Abstract
Red seabream iridovirus (RSIV) causes significant mortality in many marine fishes. Polyinosinic-polycytidylic acid [Poly(I:C)] immunization with a live virus confers protection of fishes from viral infection. Thus, we applied this immunization with live RSIV to rock bream Oplegnathus fasciatus, red seabream Pagrus major and yellowtail Seriola quinqueradiata. No significant difference was observed in mortalities due to RSIV infection between the fishes that did or did not receive Poly(I:C), indicating that fishes administered Poly(I:C) were not protected from RSIV infection. It was confirmed that the Mx gene, an indicator of induced interferon, was well expressed in rock bream that received Poly(I:C). The results suggest that RSIV is probably insensitive to the transient innate immune response induced by Poly(I:C).
