Temperature impacts Atlantic salmon's (Salmo salar) immunological response to infectious salmon anemia virus (ISAv)

• Published in: Fish and shellfish immunology reports 2023-12, Vol.4, p.100099-100099, Article 100099
• Main Authors: Groves, L, Whyte, SK, Purcell, SL, Michaud, D, Cai, WC, Garber, AF, Fast, MD
• Format: Article
• Language: English
• Subjects: Anti-viral; Immune response; ISAv; Salmon; Temperature; Vaccination
• ISSN: 2667-0119; 2667-0119
• DOI: 10.1016/j.fsirep.2023.100099

•1-Mortality due to ISAv exposure was significantly higher at 10 °C compared to 20 °C, despite higher acute mortality at the higher temperature.•2-Variation in family-based susceptibility to ISAv exposure ranged from 32 to 95% survival, and was linked to temperature.•3-Viral prevalence disappeared quicker at 20 °C compared to 10 °C.•4- Innate antiviral response was higher at 10 °C as demonstrated by genes such as mx1, isg15, and vprn, as well as the Th2 response, demonstrated by il10 and il4/13a.•5- The Th1 and antigen presenting cells response was initially greater at 20 °C, as seen in il12rb2 and nkl, which may therefore play a role in viral clearance. Ocean temperatures continue to rise annually due to the ever-growing consequences of global climate change. These temperature changes can have an impact on the immunological robustness of cultured fish, especially cold-water species such as Atlantic salmon. The salmon farming industry already loses hundreds of millions of dollars each year to infectious and non-infectious diseases. One particularly important and WOAH reportable disease is infectious salmon anemia caused by the orthomyxovirus ISAv. Considering the changing environment, it is necessary to find ways to mitigate the effect of diseases on the industry. For this study, 20 Atlantic salmon families were housed in each of 38 different tanks at the AVC, with half of the fish being kept at 10 °C and half being kept at 20 °C. Donor Atlantic salmon IP- injected with a highly virulent ISAv isolate (HPR4; TCID50 of 1 × 105/mL) were added to each tank as the source of co-habitation infection. Both temperatures were sampled at onset of mortality in co-habited fish and at resolution of mortality. Family background and temperature significantly impacted ISAv load, as assessed by qPCR, time to mortality and overall mortality. Mortality was more acute at 20 °C, but overall mortality was higher at 10 °C. Based on percent mortality calculated over the course of the study, different families demonstrated different levels of survival. The three families that demonstrated the highest percent mortality, and the three families with the lowest percent mortality were then assessed for their antiviral responses using relative gene expression. Genes significantly upregulated between the unexposed fish and ISAv exposed fish included mx1, il4/13a, il12rb2, and trim25, and these were further impacted by temperature. Understanding how ISAv resistance is impacted by temperatu