An in vitro larval migration assay for assessing anthelmintic activity of different drug classes against Ascaris suum
Jianguo Zhao1, Andrew R Williams2, Tina Vicky Alstrup Hansen2
1Laboratory of Tropical Veterinary Medicine and Vector Biology, and Hainan Key Laboratory of Sustainable Utilization of Tropical Bioresources, College of Agriculture, Hainan University, Haikou 570228, China; Key Laboratory of Tropical Biological Resources of Ministry of Education, Hainan University, Haikou, Hainan 570228, China; State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu, 730046, China.
Abstract:
In vitro methods have been developed for the detection of anthelmintic resistance in a range of nematode species. However, the life cycle of Ascaris suum renders the commonly used egg hatch assay and larval development assay unusable. In this study we developed a combined multi-well culture and agar gel larval migration assay to test the effect of benzimidazole and tetrahydropyrimidin/imidazothiazole anthelmintics against nine isolates of A. suum collected from locations in China and Denmark. Drugs tested were thiabendazole, fenbendazole, mebendazole, levamisole, and pyrantel. The percentages of larvae that migrated to the surface of each treated and control well were used to calculate the drug concentration which inhibits 50% of the larvae migration (EC50). The values of EC50 of thiabendazole, fenbendazole, mebendazole, levamisole, and pyrantel against A. suum isolates ranged 74-150, 4.9-13.9, 2.3-4.3, 358-1150 and 1100-4000nM, respectively. This combined multi-well culture and agar gel larval migration assay was a sensitive bioassay for anthelmintic activity and could serve as an in vitro method to detect for lowered drug efficacy against A. suum or possibly to screen for anthelmintic drug candidates.
