Australian research could end risk of deadly sheep disease

Australian researchers have mapped the genome of the blowfly, paving the way for the prevention of the deadly disease which affects sheep, flystrike.

Flystrike affects sheep in warmer climates, particularly in Australia and New Zealand during summer, and occurs when blowflies lay maggots into the folds of sheepskin.

Flystrike is estimated to cost Australia's sheep industry more than 215 million U.S dollars annually, but the breakthrough, made by scientists at the University of Melbourne, will allow researchers to hunt for more effective control measures for the parasite.

The research was published in the scientific journal Nature Communications, and Dr. Clare Anstead from the university's Veterinary and Agricultural Sciences department said the genome map brought "limitless potential" for fighting blowflies and the risk of flystrike.

"It is an extremely nasty parasite. The sheep is literally eaten alive and it's horrific," Anstead said.

"The blowfly species are responsible for more than 90 percent of flystrike in Australia and New Zealand."

Anstead said the fly had resisted traditional methods of control, but now its genes had been mapped, scientists have a better chance at fighting the damage caused by the parasite.

"This fly is especially good at evolving to resist insecticides. There has been a massive amount of research into prevention and control of flystrike, from developing a vaccine, new insecticides, to targeting weak areas of the fly, and even biological control with bacteria and fungi. But none are completely effective," she said.

"It's exciting that we have now identified more than 2,000 genes that have never been seen in any other animal or plant.

"Some of these 'orphan' genes hold the key to the parasitic relationship between the blowfly and the sheep. They could be targeted to develop a completely new method of control."

The University of Melbourne's Prof. Robin Gasser, who also took part in the genome mapping, said fighting parasites such as the blowfly had to stary by understanding its makeup.

"If you want to develop effective interventions against this fly, you need to know it inside out and understand its biology, starting by identifying all the genes. And, we have done that," he said.

The team have identified a way of restricting the fly's chance of finding host sheep, by altering the parasite's genes so that it cannot use its sense of smell.

The university's Prof. Phil Batterham said new technology, called CRISPR, would attempt to "switch off" some genes, rendering the fly's remarkable sense of smell useless.

"Flies have an extremely sophisticated sense of smell. They can smell the difference between sheep that are resistant to the fly and those that aren't," Batterham said.

"We want to produce a fly that cannot smell, so that we can understand how important that sense of smell is in the initiation of flystrike." Endi