in small ruminants and is a widespread zoonosis, whereas Neospora caninum infection is one of the most important causes of abortion in cattle worldwide. Vaccination has been considered the most economic measure for controlling these diseases. However, despite vaccine development efforts, only a live-attenuated T. gondii vaccine has been licensed for veterinary use, and no promising vaccines against ne-osporosis have been developed; therefore, vaccine development remains a key goal. Additionally, drug therapy could be a valuable strategy for disease control in farm ruminants, as several drugs that limit T. gondii and N. caninum proliferation and dissemination have been evaluated. This approach may also be relevant to performing an initial drug screening for potential human therapy for zoonotic parasites. Treat-ments can be applied against infections in adult ruminants to minimize the outcomes of a primo-infection or the reactivation of a chronic infection during gestation or in newborn ruminants to avoid infection chronification. In this review, the current status of drug development against toxoplasmosis and neosporo-sis in farm ruminants is presented, and in an effort to promote additional treatment options, prospective drugs that have shown efficacy in vitro and in laboratory animal models of toxoplasmosis and neosporosis are examined
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Affiliation(s)
- Roberto Sánchez-Sánchez
- SALUVET, Animal Health Department, Faculty of Veterinary Sciences, Complutense University of Madrid, Ciudad Universitaria s/n, 28040, Madrid, Spain
| | - Patricia Vázquez
- SALUVET, Animal Health Department, Faculty of Veterinary Sciences, Complutense University of Madrid, Ciudad Universitaria s/n, 28040, Madrid, Spain
| | - Ignacio Ferre
- SALUVET, Animal Health Department, Faculty of Veterinary Sciences, Complutense University of Madrid, Ciudad Universitaria s/n, 28040, Madrid, Spain
| | - Luis Miguel Ortega-Mora
- SALUVET, Animal Health Department, Faculty of Veterinary Sciences, Complutense University of Madrid, Ciudad Universitaria s/n, 28040, Madrid, Spain
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Anghel N, Balmer V, Müller J, Winzer P, Aguado-Martinez A, Roozbehani M, Pou S, Nilsen A, Riscoe M, Doggett JS, Hemphill A. Endochin-Like Quinolones Exhibit Promising Efficacy Against Neospora Caninum in vitro and in Experimentally Infected Pregnant Mice. Front Vet Sci 2018; 5:285. [PMID: 30510935 PMCID: PMC6252379 DOI: 10.3389/fvets.2018.00285] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2018] [Accepted: 10/26/2018] [Indexed: 12/21/2022] Open
Abstract
We report on the efficacy of selected endochin-like quinolones (ELQs) against N. caninum tachyzoites grown in human foreskin fibroblasts (HFF), and in a pregnant BALB/c mouse model. Fourteen ELQs were screened against transgenic N. caninum tachyzoites expressing β-galactosidase (Nc-βgal). Drugs were added concomitantly to infection and the values for 50% proliferation inhibition (IC50) were determined after 3 days. Three compounds exhibited IC50 values below 0.1 nM, 3 ELQs had IC50s between 0.1 and 1 nM, for 7 compounds values between 1 and 10 nM were noted, and one compound had an IC50 of 22.4 nM. Two compounds, namely ELQ-316 and its prodrug ELQ-334 with IC50s of 0.66 and 3.33 nM, respectively, were previously shown to display promising activities against experimental toxoplasmosis and babesiosis caused by Babesia microti in mice, and were thus further studied. They were assessed in long-term treatment assays by exposure of infected HFF to ELQs at 0.5 μM concentration, starting 3 h after infection and lasting for up to 17 days followed by release of drug pressure. Results showed that the compounds substantially delayed parasite proliferation, but did not exert parasiticidal activities. TEM of drug treated parasites detected distinct alterations within the parasite mitochondria, but not in other parasite organelles. Assessment of safety of ELQ-334 in the pregnant mouse model showed that the compound did not interfere in fertility or pregnancy outcome. In N. caninum infected pregnant mice treated with ELQ-334 at 10 mg/kg/day for 5 days, neonatal mortality (within 2 days post partum) was found in 7 of 44 pups (15.9%), but no postnatal mortality was noted, and vertical transmission was reduced by 49% compared to the placebo group, which exhibited 100% vertical transmission, neonatal mortality in 15 of 34 pups (44%), and postnatal mortality for 18 of the residual 19 pups during the 4 weeks follow-up. These findings encourage more research on the use of ELQs for therapeutic options against N. caninum infection.
