A new technique for diagnosing Koi Herpes Virus (KHV) is claimed to be the most sensitive yet.
The new method doesn't give false results by picking up other viruses, and is more sensitive in detecting KHV than other existing assays based on the widely used Polymerase Chain Reaction (PCR).
The new PCR technique, which is based around thymidine kinase (TK), is claimed to be as sensitive as virus isolation, with the ability to pick up the presence of as little as 30 virus particles (virions) or 10 fentograms of viral KHV DNA.
The team of KHV virologists, who have just reported their findings in BMC Microbiology, used a gene sequence found in the KHV genome which codes thymidine kinase (TK).
The paper says: "Preliminary characterization of the recombinant TK showed that it has a kinase activity using dTTP but not dCTP as a substrate. A PCR assay based on primers selected from the defined DNA sequence of the TK gene was developed and resulted in a 409 bp amplified fragment.
"The TK based PCR was compared to previously described PCR assays and to viral culture in diseased fish and was shown to be the most sensitive method of diagnosis of KHV infection."
For more details see the paper: Bercovier H, Fishman Y, Nahary R, Sinai S, Zlotkin A, Eyngor M, Gilad O, Eldar A, Hedrick RP (2005) - Cloning of the koi herpesvirus (KHV) gene encoding thymidine kinase and its use for a highly sensitive PCR based diagnosis. BMC Microbiol. 2005 Mar 17; 5(1): 13