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Chemoprophylactic prevention of veterinary heartworm disease in companion animals, caused by the vector-borne nematode parasite Dirofilaria immitis, is a multi-billion-dollar global market. Experimental use of cats and dogs in preclinical heartworm drug testing is increasing due to evolving drug-resistance to frontline macrocyclic lactones and renewed investment in alternative preventative drug research. We and others recently published data demonstrating proof-of-concept of utilising lymphopenic severe-combined immunodeficient (SCID) or Recombination Activating Gene (RAG)2 deficient mice with additional knockout of the IL-2/7 receptor gamma chain (γc) as alternative preventative drug screening research models of dirofilariasis. Here we summarise the current knowledge of candidate immunodeficient mouse models tested, including a comparison of susceptibility using different background strains of mice, different D. immitis isolates, following use of anti-inflammatory treatments to further suppress residual innate immunity, and efficacies achieved against different reference anthelmintics. We supplement this precis with new data on treatment response to the veterinary anthelmintic, oxfendazole, and initial evaluation of D. immitis susceptibility in CB.17 SCID and C57BL/6 RAG2 -/-γc -/- mice. We conclude that in addition to NSG and NXG mice, RAG2 -/-γc -/- mice on either a BALB/c or C57BL/6 background offer an alternative screening model option, widening access to academic and commercial laboratories wishing to pursue initial rapid in vivo drug screening whilst avoiding potentially unnecessary cat or dog testing.
Assuntos
Dirofilariose , Modelos Animais de Doenças , Camundongos SCID , Animais , Cães , Gatos , Camundongos , Dirofilariose/prevenção & controle , Dirofilariose/tratamento farmacológico , Dirofilaria immitis/efeitos dos fármacos , Dirofilaria immitis/imunologia , Doenças do Gato/prevenção & controle , Doenças do Gato/parasitologia , Doenças do Gato/tratamento farmacológico , Doenças do Gato/imunologia , Doenças do Cão/prevenção & controle , Doenças do Cão/parasitologia , Doenças do Cão/tratamento farmacológico , Anti-Helmínticos/uso terapêutico , Avaliação Pré-Clínica de MedicamentosRESUMO
The interplay between humans and their microbiome is crucial for various physiological processes, including nutrient absorption, immune defense, and maintaining homeostasis. Microbiome alterations can directly contribute to diseases or heighten their likelihood. This relationship extends beyond humans; microbiota play vital roles in other organisms, including eukaryotic pathogens causing severe diseases. Notably, Wolbachia, a bacterial microbiota, is essential for parasitic worms responsible for lymphatic filariasis and onchocerciasis, devastating human illnesses. Given the lack of rapid cures for these infections and the limitations of current treatments, new drugs are imperative. Here, we disrupt Wolbachia's symbiosis with pathogens using boron-based compounds targeting an unprecedented Wolbachia enzyme, leucyl-tRNA synthetase (LeuRS), effectively inhibiting its growth. Through a compound demonstrating anti-Wolbachia efficacy in infected cells, we use biophysical experiments and x-ray crystallography to elucidate the mechanism behind Wolbachia LeuRS inhibition. We reveal that these compounds form adenosine-based adducts inhibiting protein synthesis. Overall, our study underscores the potential of disrupting key microbiota to control infections.
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Microbiota , Wolbachia , Wolbachia/efeitos dos fármacos , Humanos , Animais , Leucina-tRNA Ligase/metabolismo , Leucina-tRNA Ligase/antagonistas & inibidores , Aminoacil-tRNA Sintetases/metabolismo , Aminoacil-tRNA Sintetases/antagonistas & inibidores , Cristalografia por Raios X , Compostos de Boro/farmacologia , Compostos de Boro/química , Simbiose , Modelos MolecularesRESUMO
AWZ1066S has been developed as a potential treatment for the neglected tropical diseases lymphatic filariasis and onchocerciasis. AWZ1066S targets the Wolbachia bacterial endosymbiont present in the causative nematode parasites. This phase 1, first-in-human study aimed to assess the safety and pharmacokinetics of AWZ1066S in healthy human participants. In a randomized double-blind, placebo-controlled, single ascending dose study, healthy adults received a single oral dose of AWZ1066S (or placebo) and were followed up for 10 days. The planned single doses of AWZ1066S ranged from 100 to 1600 mg, and each dose was administered to a cohort of 8 participants (6 AWZ1066S and 2 placebo). In total 30 people participated, 18 (60%) female, median age 30.0 years (minimum 20, maximum 61). The cohorts administered 100, 200, 300, and 400 mg of AWZ1066S progressed unremarkably. After single 700-mg doses all 4 participants developed symptoms of acute gastritis and transient increases in liver enzymes. The severity of these adverse events ranged from mild to severe, with 1 participant needing hospital admission. Pharmacokinetic analysis indicated that AWZ1066S is rapidly absorbed with predictable pharmacokinetics. In conclusion, safety concerns prevented this study from reaching the human exposures needed for AWZ1066S to be clinically effective against lymphatic filariasis and onchocerciasis.
