Mapping triclabendazole resistance in Fasciola hepatica using next generation sequencing technologies

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Fasciolosis is a common and important disease of livestock. In the UK it is the most commonly reported infection associated with the digestive tract of ruminants. It is caused by Fasciola hepatica, a flatworm found in the liver and transmitted by a mud snail. Fasciolosis is controlled predominantly using drug treatment and the most commonly used drug is triclabendazole (TCBZ). This is the only drug that is effective against the immature stages of the parasite that are responsible for acute, often fatal disease. It is also the drug of choice for human fasciolosis, caused by the same parasite. Resistance to TCBZ was first reported in Australia in 1995 and is now thought to be widespread worldwide. Very little is known about mechanisms of drug resistance in F. hepatica, which genes are involved and how resistance is evolving. This proposal aims to exploit our ability to create clones of resistant and susceptible F. hepatica; to derive genetically identical infections of TCBZ-susceptible and TCBZ-resistant isolates in sheep, from which we will generate second generation populations. These populations will be used to identify markers, in this case single mutations at the DNA level that associate with resistance genes during the crossing of resistant and susceptible clones. We will use rapid, high throughput, next generation sequencing technologies, which allow us to produce a preliminary F. hepatica genome map. The resistance markers will be mapped onto this preliminary genome and allow us to identify regions of the genome where the gene or genes responsible for encoding resistance are found. At the end of the project we will have genetic markers for resistance that could be used to detect and track the emergence of resistance in populations of F. hepatica in naturally infected sheep and cattle in the UK, but, importantly they will also be used in future projects to start to home in and identify genes encoding resistance. There will be other important outputs for the wider scientific community from the project, such as a bank of genome data for the parasite and clones of the parasite whose resistance status is well characterised. Genome data will be made available through a publicly accessible website and the parasite clones will be made available to other groups by lodging them with our industrial partner, Ridgeways Research Ltd.