Abstract
Arctic charr ( Salvelinus alpinus ) are the northernmost distributed freshwater fish and can grow at water temperatures as low as 0.2 °C. Other teleost species have impaired immune function at temperatures that Arctic charr thrive in, and thus, charr may maintain immune function at these temperatures. In this study, a fibroblastic cell line, named ACBA , derived from the bulbus arteriosus ( BA ) of Arctic charr was developed for use in immune studies at various temperatures. ACBA has undergone more than forty passages at 18 °C over 3 years, while showing no signs of senescence‐associated β‐galactosidase activity and producing nitric oxide. Remarkably, ACBA cells survived and maintained some mitotic activity even at 1 °C for over 3 months. At these low temperatures, ACBA also continued to produce MH class I proteins. After challenge with poly I:C, only antiviral Mx proteins were induced while MH proteins remained constant. When exposed to live viruses, ACBA was shown to permit viral infection and replication of IPNV , VHSV IV a and CSV at 14 °C. Yet at the preferred temperature of 4 °C, only VHSV IV a was shown to replicate within ACBA . This study provides evidence that Arctic charr cells can maintain immune function while also resisting infection with intracellular pathogens at low temperatures.