Study Of Detection Of Benzimidazoles Resistance And PCR-SSCP Analysis In Ggastro-intestinal Nematodes Of Small Domestic Ruminants

Anthelmintic resistance of gastro-intestinal nematodes of small domestic ruminants was a severe problem throuhout the world, which has not yet been concened in China. With the need for our sheep and goats production and for control of parasites, the study was carried out in three aspects. The results were as follows:(1)A suspected-resistant worm population from a district in Ningxia was selected by hatched in Thiabendazole(TBZ) solution. The initial ED50 value was 0.057μg/ml by egg hatch assay(EHA). But, the ED50 value rised to 0.146μg/ml after a vitro selection experiment and exceed the commended critical value of World Association for the Advancement of Veterinary Parasitology (WAAVP).(2)With the vitro selected resistant isolate population and the sencitive ones from the field as the control groups, A modified larval development assay (LDA)was used as the method to detect Benzimidazoles(BZs), Levamisole(LEV)and Avermectins(AVMs).(3)The polymorphism in partial fragment of the beta-tubulin gene was examined in H. contortus from treated and untreated populations using single-strand confirmation polymorphism(SSCP)analysis. The results of 181 male adults analysis revealed 20%(3/15)mutant individuals, 60%(9/15)heterozygous ones and 20%(3/15)normal ones in the treated populations, and 3.6%(6/166), 7.8%(13/166)and 88.6%(147/166)respectively in the natural infectious populations.