Norway’s seafood industry has nearly eliminated the use of antibiotics on farmed salmon thanks to effective bacterial vaccines. Now the focus has turned to combating viruses through innovative genomics and the groundbreaking use of live vaccines.
Norway’s aquaculture industry has grown to more than 1 million tons mainly due to an average 10% annual increase in the past decade. Part of the growth is from new concessions and technology for using very large net pens, but most of it is from better fish health and welfare, according to Kjell Naas, special advisor at HAVBRUK, the Research Council’s large-scale program initiative focusing on economically, environmentally and socially sustainable growth in Norwegian aquaculture. A number of new ground breaking vaccines have come into the market to stem the tide of bacterial infectious fish disease outbreaks, notably cold-water vibriosis (also known as Hitra disease) in the 1980s and furuncolosis in the 1990s.
“This was a difficult period for fish farming,” says Naas. The majority of HAVBRUK’s projects focus on fish health, including vaccines, epidemiology and immunology and vaccine development.
“If the outbreaks of bacterial diseases had not been controlled in the eighties and nineties, Norway’s aquaculture industry would have been destroyed,” adds Espen Rimstad, professor in microbiology, immunology and parasitology at the Norwegian School of Veterinary Sciences, part of the Norwegian University of Life Sciences in Oslo.
Rimstad was recently granted a NOK 24 million grant from the HAVBRUK program for his project ViVa Fish. During the next four years, researchers will study the possibility of using live attenuated viruses in farmed salmon, possibly through either feed or bathing methods rather than only injections.
This would be a first for the industry. Attenuated, or weakened viruses, may be the norm for immunizing children. But farmed salmon have been vaccinated manually with dead viruses because of the risks involved with injecting the fish with live viruses in an open system where it could spread. Annually, there are about 300-400 million farmed Norwegian salmon that are anesthetized and then injected with vaccines during the fresh water phase.
If successful, the new method could have enormous impact for the Norwegian aquaculture industry, which is dealing with four main viral outbreaks: infectious salmon anemia (ISA), salmonpancreas disease (SPD), piscine myocarditis (PMC), and piscine orthoreovirus (PRV), the latter of which was found in 2010 to be linked to Heart and Skeletal Muscle Inflammation (HSMI).
“In general, infectious diseases in farmed fish have increasing importance,” says Rimstad. “The viral diseases were overshadowed by the bacterial diseases (in the 1980s and 1990s). Still after 20 years, we don’t have good viral vaccines.”
ViVa Fish will focus on these four viruses in particular. Currently, the most problematic is pancreas disease which has escalated from 89 sites diagnosed in 2011 to 137 in 2012, according to the Norwegian Veterinary Institute’s Fish Health Report 2012. The goal of ViVa Fish is to develop live vaccines that are environmentally friendly and not spread between the fish as well as developing an alternative to live vaccines in the form of recombinant variants of parts of viruses.
“We have to make this the standard,” says Rimstad. “Currently, inactivated viruses have been involved.”
Part of the challenge will be to make the new vaccine cost effective. For example, the project will have to make most of the molecular tools itself because they are not commercially available. Another big issue will be to understand the fish immunology and intimate interaction of the virus and the fish cells they manipulate.
To help reach its goal, ViVa Fish is working together with, among others, industry partner Pharmaq. The Norwegian company has been commercially successfully abroad in marketing its fish vaccines. Most recently, the company opened up an affiliate in Panama targeting tilapias and was the first in 2013 to introduce a fish vaccine in Vietnam, ALPHA JECT®Panga 1, that provides protection against the bacteria Edwardsiella ictaluri causing disease in pangasius.
ViVa Fish will also collaborate with Merck in the US and its R&D department in Bergen, Novartis in Switzerland, as well as Norwegian research partners: National Veterinary Institute in Oslo, University of Tromsø, and the Institute of Marine Research in Bergen. Internationally, ViVa Fish is collaborating with research partners in the US (College of William and Mary in Virginia and the University of New Mexico), Germany (FLI Reims), Wageningen University in the Netherlands, and INRA in France.
The success of the ViVa Fish study will be important for the aquaculture industry in general. The Food and Agriculture Organization has set a target of 5% annual growth in aquaculture. The control of viral diseases will be key for reaching this extremely high growth rate, according to Rimstad. This can most effectively be achieved through vaccines, resistance through genetic selection, and biosecurity measures.
Gene Marking for IPN
One of the companies that have been extremely successful with gene marking is Norwegian selective breeding company Aqua Gen. It has developed a genetic marker that enables it to produce Quantitative Trait Locus (QTL) eggs to prevent infectious pancreatic necrosis (IPN) in salmon. The product came as result of an innovation project for the industrial sector with the Research Council that studied how to select parent fish with the right traits most resistant to IPN with better than 80% certainty.
“The product was well received when we launched it in 2009,” Nina Santi, Aqua Gen research and development director, said in the Research Council’s newsletter HAVBRUK. “Now all the eggs we supply are QTL eggs. So far no major IPN outbreaks have been reported at farms using fish form QTL eggs, and our product has helped to rid the industry of the disease.”
IPN is a highly contagious viral disease that came to Norway in 2002 and reached a peak outbreak during 2009, according to The Norwegian Veterinary Institute Fish Health Report 2012. However, in the two years during 2010-2012, the number of IPN outbreaks was nearly halved from 198 to 119. The authorities believe breeding for increased resistance through QTL eggs, and eradication of house strains in hatcheries, are two of the most important factors behind the marked improvement.