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Shrestha H, McCulloch K, Chisholm RH, Armoo SK, Veriegh F, Sirwani N, Crawford KE, Osei-Atweneboana MY, Grant WN, Hedtke SM. Synthesizing environmental, epidemiological and vector and parasite genetic data to assist decision making for disease elimination. Mol Ecol 2024; 33:e17357. [PMID: 38683054 DOI: 10.1111/mec.17357] [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: 11/27/2023] [Revised: 02/27/2024] [Accepted: 04/05/2024] [Indexed: 05/01/2024]
Abstract
We present a framework for identifying when conditions are favourable for transmission of vector-borne diseases between communities by incorporating predicted disease prevalence mapping with landscape analysis of sociological, environmental and host/parasite genetic data. We explored the relationship between environmental features and gene flow of a filarial parasite of humans, Onchocerca volvulus, and its vector, blackflies in the genus Simulium. We generated a baseline microfilarial prevalence map from point estimates from 47 locations in the ecological transition separating the savannah and forest in Ghana, where transmission of O. volvulus persists despite onchocerciasis control efforts. We generated movement suitability maps based on environmental correlates with mitochondrial population structure of 164 parasites from 15 communities and 93 vectors from only four sampling sites, and compared these to the baseline prevalence map. Parasite genetic distance between sampling locations was significantly associated with elevation (r = .793, p = .005) and soil moisture (r = .507, p = .002), while vector genetic distance was associated with soil moisture (r = .788, p = .0417) and precipitation (r = .835, p = .0417). The correlation between baseline prevalence and parasite resistance surface maps was stronger than that between prevalence and vector resistance surface maps. The centre of the study area had high prevalence and suitability for parasite and vector gene flow, potentially contributing to persistent transmission and suggesting the importance of re-evaluating transmission zone boundaries. With suitably dense sampling, this framework can help delineate transmission zones for onchocerciasis and would be translatable to other vector-borne diseases.
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Affiliation(s)
- Himal Shrestha
- Department of Environment and Genetics, School of Agriculture, Biomedicine and Environment, La Trobe University, Bundoora, Victoria, Australia
| | - Karen McCulloch
- Department of Environment and Genetics, School of Agriculture, Biomedicine and Environment, La Trobe University, Bundoora, Victoria, Australia
| | - Rebecca H Chisholm
- Department of Mathematical and Physical Sciences, La Trobe University, Bundoora, Victoria, Australia
- Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Victoria, Australia
| | - Samuel K Armoo
- Biomedical and Public Health Research Unit, CSIR-Water Research Institute, Accra, Ghana
| | - Francis Veriegh
- Biomedical and Public Health Research Unit, CSIR-Water Research Institute, Accra, Ghana
| | - Neha Sirwani
- Department of Environment and Genetics, School of Agriculture, Biomedicine and Environment, La Trobe University, Bundoora, Victoria, Australia
| | - Katie E Crawford
- Department of Environment and Genetics, School of Agriculture, Biomedicine and Environment, La Trobe University, Bundoora, Victoria, Australia
| | | | - Warwick N Grant
- Department of Environment and Genetics, School of Agriculture, Biomedicine and Environment, La Trobe University, Bundoora, Victoria, Australia
| | - Shannon M Hedtke
- Department of Environment and Genetics, School of Agriculture, Biomedicine and Environment, La Trobe University, Bundoora, Victoria, Australia
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2
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Furnival-Adams J, Kiuru C, Sagna AB, Mouline K, Maia M, Chaccour C. Ivermectin resistance mechanisms in ectoparasites: a scoping review. Parasitol Res 2024; 123:221. [PMID: 38787430 PMCID: PMC11126493 DOI: 10.1007/s00436-024-08223-z] [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: 03/05/2024] [Accepted: 04/24/2024] [Indexed: 05/25/2024]
Abstract
Ivermectin mass drug administration has been used for decades to target human and veterinary ectoparasites, and is currently being considered for use against malaria vectors. Although there have been few reports of resistance to date in human ectoparasites, we must anticipate the development of resistance in mosquitoes in the future. Hence, through this review, we mapped the existing evidence on ivermectin resistance mechanisms in human ectoparasites. A search was conducted on the 8th November 2023 through databases, PubMed, Web of Science, and Google Scholar, using terms related to ivermectin, human and veterinary ectoparasites, and resistance. Abstracts (5893) were screened by JFA and CK. Data on the study organism, the type of resistance, the analysis methods, and, where applicable, the gene loci of interest were extracted from the studies. Details of the methodology and results of each study were summarised narratively and in a table. Eighteen studies were identified describing ivermectin resistance in ectoparasites. Two studies described target site resistance; and 16 studies reported metabolic resistance and/or changes in efflux pump expression. The studies investigated genetic mutations in resistant organisms, detoxification, and efflux pump expression in resistant versus susceptible organisms, and the effect of synergists on mortality or detoxification enzyme/efflux pump transcription. To date, very few studies have been conducted examining the mechanisms of ivermectin resistance in ectoparasites, with only two on Anopheles spp. Of the existing studies, most examined detoxification and efflux pump gene expression, and only two studies in lice investigated target-site resistance. Further research in this field should be encouraged, to allow for close monitoring in ivermectin MDA programmes, and the development of resistance mitigation strategies.
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Affiliation(s)
- Joanna Furnival-Adams
- Barcelona Institute for Global Health (ISGlobal), Barcelona, Spain.
- Facultat de Medicina i Ciències de la Salut, Universitat de Barcelona (UB), Barcelona, Spain.
| | - Caroline Kiuru
- Barcelona Institute for Global Health (ISGlobal), Barcelona, Spain
- Centro de Investigação Em Saúde de Manhiça (CISM), Maputo, Mozambique
| | | | - Karine Mouline
- MIVEGEC, University of Montpellier, IRD, CNRS, Montpellier, France
| | - Marta Maia
- Kenya Medical Research Institute, Wellcome Trust Research Programme, Kilifi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Carlos Chaccour
- Barcelona Institute for Global Health (ISGlobal), Barcelona, Spain
- CIBER de Enfermedades Infecciosas, Madrid, Spain
- Universidad de Navarra, Pamplona, Spain
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3
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Shaver AO, Miller IR, Schaye ES, Moya ND, Collins JB, Wit J, Blanco AH, Shao FM, Andersen EJ, Khan SA, Paredes G, Andersen EC. Quantifying the fitness effects of resistance alleles with and without anthelmintic selection pressure using Caenorhabditis elegans. PLoS Pathog 2024; 20:e1012245. [PMID: 38768235 PMCID: PMC11142691 DOI: 10.1371/journal.ppat.1012245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Revised: 05/31/2024] [Accepted: 05/07/2024] [Indexed: 05/22/2024] Open
Abstract
Albendazole (a benzimidazole) and ivermectin (a macrocyclic lactone) are the two most commonly co-administered anthelmintic drugs in mass-drug administration programs worldwide. Despite emerging resistance, we do not fully understand the mechanisms of resistance to these drugs nor the consequences of delivering them in combination. Albendazole resistance has primarily been attributed to variation in the drug target, a beta-tubulin gene. Ivermectin targets glutamate-gated chloride channels (GluCls), but it is unknown whether GluCl genes are involved in ivermectin resistance in nature. Using Caenorhabditis elegans, we defined the fitness costs associated with loss of the drug target genes singly or in combinations of the genes that encode GluCl subunits. We quantified the loss-of-function effects on three traits: (i) multi-generational competitive fitness, (ii) fecundity, and (iii) development. In competitive fitness and development assays, we found that a deletion of the beta-tubulin gene ben-1 conferred albendazole resistance, but ivermectin resistance required the loss of two GluCl genes (avr-14 and avr-15). The fecundity assays revealed that loss of ben-1 did not provide any fitness benefit in albendazole conditions and that no GluCl deletion mutants were resistant to ivermectin. Next, we searched for evidence of multi-drug resistance across the three traits. Loss of ben-1 did not confer resistance to ivermectin, nor did loss of any single GluCl subunit or combination confer resistance to albendazole. Finally, we assessed the development of 124 C. elegans wild strains across six benzimidazoles and seven macrocyclic lactones to identify evidence of multi-drug resistance between the two drug classes and found a strong phenotypic correlation within a drug class but not across drug classes. Because each gene affects various aspects of nematode physiology, these results suggest that it is necessary to assess multiple fitness traits to evaluate how each gene contributes to anthelmintic resistance.
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Affiliation(s)
- Amanda O. Shaver
- Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
- Dept. of Biology, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Isabella R. Miller
- Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Etta S. Schaye
- Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Nicolas D. Moya
- Dept. of Biology, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - J. B. Collins
- Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
- Dept. of Biology, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Janneke Wit
- Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Alyssa H. Blanco
- Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Fiona M. Shao
- Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Elliot J. Andersen
- Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Sharik A. Khan
- Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Gracie Paredes
- Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Erik C. Andersen
- Dept. of Biology, Johns Hopkins University, Baltimore, Maryland, United States of America
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Hellman S, Martin F, Tydén E, Sellin ME, Norman A, Hjertner B, Svedberg P, Fossum C. Equine enteroid-derived monolayers recapitulate key features of parasitic intestinal nematode infection. Vet Res 2024; 55:25. [PMID: 38414039 PMCID: PMC10900620 DOI: 10.1186/s13567-024-01266-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2023] [Accepted: 01/03/2024] [Indexed: 02/29/2024] Open
Abstract
Stem cell-derived organoid cultures have emerged as attractive experimental models for infection biology research regarding various types of gastro-intestinal pathogens and host species. However, the large size of infectious nematode larvae and the closed structure of 3-dimensional organoids often hinder studies of the natural route of infection. To enable easy administration to the apical surface of the epithelium, organoids from the equine small intestine, i.e. enteroids, were used in the present study to establish epithelial monolayer cultures. These monolayers were functionally tested by stimulation with IL-4 and IL-13, and/or exposure to infectious stage larvae of the equine nematodes Parascaris univalens, cyathostominae and/or Strongylus vulgaris. Effects were recorded using transcriptional analysis combined with histochemistry, immunofluorescence-, live-cell- and scanning electron microscopy. These analyses revealed heterogeneous monolayers containing both immature and differentiated cells including tuft cells and mucus-producing goblet cells. Stimulation with IL-4/IL-13 increased tuft- and goblet cell differentiation as demonstrated by the expression of DCLK1 and MUC2. In these cytokine-primed monolayers, the expression of MUC2 was further promoted by co-culture with P. univalens. Moreover, live-cell imaging revealed morphological alterations of the epithelial cells following exposure to larvae even in the absence of cytokine stimulation. Thus, the present work describes the design, characterization and usability of an experimental model representing the equine nematode-infected small intestinal epithelium. The presence of tuft cells and goblet cells whose mucus production is affected by Th2 cytokines and/or the presence of larvae opens up for mechanistic studies of the physical interactions between nematodes and the equine intestinal mucosa.
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Affiliation(s)
- Stina Hellman
- Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, SLU, P.O. Box 7028, 750 07, Uppsala, Sweden.
| | - Frida Martin
- Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, SLU, P.O. Box 7028, 750 07, Uppsala, Sweden
| | - Eva Tydén
- Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, SLU, P.O. Box 7028, 750 07, Uppsala, Sweden
| | - Mikael E Sellin
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Albin Norman
- Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, SLU, P.O. Box 7028, 750 07, Uppsala, Sweden
| | - Bernt Hjertner
- Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, SLU, P.O. Box 7028, 750 07, Uppsala, Sweden
| | - Pia Svedberg
- Vidilab AB, P.O. Box 33, 745 21, Enköping, Sweden
| | - Caroline Fossum
- Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, SLU, P.O. Box 7028, 750 07, Uppsala, Sweden
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5
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Shaver AO, Miller IR, Schaye ES, Moya ND, Collins J, Wit J, Blanco AH, Shao FM, Andersen EJ, Khan SA, Paredes G, Andersen EC. Quantifying the fitness effects of resistance alleles with and without anthelmintic selection pressure using Caenorhabditis elegans. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.01.578300. [PMID: 38370666 PMCID: PMC10871296 DOI: 10.1101/2024.02.01.578300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2024]
Abstract
Albendazole and ivermectin are the two most commonly co-administered anthelmintic drugs in mass-drug administration programs worldwide. Despite emerging resistance, we do not fully understand the mechanisms of resistance to these drugs nor the consequences of delivering them in combination. Albendazole resistance has primarily been attributed to variation in the drug target, a beta-tubulin gene. Ivermectin targets glutamate-gated chloride channel (GluCl) genes, but it is unknown whether these genes are involved in ivermectin resistance in nature. Using Caenorhabditis elegans, we defined the fitness costs associated with loss of the drug target genes singly or in combinations of the genes that encode GluCl subunits. We quantified the loss-of function effects on three traits: (i) multi-generational competitive fitness, (ii) fecundity, and (iii) development. In competitive fitness and development assays, we found that a deletion of the beta-tubulin gene ben-1 conferred albendazole resistance, but ivermectin resistance required loss of two GluCl genes (avr-14 and avr-15) or loss of three GluCl genes (avr-14, avr-15, and glc-1). The fecundity assays revealed that loss of ben-1 did not provide any fitness benefit in albendazole and that no GluCl deletion mutants were resistant to ivermectin. Next, we searched for evidence of multi-drug resistance across the three traits. Loss of ben-1 did not confer resistance to ivermectin, nor did loss of any single GluCl subunit or combination confer resistance to albendazole. Finally, we assessed the development of 124 C. elegans wild strains across six benzimidazoles and seven macrocyclic lactones to identify evidence of multi-drug resistance between the two drug classes and found a strong phenotypic correlation within a drug class but not across drug classes. Because each gene affects various aspects of nematode physiology, these results suggest that it is necessary to assess multiple fitness traits to evaluate how each gene contributes to anthelmintic resistance.
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Affiliation(s)
- Amanda O. Shaver
- Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Isabella R. Miller
- Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Etta S. Schaye
- Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Nicolas D. Moya
- Dept. of Biology, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - J.B. Collins
- Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Janneke Wit
- Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Alyssa H. Blanco
- Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Fiona M. Shao
- Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Elliot J. Andersen
- Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Sharik A. Khan
- Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Gracie Paredes
- Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Erik C. Andersen
- Dept. of Biology, Johns Hopkins University, Baltimore, Maryland, United States of America
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Otabil KB, Basáñez MG, Ankrah B, Opoku SA, Kyei DO, Hagan R, Ababio R, Bart-Plange EJ, Babae TN, Kudzordzi PC, Darko VA, Bamfo JG, Ameyaw J, Raji AS, Hadermann A, Schallig HDFH, Colebunders R. Persistence of onchocerciasis and associated dermatologic and ophthalmic pathologies after 27 years of ivermectin mass drug administration in the middle belt of Ghana. Trop Med Int Health 2023; 28:844-854. [PMID: 37846505 DOI: 10.1111/tmi.13937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2023]
Abstract
OBJECTIVES There is a pressing need to regularly evaluate the progress of onchocerciasis elimination programmes to timely identify and mitigate potential risks hindering the reaching of the 2030 targets proposed by the World Health Organization (WHO) in its roadmap on neglected tropical diseases (NTDs). We determined the prevalence of onchocerciasis and associated dermatological and ophthalmological manifestations in six endemic communities in the Bono Region of Ghana after 27 years of ivermectin mass treatment. METHODS In a cross-sectional study, 564 participants aged ≥5 years were enrolled (49.1% females), with a median age of 26 (range: 5-89) years. In 54% and 47%, skin-snip microscopy and Ov16 rapid diagnostic tests were performed, respectively. Skin disease was determined using the WHO Skin NTD App. Visual function assessments included tests of visual acuity. RESULTS The overall microfilarial prevalence was 12.5% (38/305) and Ov16 seroprevalence was 24.2% (64/265). Severe itching was recorded in 24.3%, acute papular onchodermatitis in 52.8%, chronic papular onchodermatitis in 12.5%, lichenified onchodermatitis in 0.7%, skin atrophy in 11.3%, depigmentation in 1.7% and palpable nodules in 5.3%. Of the 301 persons in which visual acuity was examined, 17% were visually impaired and 5.3% were blind and 47.3% presented with cataract. Chronic papular onchodermatitis, lichenified onchodermatitis, depigmentation and visual impairment were significantly associated with the presence of skin microfilariae and Ov16 seropositivity. CONCLUSIONS The persistence of Onchocerca volvulus infection and onchocerciasis-associated dermatological and ophthalmological pathologies after prolonged treatment is of concern. There is a need to include morbidity management in onchocerciasis elimination programmes and understand better patterns of treatment coverage, adherence and actual intake of ivermectin.
