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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"What's encouraging about this research is that there were no false-positive results. A gene negative for hypermethylation in the tumor DNA was always negative in the matched serum or peritoneal fluid DNA.

"There is no other obvious body fluid available for ovarian cancer testing except the blood," Edelson added. "In the past couple of years, we have seen detection attempts with proteomics and now with this method. It is encouraging to see so much activity regarding one of the most feared diseases for women."

The potential application of this finding could be significant because there is no reliable screening method available for ovarian cancer. Most women are diagnosed with late-stage disease after developing symptoms. The cure rate for women with advanced ovarian cancer is low, but doctors are often successful in treating early-stage disease.

"It would appear that hypermethylation is a very specific marker for this disease, and if confirmed in larger studies, methylation may be useful in ovarian cancer diagnosis," said Cairns.

In earlier research, Cairns and his colleagues have demonstrated the ability to detect prostate and kidney cancer by targeting hypermethylation.

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