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Drag M, Tielemans E, Mitchell E, McCall JW, Targa N, Bruner R, Yoon S, Colley B, Fankhauser B. Safety of an oral combination of moxidectin, afoxolaner, and pyrantel pamoate in dogs. Res Vet Sci 2024; 173:105271. [PMID: 38631075 DOI: 10.1016/j.rvsc.2024.105271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 04/12/2024] [Accepted: 04/12/2024] [Indexed: 04/19/2024]
Abstract
NexGard®PLUS (moxidectin, afoxolaner, and pyrantel pamoate), is an oral combination product for dogs indicated for the prevention of heartworm disease, the treatment and prevention of flea and tick infestations, and the treatment of gastro-intestinal nematode infections. The safety of this product in dogs was evaluated in three studies. Study #1 was a margin-of-safety study conducted in puppies, dosed six times at 28-day intervals at 1X, 3X, or 5X multiples of the maximum exposure dose (equivalent to 24 μg/kg moxidectin, 5 mg/kg afoxolaner, and 10 mg/kg pyrantel). In Study #2, the product was administered to ABCB1-deficient collie dogs at a 1X dose twice at a 28-day interval, and at a 3X or 5X dose once. Study #3 evaluated the safety of the product at 1X and 3X doses administered three times at 4-week intervals, to dogs harboring adult Dirofilaria immitis. In the three studies, the safety was evaluated on the basis of multiple clinical observations and physical examinations, including a complete assessment of toxicity to macrocyclic lactones, and on comprehensive clinical and anatomical pathology evaluations in Study #1. No clinically significant combination product-related effects were observed in any of the three studies. No signs of macrocyclic lactone toxicity were observed in the ABCB1-deficient collie dogs. Some mild and self-resolving instances of emesis or diarrhea were occasionally observed in the 3X and 5X dosed dogs. NexGard® PLUS was demonstrated to be safe following multiple administrations in puppies, in ABCB1-deficient collie dogs, and in microfilaremic dogs infected with adult D. immitis.
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Affiliation(s)
- Marlene Drag
- Boehringer Ingelheim Animal Health (BI AH), 6498 Jade Rd, Fulton, MO 65251, USA
| | - Eric Tielemans
- Boehringer Ingelheim Animal Health, 29 Avenue Tony Garnier, 69007 Lyon, France.
| | - Elizabeth Mitchell
- Boehringer Ingelheim Animal Health, 1730 Olympic Drive, Athens, GA 30601, USA
| | - John W McCall
- TRS Labs, Inc, 215 Paradise Blvd, Athens, GA 30607, USA
| | - Norba Targa
- Boehringer Ingelheim Animal Health, 1730 Olympic Drive, Athens, GA 30601, USA
| | - Richard Bruner
- Research Pathology Associates, LLC, 401 Augusta Road, Clemson, SC 29631, USA
| | - Stephen Yoon
- Boehringer Ingelheim Animal Health, 1730 Olympic Drive, Athens, GA 30601, USA
| | - Beth Colley
- Boehringer Ingelheim Animal Health (BI AH), 6498 Jade Rd, Fulton, MO 65251, USA
| | - Becky Fankhauser
- Boehringer Ingelheim Animal Health, 1730 Olympic Drive, Athens, GA 30601, USA
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Martin EM, Mitchell EB, Yoon S, McCall JW, Fankhauser B, Mansour A, McCall S, Pollmeier M. Efficacy of moxidectin, using various dose regimens, against JYD-34, a macrocyclic lactone resistant isolate of Dirofilaria immitis. Parasit Vectors 2024; 17:176. [PMID: 38575969 PMCID: PMC10996163 DOI: 10.1186/s13071-024-06149-0] [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: 10/06/2023] [Accepted: 01/21/2024] [Indexed: 04/06/2024] Open
Abstract
BACKGROUND Macrocyclic lactones (MLs) are the only class of drugs currently commercially available that are effective for preventing heartworm disease. The data presented in this article provide information on the efficacy of oral moxidectin against JYD-34, a known ML-resistant Dirofilaria immitis isolate, when dogs are treated under various dosing regimens. METHODS Fifty-two purpose-bred Beagle dogs were used in five laboratory studies. All dogs were inoculated with 50 D. immitis third-stage larvae (L3) (JYD-34 isolate) 30 days prior to the first treatment. Dogs were randomized to treatment (four to five animals in each group) with one, three, or five monthly doses of oral moxidectin ranging from 6 to 100 µg/kg body weight. In each study, control dogs were not treated. Five to 6 months after L3 inoculation, dogs were euthanized, and adult worms were counted to evaluate efficacy of the dosing regimens. RESULTS Adult heartworms were recovered from all control dogs, with an overall geometric mean of 29.7 worms (range 15.2 to 38.0, individual counts ranged from 8 to 51). Five monthly doses of 6 µg/kg provided 83.3% and 90.2%, efficacy, and the same number of monthly doses of 9 µg/kg demonstrated 98.8% and 94.1% efficacy. Three monthly doses of 30 and 50 µg/kg demonstrated 97.9% and 99.0% efficacy, respectively, while a single dose of 100 µg/kg demonstrated 91.1% efficacy. CONCLUSIONS Five monthly doses of 9 µg/kg provided similar or only marginally lower efficacy against JYD-34, a known ML-resistant isolate, compared to substantially higher doses administered for 3 months. This underscores the importance of duration of exposure to moxidectin when facing ML-resistant isolates. Repeated administration of lower doses of moxidectin are an alternative to higher doses in the prevention of heartworm disease associated with less susceptible or resistant isolates.
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Affiliation(s)
- Elizabeth M Martin
- Boehringer Ingelheim Animal Health, 1730 Olympic Drive, Athens, GA, 30601, USA.
| | | | - Stephen Yoon
- Boehringer Ingelheim Animal Health, 1730 Olympic Drive, Athens, GA, 30601, USA
| | - John W McCall
- TRS Labs, Inc, 215 Paradise Blvd, Athens, GA, 30607, USA
| | - Becky Fankhauser
- Boehringer Ingelheim Animal Health, 1730 Olympic Drive, Athens, GA, 30601, USA
| | | | - Scott McCall
- TRS Labs, Inc, 215 Paradise Blvd, Athens, GA, 30607, USA
| | - Matthias Pollmeier
- Boehringer Ingelheim Vetmedica GmbH, Binger Str. 173, 55216, Ingelheim Am Rhein, Germany
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Nogrado K, Adisakwattana P, Reamtong O. Human gnathostomiasis: A review on the biology of the parasite with special reference on the current therapeutic management. Food Waterborne Parasitol 2023; 33:e00207. [PMID: 37719690 PMCID: PMC10502356 DOI: 10.1016/j.fawpar.2023.e00207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Revised: 09/04/2023] [Accepted: 09/05/2023] [Indexed: 09/19/2023] Open
Abstract
Gnathostoma is a parasitic nematode that can infect a wide range of animal species, but human populations have become accidental hosts because of their habit of eating raw or undercooked meat from a wide variety of intermediate hosts. While gnathostomiasis is considered an endemic disease, cases of human gnathostomiasis have been increasing over time, most notably in nonendemic areas. There are several complexities to this parasitic disease, and this review provides an update on human gnathostomiasis, including the life cycle, diagnosis, treatment, and treatment strategies used to combat drug resistance. Even now, a definitive diagnosis of gnathostomiasis is still challenging because it is difficult to isolate larvae for parasitological confirmation. Another reason is the varying clinical symptoms recorded in reported cases. Clinical cases can be confirmed by immunodiagnosis. For Gnathosotoma spinigerum, the detection of IgG against a specific antigenic band with a molecular weight of 24 kDa from G. spinigerum advanced third-stage larvae (aL3), while for other species of Gnathostoma including G. binucleatum, the 33-kDa antigen protein is being used. This review also discusses cases of recurrence of gnathostomiasis and resistance mechanisms to two effective chemotherapeutics (albendazole and ivermectin) used against gnathostomiasis. This is significant, especially when planning strategies to combat anthelmintic resistance. Lastly, while no new chemotherapeutics against gnathostomiasis have been made available, we describe the management of recurrent gnathostomiasis using albendazole and ivermectin combinations or extensions of drug treatment plans.
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Affiliation(s)
- Kathyleen Nogrado
- Department of Molecular Tropical Medicine and Genetics, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Poom Adisakwattana
- Department of Helminthology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Onrapak Reamtong
- Department of Molecular Tropical Medicine and Genetics, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
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Geary TG. New paradigms in research on Dirofilaria immitis. Parasit Vectors 2023; 16:247. [PMID: 37480077 PMCID: PMC10362759 DOI: 10.1186/s13071-023-05762-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Accepted: 03/30/2023] [Indexed: 07/23/2023] Open
Abstract
BACKGROUND Since the advent of ivermectin (along with melarsomine and doxycycline), heartworm has come to be viewed as a solved problem in veterinary medicine, diminishing investment into non-clinical research on Dirofilaria immitis. However, heartworm infections continue to pose problems for practitioners and their patients and seem to be increasing in frequency and geographic distribution. Resistance to preventative therapies (macrocyclic lactones) complicates the picture. The use of chemotherapy for other kinds of pathogens has benefitted enormously from research into the basic biology of the pathogen and on the host-pathogen interface. A lack of basic information on heartworms as parasites and how they interact with permissive and non-permissive hosts greatly limits the ability to discover new ways to prevent and treat heartworm disease. Recent advances in technical platforms will help overcome the intrinsic barriers that hamper research on D. immitis, most notably, the need for experimentally infected dogs to maintain the life cycle and provide material for experiments. Impressive achievements in the development of laboratory animal models for D. immitis will enhance efforts to discover new drugs for prevention or treatment, to characterize new diagnostic biomarkers and to identify key parasite-derived molecules that are essential for survival in permissive hosts, providing a rational basis for vaccine discovery. A 'genomics toolbox' for D. immitis could enable unprecedented insight into the negotiations between host and parasite that enable survival in a permissive host. The more we know about the pathogen and how it manipulates its host, the better able we will be to protect companion animals far into the future.
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Affiliation(s)
- Timothy G Geary
- Institute of Parasitology, McGill University, Ste-Anne-de-Bellevue, QC, Canada.
- School of Biological Sciences, Queen's University-Belfast, Belfast, Northern Ireland.