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Affiliation(s)
- Kenneth Bentum Otabil
- Consortium for Neglected Tropical Diseases and One Health, Department of Biological Science, School of Sciences, University of Energy and Natural Resources, Sunyani, Bono Region, Ghana
- Department of Biological Science, School of Sciences, University of Energy and Natural Resources, Sunyani, Bono Region, Ghana
- Global Health Institute, Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium
| | - María-Gloria Basáñez
- Department of Infectious Disease Epidemiology, MRC Centre for Global Infectious Disease Analysis (MRC GIDA), and London Centre for Neglected Tropical Disease Research, School of Public Health, Imperial College London, London, UK
| | - Blessing Ankrah
- Consortium for Neglected Tropical Diseases and One Health, Department of Biological Science, School of Sciences, University of Energy and Natural Resources, Sunyani, Bono Region, Ghana
| | - Stephen Agyemang Opoku
- Department of Medical Laboratory Science, School of Sciences, University of Energy and Natural Resources, Sunyani, Bono Region, Ghana
| | - Dennis Ofori Kyei
- Department of Medical Laboratory Science, School of Sciences, University of Energy and Natural Resources, Sunyani, Bono Region, Ghana
| | - Rhoda Hagan
- Department of Medical Laboratory Science, School of Sciences, University of Energy and Natural Resources, Sunyani, Bono Region, Ghana
| | - Richmond Ababio
- Department of Medical Laboratory Science, School of Sciences, University of Energy and Natural Resources, Sunyani, Bono Region, Ghana
| | - Emmanuel John Bart-Plange
- Consortium for Neglected Tropical Diseases and One Health, Department of Biological Science, School of Sciences, University of Energy and Natural Resources, Sunyani, Bono Region, Ghana
| | - Theophilus Nti Babae
- Consortium for Neglected Tropical Diseases and One Health, Department of Biological Science, School of Sciences, University of Energy and Natural Resources, Sunyani, Bono Region, Ghana
| | - Prince-Charles Kudzordzi
- Consortium for Neglected Tropical Diseases and One Health, Department of Biological Science, School of Sciences, University of Energy and Natural Resources, Sunyani, Bono Region, Ghana
| | - Vera Achiaa Darko
- Consortium for Neglected Tropical Diseases and One Health, Department of Biological Science, School of Sciences, University of Energy and Natural Resources, Sunyani, Bono Region, Ghana
- STU Clinic, Sunyani Technical University, Sunyani, Bono Region, Ghana
| | | | | | - Abdul Sakibu Raji
- Department of Biological Science, School of Sciences, University of Energy and Natural Resources, Sunyani, Bono Region, Ghana
| | - Amber Hadermann
- Global Health Institute, Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium
| | - Henk D F H Schallig
- Department of Medical Microbiology, Experimental Parasitology Unit, Amsterdam University Medical Centres, Academic Medical Centre at the University of Amsterdam, Amsterdam, The Netherlands
| | - Robert Colebunders
- Global Health Institute, Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium
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7
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Hedtke SM, Choi YJ, Kode A, Chalasani GC, Sirwani N, Jada SR, Hotterbeekx A, Mandro M, Siewe Fodjo JN, Amambo GN, Abong RA, Wanji S, Kuesel AC, Colebunders R, Mitreva M, Grant WN. Assessing Onchocerca volvulus Intensity of Infection and Genetic Diversity Using Mitochondrial Genome Sequencing of Single Microfilariae Obtained before and after Ivermectin Treatment. Pathogens 2023; 12:971. [PMID: 37513818 PMCID: PMC10385737 DOI: 10.3390/pathogens12070971] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Revised: 07/16/2023] [Accepted: 07/17/2023] [Indexed: 07/30/2023] Open
Abstract
Onchocerciasis is a neglected tropical disease targeted for elimination using ivermectin mass administration. Ivermectin kills the microfilariae and temporarily arrests microfilariae production by the macrofilariae. We genotyped 436 microfilariae from 10 people each in Ituri, Democratic Republic of the Congo (DRC), and Maridi County, South Sudan, collected before and 4-5 months after ivermectin treatment. Population genetic analyses identified 52 and 103 mitochondrial DNA haplotypes among the microfilariae from DRC and South Sudan, respectively, with few haplotypes shared between people. The percentage of genotype-based correct assignment to person within DRC was ~88% and within South Sudan ~64%. Rarefaction and extrapolation analysis showed that the genetic diversity in DRC, and even more so in South Sudan, was captured incompletely. The results indicate that the per-person adult worm burden is likely higher in South Sudan than DRC. Analyses of haplotype data from a subsample (n = 4) did not discriminate genetically between pre- and post-treatment microfilariae, confirming that post-treatment microfilariae are not the result of new infections. With appropriate sampling, mitochondrial haplotype analysis could help monitor changes in the number of macrofilariae in a population as a result of treatment, identify cases of potential treatment failure, and detect new infections as an indicator of continuing transmission.
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Affiliation(s)
- Shannon M. Hedtke
- Department of Environment and Genetics, School of Agriculture, Biomedicine and Environment, La Trobe University, Bundoora, VIC 3086, Australia; (A.K.); (G.C.C.); (N.S.); (W.N.G.)
| | - Young-Jun Choi
- Department of Medicine, Washington University in St. Louis and McDonnell Genome Institute, St. Louis, MO 63108, USA; (Y.-J.C.); (M.M.)
| | - Anusha Kode
- Department of Environment and Genetics, School of Agriculture, Biomedicine and Environment, La Trobe University, Bundoora, VIC 3086, Australia; (A.K.); (G.C.C.); (N.S.); (W.N.G.)
| | - Gowtam C. Chalasani
- Department of Environment and Genetics, School of Agriculture, Biomedicine and Environment, La Trobe University, Bundoora, VIC 3086, Australia; (A.K.); (G.C.C.); (N.S.); (W.N.G.)
| | - Neha Sirwani
- Department of Environment and Genetics, School of Agriculture, Biomedicine and Environment, La Trobe University, Bundoora, VIC 3086, Australia; (A.K.); (G.C.C.); (N.S.); (W.N.G.)
| | | | - An Hotterbeekx
- Global Health Institute, University of Antwerp, Doornstraat 331, 2610 Antwerp, Belgium; (A.H.); (J.N.S.F.); (R.C.)
| | - Michel Mandro
- Provincial Health Division Ituri, Ministry of Health, Bunia P.O. Box 57, Democratic Republic of the Congo;
| | - Joseph N. Siewe Fodjo
- Global Health Institute, University of Antwerp, Doornstraat 331, 2610 Antwerp, Belgium; (A.H.); (J.N.S.F.); (R.C.)
| | - Glory Ngongeh Amambo
- Parasites and Vectors Research Unit, Department of Microbiology and Parasitology, Faculty of Science, University of Buea, Buea P.O. Box 63, Cameroon; (G.N.A.); (R.A.A.); (S.W.)
| | - Raphael A. Abong
- Parasites and Vectors Research Unit, Department of Microbiology and Parasitology, Faculty of Science, University of Buea, Buea P.O. Box 63, Cameroon; (G.N.A.); (R.A.A.); (S.W.)
- Research Foundation for Tropical Diseases and Environment (REFOTDE), Buea P.O. Box 474, Cameroon
| | - Samuel Wanji
- Parasites and Vectors Research Unit, Department of Microbiology and Parasitology, Faculty of Science, University of Buea, Buea P.O. Box 63, Cameroon; (G.N.A.); (R.A.A.); (S.W.)
- Research Foundation for Tropical Diseases and Environment (REFOTDE), Buea P.O. Box 474, Cameroon
| | - Annette C. Kuesel
- UNICEF/UNDP/World Bank/World Health Organization Special Programme for Research and Training in Tropical Diseases (TDR), World Health Organization, 1202 Geneva, Switzerland;
| | - Robert Colebunders
- Global Health Institute, University of Antwerp, Doornstraat 331, 2610 Antwerp, Belgium; (A.H.); (J.N.S.F.); (R.C.)
| | - Makedonka Mitreva
- Department of Medicine, Washington University in St. Louis and McDonnell Genome Institute, St. Louis, MO 63108, USA; (Y.-J.C.); (M.M.)
| | - Warwick N. Grant
- Department of Environment and Genetics, School of Agriculture, Biomedicine and Environment, La Trobe University, Bundoora, VIC 3086, Australia; (A.K.); (G.C.C.); (N.S.); (W.N.G.)
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8
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Ryan NM, Hess JA, Robertson EJ, Tricoche N, Turner C, Davis J, Petrovsky N, Ferguson M, Rinaldi WJ, Wong VM, Shimada A, Zhan B, Bottazzi ME, Makepeace BL, Gray SA, Carter D, Lustigman S, Abraham D. Adjuvanted Fusion Protein Vaccine Induces Durable Immunity to Onchocerca volvulus in Mice and Non-Human Primates. Vaccines (Basel) 2023; 11:1212. [PMID: 37515028 PMCID: PMC10385774 DOI: 10.3390/vaccines11071212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Revised: 06/23/2023] [Accepted: 06/27/2023] [Indexed: 07/30/2023] Open
Abstract
Onchocerciasis remains a debilitating neglected tropical disease. Due to the many challenges of current control methods, an effective vaccine against the causative agent Onchocerca volvulus is urgently needed. Mice and cynomolgus macaque non-human primates (NHPs) were immunized with a vaccine consisting of a fusion of two O. volvulus protein antigens, Ov-103 and Ov-RAL-2 (Ov-FUS-1), and three different adjuvants: Advax-CpG, alum, and AlT4. All vaccine formulations induced high antigen-specific IgG titers in both mice and NHPs. Challenging mice with O. volvulus L3 contained within subcutaneous diffusion chambers demonstrated that Ov-FUS-1/Advax-CpG-immunized animals developed protective immunity, durable for at least 11 weeks. Passive transfer of sera, collected at several time points, from both mice and NHPs immunized with Ov-FUS-1/Advax-CpG transferred protection to naïve mice. These results demonstrate that Ov-FUS-1 with the adjuvant Advax-CpG induces durable protective immunity against O. volvulus in mice and NHPs that is mediated by vaccine-induced humoral factors.
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Affiliation(s)
- Nathan M Ryan
- Department of Microbiology and Immunology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Jessica A Hess
- Department of Microbiology and Immunology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Erica J Robertson
- Department of Microbiology and Immunology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Nancy Tricoche
- Laboratory of Molecular Parasitology, Lindsey F. Kimball Research Institute, New York Blood Center, New York, NY 10065, USA
| | | | - Jenn Davis
- PAI Life Sciences Inc., Seattle, WA 98102, USA
| | | | | | | | | | - Ayako Shimada
- Division of Biostatistics, Department of Pharmacology and Experimental Therapeutics, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Bin Zhan
- Texas Children's Hospital Center for Vaccine Development, Department of Pediatrics, National School of Tropical Medicine, Baylor College of Medicine, Houston, TX 77030, USA
| | - Maria Elena Bottazzi
- Texas Children's Hospital Center for Vaccine Development, Department of Pediatrics, National School of Tropical Medicine, Baylor College of Medicine, Houston, TX 77030, USA
| | - Benjamin L Makepeace
- Institute of Infection, Veterinary & Ecological Sciences, University of Liverpool, Liverpool L3 5RF, UK
| | - Sean A Gray
- PAI Life Sciences Inc., Seattle, WA 98102, USA
| | | | - Sara Lustigman
- Laboratory of Molecular Parasitology, Lindsey F. Kimball Research Institute, New York Blood Center, New York, NY 10065, USA
| | - David Abraham
- Department of Microbiology and Immunology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA
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9
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Bakajika D, Kanza EM, Opoku NO, Howard HM, Mambandu GL, Nyathirombo A, Nigo MM, Kennedy KK, Masembe SL, Mumbere M, Kataliko K, Bolay KM, Attah SK, Olipoh G, Asare S, Vaillant M, Halleux CM, Kuesel AC. Effect of a single dose of 8 mg moxidectin or 150 μg/kg ivermectin on O. volvulus skin microfilariae in a randomized trial: Differences between areas in the Democratic Republic of the Congo, Liberia and Ghana and impact of intensity of infection. PLoS Negl Trop Dis 2022; 16:e0010079. [PMID: 35476631 PMCID: PMC9084535 DOI: 10.1371/journal.pntd.0010079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2021] [Revised: 05/09/2022] [Accepted: 03/13/2022] [Indexed: 11/21/2022] Open
Abstract
Background Our study in CDTI-naïve areas in Nord Kivu and Ituri (Democratic Republic of the Congo, DRC), Lofa County (Liberia) and Nkwanta district (Ghana) showed that a single 8 mg moxidectin dose reduced skin microfilariae density (microfilariae/mg skin, SmfD) better and for longer than a single 150μg/kg ivermectin dose. We now analysed efficacy by study area and pre-treatment SmfD (intensity of infection, IoI). Methodology/Principal findings Four and three IoI categories were defined for across-study and by-study area analyses, respectively. We used a general linear model to analyse SmfD 1, 6, 12 and 18 months post-treatment, a logistic model to determine the odds of undetectable SmfD from month 1 to month 6 (UD1-6), month 12 (UD1-12) and month 18 (UD1-18), and descriptive statistics to quantitate inter-interindividual response differences. Twelve months post-treatment, treatment differences (difference in adjusted geometric mean SmfD after moxidectin and ivermectin in percentage of the adjusted geometric mean SmfD after ivermectin treatment) were 92.9%, 90.1%, 86.8% and 84.5% in Nord Kivu, Ituri, Lofa and Nkwanta, and 74.1%, 84.2%, 90.0% and 95.4% for participants with SmfD 10–20, ≥20-<50, ≥50-<80, ≥80, respectively. Ivermectin’s efficacy was lower in Ituri and Nkwanta than Nord Kivu and Lofa (p≤0.002) and moxidectin’s efficacy lower in Nkwanta than Nord Kivu, Ituri and Lofa (p<0.006). Odds ratios for UD1-6, UD1-12 or UD1-18 after moxidectin versus ivermectin treatment exceeded 7.0. Suboptimal response (SmfD 12 months post-treatment >40% of pre-treatment SmfD) occurred in 0%, 0.3%, 1.6% and 3.9% of moxidectin and 12.1%, 23.7%, 10.8% and 28.0% of ivermectin treated participants in Nord Kivu, Ituri, Lofa and Nkwanta, respectively. Conclusions/Significance The benefit of moxidectin vs ivermectin treatment increased with pre-treatment IoI. The possibility that parasite populations in different areas have different drug susceptibility without prior ivermectin selection pressure needs to be considered and further investigated. Clinical Trial Registration Registered on 14 November 2008 in Clinicaltrials.gov (ID: NCT00790998). Onchocerciasis or river blindness is a parasitic disease primarily in sub-Saharan Africa and Yemen. It can cause debilitating morbidity including severe itching, skin changes, visual impairment and even blindness. Many years of control efforts, today primarily based on mass administration of ivermectin (MDA) in endemic communities, have reduced morbidity and the percentage of infected individuals so that elimination of parasite transmission is now planned. WHO estimated that in 2020 more than 239 million people required MDA. Ivermectin may not be sufficiently efficacious to achieve elimination everywhere. Our study in areas in Liberia, Ghana and the Democratic Republic of the Congo where MDA had not been implemented yet showed that one treatment with 8 mg moxidectin reduced parasite levels in the skin better and for longer than one treatment with 150 μg/kg ivermectin, the dose used during MDA. Here we show that people with higher numbers of parasites in the skin benefited more from moxidectin treatment than those with lower numbers and that the efficacy of ivermectin and moxidectin differed between study areas. Provided WHO and countries include moxidectin in guidelines and policies, this information could help decisions on when and where to use moxidectin.