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Affiliation(s)
- Nicoleta Anghel
- Vetsuisse Faculty, Institute of Parasitology, University of Bern, Bern, Switzerland
| | - Vreni Balmer
- Vetsuisse Faculty, Institute of Parasitology, University of Bern, Bern, Switzerland
| | - Joachim Müller
- Vetsuisse Faculty, Institute of Parasitology, University of Bern, Bern, Switzerland
| | - Pablo Winzer
- Vetsuisse Faculty, Institute of Parasitology, University of Bern, Bern, Switzerland
| | | | - Mona Roozbehani
- Department of Parasitology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Sovitj Pou
- VA Portland Health Care System Research and Development Service, Portland, OR, United States
| | - Aaron Nilsen
- VA Portland Health Care System Research and Development Service, Portland, OR, United States
| | - Michael Riscoe
- VA Portland Health Care System Research and Development Service, Portland, OR, United States
| | - J Stone Doggett
- VA Portland Health Care System Research and Development Service, Portland, OR, United States
| | - Andrew Hemphill
- Vetsuisse Faculty, Institute of Parasitology, University of Bern, Bern, Switzerland
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Harmse R, Wong HN, Smit FJ, Müller J, Hemphill A, N'Da DD, Haynes RK. Activities of 11-Azaartemisinin and N-Sulfonyl Derivatives against Neospora caninum and Comparative Cytotoxicities. ChemMedChem 2017; 12:2094-2098. [PMID: 29210523 DOI: 10.1002/cmdc.201700600] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Revised: 11/15/2017] [Indexed: 11/09/2022]
Abstract
Neosporosis caused by the apicomplexan parasite Neospora caninum is an economically important disease that induces abortion in dairy and beef cattle. There are no vaccines or drugs available on the market for control or treatment of the disease in bovines. The peroxide artemisinin and its derivatives used clinically for treatment of malaria are active against N. caninum and other apicomplexan parasites. We have now evaluated the activities of the readily accessible and chemically robust 11-azaartemisinin 5 and selected N-sulfonyl derivatives prepared as described in the accompanying paper against N. caninum tachyzoites grown in infected human foreskin fibroblasts. Azaartemisinin elicited an IC50 value of 150 nm, and the 2',5'-dichloro-3'-thienylsulfonyl-11-azaartemisinin 17 was found to be the most active, with an IC50 value of 40 nm. Comparison with normal human fetal lung fibroblasts HFLF WI-38 revealed relatively benign cytotoxicity. The compounds were also screened in vitro against TK-10 (renal), UACC-62 (melanoma) and MCF-7 (breast) cancer cell lines; overall, in line with activities against HFLF cells, most compounds in the series were found to be inactive.
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Affiliation(s)
- Rozanne Harmse
- Centre of Excellence for Pharmaceutical Sciences, Faculty of Health Sciences, North-West University, Potchefstroom, 2520, South Africa
| | - Ho Ning Wong
- Centre of Excellence for Pharmaceutical Sciences, Faculty of Health Sciences, North-West University, Potchefstroom, 2520, South Africa
| | - Frans J Smit
- Centre of Excellence for Pharmaceutical Sciences, Faculty of Health Sciences, North-West University, Potchefstroom, 2520, South Africa
| | - Joachim Müller
- Institute of Parasitology, Vetsuisse Faculty, University of Berne, Länggass-Strasse 122, 3012, Bern, Switzerland
| | - Andrew Hemphill
- Institute of Parasitology, Vetsuisse Faculty, University of Berne, Länggass-Strasse 122, 3012, Bern, Switzerland
| | - David D N'Da
- Centre of Excellence for Pharmaceutical Sciences, Faculty of Health Sciences, North-West University, Potchefstroom, 2520, South Africa
| | - Richard K Haynes
- Centre of Excellence for Pharmaceutical Sciences, Faculty of Health Sciences, North-West University, Potchefstroom, 2520, South Africa
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Pereira LM, de Luca G, Abichabki NDLM, Bronzon da Costa CM, Yatsuda AP. Synergic in vitro combinations of artemisinin, pyrimethamine and methylene blue against Neospora caninum. Vet Parasitol 2017; 249:92-97. [PMID: 29279093 DOI: 10.1016/j.vetpar.2017.11.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Revised: 11/23/2017] [Accepted: 11/29/2017] [Indexed: 10/18/2022]
Abstract
Neospora caninum is a member of Apicomplexa phylum, the causative agent of neosporosis. The neosporosis combat is not well established and several strategies related to vaccine, chemotherapy and immune modulation are under development. In this work, we evaluated the effects of artemisinin (Art), methylene blue (MB) and pyrimethamine (Pyr) alone or associated, on N. caninum proliferation and elimination using LacZ tagged tachyzoites. The reactive oxygen species (ROS) production after incubation with Art were also performed. Our results indicate that combinations of classical antimalarial drugs improve the parasite control, allowing the use of three drugs in a single dose. Additionally, artemisinin demonstrated distinct ROS production patterns in intra and extracellular N. caninum forms. The drug repurposing appears as a suitable approach, allowing a fast and safe method to evaluate old drugs but novel candidates against neosporosis.
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Affiliation(s)
- Luiz Miguel Pereira
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Av do Café, sn/n, 14040-903, Ribeirão Preto, SP, Brazil; Núcleo de Apoio à Pesquisa em Produtos Naturais e Sintéticos, Universidade de São Paulo, Ribeirão Preto, SP, Brazil
| | - Gabriela de Luca
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Av do Café, sn/n, 14040-903, Ribeirão Preto, SP, Brazil
| | - Nathália de Lima Martins Abichabki
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Av do Café, sn/n, 14040-903, Ribeirão Preto, SP, Brazil
| | - Cássia Mariana Bronzon da Costa
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Av do Café, sn/n, 14040-903, Ribeirão Preto, SP, Brazil
| | - Ana Patrícia Yatsuda
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Av do Café, sn/n, 14040-903, Ribeirão Preto, SP, Brazil; Núcleo de Apoio à Pesquisa em Produtos Naturais e Sintéticos, Universidade de São Paulo, Ribeirão Preto, SP, Brazil.
