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$25m Barramundi Industry To Benefit From New Vaccine

AUSTRALIA - Researchers from The University of Queensland have developed a reliable typing system for infections in barramundi that will have vaccines rapidly implemented in the industry.

The project is funded by the Fisheries Research and Development Corporation.

Dr Andrew Barnes from the School of Biological Sciences developed the vaccine in collaboration with the Darwin Aquaculture Centre and veterinarians Matt Landos, John Humphrey and Suresh Benedict.

All fish are able to be routinely vaccinated against diseases caused by bacteria in the same way that other animals and humans are vaccinated.

Vaccination exploits the natural immune system of the animal to remember and respond to a particular antigen if it encounters it again.

Streptococcus iniae is a bacterium that causes disease in farmed fish similar to meningitis and blood poisoning in humans," Dr Barnes said.

"Treating the infection with antibiotics is difficult because antibiotics must be fed to the fish and when the fish are sick, they don't eat the medicated feed.

“There is a problem of bacteria becoming resistant to antibiotic treatment, and this resistance can be transmitted to other bacteria that may be harmful to humans.

"For food and safety reasons, farmers may have to abide a ‘withdrawal period' of their stock from market to ensure residue levels of the antibiotics meet required levels. This causes problems for farmers when the fish are close to market size.”

Vaccinating barramundi against the bacteria is possible in fish but has not always been successful as vaccinated fish do not always recognise new strains of disease.

“The flu shot works in people because there are only two proteins on the surface of the virus which change and these can be identified in laboratory tests to be included into the vaccine administered each year,” Dr Barnes said.

“Typing the surface of S. iniae has been more difficult as it is a polysaccharide. Of more than 20 genes responsible for the surface capsule, changes in five have been attributed to critical changes in the surface.

“A reproducible and accurate typing system has been developed and a manual drafted and disseminated to veterinary laboratories which will enable accurate detection of any new isolates should they arise in the future."

Based on the outcomes of Dr Barnes' work, it is possible to formulate a generic vaccine for Australian barramundi.

Future work will need to include some further typing but will predominately focus on testing generic vaccine formulations in fish to ensure cross protection and on generating a dossier to permit registration of the vaccine.

the Fish Site Editor

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