• Journal of fish pathology
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• v.35 no.1
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• pp.41-46
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• 2022

Since viral haemorrhagic septicaemia virus (VHSV) was first reported in European rainbow trout (Oncorhynchus mykiss) in the 1930s, it has caused high prices in freshwater and saltwater fish around the world, causing enormous economic damage to the aquaculture industry. We have been seeking required countermeasures against viruses because of economic damage to the aquaculture industry. However, commercial vaccines have the limitations of being costly to use in farms and being effective to only one pathogen. The aquaculture industry these days is taking on new alternatives to vaccines, antibiotics and chemicals. In this study, the suitability of antiviral effects against VHSV was evaluated in vitro for various plant extracts to judge their effectiveness. Atriplex gmelinii, Ixeris repens, Arctium lappa, and Sargassum coreanum were tested to know the correlation between the amount of virus and the concentration of extract investigates if these extracts have antiviral effects. Virus and extracts at various concentrations were inoculated simultaneously as 1:1 ratio into EPC cell lines. There are no antiviral effects with Atriplex gmelinii, Ixeris repens and Arctium lappa. Extract of Sargassum coreanum only has the antiviral activity in a dose-dependent manner. These results show that extract of Sargassum coreanum can be used in aquaculture industry as an antiviral materials.

• Journal of fish pathology
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• v.30 no.2
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• pp.135-148
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• 2017

Pathogen introductions associated with aquatic invasive species threaten ecosystems and biodiversity worldwide. Bigheaded carps (BHC), including Silver Carp Hypophthalmichthys molitrix, Bighead Carp H. nobilis, and their hybrids, are prolific, invasive pests in central US rivers. However, little is known about pathogen effects on invading BHC or how BHC affect the disease risk profile for native fishes in receiving ecosystems. We therefore conducted, from May 2013-December 2014, a systematic pathogen survey for BHC and native fishes in the Wabash River watershed, Indiana, USA. We found Pseudomonas fluorescens, P. putida, and Salmonella enterica DNA in BHC as well as native fishes, although none of these bacteria were exclusively present in BHC. DNA from other bacterial taxa was detected only in native fishes and Common Carp Cyprinus carpio. No gastrointestinal helminths were detected in BHC, although they were common in most native fishes examined. We also conducted in vitro studies on BHC tissues (skin, gill, fin, and fry) and found high sensitivity to Largemouth Bass virus, viral hemorrhagic septicemia virus, and infectious pancreatic necrosis virus. We conclude that BHC are not heavily burdened by bacteria, viruses and parasites in the invaded study ecosystems, although they do harbor native bacteria and show potential for high sensitivity to endemic viruses.

• Journal of Life Science
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• v.26 no.12
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• pp.1470-1476
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• 2016

The viral hemorrhagic septicemia virus (VHSV), which belongs to the Novirhabdovirus genus of the Rhabdoviridae family, is a viral pathogen that causes severe losses in the olive flounder farming industry. Among six encoding VHSV proteins, the non-virion (NV) protein has been shown to have an impact on virulence. In our previous studies, transcriptomics microarray analysis by using VHSV-infected olive flounder showed that VHSV infection significantly down-regulated the mRNA expression of glycolytic enzymes. In addition, VHSV NV protein variants decreased the intracellular ATP level. Based on these results, we have tried to examine the effect of VHSV NV protein on glycolytic enzyme glucokinase expression, which phosphorylates glucose to glucose 6-phosphate. Our results indicated that the NV protein significantly decreased the mRNA expression of glucokinase in olive flounder HINAE cells. Furthermore, the NV protein played a negative role in the promoter activation of glucokinase. Furthermore, glucose uptake was effectively inhibited by VHSV infection and NV protein expression in olive flounder HINAE cells. These results suggest that the VHSV NV protein negatively regulates glycolytic enzyme expression by a transcription level and eventually leads to gradual morbidity of olive flounder through cellular energy deprivation. The present results may be useful for the prevention and diagnosis of VHSV infection in olive flounder.

• Research in Plant Disease
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• v.25 no.2
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• pp.49-61
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• 2019

Plant viruses are among the important pathogens that cause severe crop losses. The most efficient method to control viral diseases is currently to use virus resistant crops. In order to develop the virus resistant crops, a detailed understanding of the molecular interactions between viral and host proteins is necessary. Recessive resistance to a pathogen can be conferred when plant genes essential in the life cycle of a pathogens are deficient, while dominant resistance is mediated by host resistance (R) genes specifically interacting with effector proteins of pathogens. Thus, recessive resistance usually works more stably and broadly than dominant resistance. While most of the recessive resistance genes have so far been identified by forward genetic approaches, recent advances in genome editing technologies including CRISPR/Cas9 have increased interest in using these technologies as reverse genetic tools to engineer plant genes to confer recessive resistance. This review summarizes currently identified recessive resistance genes and introduces reverse genetic approaches to identify host interacting partner proteins of viral proteins and to evaluate the identified genes as genetic resources of recessive resistance. We further discuss recent advances in various precise genome editing technologies and how to apply these technologies to engineer plant immunity.