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12
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Two Novel Calcium-Dependent Protein Kinase 1 Inhibitors Interfere with Vertical Transmission in Mice Infected with Neospora caninum Tachyzoites. Antimicrob Agents Chemother 2017; 61:AAC.02324-16. [PMID: 28137808 DOI: 10.1128/aac.02324-16] [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: 11/01/2016] [Accepted: 01/22/2017] [Indexed: 12/30/2022] Open
Abstract
We present the effects of two novel bumped kinase inhibitors, BKI-1517 and BKI-1553, against Neospora caninum tachyzoites in vitro and in experimentally infected pregnant mice. These compounds inhibited tachyzoite proliferation of a transgenic beta-galactosidase reporter strain cultured in human foreskin fibroblasts with 50% inhibitory concentrations (IC50s) of 0.05 ± 0.03 and 0.18 ± 0.03 μM, respectively. As assessed by an alamarBlue assay, fibroblast IC50s were above 20 μM; however, morphological changes occurred in cultures treated with >5 μM BKI-1517 after prolonged exposure (>6 days). Treatment of intracellular tachyzoites with 5 μM BKI-1553 for 6 days inhibited endodyogeny by interfering with the separation of newly formed zoites from a larger multinucleated parasite mass. In contrast, parasites treated with 5 μM BKI-1517 did not form large complexes and showed much more evidence of cell death. However, after a treatment duration of 10 days in vitro, both compounds failed to completely prevent the regrowth of parasites from culture. BALB/c mice experimentally infected with N. caninum Spain7 (Nc-Spain7) and then treated during 6 days with BKI-1517 or BKI-1553 at different dosages showed a significant reduction of the cerebral parasite load. However, fertility was impaired by BKI-1517 when applied at 50 mg/kg of body weight/day. At 20 mg/kg/day, BKI-1517 significantly inhibited the vertical transmission of N. caninum to pups and increased the rate of survival of offspring. BKI-1553 was less detrimental to fertility and also provided significant but clearly less pronounced protection of dams and offspring. These results demonstrate that, when judiciously applied, this compound class protects offspring from vertical transmission and disease.
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Abstract
INTRODUCTION Despite the fact that diseases caused by protozoan parasites represent serious challenges for public health, animal production and welfare, only a limited panel of drugs has been marketed for clinical applications. AREAS COVERED Herein, the authors investigate two strategies, namely whole organism screening and target-based drug design. The present pharmacopoeia has resulted from whole organism screening, and the mode of action and targets of selected drugs are discussed. However, the more recent extensive genome sequencing efforts and the development of dry and wet lab genomics and proteomics that allow high-throughput screening of interactions between micromolecules and recombinant proteins has resulted in target-based drug design as the predominant focus in anti-parasitic drug development. Selected examples of target-based drug design studies are presented, and calcium-dependent protein kinases, important drug targets in apicomplexan parasites, are discussed in more detail. EXPERT OPINION Despite the enormous efforts in target-based drug development, this approach has not yet generated market-ready antiprotozoal drugs. However, whole-organism screening approaches, comprising of both in vitro and in vivo investigations, should not be disregarded. The repurposing of already approved and marketed drugs could be a suitable strategy to avoid fastidious approval procedures, especially in the case of neglected or veterinary parasitoses.
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Affiliation(s)
- Joachim Müller
- a Institute of Parasitology, Vetsuisse Faculty , University of Bern , Bern , Switzerland
| | - Andrew Hemphill
- a Institute of Parasitology, Vetsuisse Faculty , University of Bern , Bern , Switzerland
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In Vitro and In Vivo Effects of the Bumped Kinase Inhibitor 1294 in the Related Cyst-Forming Apicomplexans Toxoplasma gondii and Neospora caninum. Antimicrob Agents Chemother 2015; 59:6361-74. [PMID: 26248379 DOI: 10.1128/aac.01236-15] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2015] [Accepted: 07/22/2015] [Indexed: 12/11/2022] Open
Abstract
We report on the in vitro effects of the bumped kinase inhibitor 1294 (BKI-1294) in cultures of virulent Neospora caninum isolates Nc-Liverpool (Nc-Liv) and Nc-Spain7 and in two strains of Toxoplasma gondii (RH and ME49), all grown in human foreskin fibroblasts. In these parasites, BKI-1294 acted with 50% inhibitory concentrations (IC50s) ranging from 20 nM (T. gondii RH) to 360 nM (N. caninum Nc-Liv), and exposure of intracellular stages to 1294 led to the nondisjunction of newly formed tachyzoites, resulting in the formation of multinucleated complexes similar to complexes previously observed in BKI-1294-treated N. caninum beta-galactosidase-expressing parasites. However, such complexes were not seen in a transgenic T. gondii strain that expressed CDPK1 harboring a mutation (G to M) in the gatekeeper residue. In T. gondii ME49 and N. caninum Nc-Liv, exposure of cultures to BKI-1294 resulted in the elevated expression of mRNA coding for the bradyzoite marker BAG1. Unlike in bradyzoites, SAG1 expression was not repressed. Immunofluorescence also showed that these multinucleated complexes expressed SAG1 and BAG1 and the monoclonal antibody CC2, which binds to a yet unidentified bradyzoite antigen, also exhibited increased labeling. In a pregnant mouse model, BKI-1294 efficiently inhibited vertical transmission in BALB/c mice experimentally infected with one of the two virulent isolates Nc-Liv or Nc-Spain7, demonstrating proof of concept that this compound protected offspring from vertical transmission and disease. The observed deregulated antigen expression effect may enhance the immune response during BKI-1294 therapy and will be the subject of future studies.
