Host genetic variation explains reduced protection of commercial vaccines against Piscirickettsia salmonis in Atlantic salmon

Abstract

Vaccination is a widely used control strategy to prevent Piscirickettsia salmonis causing disease in salmon farming. However, it is not known why all the currently available commercial vaccines generally fail to protect against this pathogenic bacteria. Here, we report, from two different populations, that between-family variation is a strong intrinsic factor that determines vaccine protection for this disease. While in some full-sib families, the protection added by vaccination increased the survival time in 13 days in comparison with their unvaccinated siblings; in other families, there was no added protection by vaccination or even it was slightly negative. Resistance to P. salmonis, measured as days to death, was higher in vaccinated than unvaccinated fish, but only a moderate positive genetic correlation was obtained between these traits. This disputes a previous hypothesis, that stated that both traits were fully controlled by the same genes, and challenges the use of unvaccinated fish as gold standard for evaluating and selecting fish resistant to P. salmonis, particularly if the offspring will be vaccinated. More studies are necessary to evaluate if variation in the host immune response to vaccination could explain the between-family differences in resistance observed in vaccinated fish.

The Analysis of Live-Attenuated Piscirickettsia salmonis Vaccine Reveals the Short-Term Upregulation of Innate and Adaptive Immune Genes in Atlantic Salmon (Salmo salar): An In Situ Open-Sea Cages Study

“…All these factors have negative impacts on fish welfare, overall performance, and protective immune response, increasing the susceptibility to disease [ 3 ]. Farmed fish are continually exposed to pathogens, including bacteria, viruses, and parasites, which may produce outbreaks and mortality [ 4 , 5 ]. Prevention of diseases is an advisable practice in aquaculture, which is based on improved husbandry practices, movement restrictions, genetically resistant-disease stock, dietary supplements, non-specific immunostimulants, vaccine, probiotics, prebiotics, medicinal plant products, water disinfection and antimicrobial compounds as the best approaches in controlling infectious diseases of fish [ 4 , 6 ].…”

“…Moreover, infected salmonids respond poorly to these treatments, likely because of the intracellular characteristics of the infective cycle of P. salmonis and the insufficient concentrations of antibiotics that reach the intracellular niche to eliminate the bacterium [ 13 ]. This situation is further complicated by the lack of effective vaccines against P. salmonis because prophylactic vaccines do not provide acceptable levels of protection [ 4 , 13 ].…”

Induction of foxp3 during the Crosstalk between Antigen Presenting Like-Cells MHCII+CD83+ and Splenocytes CD4+IgM− in Rainbow Trout

“…Also, they are the final target for the success of vaccination strategies, which are widely used in aquaculture. Nevertheless, these strategies have not yet been able to generate an improved response, over time, against pathogens, such as P. salmonis [ 36 ]. Using a cyprinid study model, Piazzon et al [ 37 ] have proposed that phenotypic environments associated with regulatory lymphocytes not only generate the suppression of immunity, but could also be related to the maintenance of memory cells, over time.…”

Biotechnologies to Bridge the Schism in the Bioeconomy

“…Farmed fish are susceptible to many infectious diseases: as much as 10% of all cultured aquatic animals are lost to infectious diseases, with an annual loss to the industry of over USD 10 billion [84]. Excessive use of antibiotics is thought to contribute to the spread of drug-resistant pathogens in wild fish.…”