The 2004 Gumna Prefecture KHV outbreak was caused by a virus closely related to those seen in other outbreaks.
Scientists from the Gunma Prefectural Institute of Public Health and Environmental Sciences in Japan are to publish a paper in the journal Veterinary Microbiology which says that the viral strains isolated from carp in Gunma were closely related to those seen in other outbreaks of the disease.
The study, which uses another modification of the common Polymerase Chain Reaction (PCR) methodology, amplified DNA polymerase and the main envelope proteins of viruses sampled from the gills of infected carp using new primers.
KHV is a worldwide problem.
The sequences were then compared with those of other outbreaks to see how closely related genetically the different viruses were.
The technique used in this study found both DNA polymerase and major envelope proteins in 86% of the fish tested.
Although the scientists are still referring to the virus under its common name of KHV, it has recently been reclassified under a new name - Cy-HV1. It does seem unlikely that the name will ever enter common usage, though.
For more details on the study see the paper: Ishioka T, Yoshizumi M, Izumi S, Suzuki K, Suzuki H, Kozawa K, Arai M, Nobusawa K, Morita Y, Kato M, Hoshino T, Iida T, Kosuge K, Kimura H. (2005) - Detection and sequence analysis of DNA polymerase and major envelope protein genes in koi herpesviruses derived from Cyprinus carpio in Gunma prefecture, Japan. Vet Microbiol. 2005 Aug 24.