Sexual maturation in Atlantic salmon induces a constitutive Mx protein production and influences the infectious pancreatic necrosis virus carrier-status.

The aim of this study was to demonstrate for the first time that sexual maturation induces a constitutive increase in Mx gene expression and protein production in Atlantic salmon. This could explain the reduction in IPNV prevalence previously observed in broodfish at the time of ova/milt stripping. For this purpose, Mx transcript and protein levels were analysed in different tissues/samples and compared between mature broodfish (female and male) and immature parr.

The effect of sub-culturing on the basal level of type I interferon (IFN) gene expression in the Salmon Head Kidney (SHK-1) cell line.

Over sub-culturing a cell line generates a selective pressure which can result in key cellular functions being altered such as gene and protein expression. The present study set out to determine whether serial sub-culturing affects the antiviral state of the Salmon Head Kidney (SHK-1) cell line. Cells were cultured under constant conditions and real-time PCR was performed to measure the level of interferon (IFN) and Mx gene expression over different passage numbers. A significant increase in the basal level of IFN and Mx gene expression was recorded at passage number 58 (3 and 14-fold increase versus passage number 53), suggesting a sub-culturing effect on the type I IFN response in SHK-1 cells. Passage dependent variations in morphology and cell sub-populations have been previously observed in SHK-1 cells. Such variations in cell sub-types were suspected to be responsible for the fluctuations in IFN and Mx gene expression recorded in this study.