University of Stirling researchers have developed a precise method to analyse salmon lice secretions, potentially supporting new strategies to protect farmed salmon from infestations.
A University of Stirling study could support more efficient research into the secretions salmon lice use to feed on fish and avoid host defences.
The research was led by PhD researcher Alexander Dindial alongside Professor James Bron and Dr Sean Monaghan at the University’s Institute of Aquaculture, in collaboration with Kevin McLean of the Moredun Research Institute.
The team developed a new way to collect and study secretory and excretory products, known as SEPs, from individual salmon lice.
The paper was published in Veterinary Parasitology.
Salmon lice secretions analysed from individual parasites
Salmon lice feed on the skin, mucus and blood of fish, causing open wounds that can lead to infection, reduce the market value of farmed fish and increase the risk of secondary infections.
Various treatments have been developed to tackle sea lice infestations in Atlantic salmon aquaculture, but the release said some can be expensive, unreliable, environmentally damaging and harmful to animal welfare.
Previous methods for extracting SEPs involved pooling together large numbers of lice.
The Stirling-led method allows researchers to study individual lice, helping reveal natural differences that could be important for developing targeted treatments or vaccines.
New method reduces sample contamination
The new method also reduces the potential for faecal contamination in samples.
It allows researchers to collect high-quality samples from a single louse per test, with substantial yields of secretory proteins from each louse.
Researchers collected secretions by placing a small drop of solution over the mouthparts of individual salmon lice and allowing them to release proteins into it.
The proteins were then analysed using liquid chromatography tandem mass spectrometry, a technique used to separate sample components, break them into fragments and identify protein composition.
Research identifies 148 secretory proteins
The team found 148 total secretory proteins, including 64 detected in each of the tested conditions.
Some of these proteins could represent potential targets for vaccine development.
The secretory protein profiles of individual lice showed wide variation in protein number and diversity, a pattern consistent with other ectoparasites such as ticks and mosquitoes.
The published study describes a novel method for extracting secretory and excretory proteins from individual Lepeophtheirus salmonis and highlights candidates relevant to louse-host interactions.
Research could inform salmon lice control strategies
Mr Dindial said: “Salmon lice cause hundreds of millions of pounds of damage annually to the global salmon aquaculture industry through mortality, lost production and the implementation of control measures. Understanding these secretions is an important step towards understanding louse biology and developing new, safe, and effective strategies for control.”
He added: “This work has the potential to expand our knowledge of salmon louse biology and to provide insight into louse proteins that could be exploited to help fish mount an immune response against infection.
“The novel methodology developed here has the potential to directly facilitate further research into salmon louse secretory biology. It allows for the reproducible, reliable, and efficient extraction of high concentrations of salmon louse secretions, all while minimising faecal contamination.
“As well as improving the study of these secretions, the protocol could be used to investigate how drug or therapeutic treatments might alter louse secretory activity, ultimately advancing efforts to control this parasite.”
Study builds on earlier Stirling salmon lice research
The work builds on an earlier study led by Mr Dindial, which compared proteins released by infectious young larval-stage salmon lice with those found in adult lice. The University of Stirling said that study identified major differences in the secretions the parasite uses to feed and evade the immune system at different stages of its life cycle.
The latest work was funded by EastBio as part of Mr Dindial’s PhD studentship, with a funding contribution from Moredun Research Institute.
Collaborative research was also conducted with the project Towards lice-resistant salmon: functional genetics and genome editing to enhance disease resistance in aquaculture, funded by the Biotechnology and Biological Sciences Research Council, Sustainable Aquaculture Innovation Centre and Benchmark Genetics Limited.
The project involved partners from the Roslin Institute at the University of Edinburgh, the Centre for Environment, Fisheries and Aquaculture Science, the Atlantic Veterinary College at the University of Prince Edward Island, and Kames Fish Farming Ltd.
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Source: University of Stirling
