RNAi enlisted in hunt for prawn vaccines

CSIRO researchers are using a biological phenomenon called RNA interference (RNAi) in an effort to develop a major biotechnological breakthrough for the aquaculture industry - vaccines for common prawn diseases.

CSIRO Livestock Industries' Dr Marielle van Hulten says viral diseases like white spot syndrome cost the world prawn industry around US$1 billion each year and pose a significant threat to Australia's burgeoning prawn farming industry.

"The problem is that the immune system of invertebrates, like prawns, is not like that of vertebrates," Dr van Hulten says. "The common view is that prawns can't develop immunity to viruses and vaccines won't work."

However, early results from a research project involving Dr van Hulten, and scientists drawn from several CSIRO Divisions, have challenged this belief.

"RNAi is part of the cell's natural defence against RNA viruses," Dr van Hulten says.

"When cells see double stranded RNA - which is likely to be a virus - they launch an attack. Enzymes are released to cut up the RNA, effectively 'silencing' the viral material.

"We recently identified a gene in the prawn coding for the DICER enzyme. This enzyme is involved in the cutting up process," she says.

"This confirms that prawn cells can undergo RNAi. The focus now is to use this natural defence mechanism to develop vaccines."

Prior to joining CSIRO Livestock Industries in 2003, Dr van Hulten worked at Wageningen University in the Netherlands where she successfully produced a protein-based vaccine against the white spot syndrome disease.

RNAi is a key component of CSIRO's biotechnology strategy, with the organisation holding an extensive and growing intellectual property portfolio in the area. CSIRO is developing products for, and with, the plant, livestock, aquaculture, animal biotechnology and biopharmaceutical industries.

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