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Matsa R, Makam P, Anilakumari R, Sundharesan M, Mathew N, Kannan T. Design, synthesis, and in vitro evaluation of thiosemicarbazone derivatives as anti-filarial agents. Exp Parasitol 2022; 241:108363. [PMID: 36007586 DOI: 10.1016/j.exppara.2022.108363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 09/18/2021] [Accepted: 08/17/2022] [Indexed: 11/04/2022]
Abstract
Effective macrofilaricidal drugs are not commercially available, and in an endeavour to find out new macrofilaricidal agents, in this research work, thiosemicarbazone derivatives have been prepared and tested against adult Setaria digitata, a cattle filarial parasite, as a model nematode for the filarial parasite, Wuchereria bancrofti. Lipinski and Veber rules have been used to design these molecules and found out that all the designed molecules show drug-like molecular properties. The in vitro anti-filarial potential of thiosemicarbazones against S. digitata was carried out using worm motility and 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) reduction colorimetric assays at 100 μg/ml concentration for the incubation period of 24 h. The standard drugs used at present for filaria, Albendazole, Ivermectin and Diethylcarbamazine were not able to kill the adult filarial worms effectively. In contrast, phenyl thiosemicarbazones with trifluoromethyl substitution at 3rd and 4th positions, 2-pyrrolyl, and isatinyl made the adult worms immotile and also showed 69%-83% inhibition in formazan formation an indicator of non viability.
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Affiliation(s)
- Ramkishore Matsa
- Department of Chemistry, Pondicherry University, Kalapet, Puducherry, 605 014, India
| | - Parameshwar Makam
- Chemical Science Research Group, Division of Research and Development, Lovely Professional University, Phagwara, 144411, India
| | - R Anilakumari
- ICMR - Vector Control Research Centre, Indira Nagar, Puducherry, 605006, India
| | - M Sundharesan
- ICMR - Vector Control Research Centre, Indira Nagar, Puducherry, 605006, India
| | - Nisha Mathew
- ICMR - Vector Control Research Centre, Indira Nagar, Puducherry, 605006, India.
| | - Tharanikkarasu Kannan
- Department of Chemistry, Pondicherry University, Kalapet, Puducherry, 605 014, India.
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Abstract
Twenty diseases are recognized as neglected tropical diseases (NTDs) by World Health Assembly resolutions, including human filarial diseases. The end of NTDs is embedded within the Sustainable Development Goals for 2030, under target 3.3. Onchocerciasis afflicts approximately 20.9 million people worldwide with > 90% of those infected residing in Africa. Control programs have made tremendous efforts in the management of onchocerciasis by mass drug administration and aerial larviciding; however, disease elimination is not yet achieved. In the new WHO roadmap, it is recognized that new drugs or drug regimens that kill or permanently sterilize adult filarial worms would significantly improve elimination timelines and accelerate the achievement of the program goal of disease elimination. Drug development is, however, handicapped by high attrition rates, and many promising molecules fail in preclinical development or in subsequent toxicological, safety and efficacy testing; thus, research and development (R&D) costs are, in aggregate, very high. Drug discovery and development for NTDs is largely driven by unmet medical needs put forward by the global health community; the area is underfunded and since no high return on investment is possible, there is no dedicated drug development pipeline for human filariasis. Repurposing existing drugs is one approach to filling the drug development pipeline for human filariasis. The high cost and slow pace of discovery and development of new drugs has led to the repurposing of “old” drugs, as this is more cost-effective and allows development timelines to be shortened. However, even if a drug is marketed for a human or veterinary indication, the safety margin and dosing regimen will need to be re-evaluated to determine the risk in humans. Drug repurposing is a promising approach to enlarging the pool of active molecules in the drug development pipeline. Another consideration when providing new treatment options is the use of combinations, which is not addressed in this review. We here summarize recent advances in the late preclinical or early clinical stage in the search for a potent macrofilaricide, including drugs against the nematode and against its endosymbiont, Wolbachia pipientis.
