Award details

Genetic and molecular basis of triclabendazole resistance in Fasciola hepatica

Reference	BB/P001912/1
Principal Investigator / Supervisor	Dr Jane Hodgkinson
Co-Investigators / Co-Supervisors	Professor Lu-Yun Lian, Professor Steve Paterson, Professor Diana Williams
Institution	University of Liverpool
Department	Institute of Infection and Global Health
Funding type	Research
Value (£)	660,291
Status	Completed
Type	Research Grant
Start date	01/01/2017
End date	31/01/2021
Duration	49 months

Abstract

The purpose of this project is to enhance our genetic resources for F. hepatica to support finer-scale mapping of triclabendazole (TCBZ) resistance loci. We will integrate the mapping study with in vitro and in vivo transcriptomic and global metabolomic profiling of TCBZ-resistant and -susceptible clonal isolates to generate a defined set of candidate genes for TCBZ resistance. The project is divided into four related objectives: Objective 1. Deliver a genetic map for Fasciola hepatica and determine if TCBZ-R is a dominant or recessive trait. Objective 2. Validate putative TCBZ resistance markers and perform finer-scale mapping of TCBZ resistance loci using field isolates of known sensitivity to TCBZ. Objective 3. Compare transcript abundance in TCBZ-resistant (TCBZ-R) and TCBZ-susceptible (TCBZ-S) parental parasites with and without exposure to TCBZ in vivo and in vitro by RNAseq. Objective 4. Determine metabolomic differences between TCBZ-R and TCBZ-S parasites with and without exposure to TCBZ in vivo and in vitro. The project aims to determine whether TCBZ resistance has a common genetic basis across the UK, whether the same mechanism(s) is employed by both adult and immature parasites and whether TCBZ resistance is a dominant or recessive trait. Detecting TCBZ resistance alleles in the field will provide insights into practices influencing development of resistance and ultimately mitigate against the spread of drug resistance.

Summary

Fasciolosis is a common and important disease of livestock that results in substantial economic losses to the livestock sector. It is caused by the liver fluke, Fasciola hepatica, a flatworm found in the liver and transmitted via a mud snail. In the UK it is the most commonly reported infection associated with the digestive tract of ruminants. The immature stages of F. hepatica are responsible for acute disease, which has a negative impact on animal welfare and is often fatal in sheep. 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 pathogenic early immature stages. 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 reported in many locations worldwide. Little is known about the mechanisms of drug resistance in F. hepatica. This proposal aims to address this and other outstanding questions in drug resistance such as: Is there one genetic route to TCBZ resistance or multiple? What factors influence the emergence and spread of drug resistance alleles in liver fluke populations? This project will utilise outputs from our highly successful previous project, which produced a draft F. hepatica genome and located (mapped) areas of the genome of TCBZ resistant parasites that may explain their ability to survive drug treatment. Here, we will produce a number of sequencing resources to improve this mapping exercise, including; a) a linkage map to improve the organisation of the genome and b) whole-genome sequencing of fluke eggs from the faeces of sheep naturally infected with resistant parasites, from before and after TCBZ treatment. Analysing these sequences will allow us to close in on the gene or genes responsible for encoding TCBZ resistance and will help us understand how resistance is passed from one parasite generation to the next. To assist in identifying the genes involved we will expose our resistant and susceptible clonal parasites to TCBZ and characterise the total gene expression profile and chemical fingerprint (global metabolomic profile). At the end of the project we will have genetic markers for resistance that can be used to detect and track the emergence of resistance in populations of F. hepatica naturally infecting sheep and cattle in the UK. There will be other important outputs for the wider scientific community from the project, such as a bank of genomic, transcriptomic and metabolomic data. We will make all these resources available to liver fluke researchers worldwide; so that, together, we can more effectively control this parasite in future.

Impact Summary

This project will maximise outputs from existing liver fluke research projects, stimulate new areas of research and facilitate translation of research to farmers and industry. There are a number of beneficiaries from this proposal. Academic impact This project will deliver an enhanced genome assembly and a linkage map for F. hepatica; vital to mapping complex genetic traits in future. The datasets we generate will prove invaluable to the F. hepatica research community. They will build on the limited transcriptomic resources available to the liver fluke research community and deliver the first global metabolomic datasets. Our particular focus on NEJ, the primary target of control strategies, will generate transcriptional and metabolomic datasets for the development of new anthelmintics, diagnostics and vaccines. One of the most important outputs from the project will be post-doctoral scientists trained in the most up to date methodologies including bio-informatics and analysis of genomic, transcriptome and metabolome data. This will contribute to a cadre of highly skilled biomedical scientists to build science capacity in the UK. Impact for UK agriculture Agriculture is worth around £11 billion to the UK economy. Securing the UK's food supply through efficient production of beef, lamb and dairy products is essential for the health and well being of the UK population. Moreover efficient production systems will reduce the emission of greenhouse gasses from livestock. Liver fluke is a substantial constraint on meat and milk production in the UK. The parasite affects feed conversion, growth rates and milk yield and has a negative impact on farmers' incomes and climate change is predicted to exacerbate fasciolosis throughout this century. Control of fluke is now impeded by resistance to triclabendazole and this represents a major threat, particularly to sheep production in marginal areas such as upland Wales and Cumbria. By identifying the genetic regions involved in TCBZ resistance and determining whether TCBZ resistance has the same genetic basis at different UK locations, markers for TCBZ resistance can be developed that will be used to detect drug resistance alleles in the field. This in turn will provide insights into practices influencing the emergence and spread of drug resistance in F. hepatica populations, directly benefit farming communities and the agri-food sector by reducing parasite burdens and improving productivity and biological efficiency. Stakeholders and Policy impact This proposal will deliver an evidence-base for how to combat the development and spread of drug resistance which will feed into policy development by UK-based government bodies such as the Dept. for Environment, Food & Rural Affairs (DEFRA), the agriculture and horticultural development boards (AHDB) and APHA as well as the Department of Agriculture and Rural Development-NI. Through our links with the Control of Worms Sustainably industry stakeholder group (Co-I Williams), we have a direct route to promote best practice in parasite control. Wider public Consumers are becoming increasingly aware of the quality and provenance of food and it is increasingly important to the wider public that they have a reliable source of affordable and healthy food, without compromising animal health and welfare. Beef and dairy product supplies, their quality, environmental impact, price and welfare of the animals from which they are produced will be affected by the prevalence of fasciolosis. Public engagement and outreach activities are embedded within the Institute of Infection and Global Health, UofL. We will interact with farmers and the public through events such as LEAF Open Farm Sunday. Fasciolosis is listed amongst the neglected tropical diseases affecting people in resource poor countries. Improved means of diagnosing and treating liver fluke infection will be of substantial benefit to people in these settings.

Committee	Research Committee A (Animal disease, health and welfare)
Research Topics	Animal Health
Research Priority	X – Research Priority information not available
Research Initiative	X - not in an Initiative
Funding Scheme	X – not Funded via a specific Funding Scheme

I accept the terms and conditions of use (opens in new window)

export PDF file

back to list new search