E-GEOD-6924 - Salmonid host response to Hematopoietic Necrosis virus: cellular receptors, viral control and novel pathways of defence
Released on 30 March 2007, last updated on 2 May 2014
The transcriptional response of Atlantic salmon (Salmo salar) to infectious hematopoietic necrosis (IHN) virus was elucidated using 16,008 gene GRASP cDNA microarrays. S. salar were exposed to the IHN virus in a waterborne challenge, and kidney samples from five fish sampled on each of days 0, 1, 5 and 9 were analysed in the microarray study. Validation of nine of the significant genes was conducted on fish sampled on alternate days from 1 to 13 and compared to the unchallenged control sampled on day 0. The key pathways up-regulated in response to the virus included endosomal transport, type I and II interferon responses, the alternative complement pathway, apoptosis, phagocytosis and phagocytic cell oxidation, natural killer cell activity, antiviral replication via iron sequestering, virally-induced disruption of the cell cycle, retroviral DNA integration, T-cell activation and cellular immunity. Fish that did not contain viral titer on days 5 and 9 responded in a similar manner to those with titer, but further induced a number of genes involved in anti-viral replication (Glutathione peroxidase 1 and ferritin H), anti-proliferation (PTEN and B-cell receptor associated protein 32), lysosomal response (CD63 antigen), pro-inflammatory response (lipopolysaccharide binding protein, stress activated JNK1, thiol peroxidase), and T-cell activation (T-cell activation Rho-GTPase activating protein) that may increase resistance to the virus. Three genes that were potentially co-opted by the virus to enhance infectivity were also identified, including uPAR (angiogenesis), CypA (viral replication and infectivity), and BAF1 (viral protein biosynthesis). Perhaps the most notable finding was the up-regulation of uPAR which can function to increase the density of fibronectin, the receptor of the IHN virus, on the cell surface, hence facilitate viral entry into the cell. Keywords: Immunlogical response to IHN virus challenge A preliminary microarray experiment was run on the waterborne-challenged S. salar whereby the five individuals sampled on a given day were combined and run on a single slide, and we compared the expression profiles from each day (days 0 (unchallenged control) through 11). From this experiment, we noted that the most profound changes were occurring around days 1, 5, and 9, so we performed subsequent experiments at these time points, with five fish per day and 5 control fish analysed in total.
transcription profiling by array
Shaorong Li <Shaorong.Li@dfo-mpo.gc.ca>, Garth Traxler, Jon Richard, Karia Kaukinen, Kristina Miller, Norma Ginther