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Affiliation(s)
- Adela Ngwewondo
- Centre of Medical Research, Institute of Medical Research and Medicinal Plants Studies (IMPM), P.O. Box13033, Yaoundé, Cameroon
- Drugs for Neglected Diseases Initiative, Chemin Camille-Vidart 15, 1202, Geneva, Switzerland
| | - Ivan Scandale
- Drugs for Neglected Diseases Initiative, Chemin Camille-Vidart 15, 1202, Geneva, Switzerland
| | - Sabine Specht
- Drugs for Neglected Diseases Initiative, Chemin Camille-Vidart 15, 1202, Geneva, Switzerland.
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Akumtoh DN, Njouendou AJ, Metuge HM, Sjoberg HT, Pionnier NP, Chunda VC, Gandjui NVT, Ndzeshang LB, Fombad FF, Abong RA, Enyong PA, Fru-Cho J, Esum ME, Ritter M, Taylor MJ, Turner JD, Wanji S. Onchocerca ochengi male worms implanted in SCID mice and Gerbil: Relationship between microfilaridermia status of cows, nodular worm viability and fertility and worm survival in the rodents. Exp Parasitol 2021; 229:108143. [PMID: 34437906 PMCID: PMC8518880 DOI: 10.1016/j.exppara.2021.108143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2020] [Revised: 05/06/2021] [Accepted: 08/16/2021] [Indexed: 11/27/2022]
Abstract
BACKGROUND Current treatment options for onchocerciasis are sub-optimal, prompting research and development of a safe cure (macrofilaricide). Onchocerca ochengi, a parasite of cattle, is used as a close surrogate for the human parasite O. volvulus in a murine model for pre-clinical screening of macrofilaricides. Skin from naturally infected cattle have been used in previous studies as a reliable source of parasite material. However, there is limited knowledge on how source-related factors such as the microfilaridermia status of the cattle, the nodule load and nodular worm viability may affect survival of male O. ochengi worms implanted in the rodent hosts. Such relationships were investigated in this study. METHODS Dermal tissue and nodules were obtained from Gudali cattle, dissected and cultured to obtain migrating microfilariae (mf) and male worms. Emerged male worms were implanted into SCID mice and Gerbils (Meriones unguiculatus) and recovery rates were determined upon 42 days post implantation. Finally, nodules were processed for histology and embryogram analyses to assess the nodular worm viability and fertility, respectively. RESULTS Of the 69 cattle sampled, 24 (34.8%) were mf+ and 45 (65.2%) were mf-. The mean nodule loads were 180.5 ± 117.7 (mf+) and 110.6 ± 102.7 (mf-) (p = 0.0186). The mean male worm harvest from nodules were 76.8 ± 120.3 and 47.2 ± 33.4 (p = 0.2488) for mf+ and mf- cattle, respectively. The number of male worms per 100 nodules were 57/100 and 46/100 nodules for mf+ and mf- cows, respectively. Female worms from nodules of mf- cows had higher counts of both normal and abnormal embryos with higher proportions of dead nodular worms evinced by histology compared to those from mf+ cows. A total of 651 worms were implanted into mice and gerbils, out of which 129 (19.81%) were recovered. Logistic regression analysis indicated that the microfilaridermia status of the cattle (presence of mf) (OR = 4.3319; P = 0.001) is the single most important predictor of the success of male worm recovery after implantation into rodents. CONCLUSION Microfilaridermic cattle provide a promising source of adult O. ochengi. Male worms from this group of cattle have a better success rate of survival in a murine implant model. Nevertheless, in the programmatic point of view, amicrofilaridermic Gudali cattle would still constitute an important source of O. ochengi male worms with relatively good viability after implantation into rodents.
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Affiliation(s)
- Desmond N Akumtoh
- Research Foundation for Tropical Diseases and the Environment (REFOTDE), Buea, Cameroon; Parasite and Vector Research Unit (PAVRU), Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon.
| | - Abdel J Njouendou
- Research Foundation for Tropical Diseases and the Environment (REFOTDE), Buea, Cameroon; Department of Biomedical Sciences, Faculty of Health Sciences, University of Buea, Buea, Cameroon.
| | - Haelly M Metuge
- Research Foundation for Tropical Diseases and the Environment (REFOTDE), Buea, Cameroon; Parasite and Vector Research Unit (PAVRU), Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon.
| | - Hanna T Sjoberg
- Centre for Drugs and Diagnostics, Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Nicolas P Pionnier
- Centre for Drugs and Diagnostics, Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK.