RESUMO
COVID-19 is a spectrum of clinical symptoms in humans caused by infection with SARS-CoV-2. The coalescence of SARS-CoV-2 with seasonal respiratory viruses, particularly influenza viruses, is a global health concern. To understand this, transgenic mice expressing the human ACE2 receptor (K18-hACE2) were infected with influenza A virus (IAV) followed by SARS-CoV-2 and the host response and effect on virus biology was compared to K18-hACE2 mice infected with IAV or SARS-CoV-2 alone. The sequentially infected mice showed reduced SARS-CoV-2 RNA synthesis, yet exhibited more rapid weight loss, more severe lung damage and a prolongation of the innate response compared to the singly infected or control mice. Sequential infection also exacerbated the extrapulmonary encephalitic manifestations associated with SARS-CoV-2 infection. Conversely, prior infection with a commercially available, multivalent live-attenuated influenza vaccine (Fluenz Tetra) elicited the same reduction in SARS-CoV-2 RNA synthesis, albeit without the associated increase in disease severity. This suggests that the innate immune response stimulated by IAV inhibits SARS-CoV-2. Interestingly, infection with an attenuated, apathogenic influenza vaccine does not result in an aberrant immune response and enhanced disease severity. Taken together, the data suggest coinfection ('twinfection') is deleterious and mitigation steps should be instituted as part of the comprehensive public health and management strategy of COVID-19.
Assuntos
Enzima de Conversão de Angiotensina 2 , COVID-19 , Modelos Animais de Doenças , Vírus da Influenza A , Camundongos Transgênicos , Infecções por Orthomyxoviridae , SARS-CoV-2 , Animais , COVID-19/imunologia , COVID-19/virologia , Camundongos , SARS-CoV-2/imunologia , Infecções por Orthomyxoviridae/virologia , Infecções por Orthomyxoviridae/imunologia , Enzima de Conversão de Angiotensina 2/metabolismo , Enzima de Conversão de Angiotensina 2/genética , Humanos , Coinfecção/virologia , Pulmão/virologia , Pulmão/patologia , Encefalite Viral/virologia , Encefalite Viral/imunologia , Vacinas contra Influenza/imunologia , Feminino , Imunidade InataRESUMO
BACKGROUND: In 2020 the World Health Organization (WHO) declared that Malawi had successfully eliminated lymphatic filariasis (LF) as a public health problem. Understanding clinical case distributions at a national and sub-national level is important, so essential care packages can be provided to individuals living with LF symptoms. This study aimed to develop a national database and map of LF clinical cases across Malawi using geostatistical modelling approaches, programme-identified clinical cases, antigenaemia prevalence and climate information. METHODOLOGY: LF clinical cases identified through programme house-to-house surveys across 90 sub-district administrative boundaries (Traditional Authority (TA)) and antigenaemia prevalence from 57 sampled villages in Malawi were used in a two-step geostatistical modelling process to predict LF clinical cases across all TAs of the country. First, we modelled antigenaemia prevalence in relation to climate covariates to predict nationwide antigenaemia prevalence. Second, we modelled clinical cases for unmapped TAs based on our antigenaemia prevalence spatial estimates. PRINCIPLE FINDINGS: The models estimated 20,938 (95% CrI 18,091 to 24,071) clinical cases in unmapped TAs (70.3%) in addition to the 8,856 (29.7%), programme-identified cases in mapped TAs. In total, the overall national number of LF clinical cases was estimated to be 29,794 (95% CrI 26,957 to 32,927). The antigenaemia prevalence and clinical case mapping and modelling found the highest burden of disease in Chikwawa and Nsanje districts in the Southern Region and Karonga district in the Northern Region of the country. CONCLUSIONS: The models presented in this study have facilitated the development of the first national LF clinical case database and map in Malawi, the first endemic country in sub-Saharan Africa. It highlights the value of using existing LF antigenaemia prevalence and clinical case data together with modelling approaches to produce estimates that may be used for the WHO dossier requirements, to help target limited resources and implement long-term health strategies.
Assuntos
Filariose Linfática , Humanos , Filariose Linfática/epidemiologia , Malaui/epidemiologia , Prevalência , Gerenciamento de Dados , Inquéritos e QuestionáriosRESUMO
Lymphatic filariasis and onchocerciasis are two major neglected tropical diseases that are responsible for causing severe disability in 50 million people worldwide, whilst veterinary filariasis (heartworm) is a potentially lethal parasitic infection of companion animals. There is an urgent need for safe, short-course curative (macrofilaricidal) drugs to eliminate these debilitating parasite infections. We investigated combination treatments of the novel anti-Wolbachia azaquinazoline small molecule, AWZ1066S, with benzimidazole drugs (albendazole or oxfendazole) in up to four different rodent filariasis infection models: Brugia malayi-CB.17 SCID mice, B. malayi-Mongolian gerbils, B. pahangi-Mongolian gerbils, and Litomosoides sigmodontis-Mongolian gerbils. Combination treatments synergised to elicit threshold (>90%) Wolbachia depletion from female worms in 5 days of treatment, using 2-fold lower dose-exposures of AWZ1066S than monotherapy. Short-course lowered dose AWZ1066S-albendazole combination treatments also delivered partial adulticidal activities and/or long-lasting inhibition of embryogenesis, resulting in complete transmission blockade in B. pahangi and L. sigmodontis gerbil models. We determined that short-course AWZ1066S-albendazole co-treatment significantly augmented the depletion of Wolbachia populations within both germline and hypodermal tissues of B. malayi female worms and in hypodermal tissues in male worms, indicating that anti-Wolbachia synergy is not limited to targeting female embryonic tissues. Our data provides pre-clinical proof-of-concept that sub-seven-day combinations of rapid-acting novel anti-Wolbachia agents with benzimidazole anthelmintics are a promising curative and transmission-blocking drug treatment strategy for filarial diseases of medical and veterinary importance.