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Mathur S, Malpas PB, Mahabir S, Boucher J, Pullins A, Gagnon G, McTier TL, Maeder S. Safety of Simparica Trio ® (sarolaner, pyrantel, moxidectin) in heartworm-infected dogs. Parasit Vectors 2023; 16:119. [PMID: 37004097 PMCID: PMC10064668 DOI: 10.1186/s13071-023-05700-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Accepted: 02/13/2023] [Indexed: 04/03/2023] Open
Abstract
BACKGROUND Assessment of the safety of heartworm preventatives in dogs with pre-existing patent heartworm (Dirofilaria immitis) infections is necessary because rapid adult worm and microfilarial death can lead to severe clinical complications, including thromboembolism and anaphylactic shock in dogs. The aim of this study was to determine the clinical safety of Simparica Trio® (sarolaner, pyrantel, moxidectin) in heartworm-infected dogs and the degree of microfilaricidal and adulticidal activity of three consecutive monthly treatments of Simparica Trio. METHODS Twenty-four laboratory Beagle dogs were implanted with 10 male and 10 female D. immitis (ZoeKY isolate), and once infection was patent, they were randomized equally among three groups to receive no treatment, 1× or 3× the maximum recommended label dose of Simparica Trio. Dogs in the treated groups received Simparica Trio on days 0, 28 and 56. In-life assessments included body weight, physical examinations, clinical observations, daily general health observations, a quantitative estimate of food consumption and blood collections for pharmacokinetic (PK) analysis, microfilariae (MF) counts and D. immitis antigen testing. At the end of the study the heart, lungs and pleural and peritoneal cavities were examined for adult D. immitis worms. RESULTS Simparica Trio was generally well tolerated. Emesis occurred at low frequency in all groups including control. Abnormal stool occurred occasionally in the 1× and 3× groups throughout the 3-month study. Fever (> 104 °F/40 °C) was recorded in one 1× and one 3× dog 1 day after the first dose and resolved by the following day. No severe hypersensitivity reactions occurred. The mean number of circulating microfilariae (MF) counts in the control group increased from 12,000/ml at study start (Day 0) to > 20,000/ml at Day 28 and remained > 20,000/ml for the duration of the study. The least squares means of circulating MF were reduced by 69.8% on Day 1 and 97.4% on Day 7 for the 1× group and remained at > 99% lower than the control group for the remainder of the study. Similarly, least squares means of circulating MF were reduced by 85.3% on Day 1 and 93.9% on Day 7 for the 3× group and remained > 98% lower than the control group for the remainder of the study. At the end of the study, the mean number of implanted adult worms recovered was < 10 per sex in all groups with 90%, 85% and 75% of live adult heartworms recovered in control, 1× and 3× treatment groups, respectively. Low numbers of dead adult worms were recovered in 1× and 3×, with none in control. Following each dose, the moxidectin and sarolaner AUC and Cmax had close to dose proportional increases. CONCLUSIONS This study demonstrated that Simparica Trio (sarolaner, pyrantel, moxidectin) was well tolerated when administered to heartworm-positive dogs at 1× and 3× the maximum recommended dose at 28-day intervals for 3 consecutive months. Simparica Trio significantly reduced microfilaria counts in both treatment groups, without significant clinical consequences. At the doses administered, Simparica Trio had minor adulticidal activity but resulted in no clinical sequelae.
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Affiliation(s)
- Sheerin Mathur
- Zoetis, Veterinary Medicine Research and Development, Michigan, 49007, USA.
| | - Phyllis B Malpas
- Zoetis, Veterinary Medicine Research and Development, Michigan, 49007, USA
| | - Sean Mahabir
- Zoetis, Veterinary Medicine Research and Development, Michigan, 49007, USA
| | - Joseph Boucher
- Zoetis, Veterinary Medicine Research and Development, Michigan, 49007, USA
| | - Aleah Pullins
- Zoetis, Veterinary Medicine Research and Development, Michigan, 49007, USA
| | - Genevieve Gagnon
- Zoetis, Veterinary Medicine Research and Development, Michigan, 49007, USA
| | - Tom L McTier
- Zoetis, Veterinary Medicine Research and Development, Michigan, 49007, USA
| | - Steven Maeder
- Zoetis, Veterinary Medicine Research and Development, Michigan, 49007, USA
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Savadelis MD, McTier TL, Kryda K, Maeder SJ, Woods DJ. Moxidectin: heartworm disease prevention in dogs in the face of emerging macrocyclic lactone resistance. Parasit Vectors 2022; 15:82. [PMID: 35277180 PMCID: PMC8915515 DOI: 10.1186/s13071-021-05104-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 11/18/2021] [Indexed: 12/04/2022] Open
Abstract
Heartworm (Dirofilaria immitis) disease continues to increase and spread, remaining one of the most important and pathogenic parasitic diseases of dogs, despite the regular use of macrocyclic lactones (MLs) in preventive products. Dogs harboring strains of D. immitis resistant to MLs, the only drug class available for heartworm prevention in the United States, have been documented and proven. As no new products are available utilizing a novel drug class for the prevention of this disease, the only options for combating ML resistance include increasing the dose and/or changing the dosage regime of current MLs, or by optimizing the formulations of MLs currently available. Moxidectin provides a unique opportunity for optimization of the dose and formulation, which may provide improved efficacy against ML-resistant strains. Currently there are oral, topical, and injectable moxidectin products approved for heartworm prevention in the USA. Two new products (ProHeart® 12 and Simparica Trio®), available in many countries around the world including the USA, take advantage of the unique attributes of moxidectin for providing robust heartworm prevention against the strains of heartworm to which most dogs in the USA will likely be exposed. Both products have demonstrated 100% preventive efficacy in laboratory studies against recently collected field strains of heartworm, and also in large field studies, where the majority of dogs were living in the southern USA in areas where ML resistance has been confirmed to occur, therefore under elevated heartworm challenge. Based on the data summarized here, these products offer important advances in heartworm prevention and provide additional options for veterinarians and pet owners to protect their dogs from developing heartworm disease.
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7
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Wolstenholme AJ, Neveu C. The avermectin/milbemycin receptors of parasitic nematodes. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2022; 181:105010. [PMID: 35082033 DOI: 10.1016/j.pestbp.2021.105010] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 11/24/2021] [Accepted: 12/10/2021] [Indexed: 06/14/2023]
Abstract
Glutamate-gated chloride channels are the most important target of ivermectin and related compounds in parasitic nematodes. A small family of genes encode subunits of these channels, allowing the assembly of multiple channel subtypes; the subunit composition of most of the native receptors is unknown. The members of the gene family vary between species, making extrapolation from C. elegans to parasites difficult. Expression of recombinant receptors in Xenopus oocytes can identify subunits that have the ability to co-assemble into novel channels, but localisation data, ideally at the single-cell level, is required to confirm that these subunits are expressed in the same cells and tissues. Fortunately, recent advances in this area are starting to make this information available; this information is adding to our understanding of how the drugs act and of the possible subunit combinations that create their targets in vivo.
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Affiliation(s)
- Adrian J Wolstenholme
- UMR1282 Infectiologie et Santé Publique, INRAE Centre Val de Loire, 37380 Nouzilly, France.
| | - Cedric Neveu
- UMR1282 Infectiologie et Santé Publique, INRAE Centre Val de Loire, 37380 Nouzilly, France.
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Nunes B, Pinheiro D, Gomes A. Effect of sublethal concentrations of the antiparasitic ivermectin on the polychaeta species Hediste diversicolor: biochemical and behavioral responses. ECOTOXICOLOGY (LONDON, ENGLAND) 2021; 30:1841-1853. [PMID: 34224071 DOI: 10.1007/s10646-021-02444-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 06/08/2021] [Indexed: 06/13/2023]
Abstract
Pharmaceutical drugs have emerged as major micropollutants in aquatic ecosystems. Their presence has been systematically reported in monitoring surveys, and their wide distribution and constant presence in the wild is a direct consequence of their massive use, in both human and veterinary therapeutics. Drugs used to treat parasitic infections in livestock are major contaminants, given the amounts in which they are administered, and reach the aquatic compartment in high amounts, where they may affect non target species. Some of these drugs are prone to find their final deposit in sediments of estuarine areas, exerting their toxic effects preferentially at these locations. Sediment dwelling organisms of coastal areas, such as polychaetas, are especially prone to have their major physiological functions compromised after being exposed to pharmaceutical drugs. Ivermectin is one of the most used antiparasitic drugs, and its effects are not limited to biochemical traits, but also behavioral features may be compromised considering their neurotoxic actions. Despite these putative effects, little is known about their toxicity on polychaetas. The present study aimed to characterize the toxicity of realistic levels of ivermectin on the polychaeta Hediste diversicolor, in biochemical and behavioral terms. The obtained results showed that low levels of ivermectin are capable of causing significant disturbances in mobility and burrowing activity of exposed worms, as well as alterations of metabolic and anti-oxidant defense efficacy of exposed animals, suggesting that its environmental presence may mean a major environmental concern.
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Affiliation(s)
- B Nunes
- Departamento de Biologia da Universidade de Aveiro, Campus de Santiago, 3810-193, Aveiro, Portugal.
- Centro de Estudos do Ambiente e do Mar (CESAM), Campus de Santiago, Universidade de Aveiro, 3810-193, Aveiro, Portugal.
| | - D Pinheiro
- Departamento de Física da Universidade de Aveiro, Campus de Santiago, 3810-193, Aveiro, Portugal
| | - A Gomes
- Departamento de Biologia da Universidade de Aveiro, Campus de Santiago, 3810-193, Aveiro, Portugal
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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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Noack S, Harrington J, Carithers DS, Kaminsky R, Selzer PM. Heartworm disease - Overview, intervention, and industry perspective. Int J Parasitol Drugs Drug Resist 2021; 16:65-89. [PMID: 34030109 PMCID: PMC8163879 DOI: 10.1016/j.ijpddr.2021.03.004] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 03/26/2021] [Accepted: 03/30/2021] [Indexed: 02/06/2023]
Abstract
Dirofilaria immitis, also known as heartworm, is a major parasitic threat for dogs and cats around the world. Because of its impact on the health and welfare of companion animals, heartworm disease is of huge veterinary and economic importance especially in North America, Europe, Asia and Australia. Within the animal health market many different heartworm preventive products are available, all of which contain active components of the same drug class, the macrocyclic lactones. In addition to compliance issues, such as under-dosing or irregular treatment intervals, the occurrence of drug-resistant heartworms within the populations in the Mississippi River areas adds to the failure of preventive treatments. The objective of this review is to provide an overview of the disease, summarize the current disease control measures and highlight potential new avenues and best practices for treatment and prevention.
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Affiliation(s)
- Sandra Noack
- Boehringer Ingelheim Animal Health, Binger Str. 173, 55216, Ingelheim am Rhein, Germany
| | - John Harrington
- Boehringer Ingelheim Animal Health, 1730 Olympic Drive, 30601, Athens, GA, USA
| | - Douglas S Carithers
- Boehringer Ingelheim Animal Health, 3239 Satellite Blvd, 30096, Duluth, GA, USA
| | - Ronald Kaminsky
- paraC Consulting, Altenstein 13, 79685, Häg-Ehrsberg, Germany
| | - Paul M Selzer
- Boehringer Ingelheim Animal Health, Binger Str. 173, 55216, Ingelheim am Rhein, Germany.
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11
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Wilson NE, Reaves BJ, Wolstenholme AJ. Lack of detectable short-term effects of a single dose of ivermectin on the human immune system. Parasit Vectors 2021; 14:304. [PMID: 34090504 PMCID: PMC8179708 DOI: 10.1186/s13071-021-04810-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Accepted: 05/25/2021] [Indexed: 12/03/2022] Open
Abstract
Background Ivermectin is widely used in human and animal medicine to treat and prevent parasite nematode infections. It has been suggested that its mode of action requires the host immune system, as it is difficult to reproduce its clinical efficacy in vitro. We therefore studied the effects of a single dose of ivermectin (Stromectol®—0.15 mg/kg) on cytokine levels and immune cell gene expression in human volunteers. This dose reduces bloodstream microfilariae rapidly and for several months when given in mass drug administration programmes. Methods Healthy volunteers with no travel history to endemic regions were given 3–4 tablets, depending on their weight, of either ivermectin or a placebo. Blood samples were drawn immediately prior to administration, 4 h and 24 h afterwards, and complete blood counts performed. Serum levels of 41 cytokines and chemokines were measured using Luminex® and expression levels of 770 myeloid-cell-related genes determined using the NanoString nCounter®. Cytokine levels at 4 h and 24 h post-treatment were compared to the levels pre-treatment using simple t tests to determine if any individual results required further investigation, taking p = < 0.05 as the level of significance. NanoString data were analysed on the proprietary software, nSolver™. Results No significant differences were observed in complete blood counts or cytokine levels at either time point between people given ivermectin versus placebo. Only three genes showed a significant change in expression in peripheral blood mononuclear cells 4 h after ivermectin was given; there were no significant changes 24 h after drug administration or in polymorphonuclear cells at either time point. Leukocytes isolated from those participants given ivermectin showed no difference in their ability to kill Brugia malayi microfilariae in vitro. Conclusions Overall, our data do not support a direct effect of ivermectin, when given at the dose used in current filarial elimination programmes, on the human immune system. Trial registration ClinicalTrials.gov NCT03459794 Registered 9th March 2018, Retrospectively registered https://clinicaltrials.gov/ct2/show/NCT03459794?term=NCT03459794&draw=2&rank=1. Graphic abstract ![]()
Supplementary Information The online version contains supplementary material available at 10.1186/s13071-021-04810-6.