• Journal of fish pathology
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• v.26 no.1
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• pp.19-30
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• 2013

Megalocytivirus is a major fish pathogen in marine aquaculture of Asian countries including Korea. Despite of many species affected by this pathogen, little is known interaction between megalocytivirus and the fish immune system. One of the cyclooxygenase isoforms, named COX-2, is playing an important role in immune regulation, and distinct from COX-1 isoform of constitutive activity. COX-2 enzyme is induced by various inflammatory signals, including injection of lipopolysaccharide or infection by pathogenic agents. We cloned COX-2 gene in rock bream using degenerated primers designed from reported sequences of other fish species in PCR followed with 5'- and 3'-end RACE-PCR. The full length of cDNA of rbCOX2 (rock bream COX-2) gene are 2655 bp and that translates into 609 amino acids. The rbCOX-2 genomic organization are found to span 10 exons separated by 9 introns. We also studied if the experimental infection of rock bream with megalocytivirus could affect the expression of COX-2 gene. When injected with LPS, expression of the COX-2 gene was reached peak level at 1 day post injection and showed 13.10 fold increased level compared with that of control. While, when injected with megalocytivirus, we were not able to find significantly increased COX-2 gene expression different from that of control. Cloned and analyzed COX-2 gene in rock bream will help to understand defence mechanisms in fish after viral infection and will also support the development of the measures for treatment and prevention of viral infection.

• International Journal of Industrial Entomology and Biomaterials
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• v.31 no.2
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• pp.70-74
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• 2015

The current market size of insect industry in Korea is estimated at 300 million dollars and more than 500 local farms are related to many insect industry. One of the strong candidates for insect industry is Korean horn beetle, Allomyrina dichotoma. Early this year, we reported a viral disease extremely fatal to A. dichotoma larvae. While we were proceeding a nationwide investigation of this disease, it was informed that similar disease symptom has been occurred occasionally during past over 10 years. The symptom can be easily confused with early stage of bacterial infection or physiological damage such as low temperature and high humidity. A peroral infection with the purified virus to healthy larvae produced a result that only 21% of larvae survived and became pupae. Although some of the survived adult beetle was deformational, many of them had no abnormal appearance and even succeeded in mating. Later, these beetles were examined if they were carrying the virus, and all except one were confirmed as live virus carrier. This implies that these beetles may fly out and spread the disease to the nature. We found the evidence for this possibility by collecting a few wild A. dichotoma larvae which were virus infected, near two local farms rearing A. dichotoma larvae. So far, transovarial transmission of this virus to the eggs, or horizontal transmission to other commercially reared insects is not known yet.

• Korean Journal of Clinical Laboratory Science
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• v.43 no.4
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• pp.145-149
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• 2011

Serum hepatitis is still recognized as a major public health problem in many countries. The most common etiologies are acute viral hepatitis A and B, and hepatitis B virus (HBV) was known as the pathogen of serum hepatitis. since the HBV causes chronic hepatitis. HBV infection is hyperendemic in Korea. It is known that 8% and 1% of the Korean population is chronic carriers of HBV. The total number of 487 serum specimen (old people's home 190, causal ward-Daegu hope village 297) were collected at the laboratory of Department of Clinical Pathology of Daegu medical center. The laboratory tested the specimen to detect for hepatitis B surface antigen (HBsAg) and anti-HBs using reverse passive hemag-glutination (RPHA) and passive hemagglutination (PHA) method between April, 2011 and June, 2011. In one-step test, HBsAg and anti-HBs of Humasis were used. The positive rate for HBsAg was 6.80% (33/487), and the rate in male was 6.93% (19/274) higher than that of female 6.57% (14/213). In the positive rate of HBsAg by age group, the highest positive rate group was in the group of 40-49 years in male (12.0%), and 50-59 years in female (17.65 %). The overall positive rate for anti-HBs was 42.70% (208/487), showing the higher positive rate of 43.80% in male (120/274) than that of 41.30% (88/213) in female. The highest positive rate of anti-HBs in age group was the 40-49 years group in male (52.00%) and the group of under 29 in female (66.67%).