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BACKGROUND: This study aimed to determine the key mental health indicators affecting people affected by lymphatic filariasis (LF) lymphoedema by assessing the prevalence of depressive symptoms and quality of life (QOL), identifying associated sociodemographic and clinical risk factors, and evaluating the impact of an enhanced self-care intervention for lymphoedema management. METHODS: A prospective cohort study of adults with filarial lymphoedema from two regions of Malawi was conducted over six months in 2021. Depressive symptoms and QOL were assessed using Patient Health Questionnaire (PHQ-9) and LF Specific QOL Questionnaire, respectively, at baseline (pre-intervention), 3- and 6-months (postintervention). Beta regression analysis identified risk factors, and assessed the impact of the intervention. RESULTS: Three hundred eleven affected individuals were surveyed with 23% (95% CI 18%-29%) reporting mild/moderate depressive symptoms and 31% (95% CI 26%-37%) reporting moderately low/low QOL. Higher depressive symptom scores were associated with high frequency of acute filarial attack episodes. Individuals with higher depressive symptoms (Adjusted Odds Ratios (AOR) 0.93, 95% CI 0.93-0.93) and lower QOL (AOR 0.98, 0.98-0.98) showed greatest improvement in mental health indicators over 3-months but was not sustained to the same level at 6-months. CONCLUSIONS: Sustained morbidity management and psychological support is recommended for affected persons to ensure long-term positive mental health and clinical outcomes. CONTEXTE: Cette étude vise à déterminer les principaux indicateurs de santé mentale affectant les personnes atteintes de lymphÅdème dû à la filariose lymphatique (FL) en évaluant la prévalence des symptômes dépressifs et la qualité de vie (QV), en identifiant les facteurs de risque sociodémographiques et cliniques associés, et en évaluant l'impact d'une intervention améliorée d'autosoins pour la gestion du lymphÅdème. MÉTHODES: Une étude de cohorte prospective d'adultes atteints de lymphoedème filaire dans deux régions du Malawi a été menée pendant six mois en 2021. Les symptômes dépressifs et la qualité de vie ont été évalués à l'aide du questionnaire sur la santé des patients (PHQ-9) et du questionnaire sur la qualité de vie spécifique au lymphÅdème, respectivement, au début de l'étude (avant l'intervention), et à 3 puis 6 mois après l'intervention. Une analyse de régression beta a permis d'identifier les facteurs de risque et d'évaluer l'impact de l'intervention. RÉSULTATS: Trois cent onze personnes affectées ont été interrogées, dont 23% (95% CI 18%-29%) ont déclaré des symptômes dépressifs légers/modérés et 31% (95% CI 26%-37%) ont déclaré une qualité de vie modérément faible/faible. Des scores élevés de symptômes dépressifs ont été associés à une fréquence élevée d'épisodes de crises filariennes aiguës. Les personnes présentant des symptômes dépressifs plus élevés (rapport de cotes ajusté (RCA) 0.93, IC à 95 % 0.93-0.93) et une qualité de vie plus faible (RCA 0.98, 0.98-0.98) ont montré la plus grande amélioration des indicateurs de santé mentale au cours des trois mois, mais cette amélioration ne s'est pas maintenue au même niveau au cours des six mois suivants. CONCLUSION: Gestion de la morbidité et soutien psychologique sont des éléments clés pour garantir une santé mentale et des résultats cliniques satisfaisants de personnes atteintes sur le long terme. ANTECEDENTES: Este estudio tuvo como objetivo determinar los indicadores clave de salud mental que afectan a las personas afectadas por linfedema por filariasis linfática (FL) mediante la evaluación de la prevalencia de síntomas depresivos y calidad de vida (CdV), la identificación de factores de riesgo sociodemográficos y clínicos asociados, y la evaluación del impacto de una intervención de autocuidado mejorada para el manejo del linfedema. MÉTODOS: Se realizó un estudio prospectivo de cohortes de adultos con linfedema filarial de dos regiones de Malawi durante seis meses en 2021. Los síntomas depresivos y la calidad de vida se evaluaron mediante el Cuestionario de Salud del Paciente (PHQ-9) y el Cuestionario de Calidad de Vida específico para el LF Cuestionario, respectivamente, al inicio (preintervención) y a los 3 y 6 meses (posintervención). El análisis de regresión beta identificó los factores de riesgo y evaluó el impacto de la intervención. RESULTADOS: Se encuestó a 311 afectados, de los cuales el 23% (IC 95%, 18%-29%) presentaba síntomas depresivos leves/moderados y el 31% (IC 95%, 26%-37%) una CdV moderadamente baja/baja CdV. Las puntuaciones más altas de síntomas depresivos se asociaron con una alta frecuencia de episodios de ataques agudos de filarias. Los individuos con mayores síntomas depresivos (Odds Ratios Ajustados [ORA] 0.93; IC 95%: 0.93-0.93) y menor CdV (ORA 0.98; 0.98-0.98) mostraron la mayor mejoría en los indicadores de salud mental a los 3 meses, pero no se mantuvo al mismo nivel a los 6 meses. CONCLUSIONES: Se recomienda el manejo sostenido de la morbilidad y el apoyo psicológico a las personas afectadas para garantizar resultados clínicos y de salud mental positivos a largo plazo.