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Affiliation(s)
- Natalie E Wilson
- Department of Infectious Diseases, University of Georgia, Athens, GA, 30602, USA.,Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, 30602, USA
| | - Barbara J Reaves
- Department of Infectious Diseases, University of Georgia, Athens, GA, 30602, USA.,Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, 30602, USA
| | - Adrian J Wolstenholme
- Department of Infectious Diseases, University of Georgia, Athens, GA, 30602, USA. .,Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, 30602, USA. .,INRAE Centre Val du Loire, 37380, Nouzilly, France.
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Keiser J, Häberli C. Evaluation of Commercially Available Anthelminthics in Laboratory Models of Human Intestinal Nematode Infections. ACS Infect Dis 2021; 7:1177-1185. [PMID: 33410658 DOI: 10.1021/acsinfecdis.0c00719] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Drug repurposing from veterinary to human medicine has been the main strategy to develop the four recommended human anthelminthics, albendazole, mebendazole, levamisole, and pyrantel pamoate, for the treatment of soil-transmitted helminthiasis. A systematic, head-to-head comparison of the anthelminthic activity profile of derivatives of these drugs and other anthelminthics developed in succession has not been conducted to date. We studied eight benzimidazoles, five macrocyclic lactones, tribendimidine, levamisole, and pyrantel pamoate in laboratory models of human intestinal nematode infections. In vitro studies were performed on Trichuris muris L1 larval stage and adults, as well as Ancylostoma ceylanicum, Necator americanus, Heligmosomoides polygyrus, and Strongyloides ratti L3 larvae and adults. The benzimidazoles showed pronounced differences against larval and adult stages, with low activity against larvae and the highest activity observed against adult N. americanus (IC50 of flubendazole 1.1 μM). The macrocyclic lactones, on the other hand, revealed a higher activity on the larval stages, with the lowest IC50 values observed against N. americanus L3 (IC50 values of 0.03-3 μM). In vivo studies were performed in the T. muris and H. polygyrus mice models, with moxidectin and milbemycin oxime showing the highest activity against H. polygyrus (ED50 values of 0.009 and 0.006 mg/kg, respectively) and moxidectin and abamectin being the most effective drugs against T. muris (ED50 values of 0.2 and 0.5 mg/kg, respectively). Laboratory models for soil-transmitted helminthiasis can assist characterizing potential drug candidates. Drugs should be evaluated against different species, and both the adult and larval stages as activities could differ considerably.
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Affiliation(s)
- Jennifer Keiser
- Swiss Tropical and Public Health Institute, Socinstrasse 57, CH-4051 Basel, Switzerland
- University of Basel, CH-4003 Basel, Switzerland
| | - Cécile Häberli
- Swiss Tropical and Public Health Institute, Socinstrasse 57, CH-4051 Basel, Switzerland
- University of Basel, CH-4003 Basel, Switzerland
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Bedair A, Mansour FR. Insights into the FDA 2018 New Drug Approvals. Curr Drug Discov Technol 2021; 18:293-306. [PMID: 31793428 DOI: 10.2174/1570163816666191202104315] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 11/09/2019] [Accepted: 11/11/2019] [Indexed: 11/22/2022]
Abstract
OBJECTIVE The Center of Drug Evaluation and Research (CDER) in the food and drug administration (FDA) approves new drugs every year. This review discusses the novel drugs of the FDA in 2018, with emphasis on the breakthrough drugs, the milestones in the approved list, and drugs with the highest expected sales in 2024. METHODS The following scientific search engines were surveyed for the clinical trials of the drugs approved by the FDA in 2018: Pubmed, Springer link, ScienceDirect, Scopus, Wiley online library, Taylor and Francis, and Google Scholar. The total forecast sales were compared based on information from the Cortellis database, EvaluatePharma, and Nature Biobusiness Briefs. RESULTS The 2018 year was full of good news for the drug market in the USA, with 59 new drug approvals by the FDA, which is the highest number of approvals in the last twenty years. The oncology and the antimicrobial drugs represent almost 50% of the new list, which gives hope to cancer patients and subjects with infectious diseases. In the 2018 FDA list, a number of drugs are expected to exceed 1$ billion dollars of sales by 2024. CONCLUSION The new drugs approved by the FDA in 2018 have been reviewed. This year showed the highest number of new drug approvals in the last two decades. Among the 59 drugs approved in 2018, 14 drugs are considered breakthroughs, which revive hope for many poorly managed diseases. The list also contains 19 drugs that are first in class and 43 that were given priority reviews.
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Affiliation(s)
- Alaa Bedair
- Department of Pharmaceutical Analytical Chemistry, Faculty of Pharmacy, University of Sadat City, 32958, Egypt
| | - Fotouh R Mansour
- Department of Pharmaceutical Analytical Chemistry, Faculty of Pharmacy, Tanta University, 31111, Egypt
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14
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Ponraj P, De AK, Mondal S, Ravi SK, Sawhney S, Sarkar G, Bera AK, Malakar D, Kumar A, Singh LB, Ahmed SZ, Muniswamy K, Jerard BA, Bhattacharya D. Tri-Model Therapy: Combining Macrocyclic Lactone, Piperazine Derivative and Herbal Preparation in Treating Humpsore in Cattle. Vet Sci 2021; 8:vetsci8020027. [PMID: 33668568 PMCID: PMC7918163 DOI: 10.3390/vetsci8020027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Revised: 02/06/2021] [Accepted: 02/09/2021] [Indexed: 11/23/2022] Open
Abstract
Stephanofilariasis or humpsore is a chronic parasitic dermatitis of cattle. Various treatment regimens were attempted in the past but were found to be partially effective. Here, we claim a successful treatment regime using an FDA-approved macrocyclic lactone, a piperazine derivative, and an herbal preparation. Twenty-four cattle (18 affected and 6 unaffected) were selected and divided into Gr 1: positive control (infected without treatment; n = 6), Gr 2: treatment group (infected with treatment with ivermectin; n = 6), Gr 3: treatment group (infected with treatment with tri-model therapy including ivermectin, diethylcarbamazine citrate, and an herbal ointment, n = 6), and Gr 4: negative control (non-infected animals; n = 6). In Gr 2 and Gr 3, treatment to the ailing animals were given for 30 days. Lesion was significantly reduced in day 15 of post-treatment and completely healed on day 30 of post-treatment in Gr 3. Tri-model therapy recorded significant improvement in the surface area of the sore as compared to ivermectin administration alone. Antioxidants were increased and malondialdehyde (MDA) and cortisol concentrations were decreased significantly (p < 0.05) in Gr 3 than in untreated control group at day 14, 21 and 28. Histopathological changes in infected animals were characterized by parakeratotic hyperkeratosis along with presence of nucleated keratinocytes. There were infiltrations of polymorphonuclear cells specially eosinophils along with a few monomorphonuclear cells. Microfilarial organism was observed beneath the epidermis, which was surrounded by fibrocytes and infiltrated cells. In the tri-model-treated animal after recovery, the skin revived a normal architecture. Therefore, tri-model therapy has the potential to cure humpsore.
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Affiliation(s)
- Perumal Ponraj
- Animal Science Division, ICAR-Central Island Agricultural Research Institute, Port Blair 744101, Andaman and Nicobar Islands, India; (P.P.); (S.K.R.); (S.S.); (K.M.); (D.B.)
| | - Arun Kumar De
- Animal Science Division, ICAR-Central Island Agricultural Research Institute, Port Blair 744101, Andaman and Nicobar Islands, India; (P.P.); (S.K.R.); (S.S.); (K.M.); (D.B.)
- Correspondence: ; Tel.: +91-967-951-5260
| | - Samiran Mondal
- Department of Veterinary Pathology, West Bengal University of Animal and Fishery Sciences, Kolkata 700037, West Bengal, India; (S.M.); (G.S.)
| | - Sanjay Kumar Ravi
- Animal Science Division, ICAR-Central Island Agricultural Research Institute, Port Blair 744101, Andaman and Nicobar Islands, India; (P.P.); (S.K.R.); (S.S.); (K.M.); (D.B.)
| | - Sneha Sawhney
- Animal Science Division, ICAR-Central Island Agricultural Research Institute, Port Blair 744101, Andaman and Nicobar Islands, India; (P.P.); (S.K.R.); (S.S.); (K.M.); (D.B.)
| | - Gopal Sarkar
- Department of Veterinary Pathology, West Bengal University of Animal and Fishery Sciences, Kolkata 700037, West Bengal, India; (S.M.); (G.S.)
| | - Asit Kumar Bera
- Reservoir and Wetland Fisheries Division, ICAR-Central Inland Fishery Research Institute, Barrackpore, Kolkata 700120, West Bengal, India;
| | - Dhruba Malakar
- Animal Biotechnology Centre, National Dairy Research Institute, Karnal 132001, Haryana, India;
| | - Ashish Kumar
- CTARA, IIT Bombay, Mumbai 400076, Maharashtra, India;
| | - Laishram Brojendra Singh
- Krishi Vigyan Kendra, ICAR-Central Island Agricultural Research Institute, Port Blair 744101, Andaman and Nicobar Islands, India;
| | - Sheikh Zamir Ahmed
- Social Science Section, ICAR-Central Island Agricultural Research Institute, Port Blair 744101, Andaman and Nicobar Islands, India;
| | - Kangayan Muniswamy
- Animal Science Division, ICAR-Central Island Agricultural Research Institute, Port Blair 744101, Andaman and Nicobar Islands, India; (P.P.); (S.K.R.); (S.S.); (K.M.); (D.B.)
| | - Bosco Augustine Jerard
- Horticulture and Forestry Division, ICAR-Central Island Agricultural Research Institute, Port Blair 744101, Andaman and Nicobar Islands, India;
| | - Debasis Bhattacharya
- Animal Science Division, ICAR-Central Island Agricultural Research Institute, Port Blair 744101, Andaman and Nicobar Islands, India; (P.P.); (S.K.R.); (S.S.); (K.M.); (D.B.)
