• Fisheries and Aquatic Sciences
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• v.26 no.7
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• pp.437-446
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• 2023

Cyprinids are popular species for aquaculture worldwide, with Asia being a significant contributor to their production. In Korea, common carp (Cyprinus carpio), koi carp (Cyprinus rubrofuscus), and goldfish (Carassius auratus) are cultivated domestically and imported for ornamental or human consumption purposes. Among the viruses that infect cyprinids, cyprinid herpesvirus-2 (CyHV-2), koi herpesvirus (KHV, also known as cyprinid herpesvirus-3), and carp edema virus (CEV) are of particular concern as they cause substantial economic losses to the aquaculture industry. In this study, we investigated these viruses in both of domestic and imported cyprinids. Our results revealed that CyHV-2 was only detected in imported goldfish from Thailand. To further investigate the genetic characteristics of them, the marker A region was analyzed. Despite belonging to the same cluster with isolates from China, France, Poland, and Israel, CyHV-2 detected in this study showed distinct differences in their repetitive sequence sizes. Furthermore, two different forms of KHV/CEV coinfection were identified from domestic koi carp, both of which exhibited typical symptoms. Phylogenetic analysis showed that one KHV isolate (ScKc-2105-K) was of the Asian type and closely related to isolates from Japan, Indonesia, Belgium, Taiwan, and China. Two CEV isolates (ScKc-2105-CE and GhKc-2207-CE) be- longed to the IIa type and showed high similarity with isolates from the USA, France, and Korea. Notably, koi carp injected with cultured KHV (ScKc-2105-K) showed 78.0% cumulative mortality within 14 days post-injection (dpi). Our findings support the importance of regular surveillance of viral diseases in cyprinids.

• Development and Reproduction
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• v.24 no.4
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• pp.277-285
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• 2020

The disease-causing koi herpes virus (KHV), also known as cyprinid herpesvirus-3 (CyHV3), causes mass mortality of koi and carp. Koi (Cyprinus carpio) is a host for KHV, one of 12 virus species in the Alloherpesviridae family. We examined the effects of KHV disease koi (KK), and on koi×red common carp (KR) and red common carp×koi (RK) cross, using a virus challenge test. The infected fish had clinical signs that included gill necrosis and skin lesions. The RK and KR were highly more resistant (cumulative mortality: RK; 6% and KR; 8%) to KHV infection than KK fish (cumulative mortality: 28%). KHV DNA was confirmed in the tissues of all dead fish in groups by use of polymerase chain reaction (PCR), and the presence of the KHV protein in kidney was confirmed by immunohistochemistry. Histological analysis showed severe gill lesions and fusion of the lamellae in KK fish, but less severe damage in RK fish. In immunohistochemistry analysis, the KHV protein localized in the cytoplasm of infected kidney cells of KK, but the cross groups had lower levels of KHV antigen. Our data indicate that the cross groups had increased resistance to KHV disease.

• Development and Reproduction
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• v.21 no.4
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• pp.361-370
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• 2017

Koi herpesvirus (KHV), also known as Cyprinid herpes virus 3 (Cyprinid 3) is lethal disease in common carp and koi (Cyprinus carpio). Two different groups (KK and RK) were infected KHV by intraperitoneal injection. Fish for gene expression analysis were sampled at 0 h, 12 h, 24 h, 48 h and 72 h post infection (p.i). The results showed that two immune related gene, Interferons (INFs) ${\alpha}{\beta}$ and Interleukin (IL)-12 p35 induced a high response in RK. The IL-12 p35 cytokine and Toll-like receptor (TLR) 9 were significantly high expressed on 48 h post infection (p.i) in RK as compared to the KK. The histopatological examination reveals focal necrosis in liver and infiltrate of lymphocytes in spleen of KK as compared to the RK. In immunohistochemistry analysis, the KHV protein high expressed in the infected kidney cell and slenocyte of KK. Therefore, the expression of IL-12 p35, IFN ${\alpha}{\beta}$ and TLR 9 may provide a potentially genes related with KHV resistance in Koi and red common carp ${\times}$ koi.

• Fisheries and Aquatic Sciences
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• v.13 no.1
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• pp.79-83
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• 2010

Since 1998, a new viral disease with high mortality has been consistently recorded in Korea in cultured carp, Cyprinus carpio. In this study, we investigated an epizootic of the disease that caused high mortality rates in carp obtained from 11 farms in Korea between 1999 and 2007. Assessment of koi herpesvirus (KHV) levels in diseased carp was carried out to determine if this virus was the etiologic agent of disease in this instance. High mortality rates in carp were recorded mainly in the spring and autumn at water temperatures between $19^{\circ}C$ and $24^{\circ}C$. Diseased fish typically showed surface discoloration, with a thick opaque mucus covering the body and gills. Protozoan parasites and bacteria were recovered from 7/29 (24%) and 2/26 (8%) of fish, respectively. Evidence of viral infection was marked; cytopathic effects (CPEs), characterized by cell rounding and an extended cytoplasm in fathead minnow (FHM) cells, were detected in 40/41 fish (98%). A high mortality rate (80%) resulted when supernatants of cell cultures showing CPEs were applied to previously healthy fish. KHV was detected by polymerase chain reaction in 6/41 fish (15%), but was not detected in supernatants obtained from cell cultures showing CPEs. These results suggest that KHV may not be the etiologic agent of the high mortality occurring among cultured carp in Korea; therefore, some other-as yet unidentified-infective agent must be responsible.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.51 no.4
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• pp.383-388
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• 2018

Goldfish hematopoietic necrosis (GHN) affects hematopoietic organs and causes high mortality in goldfish. The causative agent of GHN is cyprinid herpesvirus 2 (CyHV-2). The purpose of this study was to detect CyHV-2 in ornamental cyprinid fish. CyHV-2 monitoring was conducted on a monthly basis for 1 year using goldfish Carassius auratus and pearlscale goldfish Carassius auratus that had been cultured at a domestic aquafarm and imported from Singapore, respectively. The results of polymerase chain reaction (PCR) assays using specific primers for the CyHV-2 helicase gene showed that 27.8% of goldfish and 33.3% of pearlscale goldfish were positive for CyHV-2. No cytophatic effects were detected in koi fin or common carp brain cells inoculated with tissue homogenates from either fish. Our data provides the useful data for establishing future quarantine and disinfection policies.

