Triclabendazole-resistant Fasciola hepatica: beta-tubulin and response to in vitro treatment with triclabendazole.
Resistance in Fasciola hepatica to triclabendazole ('Fasinex') has emerged in several countries. Benzimidazole resistance in parasitic nematodes has been linked to a single amino acid substitution (phenylalanine to tyrosine) at position 200 on the beta-tubulin molecule. Sequencing of beta-tubulin cDNAs from triclabendazole-susceptible and triclabendazole-resistant flukes revealed no amino acid differences between their respective primary amino acid sequences. In order to investigate the mechanism of triclabendazole resistance, triclabendazole-susceptible and triclabendazole-resistant flukes were incubated in vitro with triclabendazole sulphoxide (50 microg/ml). Scanning and transmission electron microscopy revealed extensive damage to the tegument of triclabendazole-susceptible F. hepatica, whereas triclabendazole-resistant flukes showed only localized and relatively minor disruption of the tegument covering the spines. Immunocytochemical studies, using an anti-tubulin antibody, showed that tubulin organization was disrupted in the tegument of triclabendazole-susceptible flukes. No such disruption was evident in triclabendazole-resistant F. hepatica. The significance of these findings is discussed with regard to the mechanism of triclabendazole resistance in F. hepatica.
Robinson
M W
MW
School of Biology and Biochemistry, Medical Biology Centre, Queen's University of Belfast.
Trudgett
A
A
Hoey
E M
EM
Fairweather
I
I
D000818:Animals; D000871:Anthelmintics / Q000494:pharmacology*; D001562:Benzimidazoles / Q000494:pharmacology*; D018509:DNA, Helminth / Q000737:chemistry / Q000235:genetics; D005210:Fasciola hepatica / Q000187:drug effects / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D007150:Immunohistochemistry; D008855:Microscopy, Electron, Scanning; D018510:RNA, Helminth / Q000737:chemistry / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D000077682:Triclabendazole; D014404:Tubulin / Q000235:genetics* / Q000648:ultrastructure
D000871:Anthelmintics; D001562:Benzimidazoles; D018509:DNA, Helminth; D018510:RNA, Helminth; D014404:Tubulin; D000077682:Triclabendazole