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Affiliation(s)
- Didier Bakajika
- Centre de Recherche en Maladies Tropicale de l’Ituri, Hôpital Générale de Référence de Rethy, Ituri, Democratic Republic of the Congo Democratic Republic of the Congo (DRC)
| | - Eric M. Kanza
- Centre de Recherche Clinique de Butembo, Université Catholique du Graben, Site Horizon, Butembo, Nord Kivu, Democratic Republic of the Congo (DRC)
| | | | - Hayford M. Howard
- Clinical Research Center, Liberia Institute for Biomedical Research, Bolahun, Liberia
| | - Germain L. Mambandu
- Centre de Recherche en Maladies Tropicale de l’Ituri, Hôpital Générale de Référence de Rethy, Ituri, Democratic Republic of the Congo Democratic Republic of the Congo (DRC)
| | - Amos Nyathirombo
- Centre de Recherche en Maladies Tropicale de l’Ituri, Hôpital Générale de Référence de Rethy, Ituri, Democratic Republic of the Congo Democratic Republic of the Congo (DRC)
| | - Maurice M. Nigo
- Centre de Recherche en Maladies Tropicale de l’Ituri, Hôpital Générale de Référence de Rethy, Ituri, Democratic Republic of the Congo Democratic Republic of the Congo (DRC)
| | - Kambale Kasonia Kennedy
- Centre de Recherche Clinique de Butembo, Université Catholique du Graben, Site Horizon, Butembo, Nord Kivu, Democratic Republic of the Congo (DRC)
| | - Safari L. Masembe
- Centre de Recherche Clinique de Butembo, Université Catholique du Graben, Site Horizon, Butembo, Nord Kivu, Democratic Republic of the Congo (DRC)
| | - Mupenzi Mumbere
- Centre de Recherche Clinique de Butembo, Université Catholique du Graben, Site Horizon, Butembo, Nord Kivu, Democratic Republic of the Congo (DRC)
| | - Kambale Kataliko
- Centre de Recherche Clinique de Butembo, Université Catholique du Graben, Site Horizon, Butembo, Nord Kivu, Democratic Republic of the Congo (DRC)
| | - Kpehe M. Bolay
- Clinical Research Center, Liberia Institute for Biomedical Research, Bolahun, Liberia
| | - Simon K. Attah
- Onchocerciasis Chemotherapy Research Center, Hohoe, Ghana
| | - George Olipoh
- Onchocerciasis Chemotherapy Research Center, Hohoe, Ghana
| | - Sampson Asare
- Onchocerciasis Chemotherapy Research Center, Hohoe, Ghana
| | - Michel Vaillant
- Competence Center for Methodology and Statistics, Luxembourg Institute of Health, Strassen, Grand Duchy of Luxembourg
| | - Christine M. Halleux
- UNICEF/UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases (WHO/TDR), World Health Organization, Geneva, Switzerland
| | - Annette C. Kuesel
- UNICEF/UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases (WHO/TDR), World Health Organization, Geneva, Switzerland
- * E-mail:
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10
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Anti-Th17 and anti-Th2 responses effects of hydro-ethanolic extracts of Aframomum melegueta, Khaya senegalensis and Xylopia aethiopica in hyperreactive onchocerciasis individuals’ peripheral blood mononuclear cells. PLoS Negl Trop Dis 2022; 16:e0010341. [PMID: 35468134 PMCID: PMC9071127 DOI: 10.1371/journal.pntd.0010341] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 05/05/2022] [Accepted: 03/18/2022] [Indexed: 12/04/2022] Open
Abstract
Hyperreactive onchocerciasis (HO) is characterized by a severe skin inflammation with elevated Th17-Th2 combined responses. We previously demonstrated the anthelminthic activity of Aframomum melegueta (AM), Xylopia aethiopica (XA) and Khaya senegalensis (KS) used by traditional healers to treat helminthiasis in the endemic area of Togo. However, their effect on severe onchocerciasis is poorly investigated. The present study aimed to investigate the anti-Th17 and anti-Th2 effects of hydro-ethanolic extracts of AM, XA and KS during HO. Onchocerca volvulus-infected individuals were recruited in the Central region of Togo in 2018. Isolated peripheral blood mononuclear cells (PBMCs) from both generalized onchocerciasis (GEO) and HO forms were activated with anti-CD3 and anti-CD28 monoclonal antibodies in the presence or absence of the hydro-ethanolic extracts of AM, XA and KS as well as their delipidated, deproteinized and deglycosylated fractions. After 72 hours, cytokines were assayed from cell culture supernatants. Then, flow cytometry was used to investigate the effects of the extracts on cell activation, proliferation, intracellular cytokines and T cells transcription factors. The production of both Th17 and Th2 cytokines IL-17A and IL-5 were significantly inhibited upon T-cell receptor (TCR) activation in the presence of the hydro-ethanolic extracts of AM, XA and KS in HO individuals’ PBMCs in vitro. AM and XA inhibited CD4+RORC2+IL-17A+ and CD4+GATA3+IL-4+ cell populations induction. This inhibition was not Th1 nor Treg-dependent since both IFN-γ and IL-10 were also inhibited by the extracts. AM and XA did not interfere with T cell activation and proliferation for their inhibitory pathways. Lipid and protein compounds from AM and XA were associated with the inhibition of IL-17A. This study showed that in addition to their anthelminthic effects, hydro-ethanolic extracts of Aframomum melegueta, Xylopia aethiopica and Khaya senegalensis could downregulate both Th17 and Th2 responses and prevent the severe skin disorder observed. Severe form of human onchocerciasis also called hyperreactive onchocerciasis (HO) is characterized by skin disorders such as dermatitis. Our previous study showed that concomitant Th2 and Th17 responses play a role in the pathophysiology of the disease. In Onchocerca volvulus endemic areas such as Togo, traditional healers (TH) used to treat this disease with medicinal plants such as Aframomum melegueta (AM), Xylopia aethiopica (XA) and Khaya senegalensis (KS). Mass drug administration including ivermectin and albendazole has been used over the past decade to control and eradicate helminths infections. Despite its successes, resistance to ivermectin has been reported and therefore, alternative drugs are urgently needed. We previously confirmed in vitro the anthelminthic effects of Aframomum melegueta (AM), Xylopia aethiopica (XA) and Khaya senegalensis (KS). However, their effect on severe onchocerciasis has not been demonstrated. Here, the anti-Th17 and anti-Th2 effects of hydro-ethanolic extracts of AM, XA and KS during HO were investigated. The data showed that in addition to their helminth-killing effects, plant-derived molecules AM, XA and KS downregulated Th2 and Th17 profiles and therefore, could be candidates for the development of new drugs not only for the treatment of helminth-induced inflammatory pathologies but also auto-immune Th2/Th17-dependent inflammatory diseases in general.
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11
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Single-Nucleotide Polymorphism Associates' β-Tubulin Isotype-1 Gene in Onchocerca volvulus Populations in Ivermectin-Treated Communities in Taraba State, Nigeria. Acta Parasitol 2022; 67:267-274. [PMID: 34279775 DOI: 10.1007/s11686-021-00427-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 05/24/2021] [Indexed: 10/20/2022]
Abstract
PURPOSE The occurrence of Single-Nucleotide Polymorphisms (SNPs) associated with repeated ivermectin treatment and sub-optimal responses reported by previous findings is of great concern in Onchocerciasis endemic areas. This study investigated SNPs' occurrence after 15 years of ivermectin intervention in Onchocerciasis endemic communities in two Local Government Areas of Taraba State, Nigeria. METHODS Microfilariae samples were collected by skin snip from individuals treated with ivermectin for 10-15 years of annual distribution and preserved in RNAlater® in a 1.5 ml micro-centrifuge tube. Genomic DNA was extracted from microfilariae and residual skin, amplification in two regions within the β-tubulin gene, sequenced and analyzed for SNPs using Bioinformatics tools. RESULTS Three distinct SNP positions: 1183 (T/G), 1188 (T/C) and 1308 (C/T) on the β-tubulin gene on the targeted 1083-1568 bp fragment, associate's with the ivermectin-treated population. Furthermore, SNPs positions detected in this study are 1730 (A/G) and 1794 (T/G) in the β-tub gene in the 1557-1857 (bp) region. The 1794 (T/G) SNP position (Phe243Val) in the exon within the β-tubulin gene region were observed in this study. CONCLUSION The present study indicates that SNPs are observed in Onchocerca volvulus, thus strengthening the warning that genetic changes could occur in some parasite populations in some ivermectin-treated areas.
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12
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Abraham D, Graham-Brown J, Carter D, Gray SA, Hess JA, Makepeace BL, Lustigman S. Development of a recombinant vaccine against human onchocerciasis. Expert Rev Vaccines 2021; 20:1459-1470. [PMID: 34488533 DOI: 10.1080/14760584.2021.1977125] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 09/02/2021] [Indexed: 01/02/2023]
Abstract
INTRODUCTION Human onchocerciasis caused by the filarial nematode parasite Onchocerca volvulus remains a major cause of debilitating disease infecting millions primarily in Sub-Saharan Africa. The development of a prophylactic vaccine, along with mass drug administration, would facilitate meeting the goal of onchocerciasis elimination by 2030. AREAS COVERED Models used to study immunity to Onchocerca include natural infection of cattle with Onchocerca ochengi and O. volvulus infective third-stage larvae implanted within diffusion chambers in mice. A vaccine, comprised of two adjuvanted recombinant antigens, induced protective immunity in genetically diverse mice suggesting that it will function similarly in diverse human populations. These antigens were recognized by immune humans and also induced protective immunity against Brugia malayi. We describe the development of a fusion protein composed of the two vaccine antigens with the plan to test the vaccine in cows and non-human primates as a prelude to the initiation of phase 1 clinical trials. EXPERT OPINION The adjuvanted O. volvulus vaccine composed of two antigens Ov-103 and Ov-RAL-2 was shown to be consistently effective at inducing protective immunity using multiple immune mechanisms. The vaccine is ready for further evaluation in other animal models before moving to clinical trials in humans.
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Affiliation(s)
- David Abraham
- Department of Microbiology and Immunology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA
| | - John Graham-Brown
- Institute of Infection, Veterinary & Ecological Sciences, University of Liverpool, Liverpool, UK
| | | | | | - Jessica A Hess
- Department of Microbiology and Immunology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA
| | - Benjamin L Makepeace
- Institute of Infection, Veterinary & Ecological Sciences, University of Liverpool, Liverpool, UK
| | - Sara Lustigman
- Laboratory of Molecular Parasitology, Lindsley F. Kimball Research Institute, New York Blood Center, New York, NY, USA
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13
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Ngwewondo A, Scandale I, Specht S. Onchocerciasis drug development: from preclinical models to humans. Parasitol Res 2021; 120:3939-3964. [PMID: 34642800 PMCID: PMC8599318 DOI: 10.1007/s00436-021-07307-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Accepted: 08/30/2021] [Indexed: 11/30/2022]
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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14
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Ryan NM, Hess JA, de Villena FPM, Leiby BE, Shimada A, Yu L, Yarmahmoodi A, Petrovsky N, Zhan B, Bottazzi ME, Makepeace BL, Lustigman S, Abraham D. Onchocerca volvulus bivalent subunit vaccine induces protective immunity in genetically diverse collaborative cross recombinant inbred intercross mice. NPJ Vaccines 2021; 6:17. [PMID: 33500417 PMCID: PMC7838260 DOI: 10.1038/s41541-020-00276-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 12/11/2020] [Indexed: 01/04/2023] Open
Abstract
This study tests the hypothesis that an Onchocerca volvulus vaccine, consisting of two recombinant antigens (Ov-103 and Ov-RAL-2) formulated with the combination-adjuvant Advax-2, can induce protective immunity in genetically diverse Collaborative Cross recombinant inbred intercross mice (CC-RIX). CC-RIX lines were immunized with the O. volvulus vaccine and challenged with third-stage larvae. Equal and significant reductions in parasite survival were observed in 7 of 8 CC-RIX lines. Innate protective immunity was seen in the single CC-RIX line that did not demonstrate protective adaptive immunity. Analysis of a wide array of immune factors showed that each line of mice have a unique set of immune responses to vaccination and challenge suggesting that the vaccine is polyfunctional, inducing different equally-protective sets of immune responses based on the genetic background of the immunized host. Vaccine efficacy in genetically diverse mice suggests that it will also be effective in genetically complex human populations.
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Affiliation(s)
- Nathan M Ryan
- Department of Microbiology and Immunology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA
| | - Jessica A Hess
- Department of Microbiology and Immunology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA
| | | | - Benjamin E Leiby
- Division of Biostatistics, Department of Pharmacology and Experimental Therapeutics, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA
| | - Ayako Shimada
- Division of Biostatistics, Department of Pharmacology and Experimental Therapeutics, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA
| | - Lei Yu
- Flow Cytometry Core Facility, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, USA
| | - Amir Yarmahmoodi
- Flow Cytometry Core Facility, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, USA
| | | | - Bin Zhan
- Department of Pediatrics, National School of Tropical Medicine, Baylor College of Medicine, Houston, TX, USA
- Texas Children's Hospital Center for Vaccine Development, 1102 Bates St, Ste. 550, Houston, TX, USA
| | - Maria Elena Bottazzi
- Department of Pediatrics, National School of Tropical Medicine, Baylor College of Medicine, Houston, TX, USA
- Texas Children's Hospital Center for Vaccine Development, 1102 Bates St, Ste. 550, Houston, TX, USA
| | - Benjamin L Makepeace
- Institute of Infection, Veterinary & Ecological Sciences, University of Liverpool, 146 Brownlow Hill, Liverpool, L3 5RF, UK
| | - Sara Lustigman
- Laboratory of Molecular Parasitology, Lindsey F. Kimball Research Institute, New York Blood Center, 310 E 67th St, New York, NY, USA
| | - David Abraham
- Department of Microbiology and Immunology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA.
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15
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Milton P, Hamley JID, Walker M, Basáñez MG. Moxidectin: an oral treatment for human onchocerciasis. Expert Rev Anti Infect Ther 2020; 18:1067-1081. [PMID: 32715787 DOI: 10.1080/14787210.2020.1792772] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
INTRODUCTION Moxidectin is a milbemycin endectocide recently approved for the treatment of human onchocerciasis. Onchocerciasis, earmarked for elimination of transmission, is a filarial infection endemic in Africa, Yemen, and the Amazonian focus straddling Venezuela and Brazil. Concerns over whether the predominant treatment strategy (yearly mass drug administration (MDA) of ivermectin) is sufficient to achieve elimination in all endemic foci have refocussed attention upon alternative treatments. Moxidectin's stronger and longer microfilarial suppression compared to ivermectin in both phase II and III clinical trials indicates its potential as a novel powerful drug for onchocerciasis elimination. AREAS COVERED This work summarizes the chemistry and pharmacology of moxidectin, reviews the phase II and III clinical trials evidence on tolerability, safety, and efficacy of moxidectin versus ivermectin, and discusses the implications of moxidectin's current regulatory status. EXPERT OPINION Moxidectin's superior clinical performance has the potential to substantially reduce times to elimination compared to ivermectin. If donated, moxidectin could mitigate the additional programmatic costs of biannual ivermectin distribution because, unlike other alternatives, it can use the existing community-directed treatment infrastructure. A pediatric indication (for children <12 years) and determination of its usefulness in onchocerciasis-loiasis co-endemic areas will greatly help fulfill the potential of moxidectin for the treatment and elimination of onchocerciasis.
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Affiliation(s)
- Philip Milton
- London Centre for Neglected Tropical Disease Research and MRC Centre for Global Infectious Disease Analysis (MRC GIDA), Department of Infectious Disease Epidemiology, Imperial College London , London, UK
| | - Jonathan I D Hamley
- London Centre for Neglected Tropical Disease Research and MRC Centre for Global Infectious Disease Analysis (MRC GIDA), Department of Infectious Disease Epidemiology, Imperial College London , London, UK
| | - Martin Walker
- London Centre for Neglected Tropical Disease Research and MRC Centre for Global Infectious Disease Analysis (MRC GIDA), Department of Infectious Disease Epidemiology, Imperial College London , London, UK.,London Centre for Neglected Tropical Disease Research, Department of Pathobiology and Population Sciences, Royal Veterinary College , Hatfield, UK
| | - María-Gloria Basáñez
- London Centre for Neglected Tropical Disease Research and MRC Centre for Global Infectious Disease Analysis (MRC GIDA), Department of Infectious Disease Epidemiology, Imperial College London , London, UK
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Kempf DJ, Marsh KC. Assembling Pharma Resources to Tackle Diseases of Underserved Populations. ACS Med Chem Lett 2020; 11:1094-1100. [PMID: 32550987 DOI: 10.1021/acsmedchemlett.0c00051] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 03/27/2020] [Indexed: 01/11/2023] Open
Abstract
Tropical diseases that disproportionally affect the world's poorest people have traditionally been neglected from research efforts toward the discovery and development of new and effective therapies. Over the past two decades, major global health funders have made efforts to bring together various research institutions to work together in these disease areas offering little or no commercial return. This work describes the genesis and growth of an informal program devoted to contributing to new therapies for neglected tropical diseases within the environment of a major biopharmaceutical company (AbbVie).
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Hedtke SM, Kuesel AC, Crawford KE, Graves PM, Boussinesq M, Lau CL, Boakye DA, Grant WN. Genomic Epidemiology in Filarial Nematodes: Transforming the Basis for Elimination Program Decisions. Front Genet 2020; 10:1282. [PMID: 31998356 PMCID: PMC6964045 DOI: 10.3389/fgene.2019.01282] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 11/21/2019] [Indexed: 11/25/2022] Open
Abstract
Onchocerciasis and lymphatic filariasis are targeted for elimination, primarily using mass drug administration at the country and community levels. Elimination of transmission is the onchocerciasis target and global elimination as a public health problem is the end point for lymphatic filariasis. Where program duration, treatment coverage, and compliance are sufficiently high, elimination is achievable for both parasites within defined geographic areas. However, transmission has re-emerged after apparent elimination in some areas, and in others has continued despite years of mass drug treatment. A critical question is whether this re-emergence and/or persistence of transmission is due to persistence of local parasites-i.e., the result of insufficient duration or drug coverage, poor parasite response to the drugs, or inadequate methods of assessment and/or criteria for determining when to stop treatment-or due to re-introduction of parasites via human or vector movement from another endemic area. We review recent genetics-based research exploring these questions in Onchocerca volvulus, the filarial nematode that causes onchocerciasis, and Wuchereria bancrofti, the major pathogen for lymphatic filariasis. We focus in particular on the combination of genomic epidemiology and genome-wide associations to delineate transmission zones and distinguish between local and introduced parasites as the source of resurgence or continuing transmission, and to identify genetic markers associated with parasite response to chemotherapy. Our ultimate goal is to assist elimination efforts by developing easy-to-use tools that incorporate genetic information about transmission and drug response for more effective mass drug distribution, surveillance strategies, and decisions on when to stop interventions to improve sustainability of elimination.