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Marino V, Gálvez R, Mascuñán C, Domínguez I, Sarquis J, Montoya A, Barrera JP, Zenker C, Checa R, Hernández M, Miró G. Update on the treatment and prevention of ocular thelaziosis (Thelazia callipaeda) in naturally infected dogs from Spain. Int J Parasitol 2021; 51:73-81. [PMID: 33091413 DOI: 10.1016/j.ijpara.2020.08.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 07/23/2020] [Accepted: 08/04/2020] [Indexed: 01/19/2023]
Abstract
This study examines the therapeutic and year-round prophylactic efficacy of different formulations used in dogs in three Spanish areas where canine thelaziosis is endemic. The study was conducted as a Good Clinical Practice, multicentre, randomised field study in privately owned outdoor dogs naturally infected with Thelazia callipaeda. The active pharmaceutical ingredients tested were: an oral formulation of milbemycin oxime 12.5 mg combined with praziquantel 125 mg (A), a subcutaneous sustained-release formulation of moxidectin 10 g (B), a moxidectin 2.5% weight/volume (w/v) spot-on formulation combined with imidacloprid 10% w/v (C), and an eye drop formulation (6 µg) of ivermectin 10 mg/ml diluted 10% in propylene glycol (D). Infected dogs were randomly allocated to treatment Groups A, B, C and D. Dogs testing negative for T. callipaeda inspection in two visits (Day 7/Day 14 and D30) were enrolled in the prophylaxis trial and reallocated to the corresponding study group (A, B, C or D). Treatment efficacy ranged from 70.4% recorded in Group A 1 week after treatment, to 100% recorded in Group C on Day 30 and in Group B on Day 60. Treatment was more efficacious in Group D (85.7% 1 week after treatment) than A, but was never 100% efficacious as in Groups B and C. Year-round prophylactic efficacy was 83.3% in Group A, 100% in Group B, 93.5% in Group C and 87.5% in Group D. In conclusion, products containing moxidectin were highly efficacious both in treating and preventing canine thelaziosis. Milbemycin also emerged as a good option. However, the off-label use of topical or subcutaneous ivermectin should be avoided due to possible adverse reactions such as pruritus, irritation or redness. In endemic areas, monthly prophylaxis to limit the spread of T. callipaeda to new areas across Europe and reduce zoonotic risks is essential.
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Affiliation(s)
- Valentina Marino
- Animal Health Department, Veterinary Faculty, Universidad Complutense de Madrid, Madrid, Spain
| | - Rosa Gálvez
- Department of Specific Didactics, School of Education and Teacher Training, Universidad Autónoma de Madrid, Madrid, Spain
| | - Carmen Mascuñán
- La Cruz Verde Veterinary Clinic, Miraflores de la Sierra, Madrid, Spain
| | | | - Juliana Sarquis
- Animal Health Department, Veterinary Faculty, Universidad Complutense de Madrid, Madrid, Spain
| | - Ana Montoya
- Animal Health Department, Veterinary Faculty, Universidad Complutense de Madrid, Madrid, Spain
| | - Juan Pedro Barrera
- Animal Health Department, Veterinary Faculty, Universidad Complutense de Madrid, Madrid, Spain
| | - Clara Zenker
- La Plaza Veterinary Clinic, El Escorial, Madrid, Spain
| | - Rocío Checa
- Animal Health Department, Veterinary Faculty, Universidad Complutense de Madrid, Madrid, Spain
| | | | - Guadalupe Miró
- Animal Health Department, Veterinary Faculty, Universidad Complutense de Madrid, Madrid, Spain.
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Dolzhenko T, Burkova L, Dolzhenko O, Laptiev A. Biorational insectoacaricides based on avermectins to protect grapes. BIO WEB OF CONFERENCES 2021. [DOI: 10.1051/bioconf/20213404010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The article presents an assessment of the biological effectiveness of biorational insectoacaricides based on abamectin and emamectin benzoate – metabolites of soil actinomycetes, to protect grapes from pests. We studied the effectiveness of new drugs: Mekar, ME (18 g/l abamectin) and Mabet, EC (18 g/l abamectin) against Schizotetranychus pruni; Yunona, ME (50 g/l emamectin benzoate), Emakleim, VRG (50 g/l emamectin benzoate) and Proclame Fit, WDG (400 g/kg lufenuron + 50 g/kg emamectin) against Lobesia botrana in the Krasnodar Region. According to the research results, the drugs Mekar, ME (18 g/l), Yunona, ME (50 g/l) and Proclame Fit, WDG (400 g/kg + 50 g/kg) are included in the State Catalog of Pesticides and Agrochemicals Permitted for Use on the territory of the Russian Federation and can be used in biologized and adaptively integrated grape protection systems.
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Whole-genome reference of Dirofilaria immitis from Australia to determine single nucleotide polymorphisms associated with macrocyclic lactone resistance in the USA. CURRENT RESEARCH IN PARASITOLOGY & VECTOR-BORNE DISEASES 2021; 1:100007. [PMID: 35284873 PMCID: PMC8906102 DOI: 10.1016/j.crpvbd.2021.100007] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 01/03/2021] [Accepted: 01/05/2021] [Indexed: 11/20/2022]
Abstract
For the past 30 years, chemoprophylaxis with macrocyclic lactone (ML) anthelmintics has been the primary strategy for canine heartworm (Dirofilaria immitis) control in both the USA and Australia. ML-resistant D. immitis isolates have been confirmed to exist in the USA and studies have shown that 42 single nucleotide polymorphisms (SNPs) are associated with phenotypic ML-resistance. Currently, ML-resistance has not been reported in any Australian clinical cases of canine heartworm. The aim of the study is to determine whether the 42 SNPs associated with resistance to MLs in the isolates from the USA are present in adult heartworms from a clinical case in Australia. Five adult D. immitis obtained from a dog at post-mortem (Sydney, Australia) were sequenced using the Illumina sequencing technology. The genomic analyses revealed 6 out of the 42 SNPs associated with ML-resistance to be present in our samples, 3 out of the 6 SNPs identified were nonsynonymous SNPs but not in candidate genes for ML-resistance. ML-susceptibility profile was mixed using the 42-SNP and 10-SNP models, but the 5-SNP, 3-SNP and 2-SNP models demonstrated ML susceptibility for all five individuals. In this study, the first whole-genome reference of D. immitis from Australia establishes a new baseline for comparative studies and will be valuable for tracking ML-resistance emergence. Dirofilaria immitis from Sydney, Australia, sequenced using the Illumina NGS technology. New baseline for comparative studies for tracking ML-resistance emergence in Australia. Mixed ML-susceptibility profile using the 42-SNP and 10-SNP models. 5-SNP, 3-SNP and 2-SNP models demonstrated ML susceptibility.
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18
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Nixon SA, Welz C, Woods DJ, Costa-Junior L, Zamanian M, Martin RJ. Where are all the anthelmintics? Challenges and opportunities on the path to new anthelmintics. Int J Parasitol Drugs Drug Resist 2020; 14:8-16. [PMID: 32814269 PMCID: PMC7452592 DOI: 10.1016/j.ijpddr.2020.07.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 07/07/2020] [Accepted: 07/10/2020] [Indexed: 01/03/2023]
Abstract
Control of helminth parasites is a key challenge for human and veterinary medicine. In the absence of effective vaccines and adequate sanitation, prophylaxis and treatment commonly rely upon anthelmintics. There are concerns about the development of drug resistance, side-effects, lack of efficacy and cost-effectiveness that drive the need for new classes of anthelmintics. Despite this need, only three new drug classes have reached the animal market since 2000 and no new classes of anthelmintic have been approved for human use. So where are all the anthelmintics? What are the barriers to anthelmintic discovery, and what emerging opportunities can be used to address this? This was a discussion group focus at the 2019 8th Consortium for Anthelmintic Resistance and Susceptibility (CARS) in Wisconsin, USA. Here we report the findings of the group in the broader context of the human and veterinary anthelmintic discovery pipeline, highlighting challenges unique to antiparasitic drug discovery. We comment on why the development of novel anthelmintics has been so rare. Further, we discuss potential opportunities for drug development moving into the 21st Century.
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Affiliation(s)
- Samantha A Nixon
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, Australia; CSIRO Agriculture and Food, Queensland Bioscience Precinct, St Lucia, Australia
| | | | - Debra J Woods
- Zoetis, Veterinary Medicine Research and Development, Kalamazoo, MI, USA
| | - Livio Costa-Junior
- Federal University of Maranhão, Pathology Department, São Luís, Maranhão, Brazil
| | - Mostafa Zamanian
- Department of Pathobiological Sciences, University of Wisconsin-Madison, Madison, WI, USA
| | - Richard J Martin
- Department of Biomedical Sciences, Iowa State University, Ames, IA, USA.
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19
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Loghry HJ, Yuan W, Zamanian M, Wheeler NJ, Day TA, Kimber MJ. Ivermectin inhibits extracellular vesicle secretion from parasitic nematodes. J Extracell Vesicles 2020; 10:e12036. [PMID: 33318780 PMCID: PMC7726798 DOI: 10.1002/jev2.12036] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 11/18/2020] [Accepted: 11/20/2020] [Indexed: 12/18/2022] Open
Abstract
Lymphatic filariasis (LF) is a disease caused by parasitic filarial nematodes that is endemic in 49 countries of the world and affects or threatens over 890 million people. Strategies to control LF rely heavily on mass administration of anthelmintic drugs including ivermectin (IVM), a macrocyclic lactone drug considered an Essential Medicine by the WHO. However, despite its widespread use the therapeutic mode of action of IVM against filarial nematodes is not clear. We have previously reported that filarial nematodes secrete extracellular vesicles (EVs) and that their cargo has immunomodulatory properties. Here we investigate the effects of IVM and other anti-filarial drugs on parasitic nematode EV secretion, motility, and protein secretion. We show that inhibition of EV secretion was a specific property of IVM, which had consistent and significant inhibitory effects across nematode life stages and species, with the exception of male parasites. IVM inhibited EV secretion, but not parasite motility, at therapeutically relevant concentrations. Protein secretion was inhibited by IVM in the microfilariae stage, but not in any other stage tested. Our data provides evidence that inhibiting the secretion of immunomodulatory EVs by parasitic nematodes could explain, at least in part, IVM mode of action and provides a phenotype for novel drug discovery.
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Affiliation(s)
- Hannah J. Loghry
- Department of Biomedical SciencesCollege of Veterinary MedicineIowa State UniversityAmesIowaUSA
| | - Wang Yuan
- Department of Biomedical SciencesCollege of Veterinary MedicineIowa State UniversityAmesIowaUSA
| | - Mostafa Zamanian
- Department of Pathobiological SciencesUniversity of Wisconsin‐MadisonMadisonWisconsinUSA
| | - Nicolas J. Wheeler
- Department of Pathobiological SciencesUniversity of Wisconsin‐MadisonMadisonWisconsinUSA
| | - Timothy A. Day
- Department of Biomedical SciencesCollege of Veterinary MedicineIowa State UniversityAmesIowaUSA
| | - Michael J. Kimber
- Department of Biomedical SciencesCollege of Veterinary MedicineIowa State UniversityAmesIowaUSA
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20
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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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21
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Partridge FA, Forman R, Bataille CJR, Wynne GM, Nick M, Russell AJ, Else KJ, Sattelle DB. Anthelmintic drug discovery: target identification, screening methods and the role of open science. Beilstein J Org Chem 2020; 16:1203-1224. [PMID: 32550933 PMCID: PMC7277699 DOI: 10.3762/bjoc.16.105] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Accepted: 05/12/2020] [Indexed: 12/13/2022] Open
Abstract
Helminths, including cestodes, nematodes and trematodes, are a huge global health burden, infecting hundreds of millions of people. In many cases, existing drugs such as benzimidazoles, diethylcarbamazine, ivermectin and praziquantel are insufficiently efficacious, contraindicated in some populations, or at risk of the development of resistance, thereby impeding progress towards World Health Organization goals to control or eliminate these neglected tropical diseases. However, there has been limited recent progress in developing new drugs for these diseases due to lack of commercial attractiveness, leading to the introduction of novel, more efficient models for drug innovation that attempt to reduce the cost of research and development. Open science aims to achieve this by encouraging collaboration and the sharing of data and resources between organisations. In this review we discuss how open science has been applied to anthelmintic drug discovery. Open resources, including genomic information from many parasites, are enabling the identification of targets for new antiparasitic agents. Phenotypic screening remains important, and there has been much progress in open-source systems for compound screening with parasites, including motility assays but also high content assays with more detailed investigation of helminth physiology. Distributed open science compound screening programs, such as the Medicines for Malaria Venture Pathogen Box, have been successful at facilitating screening in diverse assays against many different parasite pathogens and models. Of the compounds identified so far in these screens, tolfenpyrad, a repurposed insecticide, shows significant promise and there has been much progress in creating more potent and selective derivatives. This work exemplifies how open science approaches can catalyse drug discovery against neglected diseases.
