Expression of Mx mRNA following infection with IPNV is greater in IPN-susceptible Atlantic salmon post-smolts than in IPN-resistant Atlantic salmon parr

Study of the viral interference between infectious pancreatic necrosis virus (IPNV) and infectious haematopoietic necrosis virus (IHNV) in rainbow trout (Oncorhynchus mykiss)

“…They found that this period of the resistant state might be correlated to the kinetics of Mx gene expression, a molecular marker of the type I IFN production, in the head kidney. Mx mRNA expression in the liver of salmon parr reaches a minimum level 3 days after injection with IPNV and is undetectable on day 7, when in post-smolt Mx expression continues to rise to day 7 [43]. According to those results, a possible interferon activity could explain the protection observed in co-infected fish in the present study, even if the 2 viral injections were administered with an interval of 14 days.…”

Expression kinetics of ISG15 and viral major capsid protein (VP2) in Atlantic cod (Gadus morhua L.) fry following infection with infectious pancreatic necrosis virus (IPNV)

“…ISG15 transcripts in Atlantic salmon parr injected with IPNV were reported to be absent on day 3, strongly expressed on day 5 and had diminished on day 7 [19]. This differential kinetics between the salmon parr and the present data on cod fry where ISG15 expression was still upregulated on day 21, may be because parr are resistant to IPNV which appears to replicate poorly and induces very low Mx expression in comparison to the response in Atlantic salmon post-smolts [23] which are susceptible to IPN. In the present work, the cod fry were also susceptible to IPN which resulted in over 40% mortality and fish showed typical IPN histopathology (to be published elsewhere).…”

Major Quantitative Trait Loci Affect Resistance to Infectious Pancreatic Necrosis in Atlantic Salmon (Salmo salar)

“…Whether these genes play a similar role in the resistance of salmon fry to freshwater IPN is unknown, although there is a strong genetic correlation between fresh and marine water IPN resistance (Wetten et al 2007). Experimental infection of Atlantic salmon with the IPN virus has revealed that the interferon pathways are paramount in the host response, and this is particularly evident through the upregulation of interferoninduced Mx gene expression (e.g., Lockhart et al 2007). Investigation of the physiological/immune response to infection by fish with alternative QTL genotypes may give valuable insight into the genes and pathways responsible for the QTL effects.…”