COST-EFFECTIVE SEA LICE VACCINE; DEVELOPMENT AND EFFICACY EVALUATION

almon lice are the biggest disease problem for farmed salmon. The aquaculture industry is now completely dependent on therapy products to control the lice problem. The development of resistance has resulted in reduced efficacy of treatments against these parasites, and hence an urgent need for new sustainable products for salmon lice. There are environmental challenges to chemical treatments. Effective vaccine for salmon lice will reduce the need for chemical treatments and further reduce the release of toxic residues into the environment. The project is based on the research council's project Louseoff (LO1) where the aim was to identify protective salmon lice antigens (Ag) through a screening of a large number of antigen candidates. Louse off 2 has selected three antigenic candidates that have shown efficacy in the screening work performed in LO1. Project partner SINTEF has developed a lab-scale recombinant protein production process. The process shows different degrees of yield and purity for the three selected Ag. For two of the three selected candidates, protein yield and solubility have been sufficient for pilot production of antigens. These antigens have been included in various formulations with the aim of develop long-term protection in fish. Selected adjuvants have been used in effect studies in fish where one of the candidates has given reduced survival of salmon lice. Immunological assays performed by Veterinary Institute show specific antibody response to vaccine antigen. Selected vaccine candidates have been included in a small-scale field trial. The trial was ended in June 2020 and the collected lice data was be statistically analyzed by Veterinary Institute and the Norwegian Computing Center to determine the vaccine's ability to reduce lice infestations. The study provided important information on the potential of a salmon lice vaccine to reduce sea lice infestation.

Prosjekt har gitt økt kunnskap om bekjempelse av lakselus ved vaksinering. Immunparametere for måling av vaksineeffekt gir bedre forståelse av vaksineeffekt. Effekt forsøk i lab og felt har gitt bedre forståelse av potensialet til en framtidig lusevaksine. En prosess for produksjon av antigen har blitt utviklet og modifisert for å kunne oppnå en kostnadseffektiv prosess.

Louseoff 2 aims to develop an ectoparasite vaccine that protects salmon against sea lice infestations. The project builds on the NRC-supported project Louseoff (LO1) that screen for protective vaccine antigens from salmon lice (Lepeophtheirus salmonis). Louse off 2 will focus on developing large scale protein production systems and formulations that induce sufficient long term protection after one injection. The vaccine dose price is substantially lower in aquaculture compared to domestic animal and human vaccines, which challenges the need for new innovative solutions in efficient recombinant Ag production and purification. The project will explore how efficacy can be increased to a commercially feasible level by using different adjuvants and antigen combinations. Finally the project aims at evaluating long term efficacy of the new vaccine candidate-formulations in a small-scale field experiment. This study will give vital information regarding the commercial potential of a sea lice vaccine. The project will use competences in epidemiology for the optimal design and data evaluation from this trial to better characterize this effect. A protective sea lice vaccine will be an international break-through in vaccinology that will help the industry towards reduction of chemical treatments.