Impact of a candidate vaccine on the dynamics of salmon lice (Lepeophtheirus salmonis) infestation and immune response in Atlantic salmon (Salmo salar L.)

Abstract

Infection with parasitic copepod salmon louse Lepeophtheirus salmonis, represents one of the most important limitations to sustainable Atlantic salmon (Salmo salar L.) farming today in the North Atlantic region. The parasite exerts negative impact on health, growth and welfare of farmed fish as well as impact on wild salmonid populations. It is therefore central to ensure continuous low level of salmon lice with the least possible handling of the salmon and drug use. To address this, vaccination is a cost-effective and environmentally friendly control approach. In this study, efficacy of a vaccine candidate, containing a peptide derived from ribosomal protein P0, was validated post infestation with L. salmonis, at the lab-scale. The sampling results showed good potential of the vaccine candidate when administered intraperitoneally in the host, in reducing the ectoparasite load, through reduction of adult female lice counts and fecundity and with greater presumptive effect in F1 lice generation. The sampling results correlated well with the differential modulation of pro-inflammatory, Th1, Th2 and T regulatory mediators at the transcript level at different lice stages. Overall, the results supports approximately 56% efficacy when administered by intraperitoneal injection. However, additional validation is necessary under large-scale laboratory trial for further application under field conditions.

State-of-the-Art Vaccine Research for Aquaculture Use: The Case of Three Economically Relevant Fish Species

“…Very recently, the E. coli -produced chimeric protein composed by the ribosomal protein P0 from Lepeophtheirus salmonis and T cell epitopes from bacterial and viral organisms [ 104 ] was specifically tested in S. salar by IP injection alone or in combination with a bath immunization, followed by a booster [ 68 ]. In addition to assessing sea lice abundance on parasitized fish following a challenge, the authors evaluated the innate (e.g., IFN-γ, IL-8, IL-10, and IL-22) and adaptive (e.g., IgM, IgT, and CD4) responses through gene expression analysis in immunologically relevant organs/tissues.…”

To React or Not to React: The Dilemma of Fish Immune Systems Facing Myxozoan Infections

“…Teleost fish have only three Ig isotypes: IgM, IgT/Z, and IgD (39), there is no switch of Igs in the secondary response, and the production of specific antibodies is temperature dependent (40, 41) (see section 3 for more details about the different functions of Igs). In the last decade our knowledge of the immune system of fish has notably increased (42)(43)(44)(45)(46)(47)(48)(49)(50)(51)(52)(53), and in parallel, that of the immune responses against fish parasitic flagellates (54, 55), microsporidians (56), ciliates (57)(58)(59)(60), helminths (61)(62)(63)(64), amoeba (65,66) and crustaceans (67)(68)(69). However, there are methodological difficulties that limit our understanding of fish immune responses in comparison to other vertebrates.…”

Principles and Methods of Counteracting Harmful Salmon–Arthropod Interactions in Salmon Farming: Addressing Possibilities, Limitations, and Future Options

“…Due to its consistency and efficacy, the most common delousing method is medical treatments (Aaen et al, 2015). Attempts to develop resistant fish and vaccines against salmon lice have also been reported (Kaur et al, 2015;Contreras et al, 2020;Swain et al, 2020). Regulatory authorities in salmon-producing nations have established mandatory and maximum thresholds on the number of mature or motile lice per farmed fish at production sites to limit the transmission of sea lice and sea-lice larvae from farming facilities to wild salmon smolts.…”

“…Peptides from salmon lice were conjugated with T-cell epitopes (TCEs), that are universally immunogenic in mammalian systems (Panina-Bordignon et al, 1989;Leal et al, 2019). TCEs from tetanus toxin and measles virus are known to increase the immunogenicity in salmonid immune system (Leal et al, 2019;Contreras et al, 2020;Swain et al, 2020). Moreover, technologies, such as adjuvants and nanoparticles, in combination with conventional approaches for enhanced immunogenicity are additional perspectives for the future (Dadar et al, 2017;Angulo et al, 2020).…”