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Affiliation(s)
- Frederick A Partridge
- Centre for Respiratory Biology, UCL Respiratory, Division of Medicine, University College London, Gower Street, London, WC1E 6BT, United Kingdom
| | - Ruth Forman
- The Lydia Becker Institute for Immunology and Inflammation, Faculty of Biology, Medicine and Health, University of Manchester, Oxford Road, Manchester, M13 9PL, United Kingdom
| | - Carole J R Bataille
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA United Kingdom
| | - Graham M Wynne
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA United Kingdom
| | - Marina Nick
- Centre for Respiratory Biology, UCL Respiratory, Division of Medicine, University College London, Gower Street, London, WC1E 6BT, United Kingdom
| | - Angela J Russell
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA United Kingdom
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, OX1 3QT, United Kingdom
| | - Kathryn J Else
- The Lydia Becker Institute for Immunology and Inflammation, Faculty of Biology, Medicine and Health, University of Manchester, Oxford Road, Manchester, M13 9PL, United Kingdom
| | - David B Sattelle
- Centre for Respiratory Biology, UCL Respiratory, Division of Medicine, University College London, Gower Street, London, WC1E 6BT, United Kingdom
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22
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Ashour DS. Ivermectin: From theory to clinical application. Int J Antimicrob Agents 2019; 54:134-142. [PMID: 31071469 DOI: 10.1016/j.ijantimicag.2019.05.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Revised: 04/27/2019] [Accepted: 05/01/2019] [Indexed: 12/13/2022]
Abstract
Approximately 250 million people have been using ivermectin (IVM) annually to combat many parasitic diseases including filariasis, onchocerciasis, strongyloidiasis, scabies and pediculosis. Many clinical studies have proven its efficacy against these diseases and have reported the optimum dose and duration of treatment. Moreover, its antiparasitic range has increased to cover more parasitic infections, but it still requires further exploration, e.g. for trichinosis and myiasis. Furthermore, IVM showed high efficacy in killing vectors of disease-causing parasites such as mosquitoes, sandflies and tsetse flies. The World Health Organization (WHO) has managed many control programmes involving the use of IVM to achieve elimination of onchocerciasis and lymphatic filariasis and to reduce malaria transmission. However, IVM is not exempt from the possibility of resistance and, certainly, its intensive use has led to the emergence of resistance in some parasites. Recent research is investigating the possibility of novel drug delivery systems for IVM that increase its potential to treat a new range of diseases and to overcome the possibility of drug resistance. This review highlights the most common human uses of IVM, with special reference to the new and promising properties of IVM.
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Affiliation(s)
- Dalia S Ashour
- Medical Parasitology Department, Faculty of Medicine, Tanta University, Tanta, Egypt.
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Berrafato T, Coates R, Reaves BJ, Kulke D, Wolstenholme AJ. Macrocyclic lactone anthelmintic-induced leukocyte binding to Dirofilaria immitis microfilariae: Influence of the drug resistance status of the parasite. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2019; 10:45-50. [PMID: 31054498 PMCID: PMC6500911 DOI: 10.1016/j.ijpddr.2019.04.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 04/25/2019] [Accepted: 04/26/2019] [Indexed: 12/19/2022]
Abstract
The macrocyclic lactone anthelmintics are the only class of drug currently used to prevent heartworm disease. Their extremely high potency in vivo is not mirrored by their activity against Dirofilaria immitis larvae in vitro, leading to suggestions that they may require host immune functions to kill the parasites. We have previously shown that ivermectin stimulates the binding of canine peripheral blood mononuclear cells (PBMCs) and polymorphonuclear leukocytes (PMNs) to D. immitis microfilariae (Mf). We have now extended these studies to moxidectin and examined the ability of both drugs to stimulate canine PBMC and PMN attachment to Mf from multiple strains of D. immitis, including two that are proven to be resistant to ivermectin in vivo. Both ivermectin and moxidectin significantly increased the percentage of drug-susceptible parasites with cells attached at very low concentrations (<10 nM), but much higher concentrations of ivermectin (>100 nM) were required to increase the percentage of the two resistant strains, Yazoo-2013 and Metairie-2014, with cells attached. Moxidectin increased the percentage of the two resistant strains with cells attached at lower concentrations (<10 nM) than did ivermectin. The attachment of the PBMCs and PMNs did not result in any parasite killing in vitro. These data support the biological relevance of the drug-stimulated attachment of canine leukocytes to D. immitis Mf and suggest that this phenomenon is related to the drug resistance status of the parasites. Ivermectin promotes attachment of PMN and PBMC to D. immitis microfilariae in vitro. Moxidectin has a similar effect. Higher ivermectin concentrations are needed if Mf of ML-resistant strains are used. Moxidectin is more effective at promoting cell attachment to resistant Mf. Neither PMN nor PBMC attachment does not result in parasite death in vitro.
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Affiliation(s)
- Tessa Berrafato
- Department of Infectious Diseases, University of Georgia, Athens, GA, 30602, USA; Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, 30602, USA.
| | - Ruby Coates
- Department of Infectious Diseases, University of Georgia, Athens, GA, 30602, USA; Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, 30602, USA.
| | - Barbara J Reaves
- Department of Infectious Diseases, University of Georgia, Athens, GA, 30602, USA; Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, 30602, USA.
| | - Daniel Kulke
- Bayer Animal Health GmbH, 51373, Leverkusen, Germany.
| | - Adrian J Wolstenholme
- Department of Infectious Diseases, University of Georgia, Athens, GA, 30602, USA; Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, 30602, USA.
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Makhani L, Khatib A, Corbeil A, Kariyawasam R, Raheel H, Clarke S, Challa P, Hagopian E, Chakrabarti S, Schwartz KL, Boggild AK. 2018 in review: five hot topics in tropical medicine. Trop Dis Travel Med Vaccines 2019; 5:5. [PMID: 31016025 PMCID: PMC6466725 DOI: 10.1186/s40794-019-0082-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Accepted: 03/28/2019] [Indexed: 02/07/2023] Open
Abstract
The year 2018 heralded many new developments in the field of tropical medicine, including licensure of novel drugs for novel indications, licensure of existing drugs for existing indications but in novel settings, and globalized outbreaks of both vector-borne and zoonotic diseases. We herein describe five top stories in tropical medicine that occurred during 2018, and illuminate the practice-changing development within each story.
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Affiliation(s)
- Leila Makhani
- Department of Family and Community Medicine, University of Toronto, Toronto, Canada
- Tropical Disease Unit, Toronto General Hospital, 200 Elizabeth Street, 13EN-218, Toronto, ON M5G 2C4 Canada
| | - Aisha Khatib
- Department of Family and Community Medicine, University of Toronto, Toronto, Canada
- Tropical Disease Unit, Toronto General Hospital, 200 Elizabeth Street, 13EN-218, Toronto, ON M5G 2C4 Canada
| | - Antoine Corbeil
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Canada
| | | | - Hira Raheel
- Faculty of Medicine, University of Toronto, Toronto, Canada
| | - Shareese Clarke
- Tropical Disease Unit, Toronto General Hospital, 200 Elizabeth Street, 13EN-218, Toronto, ON M5G 2C4 Canada
| | - Priyanka Challa
- Department of Life Science, University of Toronto, Toronto, Canada
| | - Emma Hagopian
- Department of Arts and Science, University of Toronto, Toronto, Canada
| | - Sumontra Chakrabarti
- Tropical Disease Unit, Toronto General Hospital, 200 Elizabeth Street, 13EN-218, Toronto, ON M5G 2C4 Canada
- Department of Medicine, University of Toronto, Toronto, Canada
- Division of Infectious Diseases, Trillium Health Partners, Mississauga, Canada
| | - Kevin L. Schwartz
- Tropical Disease Unit, Toronto General Hospital, 200 Elizabeth Street, 13EN-218, Toronto, ON M5G 2C4 Canada
- Division of Infectious Diseases, St. Joseph’s Health Centre, Toronto, Canada
- Dalla Lana School of Public Health, University of Toronto, Toronto, Canada
- Public Health Ontario, Toronto, Canada
| | - Andrea K. Boggild
- Tropical Disease Unit, Toronto General Hospital, 200 Elizabeth Street, 13EN-218, Toronto, ON M5G 2C4 Canada
- Institute of Medical Science, University of Toronto, Toronto, Canada
- Department of Medicine, University of Toronto, Toronto, Canada
- Public Health Ontario, Toronto, Canada
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Effects of diethylcarbamazine and ivermectin treatment on Brugia malayi gene expression in infected gerbils ( Meriones unguiculatus). ACTA ACUST UNITED AC 2019; 5. [PMID: 33777408 PMCID: PMC7994942 DOI: 10.1017/pao.2019.1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Lymphatic filariasis (LF) threatens nearly 20% of the world’s population and has handicapped one-third of the 120 million people currently infected. Current control and elimination programs for LF rely on mass drug administration of albendazole plus diethylcarbamazine (DEC) or ivermectin. Only the mechanism of action of albendazole is well understood. To gain a better insight into antifilarial drug action in vivo, we treated gerbils harbouring patent Brugia malayi infections with 6 mg kg−1 DEC, 0.15 mg kg−1 ivermectin or 1 mg kg−1 albendazole. Treatments had no effect on the numbers of worms present in the peritoneal cavity of treated animals, so effects on gene expression were a direct result of the drug and not complicated by dying parasites. Adults and microfilariae were collected 1 and 7 days post-treatment and RNA isolated for transcriptomic analysis. The experiment was repeated three times. Ivermectin treatment produced the most differentially expressed genes (DEGs), 113. DEC treatment yielded 61 DEGs. Albendazole treatment resulted in little change in gene expression, with only 6 genes affected. In total, nearly 200 DEGs were identified with little overlap between treatment groups, suggesting that these drugs may interfere in different ways with processes important for parasite survival, development, and reproduction.
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Sarasombath PT, Thammapalo S, Loymek S, Angkanasinsiri A, Priyavoravong P, Wongkamchai S. First study of topical selamectin efficacy for treating cats naturally infected with Brugia malayi and Brugia pahangi under field conditions. Parasitol Res 2019; 118:1289-1297. [PMID: 30746583 DOI: 10.1007/s00436-019-06248-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 02/01/2019] [Indexed: 12/15/2022]
Abstract
Lymphatic filariae are important human and animal parasites. Infection by these parasites could lead to severe morbidity and has significant socioeconomic impacts. Topical selamectin is a semi-synthetic macrocyclic lactone that is widely used to prevent heartworm infection. Up until now, there were no studies that investigated the efficacy of selamectin in lymphatic filariae. Therefore, we aimed to study the chemotherapeutic and chemoprophylactic efficacies of selamectin use for cats in brugian filariasis-endemic areas in Southern Thailand. To assess chemotherapeutic efficacy of topical selamectin, eight Brugia malayi and six Brugia pahangi microfilaremic cats were treated with a single administration of topical selamectin. For chemoprophylactic efficacy assessment, a single application of topical selamectin was administrated to 9 healthy, uninfected cats. The cats in both groups were subjected to a monthly blood testing for microfilariae and filarial DNA for 1 year. Topical selamectin treatment in B. malayi and B. pahangi microfilaremic cats showed 100% effectivity in eradicating microfilaremia but only 78.5% effectivity in eliminating filarial DNA. In the chemoprophylactic group, selamectin demonstrated 66.7% efficacy in preventing B. malayi infection. Our findings suggest that a single administration of 6 mg/kg topical selamectin given every two months could effectively prevent B. malayi infection. Application of topical selamectin twice a year could block circulating microfilariae. Since there are no treatment guidelines currently available for lymphatic filarial infection in cats, the data obtained from this study could be used to guide the management of brugian lymphatic filarial infection in reservoir cats.