| | - Valerine C Chunda
- Research Foundation for Tropical Diseases and the Environment (REFOTDE), Buea, Cameroon; Parasite and Vector Research Unit (PAVRU), Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon.
| | - Narcisse Victor T Gandjui
- Research Foundation for Tropical Diseases and the Environment (REFOTDE), Buea, Cameroon; Parasite and Vector Research Unit (PAVRU), Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon.
| | - Lontum B Ndzeshang
- Research Foundation for Tropical Diseases and the Environment (REFOTDE), Buea, Cameroon; Parasite and Vector Research Unit (PAVRU), Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon.
| | - Fanny F Fombad
- Research Foundation for Tropical Diseases and the Environment (REFOTDE), Buea, Cameroon; Department of Zoology and Animal Physiology, Faculty of Science, University of Buea, Buea, Cameroon.
| | - Raphael A Abong
- Research Foundation for Tropical Diseases and the Environment (REFOTDE), Buea, Cameroon; Parasite and Vector Research Unit (PAVRU), Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon.
| | - Peter A Enyong
- Research Foundation for Tropical Diseases and the Environment (REFOTDE), Buea, Cameroon; Parasite and Vector Research Unit (PAVRU), Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon.
| | - Jerome Fru-Cho
- Research Foundation for Tropical Diseases and the Environment (REFOTDE), Buea, Cameroon; Parasite and Vector Research Unit (PAVRU), Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon.
| | - Mathias E Esum
- Research Foundation for Tropical Diseases and the Environment (REFOTDE), Buea, Cameroon; Parasite and Vector Research Unit (PAVRU), Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon.
| | - Manuel Ritter
- Institute of Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Germany; German Center for Infection Research (DZIF), Bonn - Cologne Partner Site, Bonn, Germany.
| | - Mark J Taylor
- Centre for Drugs and Diagnostics, Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK.
| | - Joseph D Turner
- Centre for Drugs and Diagnostics, Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK.
| | - Samuel Wanji
- Research Foundation for Tropical Diseases and the Environment (REFOTDE), Buea, Cameroon; Parasite and Vector Research Unit (PAVRU), Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon.
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Kushwaha V, Rastogi S, Pandey MM, Saxena K, Khatoon S, Rawat AKS, Murthy PK. In Vitro and In Vivo Antifilarial Activity of Standardized Extract of Calotropis procera Flowers against Brugia malayi. Curr Top Med Chem 2019; 19:1252-1262. [PMID: 31218959 DOI: 10.2174/1568026619666190620154054] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2018] [Revised: 02/02/2019] [Accepted: 03/05/2019] [Indexed: 11/22/2022]
Abstract
BACKGROUND Lymphatic filariasis (LF) is a parasitic disease that causes permanent disability (elephantiasis). Currently used antifilarial drugs are failing to control LF and there is resurgence in some areas. Looking for new antifilarial leads, we found that Calotropis procera plant parts have been used in traditional medicine for alleviating elephantiasis but the antifilarial activity is not known. OBJECTIVE In the present study, the antifilarial activity of ethanolic extract (A001) and its hexane fraction (F001) of C. procera flowers was investigated using the human filarial parasite Brugia malayi. METHODS A001 and F001 were tested for antifilarial activity using motility and 3-(4,5-dimethylthiazol-2- yl)-2,5 diphenyltetrazolium bromide (MTT) assays (in vitro) and in the rodent models B. malayi- Meriones unguiculatus and B. malayi-Mastomys coucha. In the rodent models, A001 and F001 were administered orally for 5 consecutive days, and the adult worm burden and course of microfilaraemia were determined. RESULTS Both A001 and F001 showed microfilaricidal and macrofilaricidal activity in vitro. In animal models, A001 killed ~49-54% adult worms. In M. coucha model, F001 killed 12-60% adult worms in a dose (125-500 mg/kg) dependent manner; A001 and F001 suppressed microfilaraemia till days 91 and 35 post initiation of treatment, respectively. HPTLC revealed 0.61% lupeol, 0.50% β-sitosterol and 1.50% triacontanol in F001. CONCLUSION Flowers of C. procera have definite microfilaricidal and macrofilaricidal activities. Whether this activity is due to lupeol, β-sitosterol and triacontanol found in the hexane fraction remains to be investigated. This is the first report on the antifilarial efficacy of flowers of the plant C. procera.