Assuntos
Linfedema , Qualidade de Vida , Adulto , Humanos , Estudos Prospectivos , Saúde Mental , Autocuidado , Prevalência , Malaui/epidemiologia , Linfedema/epidemiologia , Linfedema/terapiaRESUMO
Lymphatic filariasis and onchocerciasis are major neglected tropical diseases affecting over 90 million people worldwide with painful and profoundly disfiguring pathologies (such as lymphoedema or blindness). Type 2 inflammation is a hallmark of filarial nematode tissue infection and is implicated both in eosinophil dependent immunity and lymphatic or ocular immunopathologies. Type-2 innate lymphoid cells (ILC2) are known to play an important role in the initiation of type 2 inflammation in helminth infection. We therefore tracked comparative IL-12Rß2+ ILC1, ST2+ ILC2 and NKp46+ natural killer (NK) innate lymphoid cell population expansions during Brugia malayi experimental peritoneal filarial infections using either immunocompetent or immunodeficient mice. In immunocompetent BALB/c animals, NKp46+ NK cells rapidly expanded representing over 90% of the ILC population in the first week of infection, whereas, surprisingly, ST2+ ILC2 failed to expand. NKp46+ NK cell expansions were confirmed in RAG2 deficient mice lacking adaptive immunity. Ablation of the NKp46+ NK cell compartment in RAG2 common gamma chain (gc) mice led to increased susceptibility to chronic adult B. malayi infection. This data was recapitulated using an Onchocerca ochengi male worm peritoneal implant model. When NKp46+ NK cells were depleted in RAG2 deficient mice using anti-NKp46 or asialo GM1 antibody injections over the first five weeks of B. malayi infection, susceptibility to adult B. malayi infection was significantly increased by 2-3 fold with concomitant impairment in eosinophil or neutrophil recruitments. Finally, we demonstrate that in RAG2 deficient mice, drug clearance of a primary adult B. malayi infection followed by challenge infection leads to resistance against early larval B. malayi establishment. This innate resistance is associated with bolstered NK and eosinophils whereby NKp46+ NK cells express markers of memory-like/enhanced activation (increased expression of interferon gamma and Ly6C). Our data promotes a novel functional role for NKp46+ NK cells in immunoprotection against experimental primary and secondary filarial infection which can proceed in the absence of adaptive immune regulation.
Assuntos
Imunidade Inata , Interferon gama , Animais , Antígenos Ly , Inflamação , Proteína 1 Semelhante a Receptor de Interleucina-1 , Células Matadoras Naturais , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Receptor 1 Desencadeador da Citotoxicidade Natural , FenótipoRESUMO
BACKGROUND: Onchocerciasis control using ivermectin alone has been achieved in some endemic savannah zones of Africa. In the forest regions, the co-endemicity with Loa loa has led to severe adverse events (SAEs) resulting in poor adherence of community members to ivermectin mass drug administration (MDA). This may jeopardize achieving the interruption of transmission of onchocerciasis. Therefore, to accelerate the elimination of onchocerciasis in L. loa co-endemic zones, alternative treatment strategies (ATS) including ground larviciding may be necessary. This study aimed at identifying Simulium breeding sites, cytospecies, transmission profile, susceptibility of Simulium larvae to insecticide (temephos) and identification of some non-target aquatic fauna prior to the implementation of the COUNTDOWN consortium ground larviciding alternative strategy in the Meme River Basin in South West Cameroon. METHODS: A topographic map and entomological survey were used to determine breeding sites. Larvae and adults were identified using standard identification keys. Susceptibility tests were carried out on collected larvae by exposing them to decreasing concentrations of temephos and assessing survival rates while the cytospecies were identified using cytotaxonomy. Various entomological indicators were assessed from dissected flies. Fishing was used as proxy to traps to assess some aquatic fauna at different sites. RESULTS: Twenty-two breeding sites were prospected in the Meme River Basin with eight productive for larvae. A concentration of 0.5-0.1 mg/l temephos induced 100% larval mortality. As the concentration of temephos decreased from 0.05 to 0.0025 mg/l, mortality of larvae also decreased from 98.7 to 12%. Nine cytospecies were observed in the Meme River Basin; 13,633 flies were collected and 4033 dissected. A total of 1455 flies were parous (36.1%), 224 flies were infected (5.5%), and 64 were infective (1.6%). Aquatic fauna observed included Cyprinus spp., Clarias spp., crabs, tadpoles, beetles and larvae of damsel fly. CONCLUSIONS: Onchocerciasis is being actively transmitted within the Meme River Basin. Simulium larvae are susceptible to temephos, and nine cytospecies are present. Non-target fauna observed included fishes, frogs, crabs and insects. Besides treatment with ivermectin, vector control through ground larviciding may be a complementary strategy to accelerate onchocerciasis elimination in the study area.
