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[SANTIAGO] A vaccine against bacteria that cause annual losses of US$150 million to Chile's farmed salmon industry will be commercially available for the first time next year. The announcement was made at the 12th International Biotechnology Symposium, held in Santiago from 17 to 22 October.

The vaccine will also benefit the environment. Preventive vaccination of fish could reduce the need for antibiotics and other pharmaceutical drugs, which can have negative impacts on life in the seas surrounding fish farms.

The Piscirickettsia salmonis bacterium grows within salmon liver cells, causing a disease called salmonid rickettsial septicaemia (SRS), which results in swelling of the liver and kidneys, and eventually, death.

Since it was first recognised and isolated in Southern Chile in 1989, P. salmonis has caused widespread deaths in Chilean salmon farms. But little is known about the microbe's biology or how it infects fish, and so far there have been no commercially available vaccines.

"The disease has not had the same impact in salmon producing countries in the northern hemisphere, and little effort has been made to search for efficient methods to prevent it," said Pablo Valenzuela, lead author of the research and director of the Fundación Ciencia para la Vida (Science for Life Foundation), a private Chilean organisation that promotes collaborations between scientists and industry.

The increasing importance of fish farming to the Chilean economy prompted Valenzuela's project. With an annual production of 494,000 tonnes, Chile is the second largest producer of salmon and trout, after Norway.

Valenzuela and colleagues at the Millennium Institute of Fundamental and Applied Biology followed a "genomic approach" for the development of the vaccine.

First, they sequenced all the micro-organism's genes. This allowed them to identify specific genes involved in the infection process.

The researchers picked 16 genes that, based on comparisons with other known bacterial genes, could be used for developing a vaccine. The proteins created by each of the genes were integrated into five different vaccines, which were tested in the laboratory and then at fish farms in southern Chile.

After being vaccinated, the salmon were exposed to lethal amounts of P. salmonis. Whereas all the unvaccinated specimens died in the following days, the most successful vaccine protected 96 per cent of the fish.

The final vaccine, licensed to Novartis Animal Vaccines Inc., will be on the market next year, subject to the approval of local authorities.

According to figures presented by Valenzuela, the expected market for the vaccine is around US$50 million per year. Research costs for its development were about only US$1 million.

"Applying biotechnology to production processes pays very well," commented Valenzuela.

The vaccine's development was financed in part by Corfo (Corporacion de Fomento de la Produccion), in collaboration with Fundacion Chile and the biotech company BiosChile.

In another presentation at the symposium, Eric Mathur, vice-president of scientific affairs of Diversa Corporation, presented a second vaccine against P. salmonis. Based in San Diego, United States, Diversa Corp this year formed an alliance with Bayer Animal Health. Like Valenzuela's team, they plan to begin the commercialisation of their product soon.