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Affiliation(s)
- Vikas Kushwaha
- Division of Parasitology, CSIR-Central Drug Research Institute, New Campus, BS 10/1, Sector 10, Jankipuram Extension, Sitapur Road, Lucknow 226 031, India
| | - Subha Rastogi
- Pharmacognosy & Ethnopharmacology Division, CSIR-National Botanical Research Institute, Lucknow 226 001, India
| | - Madan Mohan Pandey
- Pharmacognosy & Ethnopharmacology Division, CSIR-National Botanical Research Institute, Lucknow 226 001, India
| | - Kirti Saxena
- Division of Parasitology, CSIR-Central Drug Research Institute, New Campus, BS 10/1, Sector 10, Jankipuram Extension, Sitapur Road, Lucknow 226 031, India
| | - Sayyada Khatoon
- Pharmacognosy & Ethnopharmacology Division, CSIR-National Botanical Research Institute, Lucknow 226 001, India
| | - Ajay Kumar Singh Rawat
- Pharmacognosy & Ethnopharmacology Division, CSIR-National Botanical Research Institute, Lucknow 226 001, India
| | - P Kaplana Murthy
- Division of Parasitology, CSIR-Central Drug Research Institute, New Campus, BS 10/1, Sector 10, Jankipuram Extension, Sitapur Road, Lucknow 226 031, India
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O'Neill M, Ballesteros C, Tritten L, Burkman E, Zaky WI, Xia J, Moorhead A, Williams SA, Geary TG. Profiling the macrofilaricidal effects of flubendazole on adult female Brugia malayi using RNAseq. Int J Parasitol Drugs Drug Resist 2016; 6:288-296. [PMID: 27733308 PMCID: PMC5196492 DOI: 10.1016/j.ijpddr.2016.09.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Revised: 09/12/2016] [Accepted: 09/13/2016] [Indexed: 11/30/2022]
Abstract
The use of microfilaricidal drugs for the control of onchocerciasis and lymphatic filariasis (LF) necessitates prolonged yearly dosing. Prospects for elimination or eradication of these diseases would be enhanced by the availability of a macrofilaricidal drug. Flubendazole (FLBZ), a benzimidazole anthelmintic, is an appealing candidate. FLBZ has demonstrated potent macrofilaricidal effects in a number of experimental rodent models and in one human trial. Unfortunately, FLBZ was deemed unsatisfactory for use in mass drug administration campaigns due to its limited oral bioavailability. A new formulation that enables sufficient bioavailability following oral administration could render FLBZ an effective treatment for onchocerciasis and LF. Identification of drug-derived effects is important in ascertaining a dosage regimen which is predicted to be lethal to the parasite in situ. In previous histological studies, exposure to FLBZ induced damage to tissues required for reproduction and survival at pharmacologically relevant concentrations. However, more precise and quantitative indices of drug effects are needed. This study assessed drug effects using a transcriptomic approach to confirm effects observed histologically and to identify genes which were differentially expressed in treated adult female Brugia malayi. Comparative analysis across different concentrations (1 μM and 5 μM) and durations (48 and 120 h) provided an overview of the processes which are affected by FLBZ exposure. Genes with dysregulated expression were consistent with the reproductive effects observed via histology in our previous studies. This study revealed transcriptional changes in genes involved in embryo development. Additionally, significant downregulation was observed in genes encoding cuticle components, which may reflect changes in developing embryos, the adult worm cuticle or both. These data support the hypothesis that FLBZ acts predominantly on rapidly dividing cells, and provides a basis for selecting molecular markers of drug-induced damage which may be of use in predicting efficacious FLBZ regimens.
