• Journal of fish pathology
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• v.19 no.1
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• pp.55-64
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• 2006

Rhabdovirus-like virus were isolated from the fry (15~30 days post hatching, dph) and rearing water of the snakehead fish Channa arga exhibiting mass mortality in spring of 2003 and 2004 in Korea. The isolates were propagated in EPC and SSN-1 cells but not replicated in FHM cells. The bullet-shaped viral particles (45×100 nm) appeared to be compact and a similar morphology to those of the rhabdoviruses in the infected EPC cells. The optimum temperature for virus replication was 20 to 25℃ but they could not replicate at 15℃. The isolates ShFRV-3 and ShFRV-5 from snakehead fish showed high pathogenicity against the fry (15 dph) and fingering (40 dph) of snakehead fish but did not in the larger size (90 dph).

• Journal of fish pathology
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• v.23 no.1
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• pp.119-122
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• 2010

Mortality and gill lesions in snakehead, Channa argus (body length range, 20.3-22.2 cm) reared in a aqua-farm in Busan, Korea, were associated with a dense bloom of Apiosoma-like ciliate, Order Petrichida. The size of parasite was $48.83{\pm}7.75{\mu}m{\times}14.29{\pm}2.66{\mu}m$. Histological examination revealed that a severe edema and collapse of the gill tissue were observed in a number of samples of snakehead. The mechanism of gill damage was likely due to physical irritation by the parasite. It is believed that this is the first report of Apiosoma-like ciliate in cultured fish in Korea.

• Journal of fish pathology
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• v.33 no.2
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• pp.163-169
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• 2020

Snakehead rhabdovirus (SHRV) is different from other fish novirhabdoviruses such as viral hemorrhagic septicemia virus (VHSV), infectious hematopoietic necrosis virus (IHNV), and hirame rhabdovirus (HIRRV) in that it replicates at high temperatures. Therefore, the delivery of foreign proteins to fish living at high water temperature would be possible by using recombinant SHRVs. In the present study, to evaluate the possible use of SHRV as a vehicle for foreign proteins delivery, we generated a recombinant SHRV that contains an enhanced-GFP (eGFP) gene between nucleoprotein (N) and phosphoprotein (P) genes (rSHRV-A-eGFP), and another recombinant SHRV expressing two heterologous genes by inserting an eGFP gene between N and P genes, and mCherry gene between P and M genes (rSHRV-AeGFP-BmCherry). Epithelioma papulosum cyprini (EPC) cells infected with the recombinant SHRVs showed strong fluorescence(s), suggesting the possible availability of recombinant SHRVs for the development of combined vaccines by expressing multiple foreign antigens.

• Journal of Fisheries and Marine Sciences Education
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• v.28 no.3
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• pp.653-660
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• 2016

Snakehead, Channa argus were intraperitoneally infected with Nocardia seriolae. at the concentrations of $1.5{\times}10^7cfu/m{\ell}$ or $1.5{\times}10^8cfu/m{\ell}$. The infected fish were kept in aquaria at $25^{\circ}C$ and $30^{\circ}C$ for 3 weeks. Clinical signs and mortality were monitored daily to evaluate the virulence. All artificially infected fish showed the same clinical sign found in naturally infected fish. All the fish infected with $1.5{\times}10^8cfu/m{\ell}$ of N. seriolae died within 24days. N. seriolae showed higher virulence to snakehead at the temperature $30^{\circ}C$. Internal lesions such as whitish nodules in the infected internal organs were not correlated with mortality but some degenerative changes were observed in all the infected organs within a week. Whitish nodules in the infected organs which are the typical character in nocardial infection was initially found at two weeks after the artificial infection in snakehead.

• Korean Journal of Microbiology
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• v.31 no.2
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• pp.113-122
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• 1993

Aeromonas veronii was isolated from the haemorrhagic ulcer of the snakehead that had been infected in natural condition, This bacterium was injected hypodermically into the healthy snakeheads and the effect was compared to the naturally infected fish. Both groups showed severe necrosis, falling off of epidermal tissue and hypodermal muscle. In both groups, severe histophathological changes were observed in gill, digestive tract and kidney just before death. Artificially injected fish showed necrosis of tissue in skin, gill and digestive tract from 2 days after injection. Then it showed necrosis or cell atrophy of tissue in kidney from 5 days after injection, and in liver and spleen just before death. Snakehead infected with haemorrhagic ulcer died within 9 days after infection, showing the symptom of skin damage and metabolic inhibition in respiration" digestion, excretion, etc. It was concluded that Aeromonas veronii (CA26) that was isolated from the naturally infected fish is the main bacterium causing haemorragic ulcer in the snakehead.

