Regulation of endogenous antigen presentation in response to suboptimal temperatures in a walleye skin fibroblast cell line

A skin fibroblast cell line WE-skin11f from walleye (Sander vitreus) was used to study the impact of temperature (26 degrees C, 20 degrees C, 14 degrees C, or 4 degrees C) on the transcript levels of genes involved in the endogenous antigen processing and presentation pathway (EAPP), which is an important antiviral pathway of vertebrates. Partial coding sequences were found for 4 previously unidentified walleye EAPP members, calreticulin, calnexin, erp57, and tapasin, and the constitutive transcript levels of these genes in WE-skin11f was unchanged by culture incubation temperature. The viral mimic poly (I:C) and viral haemorrhagic septicaemia virus (VHSV) IVb were used to study possible induction of EAPP transcripts (b2m, mhIa, and tapasin). The walleye cells were exquisitely sensitive to poly (I:C), losing adherence and viability at concentrations greater than 100 ng/mL, particularly at suboptimal temperatures. VHSV IVb viral particles were produced from infected WE-skin11f cells at 20 degrees C, 14 degrees C, and 4 degrees C but with much lower production at 4 degrees C. Under conditions where their impact on the viability of WE-skinllf cultures was slight, poly (LC) and VHSV IVb were shown to induce b2m, mida, and tapasin transcript's at 26 degrees C and 20 degrees C respectively. However, at 4 degrees C, the up-regulation of EAPP transcript levels was either delayed or completely impaired when compared to the 26 degrees C and 20 degrees C control temperatures of the respective experiments. These in vitro results suggest that suboptimal temperatures may be capable of modulating the regulation of the EAPP in walleye cells during viral infection.