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Affiliation(s)
- Maeghan O'Neill
- Institute of Parasitology, Centre for Host-Parasite Interactions, McGill University, 21,111 Lakeshore Road, Sainte-Anne-de-Bellevue, Quebec H9X 3V9, Canada
| | - Cristina Ballesteros
- Institute of Parasitology, Centre for Host-Parasite Interactions, McGill University, 21,111 Lakeshore Road, Sainte-Anne-de-Bellevue, Quebec H9X 3V9, Canada
| | - Lucienne Tritten
- Institute of Parasitology, Centre for Host-Parasite Interactions, McGill University, 21,111 Lakeshore Road, Sainte-Anne-de-Bellevue, Quebec H9X 3V9, Canada
| | - Erica Burkman
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, 501 D.W. Brooks Drive, Athens, GA 30602, USA; Filariasis Research Reagent Resource Center, Smith College, Northampton, MA 01063, USA
| | - Weam I Zaky
- Filariasis Research Reagent Resource Center, Smith College, Northampton, MA 01063, USA; Department of Biological Sciences, Smith College, Northampton, MA 01063, USA
| | - Jianguo Xia
- Institute of Parasitology, Centre for Host-Parasite Interactions, McGill University, 21,111 Lakeshore Road, Sainte-Anne-de-Bellevue, Quebec H9X 3V9, Canada; Department of Animal Science, McGill University, 21,111 Lakeshore Road, Sainte-Anne-de-Bellevue, Quebec H9X 3V9, Canada
| | - Andrew Moorhead
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, 501 D.W. Brooks Drive, Athens, GA 30602, USA; Filariasis Research Reagent Resource Center, Smith College, Northampton, MA 01063, USA
| | - Steven A Williams
- Filariasis Research Reagent Resource Center, Smith College, Northampton, MA 01063, USA; Department of Biological Sciences, Smith College, Northampton, MA 01063, USA
| | - Timothy G Geary
- Institute of Parasitology, Centre for Host-Parasite Interactions, McGill University, 21,111 Lakeshore Road, Sainte-Anne-de-Bellevue, Quebec H9X 3V9, Canada.
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Kushwaha V, Saxena K, Verma R, Verma SK, Katoch D, Kumar N, Lal B, Murthy PK, Singh B. Antifilarial activity of diterpenoids from Taxodium distichum. Parasit Vectors 2016; 9:312. [PMID: 27245322 PMCID: PMC4888613 DOI: 10.1186/s13071-016-1592-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 05/13/2016] [Indexed: 12/02/2022] Open
Abstract
BACKGROUND Lymphatic filariasis caused by Wuchereria bancrofti, Brugia malayi and B. timori, is a debilitating disease with an adverse social and economic impact. The infection remains unabated in spite of treatment with existing antifilarial drugs diethylcarbamazine (DEC) and ivermectin which are chiefly microfilaricides. There is therefore, need for macrofilaricides, embryostatic agents and better microfilaricides. In the present study we explored the antifilarial potential of crude extract and its molecular fractions of the plant Taxodium distichum using in vitro assay systems and rodent models of B. malayi infection. METHODS Ethanolic extract (A001) of aerial parts of T. distichum was solvent fractionated and sub-fractionated. Four molecules, 3-Acetoxylabda-8(20), 13-diene-15-oic acid (K001), Beta-sitosterol (K002), labda-8(20),13-diene-15-oic acid (K003) and Metasequoic acid A (K004) were isolated from the fractions and their structure determined by spectroscopic analysis. The extract, subfractions and molecules were evaluated for antifilarial activity against B. malayi by 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT) reduction and motility assays in vitro and in two animal models, Meriones unguiculatus and Mastomys coucha, harbouring B. malayi infection. RESULTS A001 was effective in killing microfilariae (mf) and adult worms in vitro. The diterpenoid K003 produced 100 % reduction in motility of both mf and adult worms and > 80 % inhibition in MTT reduction potential of adult female worms. In B. malayi-M. unguiculatus model, A001 killed all the adult worms in > 80 % of infected animals. K003 was embryostatic (> 95 %) in this model. In the B. malayi-M. coucha model, K003 killed ~54 % of adult worms (macrofilaricidal activity) and rendered > 36 % female worms sterile; it also stopped any further rise in microfilaraemia after day 42 post-initiation of treatment. CONCLUSION Ethanolic extract of aerial parts of the plant T. distichum possesses potent antifilarial activity and the active principle was localised to K003 which showed significant macrofilaricidal activity and late suppression of peripheral microfilaraemia and some embryostatic activity. These findings indicate that labdane diterpenoid molecule(s) may provide valuable leads for design and development of new macrofilaricidal agent(s). To the best of our knowledge, this is the first report on antifilarial efficacy of products from the plant T. distichum.
