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[
2008]
"The pine wood nematode (PWN), Bursaphelenchus xylophilus, is a mycophagous and phytophagous pathogen responsible for the current widespread epidemic of pine wilt disease, which has become a major threat to pine forests and a socioeconomic burden in Eastern Asia, North America, and some parts of Europe. No therapeutic drug for eradication of PWN currently exists. In addition, although several preventive chemical agents are currently available (e.g., morantel tartarate, avermectin, emamectin benzoate), each is associated with drawbacks (e.g., poor water solubility, efficacy, and specificity) that limit their use as of trunk-injection agents against PWN. Ideal trunk-injection drugs against PWN would be highly water-soluble and possess both nematocidal and antifungal activity (against blue stain fungi, the food source of PWN). To search for such a multifunctional nematocidal agent, we first established a high-throughput screening method, which yields potential hits within 6 hours. Using this high-throughput method, we screened of a large set of antifungal chemical libraries for agents with antinematodal activity. Among the compounds identified was HWY-4213 (1-n-undecyl-2-(2-fluorphenyl)methyl-3,4-dihydro-6,7-dimethoxy-isoquinolinium chloride), a water-soluble agent that exhibited potent antifungal and nematocidal activity. The potent nematocidal activity of this compound was confirmed with cotton ball assays. Further development of HWY-4213 as a therapeutic and preventive trunk injection agent against PWN is warranted. (Supported by a grant from a Forest Science & Technology Project [No. S110707L0501501 to YKP] through the Korea Forest Service)"
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[
Insect Sci,
2020]
Symbiotic microbes play a crucial role in regulating parasite-host interactions; however, the role of bacterial associates in parasite-host interactions requires elucidation. In this study, we showed that, instead of introducing numerous symbiotic bacteria, dispersal of fourth-stage juvenile (J<sub>IV</sub> ) pinewood nematodes (PWNs), Bursaphelenchus xylophilus, only introduced few bacteria to its vector beetle, Monochamus alternatus (Ma). J<sub>IV</sub> showed weak binding ability to five dominant bacteria species isolated from the beetles' pupal chamber. This was especially the case for binding to the opportunistic pathogenic species Serratia marcescens; the nematodes' bacteria binding ability at this critical stage when it infiltrates Ma for dispersal was much weaker compared with Caenorhabditis elegans, Diplogasteroides asiaticus, and propagative-stage PWN. The associated bacterium S. marcescens, which was isolated from the beetles' pupal chambers, was unfavorable to Ma, because it caused a higher mortality rate upon injection into tracheae. In addition, S. marcescens in the tracheae caused more immune effector disorders compared with PWN alone. Ma_Galectin2 (MaGal2), a pattern-recognition receptor, was up-regulated following PWN loading. Recombinant MaGal2 protein formed aggregates with five dominant associated bacteria in vitro. Moreover, MaGal2 knockdown beetles had up-regulated prophenoloxidase gene expression, increased phenoloxidase activity, and decreased PWN loading. Our study revealed a previously unknown strategy for immune evasion of this plant pathogen inside its vector, and provides novel insights into the role of bacteria in parasite-host interactions. This article is protected by copyright. All rights reserved.
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[
PLoS One,
2009]
The pinewood nematode (PWN), Bursaphelenchus xylophilus, is a mycophagous and phytophagous pathogen responsible for the current widespread epidemic of the pine wilt disease, which has become a major threat to pine forests throughout the world. Despite the availability of several preventive trunk-injection agents, no therapeutic trunk-injection agent for eradication of PWN currently exists. In the characterization of basic physiological properties of B. xylophilus YB-1 isolates, we established a high-throughput screening (HTS) method that identifies potential hits within approximately 7 h. Using this HTS method, we screened 206 compounds with known activities, mostly antifungal, for antinematodal activities and identified HWY-4213 (1-n-undecyl-2-[2-fluorphenyl] methyl-3,4-dihydro-6,7-dimethoxy-isoquinolinium chloride), a highly water-soluble protoberberine derivative, as a potent nematicidal and antifungal agent. When tested on 4 year-old pinewood seedlings that were infected with YB-1 isolates, HWY-4213 exhibited a potent therapeutic nematicidal activity. Further tests of screening 39 Caenorhabditis elegans mutants deficient in channel proteins and B. xylophilus sensitivity to Ca(2+) channel blockers suggested that HWY-4213 targets the calcium channel proteins. Our study marks a technical breakthrough by developing a novel HTS method that leads to the discovery HWY-4213 as a dual-acting antinematodal and antifungal compound.
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Engelen M, Taylor MJ, Pionnier N, Lachaud S, Tayong DB, Fombad FF, Chounna PWN, Turner JD, Quirynen L, Njouendou AJ, Wanji S, Steven A, Gandjui NVT, Ward SA, Chunda VC, Tekle F, Ndzeshang BL, Baeten B, Aljayyoussi G, Akumtoh DN, Sjoberg HT, Metuge HM
[
PLoS Negl Trop Dis,
2019]
The Onchocerca ochengi adult implant and Brugia malayi microfilariemic Severe-Combined Immunodeficient (SCID) mouse models are validated screens to measure macrofilaricidal and microfilaricidal activities of candidate onchocerciasis drugs. The purpose of this study was to assess whether 5 daily sub-cutaneous (s.c.) injections of standard flubendazole (FBZ) suspension (10mg/kg), a single s.c. injection (10mg/kg) or 5 daily repeated oral doses of FBZ amorphous solid dispersion (ASD) formulation (0.2, 1.5 or 15mg/kg) mediated macrofilaricidal efficacy against O. ochengi male worms implanted into SCID mice. The direct microfilaricidal activity against circulating B. malayi microfilariae of single dose FBZ ASD formulation (2 or 40 mg/kg) was also evaluated and compared against the standard microfilaricide, ivermectin (IVM). Systemic exposures of FBZ/FBZ metabolites achieved following dosing were measured by pharmacokinetic (PK) bioanalysis. At necropsy, five weeks following start of FBZ SC injections, there were significant reductions in burdens of motile O. ochengi worms following multiple injections (93%) or single injection (82%). Further, significant proportions of mice dosed following multiple injections (5/6; 83%) or single injection (6/10; 60%) were infection negative (drug-cured). In comparison, no significant reduction in recovery of motile adult O. ochengi adult worms was obtained in any multiple-oral dosage group. Single oral-dosed FBZ did not mediate any significant microfilaricidal activity against circulating B. malayi mf at 2 or 7 days compared with >80% efficacy of single dose IVM. In conclusion, multiple oral FBZ formulation doses, whilst achieving substantial bioavailability, do not emulate the efficacy delivered by the parenteral route in vivo against adult O. ochengi. PK analysis determined FBZ efficacy was related to sustained systemic drug levels rather than achievable Cmax. PK modelling predicted that oral FBZ would have to be given at low dose for up to 5 weeks in the mouse model to achieve a matching efficacious exposure profile.