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15
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Arranz-Solís D, Aguado-Martínez A, Müller J, Regidor-Cerrillo J, Ortega-Mora LM, Hemphill A. Dose-dependent effects of experimental infection with the virulent Neospora caninum Nc-Spain7 isolate in a pregnant mouse model. Vet Parasitol 2015; 211:133-40. [DOI: 10.1016/j.vetpar.2015.05.021] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Revised: 05/15/2015] [Accepted: 05/24/2015] [Indexed: 02/08/2023]
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In vitro effects of new artemisinin derivatives in Neospora caninum-infected human fibroblasts. Int J Antimicrob Agents 2015; 46:88-93. [PMID: 25934265 DOI: 10.1016/j.ijantimicag.2015.02.020] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Revised: 02/24/2015] [Accepted: 02/25/2015] [Indexed: 11/21/2022]
Abstract
From a panel of 34 artemisinin derivatives tested in vitro, artemisone, GC007 and GC012 were most efficacious at inhibiting Neospora caninum replication (IC50 values of 3-54nM), did not notably impair the invasiveness of tachyzoites and were non-toxic for human foreskin fibroblasts (HFFs). Transmission electron microscopy of drug-treated N. caninum-infected HFFs demonstrated severe alterations in the parasite cytoplasm, changes in the composition of the matrix of the parasitophorous vacuole (PV) and diminished integrity of the PV membrane. To exert parasiticidal activity, parasites had to be cultured continuously in the presence of 5μM artemisone or GC007 for 3 weeks. N. caninum tachyzoites readily adapted to a stepwise increase in concentrations (0.5-10μM) of GC012, but not to artemisone or GC007. Drugs induced the expression of elevated levels of NcBAG1 and NcSAG4 mRNA, but only NcBAG1 could be detected by immunofluorescence. Thus, artemisinin derivatives represent interesting leads that should be investigated further.
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17
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Müller J, Aguado-Martinez A, Manser V, Balmer V, Winzer P, Ritler D, Hostettler I, Arranz-Solís D, Ortega-Mora L, Hemphill A. Buparvaquone is active against Neospora caninum in vitro and in experimentally infected mice. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2015; 5:16-25. [PMID: 25941626 PMCID: PMC4412913 DOI: 10.1016/j.ijpddr.2015.02.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Revised: 01/29/2015] [Accepted: 02/04/2015] [Indexed: 11/16/2022]
Abstract
Buparvaquone inhibits proliferation of Neospora caninum at nanomolar concentrations. In vitro, the drug acts mainly parasitostatic. Parasiticidal effects occur at µmolar concentrations after extended periods of time. Buparvaquone acts slowly as evidenced by transmission electron microscopy. Buparvaquone prevents clinical signs of acute neosporosis in mice.
The naphthoquinone buparvaquone is currently the only drug used against theileriosis. Here, the effects of buparvaquone were investigated in vitro and in an experimental mouse model for Neospora caninum infection. In 4-day proliferation assays, buparvaquone efficiently inhibited N. caninum tachyzoite replication (IC50 = 4.9 nM; IC100 = 100 nM). However, in the long term tachyzoites adapted and resumed proliferation in the presence of 100 nM buparvaquone after 20 days of cultivation. Parasiticidal activity was noted after 9 days of culture in 0.5 µM or 6 days in 1 µM buparvaquone. TEM of N. caninum infected fibroblasts treated with 1 µM buparvaquone showed that the drug acted rather slowly, and ultrastructural changes were evident only after 3–5 days of treatment, including severe alterations in the parasite cytoplasm, changes in the composition of the parasitophorous vacuole matrix and a diminished integrity of the vacuole membrane. Treatment of N. caninum infected mice with buparvaquone (100 mg/kg) either by intraperitoneal injection or gavage prevented neosporosis symptoms in 4 out of 6 mice in the intraperitoneally treated group, and in 6 out of 7 mice in the group receiving oral treatment. In the corresponding controls, all 6 mice injected intraperitoneally with corn oil alone died of acute neosporosis, and 4 out of 6 mice died in the orally treated control group. Assessment of infection intensities in the treatment groups showed that, compared to the drug treated groups, the controls showed a significantly higher parasite load in the lungs while cerebral parasite load was higher in the buparvaquone-treated groups. Thus, although buparvaquone did not eliminate the parasites infecting the CNS, the drug represents an interesting lead with the potential to eliminate, or at least diminish, fetal infection during pregnancy.