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Affiliation(s)
- Vikas Kushwaha
- Division of Parasitology, CSIR-Central Drug Research Institute, New Campus, BS 10/1, Sector 10, Jankipuram Extension, Lucknow, 226 031, India
| | - Kirti Saxena
- Division of Parasitology, CSIR-Central Drug Research Institute, New Campus, BS 10/1, Sector 10, Jankipuram Extension, Lucknow, 226 031, India
| | - Richa Verma
- Division of Parasitology, CSIR-Central Drug Research Institute, New Campus, BS 10/1, Sector 10, Jankipuram Extension, Lucknow, 226 031, India
| | - Shiv K Verma
- Division of Parasitology, CSIR-Central Drug Research Institute, New Campus, BS 10/1, Sector 10, Jankipuram Extension, Lucknow, 226 031, India
- Present Address: USDA, ARS, APDL, BARC-East Bldg 1001, 10300 Baltimore Avenue, Beltsville, MD, 20705, USA
| | - Deepali Katoch
- Natural Product Chemistry and Process Development Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, 176 061, HP, India
| | - Neeraj Kumar
- Natural Product Chemistry and Process Development Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, 176 061, HP, India
| | - Brij Lal
- Biodiversity Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, 176 061, HP, India
| | - P Kalpana Murthy
- Division of Parasitology, CSIR-Central Drug Research Institute, New Campus, BS 10/1, Sector 10, Jankipuram Extension, Lucknow, 226 031, India.
| | - Bikram Singh
- Natural Product Chemistry and Process Development Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, 176 061, HP, India.
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O'Neill M, Geary JF, Agnew DW, Mackenzie CD, Geary TG. In vitro flubendazole-induced damage to vital tissues in adult females of the filarial nematode Brugia malayi. Int J Parasitol Drugs Drug Resist 2015; 5:135-40. [PMID: 26288741 PMCID: PMC4534755 DOI: 10.1016/j.ijpddr.2015.06.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Revised: 06/17/2015] [Accepted: 06/19/2015] [Indexed: 11/26/2022]
Abstract
The use of a microfilaricidal drug for the control of onchocerciasis and lymphatic filariasis necessitates prolonged yearly dosing. Prospects for elimination or eradication of these diseases would be enhanced by availability of a macrofilaricidal drug. Flubendazole (FLBZ), a benzimidazole anthelmintic, is an appealing candidate macrofilaricide. FLBZ has demonstrated profound and potent macrofilaricidal effects in a number of experimental filarial rodent models and one human trial. Unfortunately, FLBZ was deemed unsatisfactory for use in mass drug administration (MDA) campaigns due to its markedly limited oral bioavailability. However, a new formulation that provided sufficient bioavailability following oral administration could render FLBZ an effective treatment for onchocerciasis and LF. This study characterized the effects of FLBZ and its reduced metabolite (FLBZ-R) on filarial nematodes in vitro to determine the exposure profile which results in demonstrable damage. Adult female Brugia malayi were exposed to varying concentrations of FLBZ or FLBZ-R (100 nM–10 μM) for up to five days, after which worms were fixed for histology. Morphological damage following exposure to FLBZ was observed prominently in the hypodermis and developing embryos at concentrations as low as 100 nM following 24 h exposure. The results indicate that damage to tissues required for reproduction and survival can be achieved at pharmacologically relevant concentrations. Detrimental effects observed in tissues required for development and survival. Damage occurs at concentrations ≥100 nM. Hypodermal and embryonic tissues exhibited the most severe damage. Oocytes and early morula are the most affected embryonic tissues.
