Detection of flounder herpesvirus (FHV) by polymerase chain reaction

We developed a polymerase chain reaction (PCR) method to detect flounder herpesvirus (FHV), the causative agent of viral epidermal hyperplasia of larval Japanese flounder Paralichthys olivaceus. The developed PCR method was specific to FHV and no PCR products were obtained in other fish-pathogenic herpesviruses and flounder-pathogenic viruses tested. FHV was detected by the PCR test with a sample containing 100 or more epidermal cells, which were derived from flounder larvae with epidermal hyperplasia. Four samples of diseased flounder larvae, which were collected from natural mass mortalities and diagnosed as viral epidermal hyperplasia by conventional methods, were positive by the PCR test for FHV. These results show that the present PCR method is useful for rapid and reliable diagnosis of fish clinically or subclinically infected with FHV.