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Affiliation(s)
- Patsharaporn T Sarasombath
- Department of Parasitology, Faculty of Medicine Siriraj Hospital, Mahidol University, 2 Wangland Road, Bangkoknoi, Bangkok, 10700, Thailand
| | - Suwich Thammapalo
- Office of Disease Prevention and Control Region 12 Songkhla, Department of Disease Control, Ministry of Public Health, Songkhla, Thailand
| | - Sumart Loymek
- Office of Disease Prevention and Control Region 12 Songkhla, Department of Disease Control, Ministry of Public Health, Songkhla, Thailand
| | - Anchisa Angkanasinsiri
- Department of Parasitology, Faculty of Medicine Siriraj Hospital, Mahidol University, 2 Wangland Road, Bangkoknoi, Bangkok, 10700, Thailand
| | | | - Sirichit Wongkamchai
- Department of Parasitology, Faculty of Medicine Siriraj Hospital, Mahidol University, 2 Wangland Road, Bangkoknoi, Bangkok, 10700, Thailand.
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Atif M, Smith JJ, Estrada-Mondragon A, Xiao X, Salim AA, Capon RJ, Lynch JW, Keramidas A. GluClR-mediated inhibitory postsynaptic currents reveal targets for ivermectin and potential mechanisms of ivermectin resistance. PLoS Pathog 2019; 15:e1007570. [PMID: 30695069 PMCID: PMC6368337 DOI: 10.1371/journal.ppat.1007570] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Revised: 02/08/2019] [Accepted: 01/08/2019] [Indexed: 12/19/2022] Open
Abstract
Glutamate-gated chloride channel receptors (GluClRs) mediate inhibitory neurotransmission at invertebrate synapses and are primary targets of parasites that impact drastically on agriculture and human health. Ivermectin (IVM) is a broad-spectrum pesticide that binds and potentiates GluClR activity. Resistance to IVM is a major economic and health concern, but the molecular and synaptic mechanisms of resistance are ill-defined. Here we focus on GluClRs of the agricultural endoparasite, Haemonchus contortus. We demonstrate that IVM potentiates inhibitory input by inducing a tonic current that plateaus over 15 minutes and by enhancing post-synaptic current peak amplitude and decay times. We further demonstrate that IVM greatly enhances the active durations of single receptors. These effects are greatly attenuated when endogenous IVM-insensitive subunits are incorporated into GluClRs, suggesting a mechanism of IVM resistance that does not affect glutamate sensitivity. We discovered functional groups of IVM that contribute to tuning its potency at different isoforms and show that the dominant mode of access of IVM is via the cell membrane to the receptor. Glutamate-gated chloride channel receptors (GluClRs) mediate chemoelectric inhibition in invertebrate animals and are targets for broad-spectrum pesticides such as ivermectin. However, resistance to ivermectin threatens the effective control of invertebrates that cause a range of agricultural and human diseases. This study investigates different isoforms of GluClR expressed by the major agricultural endoparasite, Haemonchus contortus, on a synaptic and single receptor level. We discovered that ivermectin enhances synaptic current amplitude and decay and lengthens single receptor activity. Furthermore, ivermectin is less efficacious at GluClRs that incorporate a naturally ivermectin-resistant subunit, suggesting a potential resistance mechanism. Finally, we identify two chemical interactions between the GluClR and ivermectin that determine its potency and show that ivermectin binds to GluClRs via cell membrane interactions.
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Affiliation(s)
- Mohammed Atif
- Queensland Brain Institute, The University of Queensland, Brisbane, Australia
| | - Jennifer J. Smith
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
| | | | - Xue Xiao
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
| | - Angela A. Salim
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
| | - Robert J. Capon
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
| | - Joseph W. Lynch
- Queensland Brain Institute, The University of Queensland, Brisbane, Australia
- * E-mail: (AK); (JWL)
| | - Angelo Keramidas
- Queensland Brain Institute, The University of Queensland, Brisbane, Australia
- * E-mail: (AK); (JWL)
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Reaves BJ, Wallis C, McCoy CJ, Lorenz WW, Rada B, Wolstenholme AJ. Recognition and killing of Brugia malayi microfilariae by human immune cells is dependent on the parasite sample and is not altered by ivermectin treatment. Int J Parasitol Drugs Drug Resist 2018; 8:587-595. [PMID: 30279092 PMCID: PMC6287470 DOI: 10.1016/j.ijpddr.2018.09.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 09/14/2018] [Accepted: 09/16/2018] [Indexed: 12/20/2022]
Abstract
Mass administration of macrocyclic lactones targets the transmission of the causative agents of lymphatic filariasis to their insect vectors by rapidly clearing microfilariae (Mf) from the circulation. It has been proposed that the anti-filarial action of these drugs may be mediated through the host immune system. We recently developed an in vitro assay for monitoring the attachment to and killing of B. malayi Mf by human neutrophils (PMNs) and monocytes (PBMCs), however, the levels of both cell to worm attachment and leukocyte mediated Mf killing varied greatly between individual experiments. To determine whether differences in an individual's immune cells or the Mf themselves might account for the variability in survival, PMNs and PBMCs were isolated from 12 donors every week for 4 weeks and the cells used for survival assays with a different batch of Mf, thereby keeping donors constant but varying the Mf sample. Results from these experiments indicate that, overall, killing is Mf-rather than donor-dependent. To assess whether ivermectin (IVM) or diethylcarbamazine (DEC) increase killing, Mf were incubated either alone or with immune cells in the presence of IVM or DEC. Neither drug induced a significant difference in the survival of Mf whether cultured with or without cells, with the exception of DEC at 2 h post incubation. In addition, human PBMCs and PMNs were incubated with IVM or DEC for 1 h or 16 h prior to RNA extraction and Illumina sequencing. Although donor-to-donor variation may mask subtle differences in gene expression, principle component analysis of the RNASeq data indicates that there is no significant change in the expression of any genes from the treated cells versus controls. Together these data suggest that IVM and DEC have little direct effect on immune cells involved in the rapid clearance of Mf from the circulation.
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Affiliation(s)
- Barbara J Reaves
- Department of Infectious Diseases, University of Georgia, Athens, GA, 30602, USA; Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, 30602, USA.
| | - Connor Wallis
- Department of Infectious Diseases, University of Georgia, Athens, GA, 30602, USA.
| | - Ciaran J McCoy
- Department of Infectious Diseases, University of Georgia, Athens, GA, 30602, USA; Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, 30602, USA.
| | - W Walter Lorenz
- Institute for Bioinformatics, University of Georgia, Athens, GA, 30602, USA.
| | - Balazs Rada
- Department of Infectious Diseases, University of Georgia, Athens, GA, 30602, USA.
| | - Adrian J Wolstenholme
- Department of Infectious Diseases, University of Georgia, Athens, GA, 30602, USA; Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, 30602, USA.
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Weeks JC, Robinson KJ, Lockery SR, Roberts WM. Anthelmintic drug actions in resistant and susceptible C. elegans revealed by electrophysiological recordings in a multichannel microfluidic device. Int J Parasitol Drugs Drug Resist 2018; 8:607-628. [PMID: 30503202 PMCID: PMC6287544 DOI: 10.1016/j.ijpddr.2018.10.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Revised: 10/17/2018] [Accepted: 10/18/2018] [Indexed: 12/22/2022]
Abstract
Many anthelmintic drugs used to treat parasitic nematode infections target proteins that regulate electrical activity of neurons and muscles: ion channels (ICs) and neurotransmitter receptors (NTRs). Perturbation of IC/NTR function disrupts worm behavior and can lead to paralysis, starvation, immune attack and expulsion. Limitations of current anthelmintics include a limited spectrum of activity across species and the threat of drug resistance, highlighting the need for new drugs for human and veterinary medicine. Although ICs/NTRs are valuable anthelmintic targets, electrophysiological recordings are not commonly included in drug development pipelines. We designed a medium-throughput platform for recording electropharyngeograms (EPGs)-the electrical signals emitted by muscles and neurons of the pharynx during pharyngeal pumping (feeding)-in Caenorhabditis elegans and parasitic nematodes. The current study in C. elegans expands previous work in several ways. Detecting anthelmintic bioactivity in drugs, compounds or natural products requires robust, sustained pharyngeal pumping under baseline conditions. We generated concentration-response curves for stimulating pumping by perfusing 8-channel microfluidic devices (chips) with the neuromodulator serotonin, or with E. coli bacteria (C. elegans' food in the laboratory). Worm orientation in the chip (head-first vs. tail-first) affected the response to E. coli but not to serotonin. Using a panel of anthelmintics-ivermectin, levamisole and piperazine-targeting different ICs/NTRs, we determined the effects of concentration and treatment duration on EPG activity, and successfully distinguished control (N2) and drug-resistant worms (avr-14; avr-15; glc-1, unc-38 and unc-49). EPG recordings detected anthelmintic activity of drugs that target ICs/NTRs located in the pharynx as well as at extra-pharyngeal sites. A bus-8 mutant with enhanced permeability was more sensitive than controls to drug treatment. These results provide a useful framework for investigators who would like to more easily incorporate electrophysiology as a routine component of their anthelmintic research workflow.
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Affiliation(s)
- Janis C Weeks
- Institute of Neuroscience, University of Oregon, 1254 University of Oregon, Eugene, OR, 97403-1254, USA.
| | - Kristin J Robinson
- Institute of Neuroscience, University of Oregon, 1254 University of Oregon, Eugene, OR, 97403-1254, USA.
| | - Shawn R Lockery
- Institute of Neuroscience, University of Oregon, 1254 University of Oregon, Eugene, OR, 97403-1254, USA.
| | - William M Roberts
- Institute of Neuroscience, University of Oregon, 1254 University of Oregon, Eugene, OR, 97403-1254, USA.
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30
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Hotterbeekx A, Namale Ssonko V, Oyet W, Lakwo T, Idro R. Neurological manifestations in Onchocerca volvulus infection: A review. Brain Res Bull 2018; 145:39-44. [PMID: 30458251 PMCID: PMC6382410 DOI: 10.1016/j.brainresbull.2018.08.024] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Revised: 08/22/2018] [Accepted: 08/25/2018] [Indexed: 11/17/2022]
Abstract
Human onchocerciasis, caused by infection by the filarial nematode Onchocerca volvulus, is a major neglected public health problem that affects millions of people in the endemic regions of sub-Saharan Africa and Latin America. Onchocerciasis is known to be associated with skin and eye disease and more recently, neurological features have been recognized as a major manifestation. Especially the latter poses a severe burden on affected individuals and their families. Although definite studies are awaited, preliminary evidence suggests that neurological disease may include the nodding syndrome, Nakalanga syndrome and epilepsy but to date, the exact pathophysiological mechanisms remain unclear. Currently, the only way to prevent Onchocera volvulus associated disease is through interventions that target the elimination of onchocerciasis through community distribution of ivermectin and larviciding the breeding sites of the Similium or blackfly vector in rivers. In this review, we discuss the epidemiology, potential pathological mechanisms as well as prevention and treatment strategies of onchocerciasis, focusing on the neurological disease.