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Affiliation(s)
- Maeghan O'Neill
- Institute of Parasitology and Centre for Host-Parasite Interactions, McGill University, Ste-Anne-de-Bellevue, QC H9X 3V9, Canada
| | - James F Geary
- Department of Pathobiology and Diagnostic Investigation, Michigan State University, East Lansing, MI 48824, USA
| | - Dalen W Agnew
- Department of Pathobiology and Diagnostic Investigation, Michigan State University, East Lansing, MI 48824, USA
| | - Charles D Mackenzie
- Department of Pathobiology and Diagnostic Investigation, Michigan State University, East Lansing, MI 48824, USA
| | - Timothy G Geary
- Institute of Parasitology and Centre for Host-Parasite Interactions, McGill University, Ste-Anne-de-Bellevue, QC H9X 3V9, Canada
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Bah GS, Tanya VN, Makepeace BL. Immunotherapy with mutated onchocystatin fails to enhance the efficacy of a sub-lethal oxytetracycline regimen against Onchocerca ochengi. Vet Parasitol 2015; 212:25-34. [PMID: 26100152 DOI: 10.1016/j.vetpar.2015.06.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Revised: 05/30/2015] [Accepted: 06/06/2015] [Indexed: 11/26/2022]
Abstract
Human onchocerciasis (river blindness), caused by the filarial nematode Onchocerca volvulus, has been successfully controlled by a single drug, ivermectin, for over 25 years. Ivermectin prevents the disease symptoms of severe itching and visual impairment by killing the microfilarial stage, but does not eliminate the adult parasites, necessitating repeated annual treatments. Mass drug administration with ivermectin does not always break transmission in forest zones and is contraindicated in individuals heavily co-infected with Loa loa, while reports of reduced drug efficacy in Ghana and Cameroon may signal the development of resistance. An alternative treatment for onchocerciasis involves targeting the essential Wolbachia symbiont with tetracycline or its derivatives, which are adulticidal. However, implementation of antibiotic therapy has not occurred on a wide scale due to the prolonged treatment regimen required (several weeks). In the bovine Onchocerca ochengi system, it has been shown previously that prolonged oxytetracycline therapy increases eosinophil counts in intradermal nodules, which kill the adult worms by degranulating on their surface. Here, in an "immunochemotherapeutic" approach, we sought to enhance the efficacy of a short, sub-lethal antibiotic regimen against O. ochengi by prior immunotherapy targeting onchocystatin, an immunomodulatory protein located in the adult female worm cuticle. A key asparagine residue in onchocystatin was mutated to ablate immunomodulatory activity, which has been demonstrated previously to markedly improve the protective efficacy of this vaccine candidate when used as an immunoprophylactic. The immunochemotherapeutic regimen was compared with sub-lethal oxytetracycline therapy alone; onchocystatin immunotherapy alone; a gold-standard prolonged, intermittent oxytetracycline regimen; and no treatment (negative control) in naturally infected Cameroonian cattle. Readouts were collected over one year and comprised adult worm viability, dermal microfilarial density, anti-onchocystatin IgG in sera, and eosinophil counts in nodules. Only the gold-standard antibiotic regimen achieved significant killing of adult worms, a profound reduction in microfilarial load, and a sustained increase in local tissue eosinophilia. A small but statistically significant elevation in anti-onchocystatin IgG was observed for several weeks after immunisation in the immunotherapy-only group, but the antibody response in the immunochemotherapy group was more variable. At 12 weeks post-treatment, only a transient and non-significant increase in eosinophil counts was apparent in the immunochemotherapy group. We conclude that the addition of onchocystatin immunotherapy to a sub-lethal antibiotic regimen is insufficient to induce adulticidal activity, although with booster immunisations or the targeting of additional filarial immunomodulatory proteins, the efficacy of this strategy could be strengthened.
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Affiliation(s)
- Germanus S Bah
- Institute of Infection & Global Health, University of Liverpool, 146 Brownlow Hill, Liverpool Science Park IC2, Liverpool L3 5RF, UK; Institut de Recherche Agricole pour le Développement, Regional Centre of Wakwa, BP 65 Ngaoundéré, Adamawa Region, Cameroon
| | - Vincent N Tanya
- Institut de Recherche Agricole pour le Développement, Regional Centre of Wakwa, BP 65 Ngaoundéré, Adamawa Region, Cameroon; Cameroon Academy of Sciences, BP 1457 Yaoundé, Centre Region, Cameroon
| | - Benjamin L Makepeace
- Institute of Infection & Global Health, University of Liverpool, 146 Brownlow Hill, Liverpool Science Park IC2, Liverpool L3 5RF, UK.
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