The use of DNA markers to map anthelmintic resistance loci in an intraspecific cross ofHaemonchus contortus

Abstract

SUMMARYThe use of DNA markers to track the development of anthelmintic resistance in parasites of livestock would allow informed choices for the management of this important problem. We describe a genetic mapping approach for the discovery of DNA markers for anthelmintic resistance inHaemonchus contortus. We crossed a multi-drug resistant field isolate ofH. contortuswith a well-characterized laboratory strain susceptible to 4 drug classes. The F2were separately selected with 5 anthelmintics from 4 drug classes, producing drug-resistant populations carrying gene variants derived from both the field isolate and the laboratory strain. Individual F2worms were analysed using amplicon length polymorphisms (ALPs). We looked for field isolate alleles over- or under-represented in F2populations compared to the unselected F2and/or the laboratory strain. The data we obtained suggest that marker association can be used to link neutral markers with resistance, but also that more markers and perhaps more inbred laboratory strains would make the procedure more likely to succeed.