Effect of infectious salmon anemia virus (ISAV) infection and poly I:C treatment on expression of different stress related genes in Atlantic salmon (Salmo salar L.) cells

• Main Author: Kvello, Annbjørg Ringheim
• Other Authors: Tor Gjøen
• Format: Master Thesis
• Language: Norwegian Nynorsk
• Published: 2007
• Subjects: virus infekttiøs lakseanemi atlantisk laks; VDP::568; Atlantic salmon; Salmo salar
• Online Access: http://hdl.handle.net/10852/12180; http://urn.nb.no/URN:NBN:no-18610

2 ABSTRACT Infectious salmon anemia virus (ISAV) is a virus causing severe disease in Atlantic salmon (Salmo salar L.). Although its structure and pathogenesis is well described, little is known about its effects on the expression of genes related to different stress responses in the host cell. ISAV is a virus that is probably causing apoptosis in Atlantic salmon, but the mechanisms are not yet fully understood. Interferons (IFN) and interferon induced genes (ISG), which is important of the host control of virus infections, is highly expressed after ISAV infection. But it looks like that ISAV has developed mechanisms that help it evade the host immune response. In this study we analyzed the relative expression of different stress related genes after ISAV infection and poly I:C stimulation in Atlantic salmon kidney cell line (ASK). Poly I:C is widely used as synthetic dsRNA analog in vivo and in vitro and has also demonstrated to induce antiviral responses in Atlantic salmon. When we compare these two stress situations with each other we may better understand the innate immune responses during viral infections in this commercially important fish species. As measured by quantitative real-time PCR, both ISAV and poly I:C stimulated cells induced a high up-regulation of interferon-á and interferon induced genes as expected. In confocal immunofluorescence microscopy it was detected that ISAV still replicates at day 5 post infection, and that it induces a cytophatic effect in ASK cells, indicating that interferons have little antiviral effect on ISAV. Furthermore, there was observed an up-regulation of different cytokines, stress related genes and even apoptotic related genes, like IAP, both in ISAV infected and poly I:C stimulated ASK cells. Galectin-9, that may be involved in T-cell apoptosis, was up-regulated in both ISAV infected and poly I:C stimulated cell. The protein expression of galectin-9 was analysed using immunofluorescence microscopy. The result of this study strongly indicates that different stress related genes, which may be involved in the host immune response is induced after ISAV infection. These results can lead to a better understanding of the pathogenesis of ISAV in Atlantic salmon.