Multiple Passages of Grunt Fin Cells Persistently Infected with Red Seabream Iridovirus (RSIV) at 15ºC or 30ºC to Yield Uninfected Cells.

Abstract

Red seabream iridovirus (RSIV), a member within genus Megalocytivirus (Iridoviridae), causes serious economic losses to marine fish aquaculture industry in East Asia. In this study, we established a Blue Striped Grunt Haemulon sciurus fin (grunt fin; GF) cell line persistently infected with RSIV (PI-GF) by subculturing GF cells that survived RSIV inoculation. PI-GFcells were morphologically indistinguishable from naive GF cells. They could stably produce RSIV at approximately 10genomes per microliter after 24 passages over 18 months. The optimum temperature to produce RSIV in PI-GFcells was 25°C. These cells also produced RSIV at 15, 20, and 30°C with multiple subcultures. The amount of RSIV yielded from PI-GFcells decreased gradually by multiple subculturing at 15°C or 30°C. Red seabream iridovirus was no longer detected from PI-GFcells after subcultures at these temperatures. These PI-GFcells freed from RSIV infection exhibited a level of RSIV productivity similar to those of naive GF cells after inoculation with RSIV. Therefore, we consider that these PI-GFcells were no longer infected with RSIV after multiple subculturing at 15°C or 30°C. Received October 15, 2015; accepted June 27, 2016.