Susceptibility of isogeneic ginbuna Carassius auratus langsdorfii Temminck et Schlegel to cyprinid herpesvirus-2 (CyHV-2) as a model species.

Abstract

Herpesviral haematopoietic necrosis (HVHN), caused by cyprinid herpesvirus-2 (CyHV-2), has affected the commercial production of the goldfish Carassius auratus and gibelio carp Carassiusauratus gibelio. High water temperature treatments are reported to reduce the mortality rate of infected goldfish and elicit immunity in the survivors. To define the mechanism by which this intervention induces resistance, clonal ginbuna Carassiusauratus langsdorfii, which is closely related to both species and has been used in fish immunology, may represent a promising model species. In this study, we investigated the susceptibility of clonal ginbuna strains to CyHV-2 and the effect of high water temperature treatment on infected ginbuna and goldfish. Experimental intraperitoneal infection with CyHV-2 at 25°C caused 100% mortality in ginbuna strains, which was accompanied by histopathological changes typical of HVHN. Both infected ginbuna S3n strain and goldfish, exposed to high temperature for 6days [shifting from 25°C (permissive) to 34°C (non-permissive)], showed reduced mortalities after the 1st inoculation, and subsequent 2nd virus challenge to 0%, indicating induction of immunity. It was concluded that ginbuna showed a similar susceptibility and disease development in CyHV-2 infection compared to goldfish, suggesting that ginbuna can be a useful fish model for the study of CyHV-2 infection and immunity.