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Affiliation(s)
- Joachim Müller
- Institute of Parasitology, Vetsuisse Faculty, University of Berne, Länggass-Strasse 122, Bern 3012, Switzerland
| | - Adriana Aguado-Martinez
- Institute of Parasitology, Vetsuisse Faculty, University of Berne, Länggass-Strasse 122, Bern 3012, Switzerland
| | - Vera Manser
- Institute of Parasitology, Vetsuisse Faculty, University of Berne, Länggass-Strasse 122, Bern 3012, Switzerland
| | - Vreni Balmer
- Institute of Parasitology, Vetsuisse Faculty, University of Berne, Länggass-Strasse 122, Bern 3012, Switzerland
| | - Pablo Winzer
- Institute of Parasitology, Vetsuisse Faculty, University of Berne, Länggass-Strasse 122, Bern 3012, Switzerland
| | - Dominic Ritler
- Institute of Parasitology, Vetsuisse Faculty, University of Berne, Länggass-Strasse 122, Bern 3012, Switzerland
| | - Isabel Hostettler
- Institute of Parasitology, Vetsuisse Faculty, University of Berne, Länggass-Strasse 122, Bern 3012, Switzerland
| | - David Arranz-Solís
- SALUVET, Animal Health Department, Faculty of Veterinary Sciences, Complutense University of Madrid, Ciudad Universitaria s/n, Madrid 28040, Spain
| | - Luis Ortega-Mora
- SALUVET, Animal Health Department, Faculty of Veterinary Sciences, Complutense University of Madrid, Ciudad Universitaria s/n, Madrid 28040, Spain
| | - Andrew Hemphill
- Institute of Parasitology, Vetsuisse Faculty, University of Berne, Länggass-Strasse 122, Bern 3012, Switzerland
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Bis-benzimidazole hits against Naegleria fowleri discovered with new high-throughput screens. Antimicrob Agents Chemother 2015; 59:2037-44. [PMID: 25605363 DOI: 10.1128/aac.05122-14] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Naegleria fowleri is a pathogenic free-living amoeba (FLA) that causes an acute fatal disease known as primary amoebic meningoencephalitis (PAM). The major problem for infections with any pathogenic FLA is a lack of effective therapeutics, since PAM has a case mortality rate approaching 99%. Clearly, new drugs that are potent and have rapid onset of action are needed to enhance the treatment regimens for PAM. Diamidines have demonstrated potency against multiple pathogens, including FLA, and are known to cross the blood-brain barrier to cure other protozoan diseases of the central nervous system. Therefore, amidino derivatives serve as an important chemotype for discovery of new drugs. In this study, we validated two new in vitro assays suitable for medium- or high-throughput drug discovery and used these for N. fowleri. We next screened over 150 amidino derivatives of multiple structural classes and identified two hit series with nM potency that are suitable for further lead optimization as new drugs for this neglected disease. These include both mono- and diamidino derivatives, with the most potent compound (DB173) having a 50% inhibitory concentration (IC50) of 177 nM. Similarly, we identified 10 additional analogues with IC50s of <1 μM, with many of these having reasonable selectivity indices. The most potent hits were >500 times more potent than pentamidine. In summary, the mono- and diamidino derivatives offer potential for lead optimization to develop new drugs to treat central nervous system infections with N. fowleri.
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A quantitative reverse-transcriptase PCR assay for the assessment of drug activities against intracellular Theileria annulata schizonts. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2014; 4:201-9. [PMID: 25516828 PMCID: PMC4266814 DOI: 10.1016/j.ijpddr.2014.09.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Revised: 09/01/2014] [Accepted: 09/04/2014] [Indexed: 12/15/2022]
Abstract
Quantitative RT real time PCR was used to assess metabolic impairment of Theileria schizonts. The method was validated with buparvaquone. Buparvaquone acts directly and rapidly on the parasite within 1 h of treatment. Electron microscopy confirmed these findings. A series of anti-parasitic compounds and antibiotics acted primarily on the host cells.
Intracellular schizonts of the apicomplexans Theileria annulata and Theileria parva immortalize bovine leucocytes thereby causing fatal immunoproliferative diseases. Buparvaquone, a hydroxynaphthoquinone related to parvaquone, is the only drug available against Theileria. The drug is only effective at the onset of infection and emerging resistance underlines the need for identifying alternative compounds. Current drug assays employ monitoring of proliferation of infected cells, with apoptosis of the infected host cell as a read-out, but it is often unclear whether active compounds directly impair the viability of the parasite or primarily induce host cell death. We here report on the development of a quantitative reverse transcriptase real time PCR method based on two Theileria genes, tasp and tap104, which are both expressed in schizonts. Upon in vitro treatment of T. annulata infected bovine monocytes with buparvaquone, TaSP and Tap104 mRNA expression levels significantly decreased in relation to host cell actin already within 4 h of drug exposure, while significant differences in host cell proliferation were detectable only after 48–72 h. TEM revealed marked alterations of the schizont ultrastructure already after 2 h of buparvaquone treatment, while the host cell remained unaffected. Expression of TaSP and Tap104 proteins showed a marked decrease only after 24 h. Therefore, the analysis of expression levels of mRNA coding for TaSP and Tap104 allows to directly measuring impairment of parasite viability. We subsequently applied this method using a series of compounds affecting different targets in other apicomplexan parasites, and show that monitoring of TaSP- and Tap104 mRNA levels constitutes a suitable tool for anti-theilerial drug development.