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Affiliation(s)
- An Hotterbeekx
- University of Antwerp, Global Health Institute, Antwerp, Belgium
| | | | | | - Thomson Lakwo
- Ministry of Health, Division of Vector Control, Kampala, Uganda
| | - Richard Idro
- Makerere University College of Health Sciences, Kampala, Uganda; Centre for Tropical Neuroscience, Kampala, Uganda; University of Oxford, Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, Oxford, UK.
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Anthelmintics - From Discovery to Resistance III (Indian Rocks Beach, FL, 2018). INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2018; 8:494-495. [PMID: 30429103 PMCID: PMC6287533 DOI: 10.1016/j.ijpddr.2018.11.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The third scientific meeting in the series “Anthelmintics: From Discovery to Resistance” was held in Indian Rocks Beach, Florida, at the end of January 2018. The meeting focused on a variety of topics related to the title, including the identification of novel targets and new leads, the mechanism of action of existing drugs and the genetic basis of resistance against them. Throughout there was an emphasis on the exploitation of new technologies and methods to further these aims. The presentations, oral and poster, covered basic, veterinary and medical science with strong participation by both academic and commercial researchers. This special issue contains selected papers from the meeting.
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Kinrade SA, Mason JW, Sanabria CR, Rayner CR, Bullock JM, Stanworth SH, Sullivan MT. Evaluation of the Cardiac Safety of Long-Acting Endectocide Moxidectin in a Randomized Concentration-QT Study. Clin Transl Sci 2018; 11:582-589. [PMID: 30117300 PMCID: PMC6226119 DOI: 10.1111/cts.12583] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Potential effects on cardiac repolarization of single doses of moxidectin, a potent long‐acting macrocyclic lactone endectocide, were assessed in a concentration‐QT (c‐QT; exposure‐response) study. This double‐blind, placebo‐controlled, parallel‐group study in healthy male volunteers (n = 60) randomized subjects to a single oral dose of moxidectin (4 mg, 8 mg, 16 mg, 24 mg, or 36 mg) or matching placebo. Serial plasma samples for pharmacokinetic (PK) analysis and concurrent triplicate electrocardiogram measurements were taken at baseline and 14 prespecified time points over 72 hours, yielding 900 QT interval‐plasma concentration time‐matched pairs. Moxidectin had no statistically significant or clinically relevant impact on QT interval at any dose level. The primary mixed effects model analysis revealed no treatment‐related impact on the Fridericia‐corrected QT interval‐plasma concentration gradient (−0.0077, 90% confidence interval (CI) −0.0255 to +0.0101).
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Affiliation(s)
- Sally A Kinrade
- Medicines Development for Global Health, Melbourne, Australia
| | - Jay W Mason
- Mason Cardiac Safety Consulting, Reno, Nevada, USA
| | | | | | | | | | - Mark T Sullivan
- Medicines Development for Global Health, Melbourne, Australia
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Partridge FA, Brown AE, Buckingham SD, Willis NJ, Wynne GM, Forman R, Else KJ, Morrison AA, Matthews JB, Russell AJ, Lomas DA, Sattelle DB. An automated high-throughput system for phenotypic screening of chemical libraries on C. elegans and parasitic nematodes. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2017; 8:8-21. [PMID: 29223747 PMCID: PMC5734697 DOI: 10.1016/j.ijpddr.2017.11.004] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 11/23/2017] [Accepted: 11/27/2017] [Indexed: 11/16/2022]
Abstract
Parasitic nematodes infect hundreds of millions of people and farmed livestock. Further, plant parasitic nematodes result in major crop damage. The pipeline of therapeutic compounds is limited and parasite resistance to the existing anthelmintic compounds is a global threat. We have developed an INVertebrate Automated Phenotyping Platform (INVAPP) for high-throughput, plate-based chemical screening, and an algorithm (Paragon) which allows screening for compounds that have an effect on motility and development of parasitic worms. We have validated its utility by determining the efficacy of a panel of known anthelmintics against model and parasitic nematodes: Caenorhabditis elegans, Haemonchus contortus, Teladorsagia circumcincta, and Trichuris muris. We then applied the system to screen the Pathogen Box chemical library in a blinded fashion and identified compounds already known to have anthelmintic or anti-parasitic activity, including tolfenpyrad, auranofin, and mebendazole; and 14 compounds previously undescribed as anthelmintics, including benzoxaborole and isoxazole chemotypes. This system offers an effective, high-throughput system for the discovery of novel anthelmintics.
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Affiliation(s)
- Frederick A Partridge
- Centre for Respiratory Biology, UCL Respiratory, Division of Medicine, University College London, Gower Street, London, WC1E 6BT, United Kingdom
| | - Anwen E Brown
- Centre for Respiratory Biology, UCL Respiratory, Division of Medicine, University College London, Gower Street, London, WC1E 6BT, United Kingdom
| | - Steven D Buckingham
- Centre for Respiratory Biology, UCL Respiratory, Division of Medicine, University College London, Gower Street, London, WC1E 6BT, United Kingdom
| | - Nicky J Willis
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, United Kingdom
| | - Graham M Wynne
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, United Kingdom
| | - Ruth Forman
- Faculty of Biology, Medicine and Health, University of Manchester, Oxford Road, Manchester, M13 9PL, United Kingdom
| | - Kathryn J Else
- Faculty of Biology, Medicine and Health, University of Manchester, Oxford Road, Manchester, M13 9PL, United Kingdom
| | - Alison A Morrison
- Moredun Research Institute, Pentland Science Park, Bush Loan, Penicuik, Midlothian, EH26 0PZ, United Kingdom
| | - Jacqueline B Matthews
- Moredun Research Institute, Pentland Science Park, Bush Loan, Penicuik, Midlothian, EH26 0PZ, United Kingdom
| | - Angela J Russell
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, United Kingdom; Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, OX1 3QT, United Kingdom
| | - David A Lomas
- Centre for Respiratory Biology, UCL Respiratory, Division of Medicine, University College London, Gower Street, London, WC1E 6BT, United Kingdom.
| | - David B Sattelle
- Centre for Respiratory Biology, UCL Respiratory, Division of Medicine, University College London, Gower Street, London, WC1E 6BT, United Kingdom.
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Vidyashankar AN, Jimenez Castro PD, Kaplan RM. A statistical approach for evaluating the effectiveness of heartworm preventive drugs: what does 100% efficacy really mean? Parasit Vectors 2017; 10:516. [PMID: 29143648 PMCID: PMC5688406 DOI: 10.1186/s13071-017-2440-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Background Initial studies of heartworm preventive drugs all yielded an observed efficacy of 100% with a single dose, and based on these data the US Food and Drug Administration (FDA) required all products to meet this standard for approval. Those initial studies, however, were based on just a few strains of parasites, and therefore were not representative of the full assortment of circulating biotypes. This issue has come to light in recent years, where it has become common for studies to yield less than 100% efficacy. This has changed the landscape for the testing of new products because heartworm efficacy studies lack the statistical power to conclude that finding zero worms is different from finding a few worms. Methods To address this issue, we developed a novel statistical model, based on a hierarchical modeling and parametric bootstrap approach that provides new insights to assess multiple sources of variability encountered in heartworm drug efficacy studies. Using the newly established metrics we performed both data simulations and analyzed actual experimental data. Results Our results suggest that an important source of modeling variability arises from variability in the parasite establishment rate between dogs; not accounting for this can overestimate the efficacy in more than 40% of cases. We provide strong evidence that ZoeMo-2012 and JYD-34, which both were established from the same source dog, have differing levels of susceptibility to moxidectin. In addition, we provide strong evidence that the differences in efficacy seen in two published studies using the MP3 strain were not due to randomness, and thus must be biological in nature. Conclusion Our results demonstrate how statistical modeling can improve the interpretation of data from heartworm efficacy studies by providing a means to identify the true efficacy range based on the observed data. Importantly, these new insights should help to inform regulators on how to move forward in establishing new statistically and scientifically valid requirements for efficacy in the registration of new heartworm preventative products. Furthermore, our results provide strong evidence that heartworm ‘strains’ can change their susceptibility phenotype over short periods of time, providing further evidence that a wide diversity of susceptibility phenotypes exists among naturally circulating biotypes of D. immitis.
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Affiliation(s)
| | - Pablo D Jimenez Castro
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, 30602, USA
| | - Ray M Kaplan
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, 30602, USA.
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Maclean MJ, Savadelis MD, Coates R, Dzimianski MT, Jones C, Benbow C, Storey BE, Kaplan RM, Moorhead AR, Wolstenholme AJ. Does evaluation of in vitro microfilarial motility reflect the resistance status of Dirofilaria immitis isolates to macrocyclic lactones? Parasit Vectors 2017; 10:480. [PMID: 29143656 PMCID: PMC5688452 DOI: 10.1186/s13071-017-2436-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND Several reports have confirmed that macrocyclic lactone-resistant isolates of Dirofilaria immitis are circulating in the United States; however, the prevalence and potential impact of drug resistance is unknown. We wished to assess computer-aided measurements of motility as a method for rapidly assessing the resistance status of parasite isolates. METHODS Blood containing microfilariae (MF) from two clinical cases with a high suspicion of resistance was fed to mosquitoes and the resultant L3 injected into dogs that were then treated with six doses of Heartgard® Plus (ivermectin + pyrantel; Merial Limited) at 30-day intervals. In both cases patent heartworm infections resulted despite the preventive treatment. Microfilariae isolated from these dogs and other isolates of known resistance status were exposed to varying concentrations of ivermectin in vitro and their motility assessed 24 h later using computer-processed high-definition video imaging. RESULTS We produced two isolates, Yazoo-2013 and Metairie-2014, which established patent infections despite Heartgard® Plus treatments. Measurements of the motility of MF of these and other isolates (Missouri, MP3 and JYD-27) following exposure to varying concentrations of ivermectin did not distinguish between susceptible and resistant heartworm populations. There was some evidence that the method of MF isolation had an influence on the motility and drug susceptibility of the MF. CONCLUSIONS We confirmed that drug-resistant heartworms are circulating in the southern United States, but that motility measurements in the presence of ivermectin are not a reliable method for their detection. This implies that the drug does not kill the microfilariae via paralysis.
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Affiliation(s)
- Mary J Maclean
- Department of Infectious Diseases, University of Georgia, 501 DW Brooks Drive, Athens, 30602, GA, USA.,Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, 30602, USA
| | - Molly D Savadelis
- Department of Infectious Diseases, University of Georgia, 501 DW Brooks Drive, Athens, 30602, GA, USA
| | - Ruby Coates
- Department of Infectious Diseases, University of Georgia, 501 DW Brooks Drive, Athens, 30602, GA, USA.,Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, 30602, USA
| | - Michael T Dzimianski
- Department of Infectious Diseases, University of Georgia, 501 DW Brooks Drive, Athens, 30602, GA, USA
| | - Corey Jones
- Yazoo City Animal Hospital, Yazoo City, MS, USA
| | | | - Bobby E Storey
- Department of Infectious Diseases, University of Georgia, 501 DW Brooks Drive, Athens, 30602, GA, USA
| | - Ray M Kaplan
- Department of Infectious Diseases, University of Georgia, 501 DW Brooks Drive, Athens, 30602, GA, USA
| | - Andrew R Moorhead
- Department of Infectious Diseases, University of Georgia, 501 DW Brooks Drive, Athens, 30602, GA, USA
| | - Adrian J Wolstenholme
- Department of Infectious Diseases, University of Georgia, 501 DW Brooks Drive, Athens, 30602, GA, USA. .,Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, 30602, USA.