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Affiliation(s)
- Shannon M. Hedtke
- Department of Physiology, Anatomy and Microbiology, La Trobe University, Bundoora, VIC, Australia
| | - Annette C. Kuesel
- Unicef/UNDP/World Bank/World Health Organization Special Programme for Research and Training in Tropical Diseases (TDR), World Health Organization, Geneva, Switzerland
| | - Katie E. Crawford
- Department of Physiology, Anatomy and Microbiology, La Trobe University, Bundoora, VIC, Australia
| | - Patricia M. Graves
- College of Public Health, Medical and Veterinary Sciences, James Cook University, Cairns, QLD, Australia
| | - Michel Boussinesq
- Unité Mixte Internationale 233 "TransVIHMI", Institut de Recherche pour le Développement (IRD), INSERM U1175, University of Montpellier, Montpellier, France
| | - Colleen L. Lau
- Department of Global Health, Research School of Population Health, Australian National University, Acton, ACT, Australia
| | - Daniel A. Boakye
- Parasitology Department, Noguchi Memorial Institute for Medical Research, Accra, Ghana
| | - Warwick N. Grant
- Department of Physiology, Anatomy and Microbiology, La Trobe University, Bundoora, VIC, Australia
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18
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Otabil KB, Gyasi SF, Awuah E, Obeng-Ofori D, Atta-Nyarko RJ, Andoh D, Conduah B, Agbenyikey L, Aseidu P, Ankrah CB, Nuhu AR, Schallig HDFH. Prevalence of onchocerciasis and associated clinical manifestations in selected hypoendemic communities in Ghana following long-term administration of ivermectin. BMC Infect Dis 2019; 19:431. [PMID: 31101085 PMCID: PMC6525382 DOI: 10.1186/s12879-019-4076-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Accepted: 05/09/2019] [Indexed: 11/26/2022] Open
Abstract
Background Onchocerciasis is a neglected tropical disease which is still of immense major public health concern in several areas of Africa and the Americas. The disease manifests either as ocular or as dermal onchocerciasis with several symptoms including itching, nodules, skin thickening, visual impairment and blindness. Ivermectin has been an efficient microfilaricide against the causative agent of the disease (Onchocerca volvulus) but reports from some areas in Africa suggest the development of resistance to this drug. The aim of this study was to determine the prevalence of onchocerciasis and associated clinical conditions frequently associated with the disease in three endemic communities in Ghana which have been subjected to 18 to 20 rounds of mass drug administration of ivermectin. This was to help determine whether or not onchocerciasis persists in these communities. Methods A cross-sectional study design was adopted. Three communities (Tanfiano, Senya and Kokompe) in the Nkoranza North District of Ghana where mass drug administration of ivermectin had been ongoing for more than two decades were selected for the study. The population was randomly sampled and 114 participants recruited for the study based on the eligibility criteria. The study participants were examined for the presence of parasites and clinical manifestations of onchocerciasis following established protocols. Results The study showed that the prevalence of microfilaria in the Tanfiano, Senya, Kokompe communities were 13.2, 2.4, and 2.9%, with nodule prevalence being 5.3, 4.9 and 14.3% respectively. Females in the study communities had a higher prevalence of microfilaria carriers (5.17%) relative to males (2.44%), but this difference was not statistically significant (p = 0.2800, unpaired t test). The most frequent clinical manifestation observed in this study among all participants was dermatitis (25.4%), followed by visual impairment & nodules (7.9% each) and then by blindness (4.4%). Conclusion The study showed that despite several years of mass drug administration with ivermectin, infection with onchocerciasis and the commonly associated clinical manifestations of the disease still persist in the study communities. This calls for a greater urgency for research and development aimed at discovering new or repurposed anti-filarial agents which will augment ivermectin if global onchocerciasis eradication targets are to be achieved.
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Affiliation(s)
- Kenneth Bentum Otabil
- Department of Basic and Applied Biology, School of Science, University of Energy and Natural Resources, Sunyani, Ghana. .,Amsterdam University Medical Centres, Academic Medical Centre, University of Amsterdam, Department of Medical Microbiology, Experimental Parasitology Unit, Amsterdam, The Netherlands.
| | - Samuel Fosu Gyasi
- Department of Basic and Applied Biology, School of Science, University of Energy and Natural Resources, Sunyani, Ghana
| | - Esi Awuah
- Department of Civil Engineering, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Daniels Obeng-Ofori
- Office of the Vice Chancellor, Catholic University College of Ghana, Sunyani, Ghana
| | - Robert Junior Atta-Nyarko
- Department of Community Medicine and Health, Anglican University College of Technology, Nkoranza, Ghana
| | - Dominic Andoh
- Department of Community Medicine and Health, Anglican University College of Technology, Nkoranza, Ghana
| | - Beatrice Conduah
- Department of Community Medicine and Health, Anglican University College of Technology, Nkoranza, Ghana
| | - Lawrence Agbenyikey
- Department of Community Medicine and Health, Anglican University College of Technology, Nkoranza, Ghana
| | - Philip Aseidu
- Department of Community Medicine and Health, Anglican University College of Technology, Nkoranza, Ghana
| | - Comfort Blessing Ankrah
- Department of Community Medicine and Health, Anglican University College of Technology, Nkoranza, Ghana
| | - Abdul Razak Nuhu
- Department of Community Medicine and Health, Anglican University College of Technology, Nkoranza, Ghana
| | - H D F H Schallig
- Amsterdam University Medical Centres, Academic Medical Centre, University of Amsterdam, Department of Medical Microbiology, Experimental Parasitology Unit, Amsterdam, The Netherlands
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19
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Opoku NO, Bakajika DK, Kanza EM, Howard H, Mambandu GL, Nyathirombo A, Nigo MM, Kasonia K, Masembe SL, Mumbere M, Kataliko K, Larbelee JP, Kpawor M, Bolay KM, Bolay F, Asare S, Attah SK, Olipoh G, Vaillant M, Halleux CM, Kuesel AC. Single dose moxidectin versus ivermectin for Onchocerca volvulus infection in Ghana, Liberia, and the Democratic Republic of the Congo: a randomised, controlled, double-blind phase 3 trial. Lancet 2018; 392:1207-1216. [PMID: 29361335 PMCID: PMC6172290 DOI: 10.1016/s0140-6736(17)32844-1] [Citation(s) in RCA: 96] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Revised: 09/25/2017] [Accepted: 11/02/2017] [Indexed: 11/25/2022]
Abstract
BACKGROUND The morbidity and socioeconomic effects of onchocerciasis, a parasitic disease that is primarily endemic in sub-Saharan Africa, have motivated large morbidity and transmission control programmes. Annual community-directed ivermectin treatment has substantially reduced prevalence. Elimination requires intensified efforts, including more efficacious treatments. We compared parasitological efficacy and safety of moxidectin and ivermectin. METHODS This double-blind, parallel group, superiority trial was done in four sites in Ghana, Liberia, and the Democratic Republic of the Congo. We enrolled participants (aged ≥12 years) with at least 10 Onchocerca volvulus microfilariae per mg skin who were not co-infected with Loa loa or lymphatic filariasis microfilaraemic. Participants were randomly allocated, stratified by sex and level of infection, to receive a single oral dose of 8 mg moxidectin or 150 μg/kg ivermectin as overencapsulated oral tablets. The primary efficacy outcome was skin microfilariae density 12 months post treatment. We used a mixed-effects model to test the hypothesis that the primary efficacy outcome in the moxidectin group was 50% or less than that in the ivermectin group. The primary efficacy analysis population were all participants who received the study drug and completed 12-month follow-up (modified intention to treat). This study is registered with ClinicalTrials.gov, number NCT00790998. FINDINGS Between April 22, 2009, and Jan 23, 2011, we enrolled and allocated 998 participants to moxidectin and 501 participants to ivermectin. 978 received moxidectin and 494 ivermectin, of which 947 and 480 were included in primary efficacy outcome analyses. At 12 months, skin microfilarial density (microfilariae per mg of skin) was lower in the moxidectin group (adjusted geometric mean 0·6 [95% CI 0·3-1·0]) than in the ivermectin group (4·5 [3·5-5·9]; difference 3·9 [3·2-4·9], p<0·0001; treatment difference 86%). Mazzotti (ie, efficacy-related) reactions occurred in 967 (99%) of 978 moxidectin-treated participants and in 478 (97%) of 494 ivermectin-treated participants, including ocular reactions (moxidectin 113 [12%] participants and ivermectin 47 [10%] participants), laboratory reactions (788 [81%] and 415 [84%]), and clinical reactions (944 [97%] and 446 [90%]). No serious adverse events were considered to be related to treatment. INTERPRETATION Skin microfilarial loads (ie, parasite transmission reservoir) are lower after moxidectin treatment than after ivermectin treatment. Moxidectin would therefore be expected to reduce parasite transmission between treatment rounds more than ivermectin could, thus accelerating progress towards elimination. FUNDING UNICEF/UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases.
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Affiliation(s)
- Nicholas O Opoku
- Department of Epidemiology and Biostatistics, School of Public Health, University of Health and Allied Sciences, Hohoe, Ghana
| | | | - Eric M Kanza
- Centre de Recherche Clinique de Butembo (CRCB), Departement de la Recherche aux Cliniques du Graben, Université Catholique du Graben (UCG), Butembo, Democratic Republic of the Congo
| | | | - Germain L Mambandu
- Ministère Provincial de la Santé, Kisangani, Democratic Republic of the Congo
| | - Amos Nyathirombo
- Department of Ophthalmology, Faculty of Medicine, Gulu University, Gulu, Uganda
| | - Maurice M Nigo
- Nanomedicine Research Lab, CLINAM, University Hospital Basel, Basel, Switzerland
| | - Kambale Kasonia
- Centre de Recherche Clinique de Butembo (CRCB), Departement de la Recherche aux Cliniques du Graben, Université Catholique du Graben (UCG), Butembo, Democratic Republic of the Congo
| | - Safari L Masembe
- Centre de Recherche Clinique de Butembo (CRCB), Departement de la Recherche aux Cliniques du Graben, Université Catholique du Graben (UCG), Butembo, Democratic Republic of the Congo
| | - Mupenzi Mumbere
- Centre de Recherche Clinique de Butembo (CRCB), Departement de la Recherche aux Cliniques du Graben, Université Catholique du Graben (UCG), Butembo, Democratic Republic of the Congo
| | - Kambale Kataliko
- Centre de Recherche Clinique de Butembo (CRCB), Departement de la Recherche aux Cliniques du Graben, Université Catholique du Graben (UCG), Butembo, Democratic Republic of the Congo
| | | | - Mawolo Kpawor
- Liberia Institute for Biomedical Research (LIBR), Monrovia, Liberia
| | - Kpehe M Bolay
- Liberia Institute for Biomedical Research (LIBR), Monrovia, Liberia
| | - Fatorma Bolay
- Liberia Institute for Biomedical Research (LIBR), Monrovia, Liberia
| | - Sampson Asare
- Department of Chemistry and Biochemistry, South Dakota State University, Brookings, SD, USA
| | - Simon K Attah
- Department of Microbiology, University of Ghana Medical School, Accra, Ghana
| | - George Olipoh
- Ghana Institute of Management and Public Administration, Centre for Management Development, Accra, Ghana
| | - Michel Vaillant
- Competence Center for Methodology and Statistics, Luxembourg Institute of Health, Strassen, Luxembourg
| | - Christine M Halleux
- UNICEF/UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases (TDR), WHO, Geneva, Switzerland
| | - Annette C Kuesel
- UNICEF/UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases (TDR), WHO, Geneva, Switzerland.
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Figueiredo LA, Rebouças TF, Ferreira SR, Rodrigues-Luiz GF, Miranda RC, Araujo RN, Fujiwara RT. Dominance of P-glycoprotein 12 in phenotypic resistance conversion against ivermectin in Caenorhabditis elegans. PLoS One 2018; 13:e0192995. [PMID: 29474375 PMCID: PMC5825046 DOI: 10.1371/journal.pone.0192995] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 02/03/2018] [Indexed: 12/16/2022] Open
Abstract
While diseases caused by nematodes remains a considerable drawback for the livestock, agriculture and public health, anthelmintics drug resistance has been observed over the past years and is a major concern for parasite control. Ivermectin, initially considered as a highly potent drug, currently presents a reduced anti-helminthic efficacy, which is influenced by expression of several ATP-binding cassette transporters (ABC), among them the P-glycoproteins (Pgps). Here we present some evidences of Pgps dominance during Ivermectin resistance/susceptibility using Pgps double silencing in C. elegans and the phylogenetic relationship of Pgps among nematodes, which strengthen the use of this model for study of drug resistance in nematodes. Firstly, we evaluated the quantitative gene expression of 12 out the 15 known Pgps from resistant and WT strains of C. elegans, we demonstrated the upregulation of Pgps 12 and 13 and downregulation of all remaining Pgps in ivermectin resistant strain. By using an RNAi loss-of-function approach we observed that Pgp 12 gene silencing reverts the resistance phenotype to ivermectin, while Pgp 4 gene silencing does not alter the resistance phenotype but induces a resistance in wild type strain. Interestingly, the dual silencing of Pgp 12 and Pgp 4 expression demonstrates the dominance of phenotype promoted by Pgp 12 silencing. Finally, in silico analysis reveals a close relationship between Pgps from C. elegans and several nematodes parasites. Taken together, our results indicate that Pgp 12 is crucial for the resistance to ivermectin and thus a good candidate for further studies aiming to develop specific inhibitors to this transporter, allowing the continuous use of ivermectin to control the burden on animal and human health inflicted by nematode parasites globally.
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Affiliation(s)
- Luiza Almeida Figueiredo
- Department of Parasitology, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Thais Fuscaldi Rebouças
- Department of Parasitology, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Sebastião Rodrigo Ferreira
- Department of Parasitology, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Gabriela Flavia Rodrigues-Luiz
- Department of Parasitology, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | | | - Ricardo Nascimento Araujo
- Department of Parasitology, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Ricardo Toshio Fujiwara
- Department of Parasitology, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
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21
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Doyle SR, Bourguinat C, Nana-Djeunga HC, Kengne-Ouafo JA, Pion SDS, Bopda J, Kamgno J, Wanji S, Che H, Kuesel AC, Walker M, Basáñez MG, Boakye DA, Osei-Atweneboana MY, Boussinesq M, Prichard RK, Grant WN. Genome-wide analysis of ivermectin response by Onchocerca volvulus reveals that genetic drift and soft selective sweeps contribute to loss of drug sensitivity. PLoS Negl Trop Dis 2017; 11:e0005816. [PMID: 28746337 PMCID: PMC5546710 DOI: 10.1371/journal.pntd.0005816] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Revised: 08/07/2017] [Accepted: 07/19/2017] [Indexed: 12/30/2022] Open
Abstract
Background Treatment of onchocerciasis using mass ivermectin administration has reduced morbidity and transmission throughout Africa and Central/South America. Mass drug administration is likely to exert selection pressure on parasites, and phenotypic and genetic changes in several Onchocerca volvulus populations from Cameroon and Ghana—exposed to more than a decade of regular ivermectin treatment—have raised concern that sub-optimal responses to ivermectin's anti-fecundity effect are becoming more frequent and may spread. Methodology/Principal findings Pooled next generation sequencing (Pool-seq) was used to characterise genetic diversity within and between 108 adult female worms differing in ivermectin treatment history and response. Genome-wide analyses revealed genetic variation that significantly differentiated good responder (GR) and sub-optimal responder (SOR) parasites. These variants were not randomly distributed but clustered in ~31 quantitative trait loci (QTLs), with little overlap in putative QTL position and gene content between the two countries. Published candidate ivermectin SOR genes were largely absent in these regions; QTLs differentiating GR and SOR worms were enriched for genes in molecular pathways associated with neurotransmission, development, and stress responses. Finally, single worm genotyping demonstrated that geographic isolation and genetic change over time (in the presence of drug exposure) had a significantly greater role in shaping genetic diversity than the evolution of SOR. Conclusions/Significance This study is one of the first genome-wide association analyses in a parasitic nematode, and provides insight into the genomics of ivermectin response and population structure of O. volvulus. We argue that ivermectin response is a polygenically-determined quantitative trait (QT) whereby identical or related molecular pathways but not necessarily individual genes are likely to determine the extent of ivermectin response in different parasite populations. Furthermore, we propose that genetic drift rather than genetic selection of SOR is the underlying driver of population differentiation, which has significant implications for the emergence and potential spread of SOR within and between these parasite populations. Onchocerciasis is a human parasitic disease endemic across large areas of Sub-Saharan Africa, where more than 99% of the estimated 100 million people globally at-risk live. The microfilarial stage of Onchocerca volvulus causes pathologies ranging from mild itching to visual impairment and ultimately, irreversible blindness. Mass administration of ivermectin kills microfilariae and has an anti-fecundity effect on adult worms by temporarily inhibiting the development in utero and/or release into the skin of new microfilariae, thereby reducing morbidity and transmission. Phenotypic and genetic changes in some parasite populations that have undergone multiple ivermectin treatments in Cameroon and Ghana have raised concern that sub-optimal response to ivermectin's anti-fecundity effect may increase in frequency, reducing the impact of ivermectin-based control measures. We used next generation sequencing of small pools of parasites to define genome-wide genetic differences between phenotypically characterised good and sub-optimal responder parasites from Cameroon and Ghana, and identified multiple regions of the genome that differentiated the response types. These regions were largely different between parasites from these two countries but revealed common molecular pathways that might be involved in determining the extent of response to ivermectin's anti-fecundity effect. These data reveal a more complex than previously described pattern of genetic diversity among O. volvulus populations that differ in their geography and response to ivermectin treatment.