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Liu ZY, Wenzler T, Brun R, Zhu X, Boykin DW. Synthesis and antiparasitic activity of new bis-arylimidamides: DB766 analogs modified in the terminal groups. Eur J Med Chem 2014; 83:167-73. [DOI: 10.1016/j.ejmech.2014.06.022] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Revised: 06/06/2014] [Accepted: 06/11/2014] [Indexed: 01/12/2023]
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Ojo KK, Reid MC, Kallur Siddaramaiah L, Müller J, Winzer P, Zhang Z, Keyloun KR, Vidadala RSR, Merritt EA, Hol WGJ, Maly DJ, Fan E, Van Voorhis WC, Hemphill A. Neospora caninum calcium-dependent protein kinase 1 is an effective drug target for neosporosis therapy. PLoS One 2014; 9:e92929. [PMID: 24681759 PMCID: PMC3969379 DOI: 10.1371/journal.pone.0092929] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Accepted: 02/27/2014] [Indexed: 11/18/2022] Open
Abstract
Despite the enormous economic importance of Neospora caninum related veterinary diseases, the number of effective therapeutic agents is relatively small. Development of new therapeutic strategies to combat the economic impact of neosporosis remains an important scientific endeavor. This study demonstrates molecular, structural and phenotypic evidence that N. caninum calcium-dependent protein kinase 1 (NcCDPK1) is a promising molecular target for neosporosis drug development. Recombinant NcCDPK1 was expressed, purified and screened against a select group of bumped kinase inhibitors (BKIs) previously shown to have low IC50s against Toxoplasma gondii CDPK1 and T. gondii tachyzoites. NcCDPK1 was inhibited by low concentrations of BKIs. The three-dimensional structure of NcCDPK1 in complex with BKIs was studied crystallographically. The BKI-NcCDPK1 structures demonstrated the structural basis for potency and selectivity. Calcium-dependent conformational changes in solution as characterized by small-angle X-ray scattering are consistent with previous structures in low Calcium-state but different in the Calcium-bound active state than predicted by X-ray crystallography. BKIs effectively inhibited N. caninum tachyzoite proliferation in vitro. Electron microscopic analysis of N. caninum cells revealed ultra-structural changes in the presence of BKI compound 1294. BKI compound 1294 interfered with an early step in Neospora tachyzoite host cell invasion and egress. Prolonged incubation in the presence of 1294 interfered produced observable interference with viability and replication. Oral dosing of BKI compound 1294 at 50 mg/kg for 5 days in established murine neosporosis resulted in a 10-fold reduced cerebral parasite burden compared to untreated control. Further experiments are needed to determine the PK, optimal dosage, and duration for effective treatment in cattle and dogs, but these data demonstrate proof-of-concept for BKIs, and 1294 specifically, for therapy of bovine and canine neosporosis.
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Affiliation(s)
- Kayode K. Ojo
- Center for Emerging and Re-emerging Infectious Diseases (CERID), Division of Allergy and Infectious Diseases, Department of Medicine, University of Washington, Seattle, Washington, United States of America
- * E-mail: (KKO); (WCVV); (AH)
| | - Molly C. Reid
- Center for Emerging and Re-emerging Infectious Diseases (CERID), Division of Allergy and Infectious Diseases, Department of Medicine, University of Washington, Seattle, Washington, United States of America
| | | | - Joachim Müller
- Institute of Parasitology, Vetsuisse Faculty, University of Berne, Berne, Switzerland
| | - Pablo Winzer
- Institute of Parasitology, Vetsuisse Faculty, University of Berne, Berne, Switzerland
| | - Zhongsheng Zhang
- Department of Biochemistry, University of Washington, Seattle, Washington, United States of America
| | - Katelyn R. Keyloun
- Center for Emerging and Re-emerging Infectious Diseases (CERID), Division of Allergy and Infectious Diseases, Department of Medicine, University of Washington, Seattle, Washington, United States of America
| | - Rama Subba Rao Vidadala
- Department of Chemistry, University of Washington, Seattle, Washington, United States of America
| | - Ethan A. Merritt
- Department of Biochemistry, University of Washington, Seattle, Washington, United States of America
| | - Wim G. J. Hol
- Department of Biochemistry, University of Washington, Seattle, Washington, United States of America
| | - Dustin J. Maly
- Department of Chemistry, University of Washington, Seattle, Washington, United States of America
| | - Erkang Fan
- Department of Biochemistry, University of Washington, Seattle, Washington, United States of America
| | - Wesley C. Van Voorhis
- Center for Emerging and Re-emerging Infectious Diseases (CERID), Division of Allergy and Infectious Diseases, Department of Medicine, University of Washington, Seattle, Washington, United States of America
- * E-mail: (KKO); (WCVV); (AH)
| | - Andrew Hemphill
- Institute of Parasitology, Vetsuisse Faculty, University of Berne, Berne, Switzerland
- * E-mail: (KKO); (WCVV); (AH)
