Sept. 12, 2013
Veterinary medicine researchers strike blow against ‘barber’s pole worm’
Researchers at the university’s Faculty of Veterinary Medicine are part of an international team that has sequenced the genome of the parasite Haemonchus contortus, commonly known as the barber’s pole worm — making inroads in the fight against one of the most devastating health threats facing the global livestock industry.
The study, published in the journal Genome Biology, describes the first whole genome sequence for this group of organisms.
“The genomes of parasitic worms are far larger and more complex than those of other pathogens such as bacteria and viruses and so provide a significant challenge for genomic studies,” says Dr. John Gilleard, associate dean (research). “This work now provides a much awaited genomic resource for a whole group of important livestock pathogens.”
The barber’s pole worm, named for the pink spiral gut inside its body, is a well-studied agricultural parasite that resides in the stomach of sheep and other livestock around the world. The study has wide-ranging applications for research into drug resistance, drug and vaccine discovery and diagnostics.
Understanding how parasites survive and thrive
“Just one example of the valuable information provided by the genome is the identification of five enzymes essential to the survival of the parasite. These may represent an Achilles heel for the worm and two of these proteins are of particular interest as they are already being studied as potential drug targets against other pathogens, “ says Dr. James Wasmuth, assistant professor, who worked closely with Gilleard on the project.
“To discover these targets, we determined when and where each gene is turned on or off in the cells and tissues of the parasite to reveal new insights into the worm’s lifecycle. The result is the most extensive dataset of its kind for any gastrointestinal worm.”
“This resource will also be invaluable for studying drug resistance in parasites. We sequenced a strain of H. contortus susceptible to all the major drugs,” adds Gilleard. “Comparing this genome with those of drug resistant worms will reveal a wealth of information about how and why resistance occurs and will provide critical information needed to develop more sensitive diagnostic tools.”
What this means for global animal health and production
With the world population set to exceed nine billion by the year 2050, improving the efficiency of livestock production in an environmentally sustainable way while maintaining high standards of animal welfare is a major challenge. Gastrointestinal worms are endemic on 100 per cent of farms and are estimated to cost the global livestock industry billions of dollars every year. Parasite control has become dependent on the routine use of a small number of drugs to which the parasites are now becoming resistant.
“H. contortus has already become resistant to all the available drugs and this is now happening for the closely related parasites of cattle. This is a major concern for both the economics of livestock production and for animal welfare and an emerging problem for the cattle industry here in Alberta,” Gilleard adds. “H. contortus is also of interest to the Canadian sheep industry right now since its prevalence has increased markedly over the last few years with heavy infections often being fatal to sheep.”
Implications for human health
“Not only is this worm closely related to many livestock parasites, it is also similar to several important human parasites such as hookworms,” says Wasmuth. “This makes it an extremely important model parasite species. Revealing new drug targets against H. contortus could provide much-needed new treatment opportunities against parasitic worms in humans as well as animals.”
About the project
The project is an ongoing collaboration between the University of Calgary, University of Glasgow and the Wellcome Trust Sanger Genome Institute in the UK. Gilleard, associate dean (research) in the Faculty of Veterinary Medicine, is joint senior author on the paper and Wasmuth is a co-author, together with several members of both their research groups. Dr. James Cotton is the joint senior author leading the Sanger Institute team.