• Advances in Traditional Medicine
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• v.4 no.2
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• pp.91-94
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• 2004

Water and chloroform/methanol extracts of the three local Malaysian snakehead fish, Channa striatus (striped snakehead), Channa micropeltes (giant snakehead) and Channa lucius (blotched snakehead) were evaluated for inhibitory activity in chronic inflammation, using cotton pellet granuloma test. Both water extracts of C. striatus and C. micropeltes showed marked inhibition of the transudative and proliferative components of chronic inflammation (42.9 and 31.2% respectively for C. striatus, 35.6 and 26.2% for C. micropeltes) when compared to those of mefenamic acid (25.1 and 21.3% respectively) and piroxicam (36.1 and 26.2% respectively). The chloroform/methanol extracts did not exhibit any anti-inflammatory effects. These results indicated that C. striatus has more anti-transudative and anti-proliferative activities than the extract of C. micropletes. C. lucius extract in contrast, did not inhibit these two components. This present study indicated the beneficial effects of the water extracts of C. striatus and C. micropeltes, but not C. lucius on chronic inflammation.

• Journal of fish pathology
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• v.23 no.1
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• pp.113-118
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• 2010

The present work describes myxozoan parasite found in the skin of cultured snakehead, Channa argus fingerings (total length, 5.5~7.2 cm) from Busan, Korea. Nature spores and plasmodia were found in the skin mucus of infected fishes. In fresh state, the total length of the spore was $27.96{\pm}2.50{\mu}m$. The size of spore body was $14.16{\pm}1.78{\mu}m{\times}4.88{\pm}0.61{\mu}m$. The polar capsules were pyriform and the size was $5.57{\pm}0.66{\mu}m{\times}1.36{\pm}0.33{\mu}m$. This is the first report of Henneguya sp. from cultured fish species in Korea, and further studies are necessary for definitive identification.

• Journal of fish pathology
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• v.37 no.1
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• pp.17-23
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• 2024

Spring viremia of carp virus (SVCV) poses a significant threat to numerous cyprinid fish species, particularly the common carp (Cyprinus carpio), often resulting in substantial mortalities. This study explores the potential use of a chimeric recombinant snakehead rhabdovirus carrying the SVCV G gene (rSHRV-Gsvcv) as a live vaccine against SVCV infection. Through virulence testing in zebrafish at different temperatures (15 ℃ and 20 ℃), no mortality was observed in groups infected with either rSHRV-wild or chimeric rSHRV-Gsvcv at both temperatures, whereas 100% mortality occurred in fish infected with wild-type SVCV. Subsequently, as no mortality was observed by rSHRV-Gsvcv, three independent experiments were conducted to determine the possible usage of chimeric rSHRV-Gsvcv as a vaccine candidate against SVCV infection. Fish were immunized with either rSHRV-Gsvcv or rSHRV-wild, and their survival rates against the SVCV challenge were compared with a control group injected with buffer alone at four weeks post-immunization. The results showed that chimeric rSHRV-Gsvcv induced significantly higher fish survival rates compared to rSHRV-wild and the control groups. These findings suggest that genetically engineered chimeric rSHRV-Gsvcv holds the potential for a prophylactic measure to protect fish against SVCV infection.

• Journal of fish pathology
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• v.18 no.2
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• pp.157-165
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• 2005

A new disease causing mass mortality of farmed snakehead (Channa arga) has emerged in Korea over the summer of 2005. The affected fish showed no specific external signs with the exception of a distended abdomen and hemorrhaging around the anus. After opening the abdomen, the visceral organs, liver, spleen and kidney, present numerous white nodular structures. Histopathological examination revealed these nodules to be evidence of granulomas in the visceral organs. A Gram-positive, filamentous bacterium was isolated from all of the affected fish. Development of primers for a genus-specific peR assay for Nocardia, following analysis of the sequences of the complete 16S rRNA genes from Nocardia spp. and non-Nocardia bacterial genes, allowed identification of the causative organism as Nocardia. This is the first report of a nocardial infection of fish in Korea.

• Parasites, Hosts and Diseases
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• v.45 no.1 s.141
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• pp.45-54
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• 2007

Although Vietnam has a high risk of fish borne zoonotic trematode(FZT) infections for humans, little information exists on the epidemiology of these infections in the country's fish. Because of the importance of cultured cat-fish and snakehead production in An Giang province, a major production area in the Mekong Delta of Vietnam, a survey for FZTs was carried out in randomly selected fish farms between June 2005 and March 2006. For comparison, wild fish from the same area were also surveyed. A total of 852 cultured fish from 4 districts were collected and examined by pepsin digestion to determine their FZT infection status. In Tra catfish, the prevalence of all types of metacercariae was 2.6%, of which the prevalence of Haplorchis pumilio was 0.7%. The overall prevalence of metacercariae in wild fish was 30.6%, of which 10.3% harbored zoonotic species: H. pumilio(2.8%) and Procerovum sp.(5.6%). The prevalence of Opisthorchis metacercariae, which were diagnosed as O. viverrini, was 1.9%. No metacercariae were found in cultured snake head fish, although wild-caught snakehead fish had a FZT prevalence of 10.3%: 5.1% were O. viverrini; 2.6% H. pumilio; and 2.6% were Procerovum sp. These are the first reports of H. pumilio, Procerovum sp., and O. viverrini metacercariae in Vietnamese fish. These results indicate that consumption of improperly prepared fish represents a significant risk of acquiring FZTs in this south Vietnam region.