Research led by PhD researcher Alexander Dindial alongside professor James Bron and Dr Sean Monaghan at the University’s Institute of Aquaculture, in collaboration with Moredun Research Institute’s Kevin McLean, has resulted in the development of a new and precise way to collect and study secretory and excretory products (SEPs) from salmon lice. This includes substances released from the glands of the lice that make it easier for them to feed or evade their host’s immune system.
Salmon lice feed on the skin, mucus, and blood of fish, causing open wounds that can lead to infection and secondary health problems. Infestations can also reduce production and the market value of farmed fish.
A range of treatments are already used to control sea lice in Atlantic salmon aquaculture, but infestations are estimated to cost the industry more than $1 billion a year. Some existing control methods can also be costly, unreliable or environmentally damaging, and may have negative impacts on fish welfare.
Previous methods for extracting SEPs involved pooling large numbers of salmon lice. This can mask differences between individual parasites that may provide useful information for developing more targeted treatments or vaccines.
The new approach, published in Veterinary Parasitology, allows researchers to collect high-quality samples from a single louse while reducing the risk of contamination from louse faeces.
“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,” said Dindial in a press release.
Method outline
To collect the secretions, researchers placed a small drop of solution over the mouth of each salmon louse, allowing proteins released by the parasite to enter the solution. The samples were then analysed using liquid chromatography tandem mass spectrometry, a technique that separates and identifies proteins based on their composition.
The researchers indentified 148 total secretory proteins in total, 64 of which were detected in each of the conditions tested. Some could represent potential targets for future vaccine development.
The secretory protein profiles of individual lice showed a wide variation in protein number and diversity, a pattern consistent with other ectoparasites like ticks and mosquitoes.
Dindial continued: “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.”
The work was also conducted in collaboration with the project Towards lice-resistant salmon: functional genetics and genome editing to enhance disease resistance in aquaculture, funded by the UK Biotechnology and Biological Sciences Research Council (BBSRC), the Sustainable Aquaculture Innovation Centre and Benchmark Genetics Limited. Project partners included 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.