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Affiliation(s)
- Stephen R. Doyle
- Department of Animal, Plant and Soil Sciences, La Trobe University, Bundoora, Australia
- Wellcome Trust Sanger Institute, Hinxton, Cambridge, United Kingdom
- * E-mail: (SRD); (RKP); (WNG)
| | - Catherine Bourguinat
- Institute of Parasitology, McGill University, Sainte Anne-de-Bellevue, Québec, Canada
| | - Hugues C. Nana-Djeunga
- Parasitology and Ecology Laboratory, Department of Animal Biology and Physiology, Faculty of Science, University of Yaoundé 1, Yaoundé, Cameroon
- Centre for Research on Filariasis and other Tropical Diseases (CRFilMT), Yaoundé, Cameroon
| | - Jonas A. Kengne-Ouafo
- Research Foundation in Tropical Diseases and the Environment (REFOTDE), Buea, Cameroon
| | - Sébastien D. S. Pion
- Institut de Recherche pour le Développement (IRD), IRD UMI 233 TransVIHMI – Université Montpellier – INSERM U1175, Montpellier, France
| | - Jean Bopda
- Faculty of Medicine and Biomedical Sciences, University of Yaoundé 1, Yaoundé, Cameroon
| | - Joseph Kamgno
- Centre for Research on Filariasis and other Tropical Diseases (CRFilMT), Yaoundé, Cameroon
- Faculty of Medicine and Biomedical Sciences, University of Yaoundé 1, Yaoundé, Cameroon
| | - Samuel Wanji
- Research Foundation in Tropical Diseases and the Environment (REFOTDE), Buea, Cameroon
| | - Hua Che
- Institute of Parasitology, McGill University, Sainte Anne-de-Bellevue, Québec, Canada
| | - Annette C. Kuesel
- UNICEF/UNDP/World Bank/World Health Organization Special Programme for Research and Training in Tropical Diseases (WHO/TDR), World Health Organization, Geneva, Switzerland
| | - Martin Walker
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, Faculty of Medicine, School of Public Health, Imperial College London, United Kingdom
| | - Maria-Gloria Basáñez
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, Faculty of Medicine, School of Public Health, Imperial College London, United Kingdom
| | - Daniel A. Boakye
- Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana
| | - Mike Y. Osei-Atweneboana
- Department of Environmental Biology and Health Water Research Institute, Council for Scientific and Industrial Research (CSIR), Accra, Ghana
| | - Michel Boussinesq
- Institut de Recherche pour le Développement (IRD), IRD UMI 233 TransVIHMI – Université Montpellier – INSERM U1175, Montpellier, France
| | - Roger K. Prichard
- Institute of Parasitology, McGill University, Sainte Anne-de-Bellevue, Québec, Canada
- * E-mail: (SRD); (RKP); (WNG)
| | - Warwick N. Grant
- Department of Animal, Plant and Soil Sciences, La Trobe University, Bundoora, Australia
- * E-mail: (SRD); (RKP); (WNG)
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22
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Krücken J, Fraundorfer K, Mugisha JC, Ramünke S, Sifft KC, Geus D, Habarugira F, Ndoli J, Sendegeya A, Mukampunga C, Bayingana C, Aebischer T, Demeler J, Gahutu JB, Mockenhaupt FP, von Samson-Himmelstjerna G. Reduced efficacy of albendazole against Ascaris lumbricoides in Rwandan schoolchildren. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2017; 7:262-271. [PMID: 28697451 PMCID: PMC5503839 DOI: 10.1016/j.ijpddr.2017.06.001] [Citation(s) in RCA: 80] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Revised: 06/17/2017] [Accepted: 06/21/2017] [Indexed: 12/16/2022]
Abstract
Control of human soil-transmitted helminths (STHs) relies on preventive chemotherapy of schoolchildren applying the benzimidazoles (BZ) albendazole or mebendazole. Anthelmintic resistance (AR) is a common problem in nematodes of veterinary importance but for human STHs, information on drug efficacy is limited and routine monitoring is rarely implemented. Herein, the efficacy of single dose albendazole (400 mg) was evaluated in 12 schools in the Huye district of Rwanda where Ascaris is the predominant STH. Ascaris eggs were detected by wet mount microscopy and the Mini-FLOTAC method to assess cure rate (CR) and faecal egg count reduction (FECR). Blood and faecal samples were analysed for co-infections with Plasmodium sp. and Giardia duodenalis, respectively. Ascaris positive samples collected before and after treatment were analysed for putatively BZ-resistance associated β-tubulin gene single nucleotide polymorphisms. The overall CR was 69.9% by Mini-FLOTAC and 88.6% by wet mount microscopy. The FECR was 75.4% and the 95% calculated confidence intervals were 50.4–87.8% using sample variance, 55.4–88.8% by bootstrapping, and 75.0–75.7% applying a Markov Chain Monte Carlo Bayesian approach. FECR varied widely between 0 and 96.8% for individual schools. No putative BZ-resistance associated polymorphisms were found in the four Ascaris β-tubulin isotype genes examined. Since FECRs <95% indicate reduced efficacy, these findings raise the suspicion of BZ resistance. In the absence of respective molecular evidence, heritable AR in the local Ascaris populations cannot be formally proven. However, since FECRs <95% indicate reduced efficacy, BZ resistance may be suspected which would be alarming and calls for further analyses and routine monitoring in preventive chemotherapy programs.
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Affiliation(s)
- Jürgen Krücken
- Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Robert-von-Ostertag-Str. 7-13, 14163 Berlin, Germany
| | - Kira Fraundorfer
- Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Robert-von-Ostertag-Str. 7-13, 14163 Berlin, Germany
| | - Jean Claude Mugisha
- University Teaching Hospital of Butare, University of Rwanda, Butare, Rwanda
| | - Sabrina Ramünke
- Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Robert-von-Ostertag-Str. 7-13, 14163 Berlin, Germany
| | - Kevin C Sifft
- Institute of Tropical Medicine and International Health, Charité-University Medicine Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Dominik Geus
- Institute of Tropical Medicine and International Health, Charité-University Medicine Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Felix Habarugira
- University Teaching Hospital of Butare, University of Rwanda, Butare, Rwanda
| | - Jules Ndoli
- University Teaching Hospital of Butare, University of Rwanda, Butare, Rwanda
| | - Augustin Sendegeya
- University Teaching Hospital of Butare, University of Rwanda, Butare, Rwanda
| | - Caritas Mukampunga
- University Teaching Hospital of Butare, University of Rwanda, Butare, Rwanda
| | - Claude Bayingana
- University Teaching Hospital of Butare, University of Rwanda, Butare, Rwanda
| | - Toni Aebischer
- Mycotic and Parasitic Agents and Mycobacteria, Department of Infectious Diseases, Robert Koch-Institute, Berlin, Germany
| | - Janina Demeler
- Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Robert-von-Ostertag-Str. 7-13, 14163 Berlin, Germany
| | - Jean Bosco Gahutu
- University Teaching Hospital of Butare, University of Rwanda, Butare, Rwanda
| | - Frank P Mockenhaupt
- Institute of Tropical Medicine and International Health, Charité-University Medicine Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Georg von Samson-Himmelstjerna
- Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Robert-von-Ostertag-Str. 7-13, 14163 Berlin, Germany.
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Armoo S, Doyle SR, Osei-Atweneboana MY, Grant WN. Significant heterogeneity in Wolbachia copy number within and between populations of Onchocerca volvulus. Parasit Vectors 2017; 10:188. [PMID: 28420428 PMCID: PMC5395808 DOI: 10.1186/s13071-017-2126-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Accepted: 03/30/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Wolbachia are intracellular bacteria found in arthropods and several filarial nematode species. The filarial Wolbachia have been proposed to be involved in the immunopathology associated with onchocerciasis. Higher Wolbachia-to-nematode ratios have been reported in the savannah-ecotype compared to the forest-ecotype, and have been interpreted as consistent with a correlation between Wolbachia density and disease severity. However, factors such as geographic stratification and ivermectin drug exposure can lead to significant genetic heterogeneity in the nematode host populations, so we investigated whether Wolbachia copy number variation is also associated with these underlying factors. METHODS Genomic DNA was prepared from single adult nematodes representing forest and savannah ecotypes sampled from Togo, Ghana, Côte d'Ivoire and Mali. A qPCR assay was developed to measure the number of Wolbachia genome(s) per nematode genome. Next-generation sequencing (NGS) was also used to measure relative Wolbachia copy number, and independently verify the qPCR assay. RESULTS Significant variation was observed within the forest (range: 0.02 to 452.99; median: 10.58) and savannah (range: 0.01 to 1106.25; median: 9.10) ecotypes, however, no significant difference between ecotypes (P = 0.645) was observed; rather, strongly significant Wolbachia variation was observed within and between the nine study communities analysed (P = 0.021), independent of ecotype. Analysis of ivermectin-treated and untreated nematodes by qPCR showed no correlation (P = 0.869); however, an additional analysis of a subset of the nematodes by qPCR and NGS revealed a correlation between response to ivermectin treatment and Wolbachia copy number (P = 0.020). CONCLUSIONS This study demonstrates that extensive within and between population variation exists in the Wolbachia content of individual adult O. volvulus. The origin and functional significance of such variation (up to ~ 100,000-fold between worms; ~10 to 100-fold between communities) in the context of the proposed mutualistic relationship between the worms and the bacteria, and between the presence of Wolbachia and clinical outcome of infection, remains unclear. These data do not support a correlation between Wolbachia copy number and forest or savannah ecotype, and may have implications for the development of anti-Wolbachia drugs as a macrofilaricidal treatment of onchocerciasis. The biological significance of a correlation between variation in Wolbachia copy number and ivermectin response remains unexplained.
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Affiliation(s)
- Samuel Armoo
- Department of Animal, Plant and Soil Sciences, School of Life Sciences, La Trobe University, Bundoora, 3083, VIC, Australia.,Environmental Biology and Health Division, Council for Scientific and Industrial Research, Water Research Institute, Accra, Ghana
| | - Stephen R Doyle
- Department of Animal, Plant and Soil Sciences, School of Life Sciences, La Trobe University, Bundoora, 3083, VIC, Australia.,Present address: Parasite Genomics Group, Wellcome Trust Sanger Institute, Hinxton, Cambridge, CB10 1SA, UK
| | - Mike Y Osei-Atweneboana
- Environmental Biology and Health Division, Council for Scientific and Industrial Research, Water Research Institute, Accra, Ghana
| | - Warwick N Grant
- Department of Animal, Plant and Soil Sciences, School of Life Sciences, La Trobe University, Bundoora, 3083, VIC, Australia.
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Cheke RA. Factors affecting onchocerciasis transmission: lessons for infection control. Expert Rev Anti Infect Ther 2017; 15:377-386. [PMID: 28117596 DOI: 10.1080/14787210.2017.1286980] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
INTRODUCTION Onchocerca volvulus infects in excess of 15 million people. The vectors are Simulium blackflies, varieties of which differ in their ecologies, behavior and vectorial abilities. Control of the vectors and mass administrations of ivermectin have succeeded in reducing prevalences with elimination achieved in some foci, particularly in Central and southern America. In Africa, progress towards elimination has been less successful. Areas covered: Even with community directed treatment with ivermectin (CDTI), control has been difficult in African areas with initial prevalences in excess of 55%, especially if only annual treatments are dispensed. This is partly attributable to insufficient coverage, but the appearance of incipiently resistant non-responding parasites and lack of attention to vector biology in modeling and planning outcomes of intervention programmes have also played their parts, with recrudescence now appearing in some treated areas. Expert commentary: The biology of onchocerciasis is complex involving different vectors with differing abilities to transmit parasites, diverse pathologies related to geographical and parasite variations and endosymbionts in both parasite and vector. Modeling to predict epidemiological and control outcomes is addressing this complexity but more attention needs to be given to the vectors' roles to further understanding of where and when control measures will succeed.
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Affiliation(s)
- Robert A Cheke
- a Agriculture, Health and Environment Department, Natural Resources Institute , University of Greenwich at Medway , Kent , UK.,b Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary's campus) , Imperial College London , London , UK
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25
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Kwarteng A, Ahuno ST. The Potentials and Pitfalls of Microarrays in Neglected Tropical Diseases: A Focus on Human Filarial Infections. MICROARRAYS 2016; 5:microarrays5030020. [PMID: 27600086 PMCID: PMC5040967 DOI: 10.3390/microarrays5030020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Revised: 06/01/2016] [Accepted: 06/28/2016] [Indexed: 12/01/2022]
Abstract
Data obtained from expression microarrays enables deeper understanding of the molecular signatures of infectious diseases. It provides rapid and accurate information on how infections affect the clustering of gene expression profiles, pathways and networks that are transcriptionally active during various infection states compared to conventional diagnostic methods, which primarily focus on single genes or proteins. Thus, microarray technologies offer advantages in understanding host-parasite interactions associated with filarial infections. More importantly, the use of these technologies can aid diagnostics and helps translate current genomic research into effective treatment and interventions for filarial infections. Studying immune responses via microarray following infection can yield insight into genetic pathways and networks that can have a profound influence on the development of anti-parasitic vaccines.
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Affiliation(s)
- Alexander Kwarteng
- Kumasi Centre for Collaborative Research in Tropical Medicine (KCCR), Private Mail Bag, Kwame Nkrumah University Science & Technology, KNUST, Kumasi 233, Ghana.
- Department of Biochemistry and Biotechnology, Kwame Nkrumah University Science & Technology, KNUST, Kumasi 233, Ghana.
| | - Samuel Terkper Ahuno
- Department of Biochemistry and Biotechnology, Kwame Nkrumah University Science & Technology, KNUST, Kumasi 233, Ghana.
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26
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Misra S, Valicherla GR, Mohd Shahab, Gupta J, Gayen JR, Misra-Bhattacharya S. UDP-galactopyranose mutase, a potential drug target against human pathogenic nematodeBrugia malayi. Pathog Dis 2016; 74:ftw072. [DOI: 10.1093/femspd/ftw072] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/13/2016] [Indexed: 01/02/2023] Open
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27
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Hess JA, Zhan B, Torigian AR, Patton JB, Petrovsky N, Zhan T, Bottazzi ME, Hotez PJ, Klei TR, Lustigman S, Abraham D. The Immunomodulatory Role of Adjuvants in Vaccines Formulated with the Recombinant Antigens Ov-103 and Ov-RAL-2 against Onchocerca volvulus in Mice. PLoS Negl Trop Dis 2016; 10:e0004797. [PMID: 27387453 PMCID: PMC4936747 DOI: 10.1371/journal.pntd.0004797] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 06/01/2016] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND In some regions in Africa, elimination of onchocerciasis may be possible with mass drug administration, although there is concern based on several factors that onchocerciasis cannot be eliminated solely through this approach. A vaccine against Onchocerca volvulus would provide a critical tool for the ultimate elimination of this infection. Previous studies have demonstrated that immunization of mice with Ov-103 and Ov-RAL-2, when formulated with alum, induced protective immunity. It was hypothesized that the levels of protective immunity induced with the two recombinant antigens formulated with alum would be improved by formulation with other adjuvants known to enhance different types of antigen-specific immune responses. METHODOLOGY/ PRINCIPAL FINDINGS Immunizing mice with Ov-103 and Ov-RAL-2 in conjunction with alum, Advax 2 and MF59 induced significant levels of larval killing and host protection. The immune response was biased towards Th2 with all three of the adjuvants, with IgG1 the dominant antibody. Improved larval killing and host protection was observed in mice immunized with co-administered Ov-103 and Ov-RAL-2 in conjunction with each of the three adjuvants as compared to single immunizations. Antigen-specific antibody titers were significantly increased in mice immunized concurrently with the two antigens. Based on chemokine levels, it appears that neutrophils and eosinophils participate in the protective immune response induced by Ov-103, and macrophages and neutrophils participate in immunity induced by Ov-RAL-2. CONCLUSIONS/SIGNIFICANCE The mechanism of protective immunity induced by Ov-103 and Ov-RAL-2, with the adjuvants alum, Advax 2 and MF59, appears to be multifactorial with roles for cytokines, chemokines, antibody and specific effector cells. The vaccines developed in this study have the potential of reducing the morbidity associated with onchocerciasis in humans.
