Goldfish hematopoietic necrosis herpesvirus (cyprinid herpesvirus 2) in the USA: Molecular confirmation of isolates from diseased fish

Moribund goldfish Carassius auratus from private collections and breeding facilities were tested for hematopoietic necrosis herpesvirus 2 (also known as cyprinid herpesvirus 2 [CyHV-2]) by degenerate polymerase chain reaction (PCR) of the viral polymerase gene followed by sequencing. The degenerate PCR method produced a fragment with a DNA sequence that was more than 99% identical to the sequence of CyHV-2. Histology and electron microscopy showed that the moribund fish had severe necrosis in the hematopoietic tissues of the kidney and spleen and that herpesvirus particles were present. In the three cases studied, the presence of the virus was associated with high mortality (Lip to 80%) that could not be attributed to any other cause. The CyHV-2 is very difficult to isolate in cell culture. but our PCR and case studies demonstrate that this virus has a wide geographic distribution in the United States and that goldfish hematopoietic necrosis herpesvirus disease is likely to be an important, but rarely detected, disease of goldfish.