Assuntos
Braquiúros , Oncocercose , Simuliidae , Animais , Camarões/epidemiologia , Ivermectina/uso terapêutico , Larva , Oncocercose/epidemiologia , Rios , Temefós/farmacologiaRESUMO
The development of new drugs targeting adult-stage lymphatic filarial nematodes is hindered by the lack of a robust long-term in vitro culture model. Testing potential direct-acting and anti-Wolbachia therapeutic candidates against adult lymphatic filariae in vitro requires their propagation via chronic infection of gerbils. We evaluated Brugia malayi parasite burden data from male Mongolian gerbils compared with two immune-deficient mouse strains highly susceptible to B. malayi: CB.17 Severe-Combined Immmuno-Deficient (SCID) and interleukin-4 receptor alpha, interleukin-5 double knockout (IL-4Rα-/-IL-5-/-) mice. Adult worms generated in IL-4Rα-/-IL-5-/- mice were tested with different feeder cells (human embryonic kidney cells, human adult dermal lymphatic endothelial cells and human THP-1 monocyte differentiated macrophages) and comparative cell-free conditions to optimise and validate a long-term in vitro culture system. Cultured parasites were compared against those isolated from mice using motility scoring, metabolic viability assay (MTT), ex vivo microfilariae release assay and Wolbachia content by qPCR. A selected culture system was validated as a drug screen using reference anti-Wolbachia (doxycycline, ABBV-4083 / flubentylosin) or direct-acting compounds (flubendazole, suramin). BALB/c IL-4Rα-/-IL-5-/- or CB.17 SCID mice were superior to Mongolian gerbils in generating adult worms and supporting in vivo persistence for periods of up to 52 weeks. Adult females retrieved from BALB/c IL-4Rα-/-IL-5-/- mice could be cultured for up to 21 days in the presence of a lymphatic endothelial cell co-culture system with comparable motility, metabolic activity and Wolbachia titres to those maintained in vivo. Drug studies confirmed significant Wolbachia depletions or direct macrofilaricidal activities could be discerned when female B. malayi were cultured for 14 days. We therefore demonstrate a novel methodology to generate adult B. malayi in vivo and accurately evaluate drug efficacy ex vivo which may be adopted for drug screening with the dual benefit of reducing overall animal use and improving anti-filarial drug development.
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Brugia Malayi , Wolbachia , Animais , Técnicas de Cocultura , Modelos Animais de Doenças , Células Endoteliais , Endotélio Linfático , Feminino , Interleucina-5 , Masculino , Camundongos , Camundongos Endogâmicos BALB CRESUMO
Lymphatic filariasis is a vector-borne neglected tropical disease prioritized for global elimination. The filarial nematodes that cause the disease host a symbiotic bacterium, Wolbachia, which has been targeted using antibiotics, leading to cessation of parasite embryogenesis, waning of circulating larvae (microfilariae [mf]), and gradual cure of adult infection. One of the benefits of the anti-Wolbachia mode of action is that it avoids the rapid killing of mf, which can drive inflammatory adverse events. However, mf depleted of Wolbachia persist for several months in circulation, and thus patients treated with antibiotics are assumed to remain at risk for transmitting infections. Here, we show that Wolbachia-depleted mf rapidly lose the capacity to develop in the mosquito vector through a defect in exsheathment and inability to migrate through the gut wall. Transcriptomic and Western blotting analyses demonstrate that chitinase, an enzyme essential for mf exsheathment, is down-regulated in Wolbachia-depleted mf and correlates with their inability to exsheath and escape the mosquito midgut. Supplementation of in vitro cultures of Wolbachia-depleted mf with chitinase enzymes restores their ability to exsheath to a similar level to that observed in untreated mf. Our findings elucidate a mechanism of rapid transmission-blocking activity of filariasis after depletion of Wolbachia and adds to the broad range of biological processes of filarial nematodes that are dependent on Wolbachia symbiosis.
