ROLE OF IFN1 IN THE REGULATION OF THE RAINBOW TROUT ENDOGENOUS ANTIGEN PRESENTATION PATHWAY AT LOW TEMPERATURE
Quinn Abram, University of Waterloo
Quinn H. Abram1, Tania Rodriguez Ramos1, Niels C. Bols1, Barbara A. Katzenback1, and Brian Dixon1
1Department of Biology, University of Waterloo, Waterloo, ON. Canada
Low temperatures generally impair teleost immune responses, including the endogenous antigen presentation pathway (EAPP). In mammals, type I interferons (IFN), the cytokine mediators of the antiviral response, are known to regulate the EAPP. However, it is unknown if this is also the case in fish, and whether potential impairments in type I IFN expression at low temperatures might contribute to EAPP impairments. The rainbow trout hypodermal fibroblast cell line RTHDF was used as an in vitro model to study the effect of suboptimal temperature on the transcript levels and secretion of IFN1, a rainbow trout type I IFN, via qRT-PCR and quantitative ELISA respectively. At 4°C, both transcript level up-regulation and secretion of IFN1 were found to be delayed relative to 20°C following stimulation with poly(I:C). Furthermore, in silico analysis predicted the presence of interferon-stimulated response elements in the promoter regions of the pathway-specific members of the EAPP (b2m, mhIa, and tapasin) in rainbow trout, which should allow them to respond to IFN1 signalling. Transcript levels of these EAPP members were also measured following stimulation with poly(I:C), and their upregulation was similarly delayed at 4°C. These results support the hypothesis that delayed IFN1 up-regulation could be involved in the impaired EAPP regulation at suboptimal temperatures, and suggest that rainbow trout antiviral responses might be impaired over the winter months. This would be problematic for Canadian aquaculture due to the potential for a greater incidence of viral infections during this time.