Macrocyclical lactone-resistance in the cow-abomasum-nematode Ostertagia ostertagi


The control of bovine parasitic gastro-enteritis in Europe is based on preventive anthelmintic treatment programs. The most important anthelmintics in use today are the macrocyclic lactones (ML). Continuous or frequent use of the same class of anthelmintics has led to the development of resistance. ML-resistance in Cooperia oncophora has been reported in New Zealand, U.K., Brazil, U.S and Argentinia, suggesting that ML-resistance in Cooperia species is gradually increasing. Resistance to ML's has also been reported in Haemonchus placei , Trichostrongylus species and very recently the first ML-resistant O. ostertagi population has been reported in the U.S. The ML-resistance status of O. ostertagi in Europe is currently not known. However, it is likely that ML-resistance in this parasite is more widespread than we realize and needs more investigation. There are non-molecular in vitro tests for resistance that can be used to test the susceptibility of a parasite population. However, these tests are relatively time consuming, show a limited sensitivity and unsatisfactory reproducibility between laboratories. Therefore, there is an urgent need for cost efficient new molecular tests with high throughput capacity.

Current research
The objectives of the current research are:
(1) To study the mechanisms of ML-resistance in C. oncophora and O. ostertagi and to develop sensitive probes for monitoring the frequency of resistance alleles. The genetic variation or polymorphisms in the ML-resistance genes will be examined in a ML-susceptible and a ML-resistant population to investigate if the presence of specific alleles is associated with the ML-resistance. Based on these studies we would like to develop a sensitive real-time PCR detection methods for ML-resistance
(2) To determine and evaluate the extent of ML-resistance in C. oncophora and O. ostertagi in Belgium. The presence of ML-resistance will be evaluated using a phenotypic (FECRT) and genotypic (Real-Time PCR) test.


Ostertagia, ostertagi-resistentance, acrocyclic lactones


Veterinary Sciences {Research discipline}
Medical Microbiology {Research discipline}


Name Role Amount
Post-Graduate Grants unknown 130.518.00 EUR


Name Role Start End
Claerebout, Edwin promotor 2004-01-01 2007-12-31
Van Zeveren, Annelies member 2004-01-01 2007-12-31


Name Role Start End
Laboratory of Parasitology unknown 2004-01-01 2007-12-31


Reference Role
Van Zeveren, A., Visser, A., Hoorens, P., Vercruysse, J., Claerebout, E., Geldhof, P., 2007. Evaluation of reference genes for quantitative real-time PCR in Ostertagia ostertagi by the Coefficient of Variation (CV) and geNorm approach. Mol Biochem Parasitol 153, 224-227. author
Van Zeveren, A.M., Casaert, S., Alvinerie, M., Geldhof, P. , Claerebout, E., Vercruysse, J., 2007. Experimental selection for ivermectin resistance in Ostertagia ostertagi in cattle. Vet Parasitol 50, 104-110 author

created:2011-12-14 14:18:59 UTC, source:iwt

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