Kyoung-Mi Won

Detection of koi herpesvirus (KHV) in healthy cyprinid seed stock

Koi herpesvirus (KHV) disease is a lethal disease in common carp, an important food fish in Asian countries, the seed of which is used in restocking programs for freshwater fishery management. We inspected apparently healthy seed stock of common carp Cyprinus carpio L. and Siberian crucian carp Carassius auratus for the presence of KHV using PCR-based diagnostic tests as a part of a stock enhancement program from 2009 to 2010 in Korea. Consequently, KHV was detected from 24 of 232 inspections with yearly detection percentages of 5.2% in 2009 and 15.5% in 2010 using PCR primer sets for TK or SphI-5 as recommended by the OIE Manual of Diagnostic Tests for Aquatic Animals. Results indicate that the SphI-5 primer set was slightly more sensitive than the TK primer set, as shown by a higher detection rate. To determine the genotype of the KHV strains detected in this study, ORF40-specific PCR amplification was conducted, and the PCR products from 6 samples showed 100% nucleotide sequence identity with a Japanese strain (GenBank accession number AP008984) but not with US (DG657948) and Israeli strains (DG177346). This report conclusively demonstrated the presence of KHV in externally healthy seed of common carp and Siberian crucian carp, indicating a possible risk that subclinically infected seed stock can be released with a potential threat to wild populations.

The First Report of a Megalocytivirus Infection in Farmed Starry Flounder, Platichthys stellatus, in Korea

In 2009, a systemic megalocytivirus infection associated with high mortality was detected for the first time in cultured starry floun der Platichthys stellatus in Korea. Diseased starry flounder had pale bodies and gill coloring and enlarged spleens. Histopathologi cal examinations revealed basophilic enlarged cells in various organs of diseased starry flounder. Polymerase chain reaction (PCR) was performed on tissue samples using three published primer sets developed for the red sea bream iridovirus. PCR products were detected for all primer sets, except 1-F/1-R, which are registered by the World Organization for Animal Health (OIE). The part of the gene corresponding to the full open reading frame encoding the viral major capsid protein (MCP) was amplified by PCR. PCR products of approximately 1,581 bp were cloned, and the nucleotide sequences were analyzed phylogenetically. The MCP gene of the starry flounder iridovirus, designated SFIV0909, was identical to that of the turbot reddish body iridovirus (AB166788).

Diagnosis Case of Viral Hemorrhagic Septicemia (VHS) in Adult Olive Flounder Paralichthys olivaceus

We examined the cause of a disease outbreak in adult olive flounder Paralichthys olivaceus, which occurred at a Korean aquaculture farm in Korea in 2011. The principal signs included an expanded abdomen and congested liver, with persistent mortality (a little over two months). At the beginning of the outbreak, farm administrators misjudged the disease as bacterial in origin, because of the aforementioned signs, persistent mortality, and the detection of bacterial species, including Vibrio spp. and Streptococcus spp. Moreover, the detection of viral hemorrhagic septicemia virus (VHSV) by reverse trasnscription-PCR analysis was complicated by use of the VHS-VN primer set, which has been in general use recently, because it produced weak bands in some samples. Therefore, we recommend the use of at least two different primer sets in the diagnosis of VHSV. Our histopathological findings indicate that necrotizing myocarditis could be considered a pathogenic sign of VHSV infection.