Assessment of albendazole resistance in Fasciola hepatica

Abstract

The main goals of the current work were to confirm the albendazole (ABZ) resistance status of a Fasciola hepatica isolate using the egg hatch test (EHT), and to compare the gene expression profiles of the efflux transporter, P-glycoprotein (P-gp), in the same specimens of F. hepatica recovered from ABZ treated or untreated control animals. Metacercariae of a F. hepatica isolated previously classified as ABZ-resistant by the EHT were used to artificially infect eight (8) healthy sheep. Sixteen (16) weeks after infection, animals were randomly distributed either in an untreated control or in an ABZ-treated (7.5 mg/kg) group. The fluckicidal efficacy of ABZ was assessed by the comparison of the number of flukes recovered from untreated and treated sheep at 7 days post-treatment. Additionally, adults F. hepatica specimens from both experimental groups were used to determine the P-gp gene expression profiles by real-time PCR, using GAPDH as a reference gene. No statistical differences were observed in the number of adult liver flukes between untreated (18.5 ± 3.6) and ABZ-treated group (18.2 ± 8.5, P<0.05), demonstrating that the isolate was resistant to ABZ. The expression level of P-gp in F. hepatica was 2.5- fold higher (P<0.05) in those recovered from ABZ-treated sheep compared to collected ftrom untreated control group. Further studies involving more individuals are needed to confirm if the higher P-gp expression observed in the ABZ-exposed F. hepatica could be a potential resistance mechanism. Furthermore, the observed results confirm that the EHT is a reliable method to determine the state of susceptibility/resistance in F. hepatica.