title: Effects of experimentally induced infections of goldfish Carassius auratus with cyprinid herpesvirus 2 (CyHV-2) at various water temperatures.
abstract: In this study, we examined the influence of water temperature on the development of herpesviral haematopoietic necrosis (HVHN) in goldfish Carassius auratus after experimentally induced infection with cyprinid herpesvirus 2 (CyHV-2). In Expt 1, Ryukin goldfish were infected with CyHV-2 by intraperitoneal injection and maintained at 4 different water temperatures. Cumulative mortalities of the 15, 20, 25 and 30°C groups were 10, 90, 90 and 60%, respectively. Therefore, the temperature range of 20-25°C is considered highly permissive for HVHN. One of 6 surviving fish of the 15°C group died after a rapid temperature increase to 25°C at 30 d post infection. All 3 Edonishiki goldfish, co-reared with the surviving Ryukin in tanks where the water temperature was increased from 15 to 25°C, died. In Expt 2, Edonishiki goldfish were exposed to CyHV-2 by bath immersion at 13 or 24°C, resulting in cumulative mortalities of 0 and 87%, respectively, at 28 d post-exposure. No mortality of the surviving Edonishiki in the 13°C treatment was observed when the water temperature was increased to 24°C. In addition, in Expt 2, no mortality was observed in any Ranchu co-reared with CyHV-2-immersed Edonishiki in the group where water temperature was increased from 13 to 24°C, even after re-immersion challenge with CyHV-2. It is interesting to note that CyHV-2 DNA was detected in the kidneys of 4 of the 5 surviving Ranchu co-reared with the CyHV-2-immersed Edonishiki group where the water temperature was increased from 13 to 24°C. Therefore, it is likely that the surviving Edonishiki of the 13°C group were virus carriers. This study indicates that most fish infected with CyHV-2 at 13-15°C acquire resistance to HVHN, but as carriers they are able to infect naïve fish.
authors.affiliation: Tamaki Laboratory, Aquatic Animal Health Division, National Research Institute of Aquaculture, Fisheries Research Agency, 224-1 Hiruta, Tamaki, Mie 519-0423, Japan.
authors.forename: Takafumi
authors.initials: T
authors.lastname: Ito
authors.forename: Yukio
authors.initials: Y
authors.lastname: Maeno
mesh_terms: D000818:Animals; D004198:Disease Susceptibility; D005393:Fish Diseases / Q000821:virology*; D006054:Goldfish; D006564:Herpesviridae / Q000145:classification*; D006566:Herpesviridae Infections / Q000473:pathology / Q000662:veterinary*; D013696:Temperature; D013997:Time Factors; D014867:Water
chemical_list: D014867:Water