• Proceedings of the Microbiological Society of Korea Conference
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• 2003.05a
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• pp.83-86
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• 2003

Major advances in positive-sense RNA virus research have been facilitated by the development of reverse genetics systems. These systems consist of an infectious cDNA clone that encompasses the genome of the virus in question. This clone is then used as a template for the subsequent synthesis of infectious RNA for the generation of synthetic viruses. However, the construction of infectious cDNA for the Japanese encephalitis virus (JEV) has been repeatedly thwarted by the instability of its cDNA. As JEV is an important human pathogen that causes permanent neuropsychiatric sequelae and even fatal disease, a reliable reverse genetics system for this virus is highly desirable. The availability of this tool would greatly and the development of effective vaccines as well as facilitate studies into the basic biology of the virus, including the molecular mechanisms of viral replication, neurovirulence, and pathogenesis. We have successfully constructed a genetically stable infectious JEV cDNA containing full-length viral RNA genome. Synthetic RNA transcripts generated in vitro from the cDNA were highly infectious upon transfection into susceptible cells, and the cDNA remained stable after it had been propagated in E. coli for 180 generations. Using this infectious JEV cDNA, we have successfully expressed a variety of reporter genes from the full-length genomic and various subgenomic RNAs in vitro transcribed from functional JEV cDNAS. In summary, we have developed a reverse genetics system for JEV that will greatly facilitate the research on this virus in a variety of different fields. It will also be useful as a heterologous gene expression vector and aid the development of a vaccine against JEV.

• Clinical and Experimental Pediatrics
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• v.58 no.11
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• pp.446-450
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• 2015

Purpose: Meningitis is among the most common infections affecting the central nervous system. It can be difficult to determine the exact pathogen responsible for the infection and patients are often treated with empiric antibiotics. This study was conducted to identify the most common clinical characteristics of enteroviral meningitis in children and evaluate the diagnostic efficacy of reverse transcriptase-polymerase chain reaction (RT-PCR) for early detection of an enterovirus. Methods: We analyzed the medical records of children admitted to Korea University Medical Center and diagnosed with meningitis on the basis of cerebrospinal fluid (CSF) analysis and RT-PCR from CSF and other samples from January 2010 to August 2013. Results: A total of 333 patients were enrolled and classified into four groups based on diagnosis: enteroviral meningitis (n=110), bacterial meningitis (n=23), other viral meningitis (n=36), and unknown etiology (n=164). Patients with bacterial meningitis were younger than those in the other groups (P<0.001). Pleocytosis in CSF was similar across all groups. Of patients in the enteroviral meningitis group, 92.7% were diagnosed based on RT-PCR findings. Mean length of hospital stay for patients with enteroviral meningitis was 6.08 days, which was significantly shorter than that for patients with meningitis of bacterial etiology (19.73 days, P<0.001). Conclusion: Diagnosis of enteroviral meningitis before viral culture results are available is possible using RT-PCR. Accurate diagnosis reduces the length of hospital stay and helps to avoid unnecessary empiric antibiotic treatment.

• The Journal of Korean Society of Virology
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• v.30 no.1
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• pp.29-37
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• 2000

The aim of this study was to investigate viral etiology in dilated cardiomyopathy (DCM) by polymerase chain reaction (PCR) or nested reverse transcription PCR (RT-PCR), and characterize the enteroviral RNA presented in the clinical specimens. Twenty-eight paraffin-embedded heart tissue samples were assayed to detect cytomegalovirus, herpes simplex virus type 1, type 2, parvovirus, adenovirus, and enterovirus (EV) with each specific primer. Of these 28 patients (mean age: 27, M: 24, F: 4), 26 were histologically diagnosed as DCM and 2 as myocardial infarction (MI). Nested RT-PCR detected enteroviral RNA in 7 (26.9%) of 26 patients with DCM, and none of patients with MI. And none of DNA viruses tested were detected from the samples. Amplified products were also genotyped by single-strand conformation polymorphism (SSCP). Three subtypes can be differentiated from 7 clinical specimens. Furthermore, direct sequence analysis was performed to determine whether genetic variation of EV is present in the explanted heart tissues from patients with DCM. Although most of the sequences among the wild isolates have the greatest similarity to those of coxsackievirus B3, there are specific regions of variable sequences (no 490 - no 510). The data suggest that enterovirus may be a major viral pathogen for the DCM in Korea and nucleotide sequence data indicate that coxsackievirus B3 may be a leading etiologic agent of DCM.