Cell-mediated and humoral immune responses of cyprinids induced by a live attenuated vaccine against cyprinid herpesvirus 2 infection in comparison to the virus non-permissive high temperature water treatment.

The live attenuated vaccine (P7-P8 strain) against cyprinid herpesvirus 2 (CyHV-2) infection of goldfish shows high protective efficacy. However, the underlying immune mechanism induced by P7-P8 vaccination remains unknown. It is known that the fish survived in the primary infection with CyHV-2 by the virus non-permissive high temperature (HT) water treatment elicit immunity against secondary virus challenge.

Effect of temperature on the protective efficacy of a live attenuated vaccine against herpesviral haematopoietic necrosis in goldfish.

The live attenuated vaccine P7-P8 strain against herpesviral haematopoietic necrosis, which is caused by cyprinid herpesvirus 2 (CyHV-2), exhibits high protective efficacy in goldfish at 25°C, the predominant temperature for this disease; however, the effect of water temperature during the vaccination period on efficacy has not been determined. In this study, an in vitro experiment revealed that the vaccine strain grew between 15 and 30°C in the goldfish cell line RyuF-2. Subsequent in vivo efficacy tests were conducted with vaccination temperatures ranging from 15 to 30°C.