Abstract
Despite increased interest in Chinook salmon aquaculture, there is inadequate understanding regarding the bacterial immune defenses of this species. This study describes the establishment and characterization of a continuous stromal-like cell line derived from Chinook salmon spleen, CHST, and its response to a heat-killed bacterial exposure challenge. Optimal growth of CHST was seen at 18 °C when grown in Leibovitz's L15 media supplemented with 20 % fetal bovine serum. DNA analyses confirmed that CHST did originate from Chinook salmon tissue. Vibrio anguillarum, a common pathogen of marine aquaculture and the causative agent of an acute hemorrhagic septicaemia known as vibriosis was used for exposure studies. V. anguillarum was heat-killed and CHST was challenged so that pro-inflammatory (IL-1β, IL-6 and TNFα) as well as anti-inflammatory (IL-10) cytokine transcript levels could be measured at 1, 4, 12, 24 and 96 hour (h) post-exposure. The heat-killed bacteria were observed to significantly stimulate the expression of all three pro-inflammatory cytokines at 4, 12, 24 and 96 h post-exposure with the peak in expression occurring at 12 and 24 h. Meanwhile, IL-10 was not observed to significantly increase until 96 h post-stimulation, which was also the time when the inflammatory cytokine expression was decreasing. The establishment and characterization of CHST provides a valuable model for studying the immune response of Chinook salmon stromal-like cells in response to stimuli, including those of bacterial origin.