ABSTRACT: Herpesviral haematopoietic necrosis has caused great economic damage to goldfish
Carassius auratus aquaculture in Japan. The existence of cyprinid herpesvirus 2 (CyHV-2), the
causative agent, has also been reported from several other countries. To prevent spread to other
areas, basic virological information such as viral kinetics in infected fish is essential. Experimental
infection trials using reliably prepared CyHV-2 for defining viral kinetics are difficult to carry out
because successful and sustainable propagation of this virus in cell culture has previously been
limited. Here we describe a method for sustainable propagation of CyHV-2 in cell culture, and the
results of fish infection experiments using the propagated virus. We found that goldfish fin (GFF)
cells and standard Ryukin Takafumi (SRTF) cells established from goldfish fin can be used for continuous
propagation of CyHV-2. Experimental infections using 2 varieties of goldfish, Ryukin and
Edonishiki, were performed with the virus passaged 7 times in GFF cells. In transmission experiments
with water temperature at 20°C, cumulative mortality was 30% in Ryukin infected by
immersion, and 90 and 100% in Edonishiki and Ryukin intraperitoneally injected with the virus,
respectively. In an experiment carried out at 25°C, 90% of Edonishiki challenged by immersion
died. PCR detection of viral DNA from the organs of infected fish showed that systemic infection
occurs and also that the kidney is a main viral multiplication site. Moreover, CyHV-2 was successfully
re-isolated in GFF cells from the dead fish.