Expression of MHC class I pathway genes in response to infectious salmon anaemia virus in Atlantic salmon (Salmo salar L.) cells

Effect of early infectious salmon anaemia virus (ISAV) infection on expression of MHC pathway genes and type I and II interferon in Atlantic salmon (Salmo salar L.) tissues

“…Together with our previous findings from in vitro infections [30] this suggests that ISAV does not counteract class I antigen presentation or some common activator of this pathway at the transcriptional level. The levels of upregulation for the specific class I pathway genes were consistent with levels from ISAV-infected salmon kidney cells (ASK) [30] and also from type I and II IFN-treated mammalian cells [31]. In mammals, cells overexpressing immunoproteasome components have enhanced T cell epitope production [32], demonstrating that antigen presentation is rate-limited by these proteins.…”

“…We have previously found IFN regulatory sites in the promoter of MHC class I akin to mammalian HLA promoters [30]. The presence of an interferon-stimulated response element (ISRE) site confirmed that type I and II IFN-induction mediated by the IFN-stimulated gene factor 3 complex (ISGF-3) is possible.…”

“…In contrast to other tissues, organs with significant induction of all MHC class I pathway genes (except PSMB9) had typically 10-fold or higher IFN-a induction plus expression of IFN-g. Similarities to the levels of type I IFN sufficient for upregulation of the same MHC genes in vitro was striking [30] and it seems as if an IFN-a induction of 10-to 20-fold may represent a threshold for significant activation of MHC class I pathway genes.…”

“…In the present study, PSMB8 was significantly induced in the major infected tissues but no induction of PSMB9 was observed. In ISAV-infected kidney cells in vitro, transcription of PSMB9 was also lower compared with PSMB8 [30]. The basis for this difference is uncertain, given that both genes are located in the classical class I region in salmonids (U. Grimholt, personal communication) which may suggest a co-regulation.…”

Expression regulation and functional characterization of a novel interferon inducible gene Gig2 and its promoter

“…IFN-␥ molecules follow a similar pathway, but in this case, two STAT1 molecules dimerize to form a homodimer and bind to specific ␥-IFN activating sites (GAS) present in the promoters of IFN-␥ inducible genes (Platanias, 2005). Some fish ISGs have been verified to have typical ISRE motifs in their promoters, such as Mx (Altmann et al, 2004;Chen et al, 2006;Collet and Secombes, 2001;Ooi et al, 2006;Plant and Thune, 2008;Yap et al, 2003), IRFs (Collet et al, 2003;Collet and Secombes, 2002;Jia and Guo, 2008), major histocompatibility complex (MHC) class I genes (Dijkstra et al, 2003;Jorgensen et al, 2006), vig-2 (Boudinot et al, 2001), and ISG15 (Seppola et al, 2007), suggesting the existence of type I IFN inducible pathways in fish. Functional analysis showed that fish Mx promoters possess one or two ISRE motifs that appear necessary for its transcriptional regulation under exposure of Poly I:C (Ooi et al, 2006;Yap et al, 2003).…”