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Affiliation(s)
- Jessica A. Hess
- Department of Microbiology and Immunology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
| | - Bin Zhan
- Department of Pediatrics, National School of Tropical Medicine, Baylor College of Medicine, Houston, Texas, United States of America
- Sabin Vaccine Institute and Texas Children’s Hospital Center for Vaccine Development, Houston, Texas, United States of America
| | - April R. Torigian
- Department of Microbiology and Immunology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
| | - John B. Patton
- Department of Microbiology and Immunology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
| | - Nikolai Petrovsky
- Department of Diabetes and Endocrinology, Flinders University, Adelaide, Australia
- Vaxine Pty Ltd, Flinders Medical Centre, Bedford Park, Adelaide, Australia
| | - Tingting Zhan
- Division of Biostatistics, Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
| | - Maria Elena Bottazzi
- Department of Pediatrics, National School of Tropical Medicine, Baylor College of Medicine, Houston, Texas, United States of America
- Sabin Vaccine Institute and Texas Children’s Hospital Center for Vaccine Development, Houston, Texas, United States of America
| | - Peter J. Hotez
- Department of Pediatrics, National School of Tropical Medicine, Baylor College of Medicine, Houston, Texas, United States of America
- Sabin Vaccine Institute and Texas Children’s Hospital Center for Vaccine Development, Houston, Texas, United States of America
| | - Thomas R. Klei
- Department of Pathobiological Sciences, LSU School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana, United States of America
| | - Sara Lustigman
- Laboratory of Molecular Parasitology, Lindsley F. Kimball Research Institute, New York Blood Center, New York, New York, United States of America
| | - David Abraham
- Department of Microbiology and Immunology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
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Kuesel AC. Research for new drugs for elimination of onchocerciasis in Africa. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2016; 6:272-286. [PMID: 27693536 PMCID: PMC5196484 DOI: 10.1016/j.ijpddr.2016.04.002] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/20/2016] [Accepted: 04/20/2016] [Indexed: 01/12/2023]
Abstract
Onchocerciasis is a parasitic, vector borne disease caused by the filarial nematode Onchocerca volvulus. More than 99% of the population at risk of infection live in Africa. Onchocerciasis control was initiated in West Africa in 1974 with vector control, later complemented by ivermectin mass drug administration and in the other African endemic countries in 1995 with annual community directed treatment with ivermectin (CDTI.) This has significantly reduced infection prevalence. Together with proof-of-concept for onchocerciasis elimination with annual CDTI from foci in Senegal and Mali, this has resulted in targeting onchocerciasis elimination in selected African countries by 2020 and in 80% of African countries by 2025. The challenges for meeting these targets include the number of endemic countries where conflict has delayed or interrupted control programmes, cross-border foci, potential emergence of parasite strains with low susceptibility to ivermectin and co-endemicity of loiasis, another parasitic vector borne disease, which slows down or prohibits CDTI implementation. Some of these challenges could be addressed with new drugs or drug combinations with a higher effect on Onchocerca volvulus than ivermectin. This paper reviews the path from discovery of new compounds to their qualification for large scale use and the support regulatory authorities provide for development of drugs for neglected tropical diseases. The status of research for new drugs or treatment regimens for onchocerciasis along the path to regulatory approval and qualification for large scale use is reviewed. This research includes new regimens and combinations of ivermectin and albendazole, antibiotics targeting the O. volvulus endosymbiont Wolbachia, flubendazole, moxidectin and emodepside and discovery of new compounds.
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Affiliation(s)
- Annette C Kuesel
- UNICEF/UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases, 20 Avenue Appia, 1211 Geneva, Switzerland.
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29
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Frempong KK, Walker M, Cheke RA, Tetevi EJ, Gyan ET, Owusu EO, Wilson MD, Boakye DA, Taylor MJ, Biritwum NK, Osei-Atweneboana M, Basáñez MG. Does Increasing Treatment Frequency Address Suboptimal Responses to Ivermectin for the Control and Elimination of River Blindness? Clin Infect Dis 2016; 62:1338-1347. [PMID: 27001801 PMCID: PMC4872292 DOI: 10.1093/cid/ciw144] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Accepted: 03/10/2016] [Indexed: 11/18/2022] Open
Abstract
The first 3 years of biannual ivermectin distribution in Ghana have substantially reduced Onchocerca volvulus infection levels in 10 sentinel communities, but longitudinal analysis indicates that some communities are still consistently responding suboptimally to treatment, with implications for onchocerciasis elimination. Background. Several African countries have adopted a biannual ivermectin distribution strategy in some foci to control and eliminate onchocerciasis. In 2010, the Ghana Health Service started biannual distribution to combat transmission hotspots and suboptimal responses to treatment. We assessed the epidemiological impact of the first 3 years of this strategy and quantified responses to ivermectin over 2 consecutive rounds of treatment in 10 sentinel communities. Methods. We evaluated Onchocerca volvulus community microfilarial intensity and prevalence in persons aged ≥20 years before the first, second, and fifth (or sixth) biannual treatment rounds using skin snip data from 956 participants. We used longitudinal regression modeling to estimate rates of microfilarial repopulation of the skin in a cohort of 217 participants who were followed up over the first 2 rounds of biannual treatment. Results. Biannual treatment has had a positive impact, with substantial reductions in infection intensity after 4 or 5 rounds in most communities. We identified 3 communities—all having been previously recognized as responding suboptimally to ivermectin—with statistically significantly high microfilarial repopulation rates. We did not find any clear association between microfilarial repopulation rate and the number of years of prior intervention, coverage, or the community level of infection. Conclusions. The strategy of biannual ivermectin treatment in Ghana has reduced O. volvulus microfilarial intensity and prevalence, but suboptimal responses to treatment remain evident in a number of previously and consistently implicated communities. Whether increasing the frequency of treatment will be sufficient to meet the World Health Organization's 2020 elimination goals remains uncertain.
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Affiliation(s)
- Kwadwo K Frempong
- Noguchi Memorial Institute for Medical Research, University of Ghana, Legon
| | - Martin Walker
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London
| | - Robert A Cheke
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London.,Natural Resources Institute, University of Greenwich at Medway, Chatham Maritime, United Kingdom
| | | | - Ernest Tawiah Gyan
- Council for Scientific and Industrial Research, Water Research Institute, Accra
| | - Ebenezer O Owusu
- Department of Animal Biology and Conservation Science, University of Ghana, Legon
| | - Michael D Wilson
- Noguchi Memorial Institute for Medical Research, University of Ghana, Legon
| | - Daniel A Boakye
- Noguchi Memorial Institute for Medical Research, University of Ghana, Legon
| | - Mark J Taylor
- Department of Parasitology, Liverpool School of Tropical Medicine, United Kingdom
| | | | | | - María-Gloria Basáñez
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London
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30
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Turner HC, Walker M, Lustigman S, Taylor DW, Basáñez MG. Human Onchocerciasis: Modelling the Potential Long-term Consequences of a Vaccination Programme. PLoS Negl Trop Dis 2015; 9:e0003938. [PMID: 26186715 PMCID: PMC4506122 DOI: 10.1371/journal.pntd.0003938] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 06/28/2015] [Indexed: 11/21/2022] Open
Abstract
Background Currently, the predominant onchocerciasis control strategy in Africa is annual mass drug administration (MDA) with ivermectin. However, there is a consensus among the global health community, supported by mathematical modelling, that onchocerciasis in Africa will not be eliminated within proposed time frameworks in all endemic foci with only annual MDA, and novel and alternative strategies are urgently needed. Furthermore, use of MDA with ivermectin is already compromised in large areas of central Africa co-endemic with Loa loa, and there are areas where suboptimal or atypical responses to ivermectin have been documented. An onchocerciasis vaccine would be highly advantageous in these areas. Methodology/Principal Findings We used a previously developed onchocerciasis transmission model (EPIONCHO) to investigate the impact of vaccination in areas where loiasis and onchocerciasis are co-endemic and ivermectin is contraindicated. We also explore the potential influence of a vaccination programme on infection resurgence in areas where local elimination has been successfully achieved. Based on the age range included in the Expanded Programme on Immunization (EPI), the vaccine was assumed to target 1 to 5 year olds. Our modelling results indicate that the deployment of an onchocerciasis vaccine would have a beneficial impact in onchocerciasis–loiasis co-endemic areas, markedly reducing microfilarial load in the young (under 20 yr) age groups. Conclusions/Significance An onchocerciasis prophylactic vaccine would reduce the onchocerciasis disease burden in populations where ivermectin cannot be administered safely. Moreover, a vaccine could substantially decrease the chance of re-emergence of Onchocerca volvulus infection in areas where it is deemed that MDA with ivermectin can be stopped. Therefore, a vaccine would protect the substantial investments made by present and past onchocerciasis control programmes, decreasing the chance of disease recrudescence and offering an important additional tool to mitigate the potentially devastating impact of emerging ivermectin resistance. Novel and alternative strategies are required to meet the demanding control and elimination (of infection) goals for human onchocerciasis (river blindness) in Africa. Due to the overlapping distribution of onchocerciasis and loiasis (African eye worm) in forested areas of central Africa, millions of people living in such areas are not well served by current interventions because they cannot safely receive the antiparasitic drug ivermectin that is distributed en masse to treat onchocerciasis elsewhere in Africa. The Onchocerciasis Vaccine for Africa—TOVA—Initiative has been established to develop and trial an onchocerciasis vaccine. We model the potential impact of a hypothetical childhood vaccination programme rolled out in areas where co-endemicity of onchocerciasis and African eye worm makes mass distribution of ivermectin difficult and potentially unsafe for treating, controlling and eliminating river blindness. We find that, 15 years into the programme, a vaccine would substantially reduce infection levels in children and young adults, protecting them from the morbidity and mortality associated with onchocerciasis. Most benefit would be reaped from a long-lived vaccine, even if only partially protective. We also discuss how a vaccine could substantially reduce the risk of re-emergence of onchocerciasis in areas freed from infection after years of successful intervention.
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Affiliation(s)
- Hugo C. Turner
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St. Mary’s Campus), Imperial College London, London, United Kingdom
- Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St. Mary’s Campus), Imperial College London, London, United Kingdom
| | - Martin Walker
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St. Mary’s Campus), Imperial College London, London, United Kingdom
- Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St. Mary’s Campus), Imperial College London, London, United Kingdom
| | - Sara Lustigman
- Laboratory of Molecular Parasitology, Lindsley F. Kimball Research Institute, New York Blood Center, New York, New York, United States of America
| | - David W. Taylor
- Division of Infection and Pathway Medicine, University of Edinburgh Medical School, The Chancellor’s Building, Edinburgh, United Kingdom
| | - María-Gloria Basáñez
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St. Mary’s Campus), Imperial College London, London, United Kingdom
- Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St. Mary’s Campus), Imperial College London, London, United Kingdom
- * E-mail:
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Dooley LA, Froese EA, Chung YT, Burkman EJ, Moorhead AR, Ardelli BF. Host ABC transporter proteins may influence the efficacy of ivermectin and possibly have broader implications for the development of resistance in parasitic nematodes. Exp Parasitol 2015; 157:35-43. [PMID: 26143231 DOI: 10.1016/j.exppara.2015.06.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Revised: 04/18/2015] [Accepted: 06/15/2015] [Indexed: 11/20/2022]
Abstract
ABC transporter proteins function to extrude compounds from the cell. These proteins present an obstacle for treatment and for overcoming drug resistance as they are expressed by both host and parasite, and function similarly. The contribution of host ABC proteins to drug efficacy was examined using ivermectin and a Brugia malayi model system. Parallel in vitro and in vivo experiments were conducted using equal concentrations of ivermectin. The motilities and fecundity of B. malayi exposed to ivermectin in vitro were significantly lower than those treated in vivo. The higher motilities were correlated with low concentrations of ivermectin in worms extracted from treated hosts. The expression of ABC proteins was significantly higher in worms treated in vitro compared to those treated in vivo as well as in gerbils treated with ivermectin than in non-treated controls. The results suggest that host ABC transporters may influence the efficacy of ivermectin.
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Affiliation(s)
- L A Dooley
- Department of Biology, Brandon University, 270-18th Street, Brandon, Manitoba R7A 6A9, Canada
| | - E A Froese
- Department of Biology, Brandon University, 270-18th Street, Brandon, Manitoba R7A 6A9, Canada
| | - Y T Chung
- Department of Biology, Brandon University, 270-18th Street, Brandon, Manitoba R7A 6A9, Canada
| | - E J Burkman
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, USA
| | - A R Moorhead
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, USA
| | - B F Ardelli
- Department of Biology, Brandon University, 270-18th Street, Brandon, Manitoba R7A 6A9, Canada.
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Gooyit M, Harris TL, Tricoche N, Javor S, Lustigman S, Janda KD. Onchocerca volvulus Molting Inhibitors Identified through Scaffold Hopping. ACS Infect Dis 2015; 1:198-202. [PMID: 27622649 DOI: 10.1021/acsinfecdis.5b00017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The anthelmintic closantel has shown promise in abrogating the L3 molting of Onchocerca volvulus, the causative agent of the infectious disease onchocerciasis. In our search for alternative scaffolds, we utilized a fragment replacement/modification approach to generate novel chemotypes with improved chitinase inhibitory properties. Further evaluation of the compounds unveiled the potential of urea-tropolones as potent inhibitors of O. volvulus L3 molting.
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Affiliation(s)
- Major Gooyit
- Departments
of Chemistry and Immunology and Microbial Science, The Skaggs Institute
for Chemical Biology, and The Worm Institute of Research and Medicine, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Tyler L. Harris
- Departments
of Chemistry and Immunology and Microbial Science, The Skaggs Institute
for Chemical Biology, and The Worm Institute of Research and Medicine, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Nancy Tricoche
- Lindsley F. Kimball Research Institute, New York Blood Center, New York, New York 10065, United States
| | - Sacha Javor
- Departments
of Chemistry and Immunology and Microbial Science, The Skaggs Institute
for Chemical Biology, and The Worm Institute of Research and Medicine, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Sara Lustigman
- Lindsley F. Kimball Research Institute, New York Blood Center, New York, New York 10065, United States
| | - Kim D. Janda
- Departments
of Chemistry and Immunology and Microbial Science, The Skaggs Institute
for Chemical Biology, and The Worm Institute of Research and Medicine, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
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Debrah AY, Specht S, Klarmann-Schulz U, Batsa L, Mand S, Marfo-Debrekyei Y, Fimmers R, Dubben B, Kwarteng A, Osei-Atweneboana M, Boakye D, Ricchiuto A, Büttner M, Adjei O, Mackenzie CD, Hoerauf A. Doxycycline Leads to Sterility and Enhanced Killing of Female Onchocerca volvulus Worms in an Area With Persistent Microfilaridermia After Repeated Ivermectin Treatment: A Randomized, Placebo-Controlled, Double-Blind Trial. Clin Infect Dis 2015; 61:517-26. [PMID: 25948064 PMCID: PMC4518165 DOI: 10.1093/cid/civ363] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Accepted: 03/23/2015] [Indexed: 11/23/2022] Open
Abstract
Sub-optimal responses to ivermectin (IVM) have emerged. Targeting the Onchocerca volvulus Wolbachia endosymbionts with doxycycline is effective in clearing microfilariae in onchocerciasis patients with persistent microfilaridermia and in enhanced killing of adult worms after repeated standard IVM treatment. Background. Ivermectin (IVM) has been the drug of choice for the treatment of onchocerciasis. However, there have been reports of persistent microfilaridermia in individuals from an endemic area in Ghana after many rounds of IVM, raising concerns of suboptimal response or even the emergence of drug resistance. Because it is considered risky to continue relying only on IVM to combat this phenomenon, we assessed the effect of targeting the Onchocerca volvulus Wolbachia endosymbionts with doxycycline for these individuals with suboptimal response. Methods. One hundred sixty-seven patients, most of them with multiple rounds of IVM, were recruited in areas with IVM suboptimal response and treated with 100 mg/day doxycycline for 6 weeks. Three and 12 months after doxycycline treatment, patients took part in standard IVM treatment. Results. At 20 months after treatment, 80% of living female worms from the placebo group were Wolbachia positive, whereas only 5.1% in the doxycycline-treated group contained bacteria. Consistent with interruption of embryogenesis, none of the nodules removed from doxycycline-treated patients contained microfilariae, and 97% of those patients were without microfilaridermia, in contrast to placebo patients who remained at pretreatment levels (P < .001). Moreover, a significantly enhanced number of dead worms were observed after doxycycline. Conclusions. Targeting the Wolbachia in O. volvulus is effective in clearing microfilariae in the skin of onchocerciasis patients with persistent microfilaridermia and in enhanced killing of adult worms after repeated standard IVM treatment. Strategies can now be developed that include doxycycline to control onchocerciasis in areas where infections persist despite the frequent use of IVM. Clinical Trials Registration. ISRCTN 66649839.
