Are researchers closing in on a vaccine for flystrike?

Researchers develop prototype vaccines for sheep flystrike

Sheep
THE HOLY GRAIL: Dr Tony Vuocolo needles a sheep with a prototype vaccine against flystrike. A commercial and effective blowfly vaccine is the Merino industry's holy grail.

THE HOLY GRAIL: Dr Tony Vuocolo needles a sheep with a prototype vaccine against flystrike. A commercial and effective blowfly vaccine is the Merino industry's holy grail.

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Researchers have developed proptotype vaccines to protect sheep against flystrike.

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Researchers are testing prototype flystrike vaccines using key proteins in blowfly larvae that are important for their growth and development.

The vaccine triggers the sheep's immune system to build a defence system in the blood using antibodies that target the larval proteins.

The antibodies react against the larvae when they try to feed on sheep by targeting and interfering with these proteins, resulting in stunted or dead blowfly larvae.

The breakthrough was announced in a review of the first year of a $2.5 million Australian Wool Innovation four-year research project to help develop a commercial vaccine to protect the flock from the Australian sheep blowfly.

A full update has been published in this month's AWI Beyond the Bale magazine.

The collaborative research project is being led by Tony Vuocolo from the CSIRO and Trent Perry from the University of Melbourne.

The CSIRO team has had to develop an alternative and cheaper way to synthesise the proteins because of the prohibitive cost of extracting them from actual flies.

"However, to generate an effective immune response the ideal protein antigen(s) for the vaccine must closely resemble the characteristics of the natural larval protein," Dr Vuocolo said.

"To do this, antigens are being produced in specialised insect cell systems in the laboratory; in addition, CSIRO is also exploring alternative ways to manufacture key protein associated structures that may be used in a vaccine.

"The next 12 months of research will determine the directions that need to be undertaken to develop an effective flystrike vaccine.

"An annual vaccination to help protect sheep from flystrike is the holy grail in flystrike control and remains the key aim of this CSIRO team."

Melbourne University researchers have collected hundreds of blowflies from across Australia and are studying them to identify the regions that flies are moving between and how they adapt to their environment.

This information will help pest management strategies, such as how to best contain insecticide resistance if it arises.

Working with CSIRO, the researchers are also examining the protein sequence of current vaccine candidate genes to help ensure the proteins they are targeting are the same in blowfly populations across Australia.

Blowfly samples were obtained from January to March 2019 from locations in Victoria, Tasmania, NSW and Queensland.

The fly samples have since been genotyped using a technique that provides information on thousands of markers distributed throughout the fly's genome and this has allowed the Melbourne Uni team to begin building a model of the Australian sheep blowfly population structure in this country.

Another area of the project is a study that aims to understand how flies establish a strike, particularly what proteins are critical in the early stages, just prior to and during the initiation of a strike.

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