FHF: Progress in the development of DNA vaccines against salmon lice

Scientists at the University of Bergen have achieved promising results that can contribute to the development of a DNA-vaccine against sea lice.

“The new findings may lead to a more sustainable and welfare-friendly way of combatting sea lice, and is a step forwards on the path towards a future vaccine,” says the FHF in a press release [issued 25 June 2025].

Sea lice is one of the fish farming sector's greatest challenges. Today’s methods for removing lice, such as mechanical delicing and use of cleaner fish, can cause significant stress and mortality among farmed fish. An effective vaccine would be able to reduce the requirement for these methods.

“Such a vaccine would have the potential to improve the important fish health and welfare issues that are associated with current methods of sea lice control. This project has also contributed to the testing of technology that can result in more effective vaccines generally. The findings can therefore potentially be of great benefit to the fish farming sector,” says Kjell Maroni, divisional director at FHF.

Several findings

The project is funded by the FHF and undertaken by researchers at the Sea Lice Research Centre (SLRC) at the University of Bergen.

The researchers have focussed on utilising the lice’s own salivary gland proteins as vaccine candidates. The idea is to teach the salmon's immune system to recognise and fight these proteins, so that the salmon becomes more resistant to lice infestation.

Several findings have been made:

• The researchers have discovered that certain changes in the vaccine design, including optimisation of the gene code and the ability to extract the antigen from the salmon cells, led to an improved antibody response.
• A method of electroporation (small electrical pulses) at the point of injection has been adapted for use on salmon. This can increase the uptake of the vaccine in the muscle cells, thus significantly enhancing the immune response.
• Several specific proteins from sea lice salivary glands have been identified as good vaccine candidates.
• It has been shown that several of these proteins can be combined into one vaccine without any notable side effects shown by the salmon. This is important, as the combining of several proteins will likely be required to arrive at an effective vaccine.
• Perhaps most important for the development of a sea lice vaccine is that the researchers have found specific antibodies in the salmon’s mucosal layer post-vaccination. This means that the vaccine can provide protection where the sea louse attacks its host.

Although significant advances have been made, there is still work to be done. The next step is to test the effect of the polyvalent test vaccine in infection trials, which will be undertaken in the ongoing SaliFilaVax project, writes the FHF.

However, these results give grounds for hope. A well-functioning DNA vaccine would not only greatly reduce costs for the industry but would also contribute to an aquaculture sector that is better for both the livestock and the environment, writes the FHF.

 

SAIC has provided this translation of the FHF's press release. Please contact the University of Bergen if you have questions about scientific details that may not be represented in this translation.

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