Detection of koi herpesvirus in koi Cyprinus carpio in Taiwan

Mass mortality occurred in 2-year-old koi (fancy carp) Cyprinus carpio in Taiwan in 2002. Affected fish did not show any external signs except swollen gills. The consistent histological changes were observed in the gills; hyperplasia of epithelial cells, infiltration of eosinophilic granular cells and fusion of the secondary lamellae. Negatively stained nucleocapsids were icosahedral and 112 +/- 1 nm in diameter. Koi herpesvirus (KHV) was detected in the diseased fish by PCR using specific primers for KHV, and sequence of the amplicon showed a 99% identity with the published data. This is the first report of KHV infection in Taiwan.