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Affiliation(s)
- Alexander Yaw Debrah
- Faculty of Allied Health Sciences, Kwame Nkrumah University of Science and Technology Kumasi Centre for Collaborative Research in Tropical Medicine, Ghana
| | - Sabine Specht
- Institutes for Medical Microbiology, Immunology and Parasitology
| | - Ute Klarmann-Schulz
- Institutes for Medical Microbiology, Immunology and Parasitology Medical Biometry, Informatics and Epidemiology, University of Bonn, Germany
| | - Linda Batsa
- Kumasi Centre for Collaborative Research in Tropical Medicine, Ghana
| | - Sabine Mand
- Institutes for Medical Microbiology, Immunology and Parasitology
| | | | - Rolf Fimmers
- Medical Biometry, Informatics and Epidemiology, University of Bonn, Germany
| | - Bettina Dubben
- Institutes for Medical Microbiology, Immunology and Parasitology
| | | | | | - Daniel Boakye
- Noguchi Memorial Institute for Medical Research, University of Ghana, Accra
| | - Arcangelo Ricchiuto
- Institutes for Medical Microbiology, Immunology and Parasitology Medical Biometry, Informatics and Epidemiology, University of Bonn, Germany
| | | | - Ohene Adjei
- School of Medical Sciences, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Charles D Mackenzie
- Centre for Neglected Tropical Diseases, Liverpool School of Tropical Medicine, United Kingdom
| | - Achim Hoerauf
- Institutes for Medical Microbiology, Immunology and Parasitology
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Bourguinat C, Lee ACY, Lizundia R, Blagburn BL, Liotta JL, Kraus MS, Keller K, Epe C, Letourneau L, Kleinman CL, Paterson T, Gomez EC, Montoya-Alonso JA, Smith H, Bhan A, Peregrine AS, Carmichael J, Drake J, Schenker R, Kaminsky R, Bowman DD, Geary TG, Prichard RK. Macrocyclic lactone resistance in Dirofilaria immitis: Failure of heartworm preventives and investigation of genetic markers for resistance. Vet Parasitol 2015; 210:167-78. [PMID: 25936435 DOI: 10.1016/j.vetpar.2015.04.002] [Citation(s) in RCA: 97] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2014] [Revised: 03/29/2015] [Accepted: 04/01/2015] [Indexed: 12/18/2022]
Abstract
Macrocyclic lactone (ML) endectocides are used as chemoprophylaxis for heartworm infection (Dirofilaria immitis) in dogs and cats. Claims of loss of efficacy (LOE) of ML heartworm preventives have become common in some locations in the USA. We directly tested whether resistance to MLs exists in LOE isolates of D. immitis and identified genetic markers that are correlated with, and therefore can predict ML resistance. ML controlled studies showed that LOE strains of D. immitis established infections in dogs despite chemoprophylaxis with oral ivermectin or injectable moxidectin. A whole genome approach was used to search for loci associated with the resistance phenotype. Many loci showed highly significant differences between pools of susceptible and LOE D. immitis. Based on 186 potential marker loci, Sequenom(®) SNP frequency analyses were conducted on 663 individual parasites (adult worms and microfilariae) which were phenotypically characterized as susceptible (SUS), confirmed ML treatment survivors/resistant (RES), or suspected resistant/loss of efficacy (LOE) parasites. There was a subset of SNP loci which appears to be promising markers for predicting ML resistance, including SNPs in some genes that have been associated with ML resistance in other parasites. These data provide unequivocal proof of ML resistance in D. immitis and identify genetic markers that could be used to monitor for ML resistance in heartworms.
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Affiliation(s)
- Catherine Bourguinat
- Institute of Parasitology, McGill University, 21111 Lakeshore Road, Sainte-Anne-de-Bellevue, QC H9X 3V9, Canada
| | - Alice C Y Lee
- College of Veterinary Medicine, Cornell University, 602 Tower Rd, Ithaca, NY 14853, USA
| | - Regina Lizundia
- Novartis Animal Health, Route de la Petite Glâne, St-Aubin 1566, Switzerland
| | - Byron L Blagburn
- College of Veterinary Medicine, Auburn University, 1500 Wire Road, Auburn, AL 36849, USA
| | - Janice L Liotta
- College of Veterinary Medicine, Cornell University, 602 Tower Rd, Ithaca, NY 14853, USA
| | - Marc S Kraus
- College of Veterinary Medicine, Cornell University, 602 Tower Rd, Ithaca, NY 14853, USA
| | - Kathy Keller
- Institute of Parasitology, McGill University, 21111 Lakeshore Road, Sainte-Anne-de-Bellevue, QC H9X 3V9, Canada
| | - Christian Epe
- Novartis Animal Health, Route de la Petite Glâne, St-Aubin 1566, Switzerland
| | - Louis Letourneau
- McGill University and Génome Québec Innovation Centre, 740, Dr. Penfield Avenue, QC H3A 0G1, Canada
| | - Claudia L Kleinman
- Lady Davis Institute for Medical Research and Department of Human Genetics, McGill University, 3755 Chemin de la Côte-Sainte-Catherine, Montreal, QC H3 T 1E2, Canada
| | - Tara Paterson
- School of Veterinary Medicine, St. George's University, True Blue, St. George's, Grenada
| | - Elena Carreton Gomez
- Faculty of Veterinary, Universidad de Las Palmas de Gran Canaria, Calle Juan de Quesada, 30, 35001 Las Palmas de Gran Canaria, Spain
| | - José Alberto Montoya-Alonso
- Faculty of Veterinary, Universidad de Las Palmas de Gran Canaria, Calle Juan de Quesada, 30, 35001 Las Palmas de Gran Canaria, Spain
| | - Hubert Smith
- Haywood Animal Hospital, 2538 N Washington Avenue, Brownsville, TN 38012, USA
| | - Aron Bhan
- Main West Animal Hospital, 1 Broadway, Welland, ON L3 C 5L2, Canada
| | - Andrew S Peregrine
- Ontario Veterinary College, University of Guelph, Gordon Street, Guelph, ON N1G 2W1, Canada
| | - James Carmichael
- Novartis Animal Health, 3200 Northline Avenue, Greensboro, NC 27408, USA
| | - Jason Drake
- Novartis Animal Health, 3200 Northline Avenue, Greensboro, NC 27408, USA
| | - Rudolf Schenker
- Novartis Animal Health, Route de la Petite Glâne, St-Aubin 1566, Switzerland
| | - Ronald Kaminsky
- Novartis Animal Health, Route de la Petite Glâne, St-Aubin 1566, Switzerland
| | - Dwight D Bowman
- College of Veterinary Medicine, Cornell University, 602 Tower Rd, Ithaca, NY 14853, USA
| | - Timothy G Geary
- Institute of Parasitology, McGill University, 21111 Lakeshore Road, Sainte-Anne-de-Bellevue, QC H9X 3V9, Canada
| | - Roger K Prichard
- Institute of Parasitology, McGill University, 21111 Lakeshore Road, Sainte-Anne-de-Bellevue, QC H9X 3V9, Canada.
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Coffeng LE, Stolk WA, Hoerauf A, Habbema D, Bakker R, Hopkins AD, de Vlas SJ. Elimination of African onchocerciasis: modeling the impact of increasing the frequency of ivermectin mass treatment. PLoS One 2014; 9:e115886. [PMID: 25545677 PMCID: PMC4278850 DOI: 10.1371/journal.pone.0115886] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2014] [Accepted: 12/02/2014] [Indexed: 11/18/2022] Open
Abstract
The African Programme for Onchocerciasis Control (APOC) is currently shifting its focus from morbidity control to elimination of infection. To enhance the likelihood of elimination and speed up its achievement, programs may consider to increase the frequency of ivermectin mass treatment from annual to 6-monthly or even higher. In a computer simulation study, we examined the potential impact of increasing the mass treatment frequency for different settings. With the ONCHOSIM model, we simulated 92,610 scenarios pertaining to different assumptions about transmission conditions, history of mass treatment, the future mass treatment strategy, and ivermectin efficacy. Simulation results were used to determine the minimum remaining program duration and number of treatment rounds required to achieve 99% probability of elimination. Doubling the frequency of treatment from yearly to 6-monthly or 3-monthly was predicted to reduce remaining program duration by about 40% or 60%, respectively. These reductions come at a cost of additional treatment rounds, especially in case of 3-monthly mass treatment. Also, aforementioned reductions are highly dependent on maintained coverage, and could be completely nullified if coverage of mass treatment were to fall in the future. In low coverage settings, increasing treatment coverage is almost just as effective as increasing treatment frequency. We conclude that 6-monthly mass treatment may only be worth the effort in situations where annual treatment is expected to take a long time to achieve elimination in spite of good treatment coverage, e.g. because of unfavorable transmission conditions or because mass treatment started recently.
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Affiliation(s)
- Luc E. Coffeng
- Department of Public Health, Erasmus MC University Medical Center Rotterdam, P.O. box 2040, 3000 CA Rotterdam, The Netherlands
- * E-mail:
| | - Wilma A. Stolk
- Department of Public Health, Erasmus MC University Medical Center Rotterdam, P.O. box 2040, 3000 CA Rotterdam, The Netherlands
| | - Achim Hoerauf
- Institute of Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Sigmund Freud Str. 25, 53105, Bonn, Germany
| | - Dik Habbema
- Department of Public Health, Erasmus MC University Medical Center Rotterdam, P.O. box 2040, 3000 CA Rotterdam, The Netherlands
| | - Roel Bakker
- Department of Public Health, Erasmus MC University Medical Center Rotterdam, P.O. box 2040, 3000 CA Rotterdam, The Netherlands
| | - Adrian D. Hopkins
- Mectizan Donation Program, 325 Swanton Way, Decatur, Georgia, 30030, United States of America
| | - Sake J. de Vlas
- Department of Public Health, Erasmus MC University Medical Center Rotterdam, P.O. box 2040, 3000 CA Rotterdam, The Netherlands
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Samje M, Metuge J, Mbah J, Nguesson B, Cho-Ngwa F. In vitro anti-Onchocerca ochengi activities of extracts and chromatographic fractions of Craterispermum laurinum and Morinda lucida. BMC COMPLEMENTARY AND ALTERNATIVE MEDICINE 2014; 14:325. [PMID: 25179014 PMCID: PMC4162957 DOI: 10.1186/1472-6882-14-325] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Accepted: 08/27/2014] [Indexed: 12/03/2022]
Abstract
BACKGROUND Onchocerciasis caused by Onchocerca volvulus is the world's second leading infectious cause of blindness. There is currently no cure for the disease. Ivermectin, the current drug of choice is only microfilaricidal and suboptimal response to it is increasingly being reported. Thus, in contributing to the search for a cure, crude extracts and chromatographic fractions of Craterispermum laurinum and Morinda lucida were screened in vitro, against the bovine and most popular model of the parasite, Onchocerca ochengi. METHODS Extracted parasites were cultured in RPMI-1640 based media for 05 days in the presence of control drugs, test drugs or drug diluents only. Microfilarial motility was scored using microscopy while adult worm viability was determined biochemically by MTT/formazan colorimetry. Cytotoxicity and acute toxicity of active fractions were tested on monkey kidney epithelial cells (LLCMK2) and in Balb/c mice, respectively. RESULTS Out of the 18 extracts screened, the methanolic extracts of the leaves of both plants recorded the highest activities against both the microfilariae (IC100 of 125 μg/ml for both extracts) and adult worms (IC100 of 250 μg/ml and 500 μg/ml for M. lucida and C. laurinum respectively). The most active chromatographic fraction was obtained from M. lucida and had an IC50 of 7.8 μg/ml and 15.63 μg/ml on microfilariae and adult worms respectively, while the most active fraction from C. laurinum had an IC50 of 15.63 μg/ml and 46.8 μg/ml, respectively on microfilariae and adult worms. The 50% cytotoxic concentration (CC50s) on LLCMK2 cells ranged from 15.625 μg/ml to 125 μg/ml for the active fractions. No acute toxicity was recorded for the extracts from both plants. Phytochemical analysis of the most active fractions revealed the presence of sterols, alkaloids, triterpenes, saponins and flavonoids. CONCLUSIONS This study validates the use of these plants by traditional health practitioners in managing the disease, and also suggests a new source for isolation of potential lead compounds against Onchocerca volvulus.
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Affiliation(s)
- Moses Samje
- />Department of Biomedical Sciences, Faculty of Health Sciences, University of Bamenda, PO Box 39, Bambili, Cameroon
- />Department of Biochemistry and Molecular Biology, Faculty of Science, University of Buea, P.O. Box 63, Buea, Cameroon
| | - Jonathan Metuge
- />Department of Biochemistry and Molecular Biology, Faculty of Science, University of Buea, P.O. Box 63, Buea, Cameroon
| | - James Mbah
- />Department of Chemistry, Faculty of Science, University of Buea, P.O. Box 63, Buea, Cameroon
| | - Brice Nguesson
- />Department of Chemistry, Faculty of Science, University of Buea, P.O. Box 63, Buea, Cameroon
| | - Fidelis Cho-Ngwa
- />Department of Biochemistry and Molecular Biology, Faculty of Science, University of Buea, P.O. Box 63, Buea, Cameroon
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Awadzi K, Opoku NO, Attah SK, Lazdins-Helds J, Kuesel AC. A randomized, single-ascending-dose, ivermectin-controlled, double-blind study of moxidectin in Onchocerca volvulus infection. PLoS Negl Trop Dis 2014; 8:e2953. [PMID: 24968000 PMCID: PMC4072596 DOI: 10.1371/journal.pntd.0002953] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Accepted: 05/06/2014] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Control of onchocerciasis as a public health problem in Africa relies on annual mass ivermectin distribution. New tools are needed to achieve elimination of infection. This study determined in a small number of Onchocerca volvulus infected individuals whether moxidectin, a veterinary anthelminthic, is safe enough to administer it in a future large study to further characterize moxidectin's safety and efficacy. Effects on the parasite were also assessed. METHODOLOGY/PRINCIPAL FINDINGS Men and women from a forest area in South-eastern Ghana without ivermectin mass distribution received a single oral dose of 2 mg (N = 44), 4 mg (N = 45) or 8 mg (N = 38) moxidectin or 150 µg/kg ivermectin (N = 45) with 18 months follow up. All ivermectin and 97%-100% of moxidectin treated participants had Mazzotti reactions. Statistically significantly higher percentages of participants treated with 8 mg moxidectin than participants treated with ivermectin experienced pruritus (87% vs. 56%), rash (63% vs. 42%), increased pulse rate (61% vs. 36%) and decreased mean arterial pressure upon 2 minutes standing still after ≥5 minutes supine relative to pre-treatment (61% vs. 27%). These reactions resolved without treatment. In the 8 mg moxidectin and ivermectin arms, the mean±SD number of microfilariae/mg skin were 22.9±21.1 and 21.2±16.4 pre-treatment and 0.0±0.0 and 1.1±4.2 at nadir reached 1 and 3 months after treatment, respectively. At 6 months, values were 0.0±0.0 and 1.6±4.5, at 12 months 0.4±0.9 and 3.4±4.4 and at 18 months 1.8±3.3 and 4.0±4.8, respectively, in the 8 mg moxidectin and ivermectin arm. The reduction from pre-treatment values was significantly higher after 8 mg moxidectin than after ivermectin treatment throughout follow up (p<0.01). CONCLUSIONS/SIGNIFICANCE The 8 mg dose of moxidectin was safe enough to initiate the large study. Provided its results confirm those from this study, availability of moxidectin to control programmes could help them achieve onchocerciasis elimination objectives. TRIAL REGISTRATION ClinicalTrials.gov NCT00300768.
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Affiliation(s)
- Kwablah Awadzi
- Onchocerciasis Chemotherapy Research Centre, Hohoe, Ghana
| | | | - Simon K. Attah
- Onchocerciasis Chemotherapy Research Centre, Hohoe, Ghana
- University of Ghana Medical School, Department of Microbiology, Accra, Ghana
| | - Janis Lazdins-Helds
- UNICEF/UNDP/World Bank/World Health Organization Special Programme for Research and Training in Tropical Diseases, World Health Organization, Geneva, Switzerland
| | - Annette C. Kuesel
- UNICEF/UNDP/World Bank/World Health Organization Special Programme for Research and Training in Tropical Diseases, World Health Organization, Geneva, Switzerland
- * E-mail:
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Gooyit M, Tricoche N, Lustigman S, Janda KD. Dual protonophore-chitinase inhibitors dramatically affect O. volvulus molting. J Med Chem 2014; 57:5792-9. [PMID: 24918716 PMCID: PMC4216208 DOI: 10.1021/jm5006435] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
The
L3-stage-specific chitinase OvCHT1 has been implicated in the
development of Onchocerca volvulus,
the causative agent of onchocerciasis. Closantel, a known anthelmintic
drug, was previously discovered as a potent and specific OvCHT1 inhibitor.
As closantel is also a known protonophore, we performed a simple scaffold
modulation to map out the structural features that are relevant for
its individual or dual biochemical roles. Furthermore, we present
that either OvCHT1 inhibition or protonophoric activity was capable
of affecting O. volvulus L3 molting
and that the presence of both activities in a single molecule yielded
more potent inhibition of the nematode’s developmental process.
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Affiliation(s)
- Major Gooyit
- Departments of Chemistry and Immunology and Microbial Science, The Skaggs Institute for Chemical Biology, and The Worm Institute of Research and Medicine, The Scripps Research Institute , 10550 North Torrey Pines Road, La Jolla, California 92037, United States
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Vaccines to combat river blindness: expression, selection and formulation of vaccines against infection with Onchocerca volvulus in a mouse model. Int J Parasitol 2014; 44:637-46. [PMID: 24907553 DOI: 10.1016/j.ijpara.2014.04.006] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Revised: 04/15/2014] [Accepted: 04/16/2014] [Indexed: 01/21/2023]
Abstract
Human onchocerciasis is a neglected tropical disease caused by Onchocerca volvulus and an important cause of blindness and chronic disability in the developing world. Although mass drug administration of ivermectin has had a profound effect on control of the disease, additional tools are critically needed including the need for a vaccine against onchocerciasis. The objectives of the present study were to: (i) select antigens with known vaccine pedigrees as components of a vaccine; (ii) produce the selected vaccine antigens under controlled conditions, using two expression systems and in one laboratory and (iii) evaluate their vaccine efficacy using a single immunisation protocol in mice. In addition, we tested the hypothesis that joining protective antigens as a fusion protein or in combination, into a multivalent vaccine, would improve the ability of the vaccine to induce protective immunity. Out of eight vaccine candidates tested in this study, Ov-103, Ov-RAL-2 and Ov-CPI-2M were shown to reproducibly induce protective immunity when administered individually, as fusion proteins or in combination. Although there was no increase in the level of protective immunity induced by combining the antigens into one vaccine, these antigens remain strong candidates for inclusion in a vaccine to control onchocerciasis in humans.