Assuntos
Antibacterianos , Quitinases , Filariose Linfática , Microfilárias , Wolbachia , Animais , Antibacterianos/farmacologia , Quitinases/genética , Filariose Linfática/transmissão , Humanos , Microfilárias/enzimologia , Microfilárias/crescimento & desenvolvimento , Microfilárias/microbiologia , Mosquitos Vetores/parasitologia , Wolbachia/efeitos dos fármacos , Wolbachia/genéticaRESUMO
The sequence diversity of natural and laboratory populations of Brugia pahangi and Brugia malayi was assessed with Illumina resequencing followed by mapping in order to identify single nucleotide variants and insertions/deletions. In natural and laboratory Brugia populations, there is a lack of sequence diversity on chromosome X relative to the autosomes (πX/πA = 0.2), which is lower than the expected (πX/πA = 0.75). A reduction in diversity is also observed in other filarial nematodes with neo-X chromosome fusions in the genera Onchocerca and Wuchereria, but not those without neo-X chromosome fusions in the genera Loa and Dirofilaria. In the species with neo-X chromosome fusions, chromosome X is abnormally large, containing a third of the genetic material such that a sizable portion of the genome is lacking sequence diversity. Such profound differences in genetic diversity can be consequential, having been associated with drug resistance and adaptability, with the potential to affect filarial eradication.
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Brugia/genética , Variação Genética , Cromossomo X/genética , Animais , Brugia/classificação , Aberrações Cromossômicas , Genoma HelmínticoRESUMO
BACKGROUND: Current treatment options for onchocerciasis are sub-optimal, prompting research and development of a safe cure (macrofilaricide). Onchocerca ochengi, a parasite of cattle, is used as a close surrogate for the human parasite O. volvulus in a murine model for pre-clinical screening of macrofilaricides. Skin from naturally infected cattle have been used in previous studies as a reliable source of parasite material. However, there is limited knowledge on how source-related factors such as the microfilaridermia status of the cattle, the nodule load and nodular worm viability may affect survival of male O. ochengi worms implanted in the rodent hosts. Such relationships were investigated in this study. METHODS: Dermal tissue and nodules were obtained from Gudali cattle, dissected and cultured to obtain migrating microfilariae (mf) and male worms. Emerged male worms were implanted into SCID mice and Gerbils (Meriones unguiculatus) and recovery rates were determined upon 42 days post implantation. Finally, nodules were processed for histology and embryogram analyses to assess the nodular worm viability and fertility, respectively. RESULTS: Of the 69 cattle sampled, 24 (34.8%) were mf+ and 45 (65.2%) were mf-. The mean nodule loads were 180.5 ± 117.7 (mf+) and 110.6 ± 102.7 (mf-) (p = 0.0186). The mean male worm harvest from nodules were 76.8 ± 120.3 and 47.2 ± 33.4 (p = 0.2488) for mf+ and mf- cattle, respectively. The number of male worms per 100 nodules were 57/100 and 46/100 nodules for mf+ and mf- cows, respectively. Female worms from nodules of mf- cows had higher counts of both normal and abnormal embryos with higher proportions of dead nodular worms evinced by histology compared to those from mf+ cows. A total of 651 worms were implanted into mice and gerbils, out of which 129 (19.81%) were recovered. Logistic regression analysis indicated that the microfilaridermia status of the cattle (presence of mf) (OR = 4.3319; P = 0.001) is the single most important predictor of the success of male worm recovery after implantation into rodents. CONCLUSION: Microfilaridermic cattle provide a promising source of adult O. ochengi. Male worms from this group of cattle have a better success rate of survival in a murine implant model. Nevertheless, in the programmatic point of view, amicrofilaridermic Gudali cattle would still constitute an important source of O. ochengi male worms with relatively good viability after implantation into rodents.
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Doenças dos Bovinos/parasitologia , Onchocerca/fisiologia , Oncocercose/veterinária , Animais , Bovinos , Modelos Animais de Doenças , Feminino , Fertilidade , Gerbillinae , Masculino , Camundongos , Camundongos SCID , Microfilárias/crescimento & desenvolvimento , Microfilárias/fisiologia , Análise Multivariada , Onchocerca/crescimento & desenvolvimento , Oncocercose/parasitologia , Análise de RegressãoRESUMO
The mutualistic association between Wolbachia endosymbionts and their filarial nematode hosts has been exploited as a validated drug target delivering macrofilaricidal outcomes. Limitations of existing antibiotics to scale-up have driven the search for new drugs, which are effective in shorter regimens of 7 days or less. Here, we review the last 14 years of anti-Wolbachia drug discovery by the anti-Wolbachia (A·WOL) consortium, which has screened more than two million compounds, delivering thousands of hit compounds. Refined screening models integrated with robust pharmacokinetic/pharmacodynamic (PK/PD) driven optimisation and selection strategies have delivered the first two drug candidates specifically designed to target Wolbachia. AWZ1066S and ABBV-4083 are currently progressing through clinical trials with the aim of delivering safe and effective macrofilaricides to support the elimination of onchocerciasis and lymphatic filariasis.