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Nakata Y, Fuse T, Yamato K, Asahi M, Nakahira K, Ozoe F, Ozoe Y. A Single Amino Acid Substitution in the Third Transmembrane Region Has Opposite Impacts on the Selectivity of the Parasiticides Fluralaner and Ivermectin for Ligand-Gated Chloride Channels. Mol Pharmacol 2017; 92:546-555. [DOI: 10.1124/mol.117.109413] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 09/09/2017] [Indexed: 01/25/2023] Open
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Eigege A, Evans DS, Noland GS, Davies E, Umaru J, Adelamo SE, Mancha B, King JD, Miri ES, Okoeguale B, Griswold EP, Richards FO. Criteria to Stop Mass Drug Administration for Lymphatic Filariasis Have Been Achieved Throughout Plateau and Nasarawa States, Nigeria. Am J Trop Med Hyg 2017; 97:677-680. [PMID: 28749759 DOI: 10.4269/ajtmh.16-0843] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Nigeria has the largest population at risk for lymphatic filariasis (LF) in Africa. This study used a transmission assessment survey (TAS) to determine whether mass drug administration (MDA) for LF could stop in 21 districts, divided into four evaluation units (EUs), of Plateau and Nasarawa States, Nigeria, after 8-12 years of annual albendazole-ivermectin treatment. A total of 7,131 first- and second-year primary school children (approximately 6-7 years old) were tested for LF antigen by immunochromatographic test (ICT) from May to June 2012. The target sample size of 1,692 was exceeded in each EU (range = 1,767-1,795). A total of 25 (0.4%) individuals were ICT positive, with the number of positives in each EU (range = 3-11) less than the TAS cutoff of 20, meaning that LF transmission had been reduced below sustainable levels. As a result, 3.5 million annual albendazole-ivermectin treatments were halted in 2013. Combined with the previous halt of MDA for LF in other parts of Plateau and Nasarawa, these are the first Nigerian states to stop LF MDA statewide. Posttreatment surveillance is ongoing to determine if LF transmission has been interrupted.
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Affiliation(s)
- Abel Eigege
- The Carter Center, Jos, Plateau State, Nigeria
| | - Darin S Evans
- United States Agency for International Development (USAID), Washington, District of Columbia.,The Carter Center, Atlanta, Georgia
| | | | | | - John Umaru
- The Carter Center, Jos, Plateau State, Nigeria
| | | | | | - Jonathan D King
- Department of Control of Neglected Tropical Diseases, World Health Organization, Geneva, Switzerland.,The Carter Center, Atlanta, Georgia
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In Vitro Efficacy of Moxidectin versus Ivermectin against Sarcoptes scabiei. Antimicrob Agents Chemother 2017; 61:AAC.00381-17. [PMID: 28559258 DOI: 10.1128/aac.00381-17] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 05/22/2017] [Indexed: 10/19/2022] Open
Abstract
Moxidectin is under consideration for development as a treatment for human scabies. As some arthropods show decreased sensitivity to moxidectin relative to ivermectin, it was important to assess this for Sarcoptes scabieiIn vitro assays showed that the concentration of moxidectin required to kill 50% of mites was lower than that of ivermectin (0.5 μM versus 1.8 μM at 24 h; P < 0.0001). This finding provides further support for moxidectin as a candidate for the treatment of human scabies.
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Degani-Katzav N, Gortler R, Weissman M, Paas Y. Mutational Analysis at Intersubunit Interfaces of an Anionic Glutamate Receptor Reveals a Key Interaction Important for Channel Gating by Ivermectin. Front Mol Neurosci 2017; 10:92. [PMID: 28428744 PMCID: PMC5382172 DOI: 10.3389/fnmol.2017.00092] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Accepted: 03/17/2017] [Indexed: 11/13/2022] Open
Abstract
The broad-spectrum anthelmintic drug ivermectin (IVM) activates and stabilizes an open-channel conformation of invertebrate chloride-selective glutamate receptors (GluClRs), thereby causing a continuous inflow of chloride ions and sustained membrane hyperpolarization. These effects suppress nervous impulses and vital physiological processes in parasitic nematodes. The GluClRs are pentamers. Homopentameric receptors assembled from the Caenorhabditis elegans (C. elegans) GluClα (GLC-1) subunit can inherently respond to IVM but not to glutamate (the neurotransmitter). In contrast, heteromeric GluClα/β (GLC-1/GLC-2) assemblies respond to both ligands, independently of each other. Glutamate and IVM bind at the interface between adjacent subunits, far away from each other; glutamate in the extracellular ligand-binding domain, and IVM in the ion-channel pore periphery. To understand the importance of putative intersubunit contacts located outside the glutamate and IVM binding sites, we introduced mutations at intersubunit interfaces, between these two binding-site types. Then, we determined the effect of these mutations on the activation of the heteromeric mutant receptors by glutamate and IVM. Amongst these mutations, we characterized an α-subunit point mutation located close to the putative IVM-binding pocket, in the extracellular end of the first transmembrane helix (M1). This mutation (αF276A) moderately reduced the sensitivity of the heteromeric GluClαF276A/βWT receptor to glutamate, and slightly decreased the receptor subunits’ cooperativity in response to glutamate. In contrast, the αF276A mutation drastically reduced the sensitivity of the receptor to IVM and significantly increased the receptor subunits’ cooperativity in response to IVM. We suggest that this mutation reduces the efficacy of channel gating, and impairs the integrity of the IVM-binding pocket, likely by disrupting important interactions between the tip of M1 and the M2-M3 loop of an adjacent subunit. We hypothesize that this physical contact between M1 and the M2-M3 loop tunes the relative orientation of the ion-channel transmembrane helices M1, M2 and M3 to optimize pore opening. Interestingly, pre-exposure of the GluClαF276A/βWT mutant receptor to subthreshold IVM concentration recovered the receptor sensitivity to glutamate. We infer that IVM likely retained its positive modulation activity by constraining the transmembrane helices in a preopen orientation sensitive to glutamate, with no need for the aforementioned disrupted interactions between M1 and the M2-M3 loop.
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Affiliation(s)
- Nurit Degani-Katzav
- Laboratory of Ion Channels, The Mina and Everard Goodman Faculty of Life Sciences, Institute of Nanotechnology and Advanced Materials, Bar-Ilan UniversityRamat Gan, Israel
| | - Revital Gortler
- Laboratory of Ion Channels, The Mina and Everard Goodman Faculty of Life Sciences, Institute of Nanotechnology and Advanced Materials, Bar-Ilan UniversityRamat Gan, Israel
| | - Marina Weissman
- Laboratory of Ion Channels, The Mina and Everard Goodman Faculty of Life Sciences, Institute of Nanotechnology and Advanced Materials, Bar-Ilan UniversityRamat Gan, Israel
| | - Yoav Paas
- Laboratory of Ion Channels, The Mina and Everard Goodman Faculty of Life Sciences, Institute of Nanotechnology and Advanced Materials, Bar-Ilan UniversityRamat Gan, Israel
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Degani-Katzav N, Klein M, Har-Even M, Gortler R, Tobi R, Paas Y. Trapping of ivermectin by a pentameric ligand-gated ion channel upon open-to-closed isomerization. Sci Rep 2017; 7:42481. [PMID: 28218274 PMCID: PMC5317004 DOI: 10.1038/srep42481] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 01/11/2017] [Indexed: 11/09/2022] Open
Abstract
Ivermectin (IVM) is a broad-spectrum anthelmintic drug used to treat human parasitic diseases like river blindness and lymphatic filariasis. By activating invertebrate pentameric glutamate-gated chloride channels (GluCl receptors; GluClRs), IVM induces sustained chloride influx and long-lasting membrane hyperpolarization that inhibit neural excitation in nematodes. Although IVM activates the C. elegans heteromeric GluClα/β receptor, it cannot activate a homomeric receptor composed of the C. elegans GluClβ subunits. To understand this incapability, we generated a homopentameric α7-GluClβ chimeric receptor that consists of an extracellular ligand-binding domain of an α7 nicotinic acetylcholine receptor known to be potentiated by IVM, and a chloride-selective channel domain assembled from GluClβ subunits. Application of IVM prior to acetylcholine inhibited the responses of the chimeric α7-GluClβR. Adding IVM to activated α7-GluClβRs, considerably accelerated the decline of ACh-elicited currents and stabilized the receptors in a non-conducting state. Determination of IVM association and dissociation rate constants and recovery experiments suggest that, following initial IVM binding to open α7-GluClβRs, the drug induces a conformational change and locks the ion channel in a closed state for a long duration. We further found that IVM also inhibits the activation by glutamate of a homomeric receptor assembled from the C. elegans full-length GluClβ subunits.
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Affiliation(s)
- Nurit Degani-Katzav
- Laboratory of Ion Channels, The Mina and Everard Goodman Faculty of Life Sciences and The Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 52900, Israel
| | - Moshe Klein
- Laboratory of Ion Channels, The Mina and Everard Goodman Faculty of Life Sciences and The Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 52900, Israel
| | - Moran Har-Even
- Laboratory of Ion Channels, The Mina and Everard Goodman Faculty of Life Sciences and The Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 52900, Israel
| | - Revital Gortler
- Laboratory of Ion Channels, The Mina and Everard Goodman Faculty of Life Sciences and The Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 52900, Israel
| | - Ruthi Tobi
- Laboratory of Ion Channels, The Mina and Everard Goodman Faculty of Life Sciences and The Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 52900, Israel
| | - Yoav Paas
- Laboratory of Ion Channels, The Mina and Everard Goodman Faculty of Life Sciences and The Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 52900, Israel
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Crump A. Ivermectin: enigmatic multifaceted 'wonder' drug continues to surprise and exceed expectations. J Antibiot (Tokyo) 2017; 70:495-505. [PMID: 28196978 DOI: 10.1038/ja.2017.11] [Citation(s) in RCA: 113] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Revised: 11/28/2016] [Accepted: 12/03/2016] [Indexed: 12/12/2022]
Abstract
Over the past decade, the global scientific community have begun to recognize the unmatched value of an extraordinary drug, ivermectin, that originates from a single microbe unearthed from soil in Japan. Work on ivermectin has seen its discoverer, Satoshi Ōmura, of Tokyo's prestigious Kitasato Institute, receive the 2014 Gairdner Global Health Award and the 2015 Nobel Prize in Physiology or Medicine, which he shared with a collaborating partner in the discovery and development of the drug, William Campbell of Merck & Co. Incorporated. Today, ivermectin is continuing to surprise and excite scientists, offering more and more promise to help improve global public health by treating a diverse range of diseases, with its unexpected potential as an antibacterial, antiviral and anti-cancer agent being particularly extraordinary.
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Affiliation(s)
- Andy Crump
- Graduate School of Infection Control Sciences, Kitasato University, Minato-Ku, Japan
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Potential Value of Triple Drug Therapy with Ivermectin, Diethylcarbamazine, and Albendazole (IDA) to Accelerate Elimination of Lymphatic Filariasis and Onchocerciasis in Africa. PLoS Negl Trop Dis 2017; 11:e0005163. [PMID: 28056015 PMCID: PMC5215784 DOI: 10.1371/journal.pntd.0005163] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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