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Repositioning of an existing drug for the neglected tropical disease Onchocerciasis.

ABSTRACT: Onchocerciasis, or river blindness, is a neglected tropical disease caused by the filarial nematode Onchocerca volvulus that affects more than 37 million people, mainly in third world countries. Currently, the only approved drug available for mass treatment is ivermectin, however, drug resistance is beginning to emerge, thus, new therapeutic targets and agents are desperately needed to treat and cure this devastating disease. Chitin metabolism plays a central role in invertebrate biology due to the critical structural function of chitin for the organism. Taken together with its absence in mammals, targeting chitin is an appealing therapeutic avenue. Importantly, the chitinase OvCHT1 from O. volvulus was recently discovered, however, its exact role in the worm's metabolism remains unknown. A screening effort against OvCHT1 was conducted using the Johns Hopkins Clinical Compound Library that contains over 1,500 existing drugs. Closantel, a veterinary anthelmintic with known proton ionophore activities, was identified as a potent and specific inhibitor of filarial chitinases, an activity not previously reported for this compound. Notably, closantel was found also to completely inhibit molting of O. volvulus infective L3 stage larvae. Closantel appears to target two important biochemical processes essential to filarial parasites. To begin to unravel closantel's effects, a retro-fragment-based study was used to define structural elements critical for closantel's chitinase inhibitor function. As resources towards the development of new agents that target neglected tropical diseases are scant, the finding of an existing drug with impact against O. volvulus provides promise in the hunt for new therapies against river blindness.

SUBMITTER: Gloeckner C

PROVIDER: S-EPMC2840490 | biostudies-other | 2010 Feb

REPOSITORIES: biostudies-other

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Repositioning of an existing drug for the neglected tropical disease Onchocerciasis.

Gloeckner Christian C Garner Amanda L AL Mersha Fana F Oksov Yelena Y Tricoche Nancy N Eubanks Lisa M LM Lustigman Sara S Kaufmann Gunnar F GF Janda Kim D KD

Proceedings of the National Academy of Sciences of the United States of America 20100208 8

Onchocerciasis, or river blindness, is a neglected tropical disease caused by the filarial nematode Onchocerca volvulus that affects more than 37 million people, mainly in third world countries. Currently, the only approved drug available for mass treatment is ivermectin, however, drug resistance is beginning to emerge, thus, new therapeutic targets and agents are desperately needed to treat and cure this devastating disease. Chitin metabolism plays a central role in invertebrate biology due to ...[more]

PMID: 20142509

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Project description:BackgroundNeglected tropical diseases (NTDs) are closely related to poverty and affect over a billion people in developing countries. The unmet treatment needs cause high mortality and disability thereby imposing a huge burden with severe social and economic consequences. Although coordinated by the World Health Organization, various philanthropic organizations, national governments and the pharmaceutical industry have been making efforts in improving the situation, the control of NTDs is still inadequate and extremely difficult today. The lack of safe, effective and affordable medicines is a key contributing factor. This paper reviews the recent advances and some of the challenges that we are facing in the fight against NTDs.Main bodyIn recent years, a number of innovations have demonstrated propensity to promote drug discovery and development for NTDs. Implementation of multilateral collaborations leads to continued efforts and plays a crucial role in drug discovery. Proactive approaches and advanced technologies are urgently needed in drug innovation for NTDs. However, the control and elimination of NTDs remain a formidable task as it requires persistent international cooperation to make sustainable progresses for a long period of time. Some currently employed strategies were proposed and verified to be successful, which involve both mechanisms of 'Push' which aims at cutting the cost of research and development for industry and 'Pull' which aims at increasing market attractiveness. Coupled to this effort should be the exercise of shared responsibility globally to reduce risks, overcome obstacles and maximize benefits. Since NTDs are closely associated with poverty, it is absolutely essential that the stakeholders take concerted and long-term measures to meet multifaceted challenges by alleviating extreme poverty, strengthening social intervention, adapting climate changes, providing effective monitoring and ensuring timely delivery.ConclusionsThe ongoing endeavor at the global scale will ultimately benefit the patients, the countries they are living and, hopefully, the manufacturers who provide new preventive, diagnostic and therapeutic products.