Assuntos
Filariose Linfática , Infecções por Nematoides , Oncocercose , Wolbachia , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Descoberta de Drogas , Filariose Linfática/tratamento farmacológico , Humanos , Infecções por Nematoides/tratamento farmacológico , Oncocercose/tratamento farmacológicoRESUMO
Nine hundred million people are infected with the soil-transmitted helminths Ascaris lumbricoides (roundworm), hookworm, and Trichuris trichiura (whipworm). However, low single-dose cure rates of the benzimidazole drugs, the mainstay of preventative chemotherapy for whipworm, together with parasite drug resistance, mean that current approaches may not be able to eliminate morbidity from trichuriasis. We are seeking to develop new anthelmintic drugs specifically with activity against whipworm as a priority and previously identified a hit series of dihydrobenzoxazepinone (DHB) compounds that block motility of ex vivo Trichuris muris. Here, we report a systematic investigation of the structure-activity relationship of the anthelmintic activity of DHB compounds. We synthesized 47 analogues, which allowed us to define features of the molecules essential for anthelmintic action as well as broadening the chemotype by identification of dihydrobenzoquinolinones (DBQs) with anthelmintic activity. We investigated the activity of these compounds against other parasitic nematodes, identifying DHB compounds with activity against Brugia malayi and Heligmosomoides polygyrus. We also demonstrated activity of DHB compounds against the trematode Schistosoma mansoni, a parasite that causes schistosomiasis. These results demonstrate the potential of DHB and DBQ compounds for further development as broad-spectrum anthelmintics.
Assuntos
Anti-Helmínticos , Brugia Malayi , Nematospiroides dubius , Parasitos , Animais , Anti-Helmínticos/farmacologia , Humanos , Schistosoma mansoni , TrichurisRESUMO
Lymphatic filariasis is the major global cause of nonhereditary lymphedema. We demonstrate that the filarial nematode Brugia malayi induced lymphatic remodeling and impaired lymphatic drainage following parasitism of limb lymphatics in a mouse model. Lymphatic insufficiency was associated with elevated circulating lymphangiogenic mediators, including vascular endothelial growth factor C. Lymphatic insufficiency was dependent on type 2 adaptive immunity, the interleukin-4 receptor, and recruitment of C-C chemokine receptor-2-positive monocytes and alternatively activated macrophages with a prolymphangiogenic phenotype. Oral treatments with second-generation tetracyclines improved lymphatic function, while other classes of antibiotic had no significant effect. Second-generation tetracyclines directly targeted lymphatic endothelial cell proliferation and modified type 2 prolymphangiogenic macrophage development. Doxycycline treatment impeded monocyte recruitment, inhibited polarization of alternatively activated macrophages, and suppressed T cell adaptive immune responses following infection. Our results determine a mechanism of action for the antimorbidity effects of doxycycline in filariasis and support clinical evaluation of second-generation tetracyclines as affordable, safe therapeutics for lymphedemas of chronic inflammatory origin.
Assuntos
Brugia Malayi/imunologia , Filariose Linfática/tratamento farmacológico , Linfangiogênese/imunologia , Receptores de Interleucina-4/imunologia , Tetraciclinas/farmacologia , Imunidade Adaptativa , Animais , Movimento Celular/genética , Movimento Celular/imunologia , Filariose Linfática/genética , Filariose Linfática/imunologia , Filariose Linfática/patologia , Linfangiogênese/genética , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Knockout , Monócitos/imunologia , Monócitos/patologia , Receptores de Interleucina-4/genética , Linfócitos T/imunologia , Linfócitos T/patologiaRESUMO
INTRODUCTION: Onchocerciasis is targeted for elimination mainly with annual community-directed treatment with ivermectin (CDTI). High infection levels have been reported in South-West Cameroon, despite ≥15 years of CDTI. The aim of this study was to assess factors associated with continued onchocerciasis transmission and skin disease. METHODS: A large-scale cross-sectional study was conducted in 2017 in 20 communities in a loiasis-risk area in South-West Cameroon. A mixed-methods approach was used. Associations between infection levels, skin disease and adherence to CDTI were assessed using mixed regression modelling. Different community members' perception and acceptability of the CDTI strategy was explored using semi-structured interviews. RESULTS: Onchocerciasis prevalence was 44.4% among 9456 participants. 17.5% of adults were systematic non-adherers and 5.9% participated in ≥75% of CDTI rounds. Skin disease affected 1/10 participants, including children. Increasing self-reported adherence to CDTI was associated with lower infection levels in participants aged ≥15 years but not in children. Adherence to CDTI was positively influenced by perceived health benefits, and negatively influenced by fear of adverse events linked with economic loss. Concern of lethal adverse events was a common reason for systematic non-adherence. CONCLUSION: CDTI alone is unlikely to achieve elimination in those high transmission areas where low participation is commonly associated with the fear of adverse events, despite the current quasi absence of high-risk levels of loiasis. Such persisting historical memories and fear of ivermectin might impact adherence to CDTI also in areas with historical presence but current absence of loiasis. Because such issues are unlikely to be tackled by CDTI adaptive measures, alternative strategies are needed for onchocerciasis elimination where negative perception of ivermectin is an entrenched barrier to community participation in programmes.
