title: Importance of the mutation of amino acid 200 of the isotype 1 beta-tubulin gene in the benzimidazole resistance of the small-ruminant parasite Teladorsagia circumcincta.
abstract: In this work we demonstrated that the acquisition of benzimidazole (BZ) resistance in the small-ruminant parasite Teladorsagia circumcincta is linked to the selection of individuals that are characterized by a tyrosine (Tyr) at amino acid 200 of their isotype 1 beta-tubulin gene. This mutation appears to be recessive, since only homozygous mutant (Tyr/Tyr) individuals survived after BZ treatment of two resistant populations in which the three genotypes (rr, rs, ss) were initially present. In comparison with natural BZ-susceptible populations, a decrease in the restriction polymorphism (RFLP) of the isotype 1 beta-tubulin gene was observed in natural resistant populations. It seems that this decrease in beta-tubulin polymorphism results from the selection of homozygous mutant individuals.
authors.affiliation: INRA, Centre de Tours, Station de Pathologie Aviaire et de Parasitologie, Nouzilly, France.
authors.forename: L
authors.initials: L
authors.lastname: Elard
authors.forename: J F
authors.initials: JF
authors.lastname: Humbert
mesh_terms: D000818:Animals; D001562:Benzimidazoles / Q000494:pharmacology*; D004351:Drug Resistance; D005808:Genes, Recessive; D006041:Goats; D006720:Homozygote; D009154:Mutation; D010028:Ostertagia / Q000187:drug effects*; D012150:Polymorphism, Restriction Fragment Length; D020033:Protein Isoforms / Q000235:genetics; D012418:Ruminants / Q000469:parasitology*; D012641:Selection, Genetic; D012756:Sheep; D014404:Tubulin / Q000235:genetics*
chemical_list: D001562:Benzimidazoles; D020033:Protein Isoforms; D014404:Tubulin; C031000:benzimidazole