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Pereira LM, Baroni L, Yatsuda AP. A transgenic Neospora caninum strain based on mutations of the dihydrofolate reductase-thymidylate synthase gene. Exp Parasitol 2014; 138:40-7. [PMID: 24440296 DOI: 10.1016/j.exppara.2014.01.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Accepted: 01/07/2014] [Indexed: 01/25/2023]
Abstract
Neospora caninum is an Apicomplexa parasite related to abortion and losses of fertility in cattle. The amenability of Toxoplasma gondii and Plasmodium to genetic manipulation offers several tools to determine the invasion and replication processes, which support posterior strategies related to the combat of these diseases. For Plasmodium the use of pyrimethamine as an auxiliary drug on malaria treatment has been affected by the rise of resistant strains and the analyses on Dihydrofolate reductase-thymidylate synthase (DHFR-TS) gene indicated several point mutations. In this work we developed a method for stable insertion of genes based on resistance to pyrimethamine. For that, the coding sequence of NcDHFR-TS (Dihydrofolate reductase-thymidylate synthase) was point mutated in two amino acids, generating DHFRM2M3. The DHFRM2M3 flanked by the promoter and 3'UTR of Ncdhfr-ts (Ncdhfr-DHFRM2M3) conferred resistance to pyrimethamine after transfection. For illustration of stability and expression, the cassette Ncdhfr-DHFRM2M3 was ligated to the reporter gene Lac-Z (β-galactosidase enzyme) controlled by the N. caninum tubulin promoter and was transfected and selected in N. caninum. The cassette was integrated into the genome and the selected tachyzoites expressed Lac-Z, allowing the detection of tachyzoites by the CPRG reaction and X-gal precipitation. The obtainment of transgenic N. caninum resistant to pyrimethamine confirms the effects on DHFR-TS among the Apicomplexa members and will support future approaches on pholate inhibitors for N. caninum prophylaxis. The construction of stable tachyzoites based on vectors with N. caninum promoters initiates the molecular manipulation of this parasite independently of T. gondii.
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Affiliation(s)
- Luiz Miguel Pereira
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Av do Café, sn/n, 14040-903 Ribeirão Preto, SP, Brazil; Núcleo de Apoio à Pesquisa em Produtos Naturais e Sintéticos, Universidade de São Paulo, Ribeirão Preto, SP, Brazil
| | - Luciana Baroni
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Av do Café, sn/n, 14040-903 Ribeirão Preto, SP, Brazil; Núcleo de Apoio à Pesquisa em Produtos Naturais e Sintéticos, Universidade de São Paulo, Ribeirão Preto, SP, Brazil
| | - Ana Patrícia Yatsuda
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Av do Café, sn/n, 14040-903 Ribeirão Preto, SP, Brazil; Núcleo de Apoio à Pesquisa em Produtos Naturais e Sintéticos, Universidade de São Paulo, Ribeirão Preto, SP, Brazil.
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In vitro effects of novel ruthenium complexes in Neospora caninum and Toxoplasma gondii tachyzoites. Antimicrob Agents Chemother 2013; 57:5747-54. [PMID: 23979747 DOI: 10.1128/aac.02446-12] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Upon the screening of 16 antiproliferative compounds against Toxoplasma gondii and Neospora caninum, two hydrolytically stable ruthenium complexes (compounds 16 and 18) exhibited 50% inhibitory concentrations of 18.7 and 41.1 nM (T. gondii) and 6.7 and 11.3 nM (N. caninum). To achieve parasiticidal activity with compound 16, long-term treatment (22 to 27 days at 80 to 160 nM) was required. Transmission electron microscopy demonstrated the rapid impact on and ultrastructural alterations in both parasites. These preliminary findings suggest that the potential of ruthenium-based compounds should thus be further exploited.
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In vitro and in vivo activities of dicationic diguanidino compounds against Echinococcus multilocularis metacestodes. Antimicrob Agents Chemother 2013; 57:3829-35. [PMID: 23716058 DOI: 10.1128/aac.02569-12] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Alveolar echinococcosis (AE) is a disease predominantly affecting the liver, with metacestodes (larvae) of the tapeworm Echinococcus multilocularis proliferating and exhibiting tumor-like infiltrative growth. For many years, chemotherapeutical treatment against alveolar echinococcosis has relied on the benzimidazoles albendazole and mebendazole, which require long treatment durations and exhibit parasitostatic rather than parasiticidal efficacy. Although benzimidazoles have been and still are beneficial for the patients, there is clearly a demand for alternative and more efficient treatment options. Aromatic dications, more precisely a small panel of di-N-aryl-diguanidino compounds, were screened for efficacy against E. multilocularis metacestodes in vitro. Only those with a thiophene core group were active against metacestodes, while furans were not. The most active compound, DB1127, was further investigated in terms of in vivo efficacy in mice experimentally infected with E. multilocularis metacestodes. This diguanidino compound was effective against AE when administered intraperitoneally but not when applied orally. Thus, thiophene-diguanidino derivatives with improved bioavailability when administered orally could lead to treatment options against AE.
