Conventional vaccines expose animals to an inactivated form of a whole virus (pathogen). This, given with a stimulating agent, helps enhance the animal's immunity to the virus. The pathogen and the stimulating agent work together to engage a response which primes immune cells in the animals body to recognise and remove any virus that appears.
What makes NAVs different?
Rather than using the whole virus, NAVs use only the relevant genetic components of the virus that trigger development of an immune response. The NAV is constructed by inserting these genetic components into a circular piece of nucleic acid called a plasmid.
The fish still needs to be out of the water and anesthetised on a vaccine table, however there is no need for accuracy when using a DNA vaccine.
"The DNA vaccine can be injected anywhere in the muscle, reducing side effects," said Dr Salonius.
Reduced side effects
The use of DNA vaccine reduces the side effects, such as reduced growth and poor flesh quality, sometimes associated with conventional vaccines.
With fewer side effects, fish can be vaccinated and returned to their normal environment immediately. They are fully recovered and eating again within 24 hours.
Dr Salonius says that the increased efficiency makes NAVs more cost efficient for producers.
To date, there are only three vaccines in the world using NAV technology. One of these is an infectious haematopoietic necrosis (IHN) vaccine produced by Novartis and used in North America.
Novartis began to invest in NAV technology in 1999, at their aquaculture facility on Prince Edward Island. With the IHN vaccine already for sale in North America, Novartis has now set Europe and Norway in their sights.
Novartis has developed an effective NAV pancreas disease (PD) vaccine, and has applied to get it licensed in Europe. Norway, Scotland and Ireland are the main targets.
"PD and sleeping disease (SD) in salmon and trout are still very prevalent in Europe and Norway despite strong use of best management practices and vaccines already available in the field.
"This is why it is important for us to develop more effective vaccines, " said Dr Salonius.
Should Novartis be successful in securing a licence for the vaccine from the European Medicines Authority, it will be the first NAV in Europe.
Dr Salonius said that the PD vaccine will be available as soon as possible in the EU and Norway, definitely within five years.
Nucelic Acid Vaccine (NAV) technology offers a more targeted approach for the prevention of disease in fish. Charlotte Johnston, TheFishSite editor talks with Kira Salonuis, Head of Global Technical Services, Aqua Vaccines for Novartis about what NAV can offer the industry.