Assuntos
Ivermectina , Oncocercose , Adulto , Camarões/epidemiologia , Criança , Estudos Transversais , Humanos , Ivermectina/uso terapêutico , Administração Massiva de Medicamentos , Oncocercose/tratamento farmacológico , Oncocercose/epidemiologiaRESUMO
The tropical disease, loiasis, caused by the filarial parasite, Loa, has gained prominence in global public health as a cause of excess mortality and a barrier to the elimination of the related prioritized neglected tropical diseases (NTDs), lymphatic filariasis and onchocerciasis, within Central Africa. There are no effective drug cures or vaccines available to treat loiasis safely. Here we review recent advances in loiasis preclinical platform technologies, including novel in vitro culturing systems, animal models and innovations in experimental infections of the L. loa vector, Chrysops, that have facilitated access to all L. loa filarial life-cycle stages. We detail applications of these new model systems in anti-filarial drug screening, diagnostic development, immunology, and pathophysiology research. Finally, we provide an overview of how loiasis preclinical platforms may be further utilized in translational medicine applications to support the development of much needed new interventions against filarial NTDs.
RESUMO
Basic and translational research on loiasis, a filarial nematode infection of medical importance, is impeded by a lack of suitable Loa loa infection models and techniques of obtaining and culturing life cycle stages. We describe the development of a new method for routine production of infective third-stage larvae (L3) of L. loa from the natural intermediate arthropod vector host, Chrysops silacea, following experimental infection with purified microfilariae. At 14-days post-infection of C. silacea, the fly survival rate was 43%. Survival was significantly higher in flies injected with 50 mf (55.2%) than those that received 100 mf (31.0%). However, yield per surviving fly and total yield of L3 was markedly higher in the group of flies inoculated with 100 mf (3474 vs 2462 L3 produced). The abdominal segment hosted the highest percentage recovery of L3 (47.7%) followed by head (34.5%) and thorax (17.9%). L. loa larval survival was higher than 90% after 30 days of in vitro culture. The in vitro moulting success rate to the L4 larval stage was 59.1%. After experimental infection of RAG2-/-IL-2γc-/-mice, the average L. loa juvenile adult worm recovery rate was 10.5% at 62 dpi. More than 87% of the worms were recovered from the muscles and subcutaneous tissues. Worms recovered measured an average 24.3 mm and 11.4 mm in length for females (n = 5) and males (n = 5), respectively. In conclusion, L. loa mf injected into C. silacea intrathoracically develop into infective larvae that remain viable and infective comparable to L3 obtained through natural feeding on the human host. This technique further advances the development of a full laboratory life cycle of L. loa where mf derived from experimentally-infected animals may be utilized to passage life cycle generations via intrathoracic injections of wild-caught vector hosts.
Assuntos
Dípteros/parasitologia , Vetores de Doenças , Larva/parasitologia , Loa/isolamento & purificação , Loíase/parasitologia , Animais , Modelos Animais de Doenças , Feminino , Humanos , Larva/crescimento & desenvolvimento , Estágios do Ciclo de Vida , Loa/citologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Microfilárias , Taxa de SobrevidaRESUMO
Helminth infections are accompanied by eosinophilia in parasitized tissues. Eosinophils are effectors of immunity to tissue helminths. We previously reported that in the context of experimental filarial nematode infection, optimum tissue eosinophil recruitment was coordinated by local macrophage populations following IL-4R-dependent in situ proliferation and alternative activation. However, in the current study, we identify that control of chronic adult filarial worm infection is evident in IL-4Rα-deficient (IL-4Rα-/-) mice, whereby the majority of infections do not achieve patency. An associated residual eosinophilia was apparent in infected IL-4Rα-/- mice. By treating IL-4Rα-/- mice serially with anti-CCR3 Ab or introducing a compound deficiency in CCR3 within IL-4Rα-/- mice, residual eosinophilia was ablated, and susceptibility to chronic adult Brugia malayi infection was established, promoting a functional role for CCR3-dependent eosinophil influx in immune control in the absence of IL-4/IL-13-dependent immune mechanisms. We investigated additional cytokine signals involved in residual eosinophilia in the absence IL-4Rα signaling and defined that IL-4Rα-/-/IL-5-/- double-knockout mice displayed significant eosinophil deficiency compared with IL-4Rα-/- mice and were susceptible to chronic fecund adult filarial infections. Contrastingly, there was no evidence that either IL-4R-dependent or IL-4R-independent/CCR3/IL-5-dependent immunity influenced B. malayi microfilarial loads in the blood. Our data demonstrate multiplicity of Th2-cytokine control of eosinophil tissue recruitment during chronic filarial infection and that IL-4R-independent/IL-5- and CCR3-dependent pathways are sufficient to control filarial adult infection via an eosinophil-dependent effector response prior to patency.