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Novel amidines and analogues as promising agents against intracellular parasites: a systematic review. Parasitology 2013; 140:929-51. [PMID: 23561006 DOI: 10.1017/s0031182013000292] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Parasitic protozoa comprise diverse aetiological agents responsible for important diseases in humans and animals including sleeping sickness, Chagas disease, leishmaniasis, malaria, toxoplasmosis and others. They are major causes of mortality and morbidity in tropical and subtropical countries, and are also responsible for important economic losses. However, up to now, for most of these parasitic diseases, effective vaccines are lacking and the approved chemotherapeutic compounds present high toxicity, increasing resistance, limited efficacy and require long periods of treatment. Many of these parasitic illnesses predominantly affect low-income populations of developing countries for which new pharmaceutical alternatives are urgently needed. Thus, very low research funding is available. Amidine-containing compounds such as pentamidine are DNA minor groove binders with a broad spectrum of activities against human and veterinary pathogens. Due to their promising microbicidal activity but their rather poor bioavailability and high toxicity, many analogues and derivatives, including pro-drugs, have been synthesized and screened in vitro and in vivo in order to improve their selectivity and pharmacological properties. This review summarizes the knowledge on amidines and analogues with respect to their synthesis, pharmacological profile, mechanistic and biological effects upon a range of intracellular protozoan parasites. The bulk of these data may contribute to the future design and structure optimization of new aromatic dicationic compounds as novel antiparasitic drug candidates.
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Müller J, Hemphill A. New approaches for the identification of drug targets in protozoan parasites. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2013; 301:359-401. [PMID: 23317822 DOI: 10.1016/b978-0-12-407704-1.00007-5] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
Antiparasitic chemotherapy is an important issue for drug development. Traditionally, novel compounds with antiprotozoan activities have been identified by screening of compound libraries in high-throughput systems. More recently developed approaches employ target-based drug design supported by genomics and proteomics of protozoan parasites. In this chapter, the drug targets in protozoan parasites are reviewed. The gene-expression machinery has been among the first targets for antiparasitic drugs and is still under investigation as a target for novel compounds. Other targets include cytoskeletal proteins, proteins involved in intracellular signaling, membranes, and enzymes participating in intermediary metabolism. In apicomplexan parasites, the apicoplast is a suitable target for established and novel drugs. Some drugs act on multiple subcellular targets. Drugs with nitro groups generate free radicals under anaerobic growth conditions, and drugs with peroxide groups generate radicals under aerobic growth conditions, both affecting multiple cellular pathways. Mefloquine and thiazolides are presented as examples for antiprotozoan compounds with multiple (side) effects. The classic approach of drug discovery employing high-throughput physiological screenings followed by identification of drug targets has yielded the mainstream of current antiprotozoal drugs. Target-based drug design supported by genomics and proteomics of protozoan parasites has not produced any antiparasitic drug so far. The reason for this is discussed and a synthesis of both methods is proposed.
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Affiliation(s)
- Joachim Müller
- Institute of Parasitology, University of Berne, Berne, Switzerland.
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Müller J, Hemphill A. In vitro culture systems for the study of apicomplexan parasites in farm animals. Int J Parasitol 2012; 43:115-24. [PMID: 23000674 DOI: 10.1016/j.ijpara.2012.08.004] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Revised: 08/08/2012] [Accepted: 08/14/2012] [Indexed: 01/02/2023]
Abstract
In vitro culture systems represent powerful tools for the study of apicomplexan parasites such as Cryptosporidium, Eimeria, Sarcocystis, Neospora, Toxoplasma, Besnoitia, Babesia and Theileria, all with high relevance for farm animals. Proliferative stages of these parasites have been cultured in vitro employing a large variety of cell culture and explant approaches. For some, such as Cryptosporidium and Eimeria, the sexual development has been reproduced in cell cultures, while for others, animal experimentation is required to fulfill the life cycle. In vitro cultures have paved the way to exploit the basic biology of these organisms, and had a major impact on the development of tools for diagnostic purposes. With the aid of in vitro cultivation, studies on host-parasite interactions, on factors involved in innate resistance, stage conversion and differentiation, genetics and transfection technology, vaccine candidates and drug effectiveness could be carried out. The use of transgenic parasites has facilitated high-throughput screening of anti-microbial compounds that are active against the proliferative stages. Here, we review the basic features of cell culture-based in vitro systems for apicomplexan parasites that are relevant for farm animals, and discuss their applications with a focus on drug identification and studies of stage differentiation.
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Affiliation(s)
- Joachim Müller
- Institute of Parasitology, Vetsuisse Faculty, University of Berne, Länggass-Strasse 122, CH-3012 Berne, Switzerland.
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