Susceptibility of Koi Carp Strains to Carp Edema Virus

Abstract

The susceptibility to two genogroup II strains of carp edema virus (CEV) was examined in various koi carp strains via experimental infection. The test groups included common carp, common-carp derived straines (Goshiki and Shusui), and strains distant from common carp (Kohaku, Taisho Sanshoku, Ogon, and Shiroutsuri). Among these, Shusui and Ogon were developed with the introduction of German carp during their breeding process. Fish were infected using the immersion method in rearing water containing the virus solution (final concentration 3.0 × 10⁶ copies/mL) for 1 h at 20°C, and then maintained at 20°C for 14 days. As the results, Kohaku, Taisho Sanshoku and Shiroutsuri exhibited higher cumulative mortality rates, suggesting that susceptibility to CEV tends to be lower in strains with a closer lineage to common carp and in those crossbred with German carp during their development.