Project description:Drug development for neglected diseases has been historically hampered due to lack of market incentives. The advent of public domain resources containing chemical information from high throughput screenings is changing the landscape of drug discovery for these diseases. In this work we took advantage of data from extensively studied organisms like human, mouse, E. coli and yeast, among others, to develop a novel integrative network model to prioritize and identify candidate drug targets in neglected pathogen proteomes, and bioactive drug-like molecules. We modeled genomic (proteins) and chemical (bioactive compounds) data as a multilayer weighted network graph that takes advantage of bioactivity data across 221 species, chemical similarities between 1.7 105 compounds and several functional relations among 1.67 105 proteins. These relations comprised orthology, sharing of protein domains, and shared participation in defined biochemical pathways. We showcase the application of this network graph to the problem of prioritization of new candidate targets, based on the information available in the graph for known compound-target associations. We validated this strategy by performing a cross validation procedure for known mouse and Trypanosoma cruzi targets and showed that our approach outperforms classic alignment-based approaches. Moreover, our model provides additional flexibility as two different network definitions could be considered, finding in both cases qualitatively different but sensible candidate targets. We also showcase the application of the network to suggest targets for orphan compounds that are active against Plasmodium falciparum in high-throughput screens. In this case our approach provided a reduced prioritization list of target proteins for the query molecules and showed the ability to propose new testable hypotheses for each compound. Moreover, we found that some predictions highlighted by our network model were supported by independent experimental validations as found post-facto in the literature.

Project description:BackgroundMass drug administration (MDA) programmes for neglected tropical diseases (NTDs) depend on voluntary community drug distributors (CDDs) to deliver drugs, and these volunteer schemes need regular training and supervision. NTD policy now includes integration of multiple disease programmes, but we are unsure if there is clarity in what is currently expected of CDDs and how they are managed. We therefore analysed World Health Organization (WHO) policy, strategy and implementation guidance, and select national NTD programme implementation plans.MethodsIncluded are a) WHO global and WHO-Regional Office for Africa guidelines, strategies, operational manuals and meeting reports published between January 2007 to February 2018 that included policy and plans for CDDs; and b) national NTD programme master plans for Cameroon, Ghana, Liberia and Nigeria. For both review components, we examined the CDD responsibilities through a framework developed iteratively against the documents and prepared a narrative synthesis.ResultsTwenty WHO policy documents met the inclusion criteria. In the twelve global and eight regional documents, the CDD role was not explicitly or comprehensively defined. Three documents mentioned CDDs will distribute drugs; some mentioned health promotion, data handling and engagement in clinical care. Four WHO documents noted a need for CDD training or management, eight detailed some aspect of this, and one regional document provided a comprehensive overview. In the national plans, additional responsibilities included case management in two countries and transmission control in two countries. Every plan included training and supervision, but this was not always explicit, and details of the purpose and frequency varied. In all national plans, CDD motivation was identified as a challenge but not comprehensively addressed, although one document mentioned provision of bicycles.ConclusionsWHO and national policies and plans assume CDDs will implement NTD programmes. However, there is almost no clear delineation of responsibilities, nor is there up-to-date practical guidance to guide managers. This ambiguity, in relation to the lack of explicit policies or programmatic guidance, probably impairs the effectiveness of NTD programmes.

Project description:Background. Limited laboratory capacity is a significant bottleneck in meeting global targets for the control and elimination of neglected tropical diseases (NTD). Laboratories are essential for providing clinical data and monitoring data about the status and changes in NTD prevalence, and for detecting early drug resistance. Currently NTD laboratory networks are informal and specialist laboratory expertise is not well publicised, making it difficult to share global expertise and provide training, supervision, and quality assurance for NTD diagnosis and research. This study aimed to identify laboratories within five World Health Organisation regions (South-East Asia, Eastern Mediterranean, Americas, Western Pacific and Europe) that provide NTD services and could be regarded as national or regional reference laboratories, and to conduct a survey to document their networks and capacity to support NTD programmes. Methods. Potential NTD reference laboratories were identified through systematic searches, snowball sampling and key informants. Results. Thirty-two laboratories responded to the survey. The laboratories covered 17 different NTDs and their main regional and national roles were to provide technical support and training, research, test validation and standard setting. Two thirds of the laboratories were based in academic institutions and almost half had less than 11 staff. Although greater than 90 per cent of the laboratories had adequate technical skills to function as an NTD reference laboratory, almost all laboratories lacked systems for external verification that their results met international standards. Conclusions. This study highlights that although many laboratories believed they could act as a reference laboratory, only a few had all the characteristics required to fulfil this role as they fell short in the standard and quality assurance of laboratory processes. Networks of high quality laboratories are essential for the control and elimination of disease and this study presents a critical first step in the development of such networks for NTDs.

Dataset Information

Repositioning of an existing drug for the neglected tropical disease Onchocerciasis.

Publications

Repositioning of an existing drug for the neglected tropical disease Onchocerciasis.

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