• Journal of fish pathology
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• v.26 no.2
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• pp.99-110
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• 2013

Hatchery-reared seeds provides a key source of animal protein for human consumption and restocking for fishery management. For stock enhancement program, we have inspected the hatchery-reared seeds of 33 species in 2009, 44 species in 2010, 43 species in 2011 and 46 species in 2012 for legally designated diseases. Results showed that abalone was the most abundant in the marine species group and then sea cucumber, olive flounder, rockfish and swimming crab were followed. Crucian carp was the most abundant and then mandarin fish, Korean bullhead, melanian snail and Chinese mitten crab were followed in the freshwater species group. The number of inspection for black sea bream, rock bream, scorpionfish, black scraper, and eel has continuously decreased for four years. The inspection for flathead mullet has been carried out only in 2009. The total number of inspection cases for eight pathogens in this study were 8,476 and disqualification cases were 56 (0.67%) by detection of aquatic animals pathogens such as koi herpesvirus, white spot syndrome virus, red sea bream iridovirus or viral haemorrhagic septicemia virus.

• Journal of fish pathology
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• v.23 no.1
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• pp.85-98
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• 2010

Ministry of Agriculture, Fisheries and Food (MAFF) and National Fisheries Research and Development Institute (NFRDI) have inspected the hatchery-reared seeds of 22 marine species and 11 freshwater species for aquatic animal diseases in stock enhancement program in 2009. Results showed that total 12 local selfgovernments have been restocking the sea with cultured juveniles. Gyeongsangnam-do, Jeollanam-do, Jejudo and Chungcheongnam-do have a preference for marine species seeds to freshwater species. On the contrary, freshwater species were released mostly in Gyeonggi-do, Jeollabuk-do and Chungcheongbuk-do. In the marine species group, abalone was the most abundant as 24.5%, and then sea cucumber (15.2%), olive flounder (11.5%), swimming crab (5.6%), black sea bream and rockfish (6.8%), rock bream (5.1%), black rockfish (4.6%) and scorpionfish (4.5%) were followed. Crucian carp was the most abundant as 19.4%, and then eel (17.0%), Korean bullhead (12.3%), melanian snail (12.0%), catfish (8.4%) were followed in the freshwater species group. The total number of inspection cases in this study were 1,080 and disqualification cases were 19 by detection of aquatic animals pathogens such as red sea bream iridovirus (RSIV), koi herpesvirus (KHV) or white spot syndrome virus (WSSV).

• Journal of fish pathology
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• v.24 no.2
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• pp.121-129
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• 2011

Aquatic animal raised in hatcheries play an important role in supplying seedling to stock enhancement and seed quality, especially, seed health is the key factor for survival in the field after release and for stocking effectiveness. We have inspected the hatchery-reared seeds of 33 marine species and 12 freshwater species for legally designated diseases in stock enhancement program in 2010. Results showed that abalone was the most abundant as 20.0% in the marine species group and then sea cucumber (15.6%), olive flounder (8.4%), rockfish (6.7%), black sea bream (6.3%) and swimming crab (6.1%) were followed. Crucian carp was the most abundant as 19.4%, and then eel (11.8%), Korean bullhead (10.9%), mandarin fish (10.8%), melanian snail (8.4%), catfish (7.7%) were followed in the freshwater species group. The total number of inspection cases for eight pathogens in this study were 2,105 and disqualification cases were 30 by detection of aquatic animals pathogens such as koi herpesvirus (KHV), red sea bream iridovirus (RSIV), white spot syndrome virus (WSSV) or viral haemorrhagic septicemia virus (VHSV).

• Journal of Marine Life Science
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• v.7 no.1
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• pp.10-14
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• 2022

Monitoring infectious diseases for fishery species takes a key role in preventing disease emergence and spreading of cultured fishery species. This research has examined a total of 1,115 fishes of four species (leather carp, fancy carp, stone moroko, carassius auratus) at 23 farm in Jeollanamdo and Jeollabukdo in 2021 for pathogen infection. As a result of disease screening for three legally designated diseases (SVC, Spring viraemia of carp, EUS, Epizootic ulcerative syndrome, and KHVD, Koi herpesvirus disease), no infectious diseases were detected in all examined samples; cyprinid fish studied in Jeolla province would provide important information for declaring a disease-free nation or disease-free region.

• Journal of fish pathology
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• v.23 no.1
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• pp.131-135
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• 2010

Unidentified viral disease with high mortalities has been recorded consistently since 1998 in cultured carp Cyprinus carpio in Korea. In the present study, we investigated the histopathological characteristics of the diseased carp to evaluate the relatedness to koi herpesvirus disease (KHVD). Histopathogical examination revealed severe necrotic changes and vacuous cells in the kidney, spleen, liver, pancreas, heart and intestine, but eosinophilic intranuclear inclusion, a typical characteristic of KHV infection was not detected. These results suggest that KHVD may be not a cause for the high mortality occurring among cultured carp in Korea and possibly other unknown viral disease could are related.