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Anderson RC, Newton CL, Millar RP, Katz AA. The Brugia malayi neuropeptide receptor-4 is activated by FMRFamide-like peptides and signals via Gαi. Mol Biochem Parasitol 2014; 195:54-8. [DOI: 10.1016/j.molbiopara.2014.07.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Revised: 07/04/2014] [Accepted: 07/07/2014] [Indexed: 01/25/2023]
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Nana-Djeunga HC, Bourguinat C, Pion SD, Bopda J, Kengne-Ouafo JA, Njiokou F, Prichard RK, Wanji S, Kamgno J, Boussinesq M. Reproductive status of Onchocerca volvulus after ivermectin treatment in an ivermectin-naïve and a frequently treated population from Cameroon. PLoS Negl Trop Dis 2014; 8:e2824. [PMID: 24762816 PMCID: PMC3998936 DOI: 10.1371/journal.pntd.0002824] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Accepted: 03/13/2014] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND For two decades, onchocerciasis control has been based on mass treatment with ivermectin (IVM), repeated annually or six-monthly. This drug kills Onchocerca volvulus microfilariae (mf) present in the skin and the eyes (microfilaricidal effect) and prevents for 3-4 months the release of new mf by adult female worms (embryostatic effect). In some Ghanaian communities, the long-term use of IVM was associated with a more rapid than expected skin repopulation by mf after treatment. Here, we assessed whether the embryostatic effect of IVM on O. volvulus has been altered following frequent treatment in Cameroonian patients. METHODOLOGY Onchocercal nodules were surgically removed just before (D0) and 80 days (D80) after a standard dose of IVM in two cohorts with different treatment histories: a group who had received repeated doses of IVM over 13 years, and a control group with no history of large-scale treatments. Excised nodules were digested with collagenase to isolate adult worms. Embryograms were prepared with females for the evaluation of their reproductive capacities. PRINCIPAL FINDINGS Oocyte production was not affected by IVM. The mean number of intermediate embryos (morulae and coiled mf) decreased similarly in the two groups between D0 and D80. In contrast, an accumulation of stretched mf, either viable or degenerating, was observed at D80. However, it was observed that the increase in number of degenerating mf between D0 and D80 was much lower in the frequently treated group than in the control one (Incidence Rate Ratio: 0.25; 95% CI: 0.10-0.63; p = 0.003), which may indicate a reduced sequestration of mf in the worms from the frequently treated group. CONCLUSION/SIGNIFICANCE IVM still had an embryostatic effect on O. volvulus, but the effect was reduced in the frequently treated cohort compared with the control population.
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Affiliation(s)
- Hugues C. Nana-Djeunga
- Parasitology and Ecology Laboratory, Department of Animal Biology and Physiology, Faculty of Science, University of Yaounde 1, Yaounde, Cameroon
- Centre for Research on Filariasis and other Tropical Diseases (CRFilMT), Yaounde, Cameroon
| | - Catherine Bourguinat
- Institute of Parasitology, McGill University, Sainte Anne-de-Bellevue, Québec, Canada
| | - Sébastien D. Pion
- Centre for Research on Filariasis and other Tropical Diseases (CRFilMT), Yaounde, Cameroon
- UMI 233, Institut de Recherche pour le Développement (IRD) and University of Montpellier 1, Montpellier, France
- * E-mail:
| | - Jean Bopda
- Centre for Research on Filariasis and other Tropical Diseases (CRFilMT), Yaounde, Cameroon
| | - Jonas A. Kengne-Ouafo
- Research Foundation in Tropical Diseases and the Environment, Buea, Cameroon
- Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon
| | - Flobert Njiokou
- Parasitology and Ecology Laboratory, Department of Animal Biology and Physiology, Faculty of Science, University of Yaounde 1, Yaounde, Cameroon
| | - Roger K. Prichard
- Institute of Parasitology, McGill University, Sainte Anne-de-Bellevue, Québec, Canada
| | - Samuel Wanji
- Research Foundation in Tropical Diseases and the Environment, Buea, Cameroon
- Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon
| | - Joseph Kamgno
- Centre for Research on Filariasis and other Tropical Diseases (CRFilMT), Yaounde, Cameroon
- Faculty of Medicine and Biomedical Sciences, University of Yaounde 1, Yaounde, Cameroon
| | - Michel Boussinesq
- UMI 233, Institut de Recherche pour le Développement (IRD) and University of Montpellier 1, Montpellier, France
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Hartmann W, Singh N, Rathaur S, Brenz Y, Liebau E, Fleischer B, Breloer M. Immunization withBrugia malayiHsp70 protects mice againstLitomosoides sigmodontischallenge infection. Parasite Immunol 2014; 36:141-9. [DOI: 10.1111/pim.12093] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Accepted: 12/11/2013] [Indexed: 11/29/2022]
Affiliation(s)
- W. Hartmann
- Department of Immunology and Virology; Bernhard Nocht Institute for Tropical Medicine; Hamburg Germany
| | - N. Singh
- Department of Biochemistry; Faculty of Science; Banaras Hindu University; Varanasi India
| | - S. Rathaur
- Department of Biochemistry; Faculty of Science; Banaras Hindu University; Varanasi India
| | - Y. Brenz
- Department of Immunology and Virology; Bernhard Nocht Institute for Tropical Medicine; Hamburg Germany
| | - E. Liebau
- Institute of Animal Physiology; University of Münster; Münster Germany
| | - B. Fleischer
- Department of Immunology and Virology; Bernhard Nocht Institute for Tropical Medicine; Hamburg Germany
- Institute of Immunology; University Medical Center Hamburg-Eppendorf; Hamburg Germany
| | - M. Breloer
- Department of Immunology and Virology; Bernhard Nocht Institute for Tropical Medicine; Hamburg Germany
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Abstract
Two of the major filarial infections, lymphatic filariasis (LF) and onchocerciasis, affect 150 million people, while 1 billion living in endemic areas are at risk of infection. Public health programs to control these infections have successfully existed for years and have evolved from activities driven by the WHO into global programs with public-private partnerships. Currently, these programs use yearly mass application of drugs that mainly kill the larval stages (the microfilariae), with the aim of preventing uptake by the transmitting insect vectors and thus, to block transmission and reduce the infections to such levels that in 15-30 years from now, they will no longer pose a public health problem. While the programs have been very successful in general, there are drawbacks such as coverage being too low within the population, reappearance of infection by migration of infected people into controlled areas, targeting of a stage (the microfilaria) that does not induce pathology in LF and thus lowers compliance, and the potential development of drug resistance, first indications of which have been clearly observed in onchocerciasis. In addition, even without drawbacks, program scopes are not the eradication of filarial infections, which is, however, an ultimate goal of control activities. There is therefore an unequivocal call for the development of higher efficient, complementary chemotherapeutical approaches that lead to a long-lasting reduction of the pathology-inducing worm stages; that is, microfilariae in onchocerciasis and adult worms in LF, or to a macrofilaricidal effect. The recent discovery that depletion of Wolbachia endosymbionts by tetracycline antibiotics leads to long-lasting sterility of adult female worms in onchocerciasis and a macrofilaricidal effect in LF fulfils these requirements. Successful regimens have already been published and agreed upon for use by expert panels. While these regimens are still too long for mass application, the antiwolbachial chemotherapy can currently be applied in the form of a suitable doxycycline regimen for 6 weeks for the treatment of individuals, and exploited in the future for the development of new drugs suitable for mass application. In addition, first data suggest that Wolbachia may also be major mediators of lymphangiogenesis and that their depletion is associated with reduction of lymph vessel-specific vascular endothelial growth factors and reduced lymph vessel size.
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Affiliation(s)
- Achim Hoerauf
- Institute of Medical Microbiology, Immunology and Parasitology, University Clinic Bonn, 53105 Bonn, Germany.
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Smits HL. Prospects for the control of neglected tropical diseases by mass drug administration. Expert Rev Anti Infect Ther 2014; 7:37-56. [DOI: 10.1586/14787210.7.1.37] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Ardelli BF. Transport proteins of the ABC systems superfamily and their role in drug action and resistance in nematodes. Parasitol Int 2013; 62:639-46. [DOI: 10.1016/j.parint.2013.02.008] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Revised: 02/20/2013] [Accepted: 02/21/2013] [Indexed: 11/28/2022]
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The cost of annual versus biannual community-directed treatment of onchocerciasis with ivermectin: Ghana as a case study. PLoS Negl Trop Dis 2013; 7:e2452. [PMID: 24069497 PMCID: PMC3777881 DOI: 10.1371/journal.pntd.0002452] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Accepted: 08/13/2013] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND It has been proposed that switching from annual to biannual (twice yearly) mass community-directed treatment with ivermectin (CDTI) might improve the chances of onchocerciasis elimination in some African foci. However, historically, relatively few communities have received biannual treatments in Africa, and there are no cost data associated with increasing ivermectin treatment frequency at a large scale. Collecting cost data is essential for conducting economic evaluations of control programmes. Some countries, such as Ghana, have adopted a biannual treatment strategy in selected districts. We undertook a study to estimate the costs associated with annual and biannual CDTI in Ghana. METHODOLOGY The study was conducted in the Brong-Ahafo and Northern regions of Ghana. Data collection was organized at the national, regional, district, sub-district and community levels, and involved interviewing key personnel and scrutinizing national records. Data were collected in four districts; one in which treatment is delivered annually, two in which it is delivered biannually, and one where treatment takes place biannually in some communities and annually in others. Both financial and economic costs were collected from the health care provider's perspective. PRINCIPAL FINDINGS The estimated cost of treating annually was US Dollars (USD) 0.45 per person including the value of time donated by the community drug distributors (which was estimated at USD 0.05 per person per treatment round). The cost of CDTI was approximately 50-60% higher in those districts where treatment was biannual than in those where it was annual. Large-scale mass biannual treatment was reported as being well received and considered sustainable. CONCLUSIONS/SIGNIFICANCE This study provides rigorous evidence of the different costs associated with annual and biannual CDTI in Ghana which can be used to inform an economic evaluation of the debate on the optimal treatment frequency required to control (or eliminate) onchocerciasis in Africa.
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Abstract
Lymphatic filariasis and onchocerciasis are diseases of severe morbidity that affect the poorest of the poor in the world. The diseases are caused by filarial nematodes that are transmitted by mosquitoes or biting blackflies and are endemic to more than 80 countries worldwide, mainly in the tropics and sub-tropics. Current control programs aim to eliminate the diseases by distributing antifilarial drugs. However, the primary effect of the drugs is to kill the microfilariae in the blood or skin, thus preventing uptake by the obligate insect vector. Since the adult worms live 10 years or longer, drug distribution requires many years of treatment, which is a heavy burden on the burgeoning health care systems. Sub-optimal response, possible resistance and inadequate population coverage lessen the chances for successful elimination in all endemic areas. The search for new drugs that could enhance elimination by permanently sterilizing or killing adult worms has identified the Wolbachia intracellular bacteria of filarial nematodes as a target. Depleting the obligate endosymbionts from the worms with doxycycline or rifampicin causes a permanent block in oogenesis, embryogenesis and development, and in slow death of the adult worms. These two antibiotics are suitable for individual drug administration, but caveats exist for their inclusion in broader drug administration programs. Here we review Wolbachia as targets for antifilarial drug discovery and highlight the natural product corallopyronin A as an effective drug that is currently being developed specifically for use against filarial nematodes.
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Fifteen years of annual mass treatment of onchocerciasis with ivermectin have not interrupted transmission in the west region of cameroon. J Parasitol Res 2013; 2013:420928. [PMID: 23691275 PMCID: PMC3652197 DOI: 10.1155/2013/420928] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Revised: 03/18/2013] [Accepted: 03/25/2013] [Indexed: 11/17/2022] Open
Abstract
We followed up the 1996 baseline parasitological and entomological studies on onchocerciasis transmission in eleven health districts in West Region, Cameroon. Annual mass ivermectin treatment had been provided for 15 years. Follow-up assessments which took place in 2005, 2006, and 2011 consisted of skin snips for microfilariae (mf) and palpation examinations for nodules. Follow-up Simulium vector dissections for larval infection rates were done from 2011 to 2012. mf prevalence in adults dropped from 68.7% to 11.4%, and nodule prevalence dropped from 65.9% to 12.1%. The decrease of mf prevalence in children from 29.2% to 8.9% was evidence that transmission was still continuing. mf rates in the follow-up assessments among adults and in children levelled out after a sharp reduction from baseline levels. Only three health districts out of 11 were close to interruption of transmission. Evidence of continuing transmission was also observed in two out of three fly collection sites that had infective rates of 0.19% and 0.18% and ATP of 70 (Foumbot) and 300 (Massangam), respectively. Therefore, halting of annual mass treatment with ivermectin cannot be done after 15 years as it might escalate the risk of transmission recrudescence.
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Attah SK, Ayeh-Kumi PF, Sittie AA, Oppong IV, Nyarko AK. Extracts of Euphorbia hirta Linn. (Euphorbiaceae) and Rauvolfia vomitoria Afzel (Apocynaceae) demonstrate activities against Onchocerca volvulus microfilariae in vitro. BMC COMPLEMENTARY AND ALTERNATIVE MEDICINE 2013; 13:66. [PMID: 23506674 PMCID: PMC3606627 DOI: 10.1186/1472-6882-13-66] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/13/2012] [Accepted: 03/13/2013] [Indexed: 11/10/2022]
Abstract
Background Onchocerciasis transmitted by Onchocerca volvulus is the second major cause of blindness in the world and it impacts negatively on the socio-economic development of the communities affected. Currently, ivermectin, a microfilaricidal drug is the only drug recommended for treating this disease. There have been speculations, of late, concerning O. volvulus resistance to ivermectin. Owing to this, it has become imperative to search for new drugs. World-wide, ethnomedicines including extracts of Euphorbia hirta and Rauvolfia vomitoria are used for treating various diseases, both infectious and non-infectious. Method In this study extracts of the two plants were evaluated in vitro in order to determine their effect against O. volvulus microfilariae. The toxicity of the E. hirta extracts on monkey kidney cell (LLCMK2) lines was also determined. Results The investigations showed that extracts of both plants immobilised microfilariae at different levels in vitro and, therefore, possess antifilarial properties. It was found that all the E. hirta extracts with the exception of the hexane extracts were more effective than those of R. vomitoria. Among the extracts of E. hirta the ethyl acetate fraction was most effective, and comparable to that of dimethanesulphonate salt but higher than that of Melarsoprol (Mel B). However, the crude ethanolic extract of E. hirta was found to be the least toxic to the LLCMK2 compared to the fractionated forms. Conclusions Extracts from both plants possess antifilarial properties; however, the crude extract of E. hirta was found to be least toxic to LLCMK2.
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Prichard RK. Ivermectin resistance and overview of the Consortium for Anthelmintic Resistance SNPs. Expert Opin Drug Discov 2013; 2:S41-52. [PMID: 23489032 DOI: 10.1517/17460441.2.s1.s41] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Ivermectin (IVM) has transformed nematode parasite control in veterinary medicine and the control of some nematode infections in humans, such as onchocerciasais, lymphatic filariasis in Africa and strongyloidiasis. Unfortunately, IVM resistance is now a serious problem for parasite control in livestock and there is a concern about resistance development and spread in nematode parasites of humans. IVM is believed to act by opening glutamate-gated chloride channels and GABA-gated channels in invertebrate neurons or muscle cells, leading to hyperpolarisation of the cells and to an inhibitory paralysis. However, in the filarial nematodes, it is not altogether clear that the effect of IVM is confined to these actions or even whether these are the most important. Alterations in some ligand-gated ion channel (LGIC) receptor subunits may play a role in the mechanisms of IVM resistance in some nematodes, but the evidence that changes in LGICs are the most important cause of IVM resistance in nematodes is far from clear. What is evident is that IVM is an excellent substrate for some ATP-binding cassette transporters, IVM selects for changes in expression levels of ABC transporters, such as P-glycoproteins, and that altered levels of some ABC transporters contribute to IVM resistance. In addition, there is growing evidence that IVM selects on β-tubulin, at least in some nematodes. Based on these various mechanisms, which contribute to IVM resistance, it may become possible to develop panels of molecular markers for IVM resistance in different nematode parasites. In order to stimulate the development of such markers, an international Consortium for Anthelmintic Resistance SNPs (CARS) has been developed to help coordinate marker development, advance our knowledge of helminth biology and possibly assist with the development of new anthelmintic molecules.
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Affiliation(s)
- Roger K Prichard
- Institute of Parasitology, McGill University, 21111 Lakeshore Road, Sainte-Anne-de-Bellevue, QC, H9X3V9, Canada 1 514 398 7729 ; +1 514 398 7594 ;
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