• 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).

• Korean Journal of Veterinary Research
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• v.58 no.1
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• pp.45-49
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• 2018

The helicase genes and hypervariable regions (HVRs) of three avian hepatitis E viruses (HEVs) detected at three different farms were sequenced and characterized. Two isolates (DW-L and GI-B2) were classified as genotype 2 and one isolate (GR-B) was classified as genotype 1. A phylogenetic tree, based on the helicase gene and HVR nucleotide sequences, revealed the newly detected viruses and other avian HEVs were classified similarly. Unlike previously reported avian HEVs, the DW-L isolate detected in broiler breeders with characteristic lesions of avian HEV had no proline-rich motif in its HVR, suggesting that the proline-rich motif is non-essential for viral replication and infection.

• Korean Journal of Microbiology
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• v.31 no.1
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• pp.79-84
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• 1993

Infection of Chinook Salmon Embryo (CHSE) cells with IPNV resulted in a significant decrease in intracellular free calcium concentration ([$Ca^{2+}$]i) compared to mock-infected cells. The degree of the decrease in [Ca$^{2+}$]i was dependent on the amount of input virus, and treatment of IPNV-infected CHSE cells with metabolic inhibitors such as cyloheximide cordycepin partially reversed the decrease in [$Ca^{2+}$]i in IPNV-infected cells. Inactiation of PINV with UV also abolished IPNV-induced decrease in [$Ca^{2+}$]i. These data suggest an active role of IPNV in the decrease of [Ca$^{2+}$]i in the infected CHSE cells. The importance of the decrease in [$Ca^{2}$i] could be supported by the finding that the production of IPNV plaques increased in the cells treated with verapamil, a calcium influex blocker, and by lowering the concentration of extracellular calcium. Decreased production of IPNV plaques was observed by elevating the extracellular calcium. Thus, it is suggested that IPNV induced a decreased in [$Ca^{2+}$]i and the decrease in [$Ca^{2+}$]i may plan an importat role in efficient replication of IPNV.ation of IPNV.

• Fisheries and Aquatic Sciences
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• v.17 no.1
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• pp.155-158
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• 2014

The objective of this study was to evaluate the antiviral activity of Phaeophyta extracts against feline calicivirus (FCV), used as a norovirus surrogate. A bioassay-guided cytotoxicity and virus infectivity assay revealed that methanolic extracts of Phaeophyta possessed significant antiviral activity against FCV. Among them, Eisenia bicyclis extract exhibited the highest antiviral activity against FCV. The 50% effective concentration of the extract ($EC_{50}$) inhibiting FCV viral replication by 50% was $80{\mu}g/mL$. The extract also showed the highest selectivity index, calculated from the ratio of the median cellular cytotoxicity concentration ($CC_{50}$) and $EC_{50}$, indicating antiviral efficacy against FCV. In addition, significant interruption of FCV infection was observed by pretreatment of host Crandall-Reese feline kidney cells with the E. bicyclis extract ($200{\mu}g/mL$) prior to virus infection, in a dosedependent manner.

• International Journal of Industrial Entomology and Biomaterials
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• v.7 no.2
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• pp.139-144
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• 2003

Over 350 million people worldwide are chronic carriers of hepatitis B virus (HBV). Chronic viral infections of the liver can progress to cirrhosis, which may ultimately lead to hepatic failure or the development of hepatocellular carcinoma. There are two antiviral drugs on the market approved for clinical management of chronic HBV infections; interferon-alpha and the nucleoside analog lamivudine. However, they showed adverse side-effects. In the rational drug design for such therapies we would like to utilize antiviral drugs that inhibit the HBV replication in the liver. Investigation of natural extracts of silkworm exhibiting antiviral potential was held in the functional HBV polymerase activity and the release of virion particle in the HepG2.2.15 cell lines. HBV-producing transgenic mouse fed with silkworm DNJ molecule was shown as an inhibitor of serum HBV particles. We could represent this DNJ molecule as an antiviral potential complementing conventional therapies after preclinical tests against WHBV-infected animal model, woodchuck.

• Journal of Microbiology and Biotechnology
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• v.16 no.10
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• pp.1634-1639
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• 2006

Hepatitis C virus (HCV)-encoded nonstructural protein 5B (NS5B) possesses RNA-dependent RNA polymerase activity, which is considered essential for viral proliferation. Thus, HCV NS5B is a good therapeutic target protein for the development of anti-HCV agents. In this study, we isolated two different kinds of nuclease-resistant RNA aptamers with 2'-fluoro pyrimidines against the HCV NS5B from a combinatorial RNA library with 40 nucleotide random sequences, using SELEX technology. The isolated RNA aptamers were observed to specifically and avidly bind the HCV NS5B with an apparent $K_d$ of 5 nM and 18 nM, respectively, in contrast with the original RNA library that hardly bound the target protein. Moreover, these aptamers could partially inhibit RNA synthesis of the HCV subgenomic replicon when transfected into Huh-7 hepatoma cell lines. These results suggest that the RNA aptamers selected in vitro could be useful not only as therapeutic agents of HCV infection but also as a powerful tool for the study of the HCV RNA-dependent RNA polymerase mechanism.

• Molecules and Cells
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• v.42 no.10
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• pp.721-728
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• 2019

Non-structural protein 1 (NS1) of influenza virus has been shown to inhibit the innate immune response by blocking the induction of interferon (IFN). In this study, we isolated two single-stranded RNA aptamers specific to NS1 with $K_d$ values of $1.62{\pm}0.30nM$ and $1.97{\pm}0.27nM$, respectively, using a systematic evolution of ligand by exponential enrichment (SELEX) procedure. The selected aptamers were able to inhibit the interaction of NS1 with tripartite motif-containing protein 25 (TRIM25), and suppression of NS1 enabled retinoic acid inducible gene I (RIG-I) to be ubiquitinated regularly by TRIM25. Additional luciferase reporter assay and quantitative real-time PCR (RT-PCR) experiments demonstrated that suppression of NS1 by the selected aptamers induced IFN production. It is noted that viral replication was also inhibited through IFN induction in the presence of the selected aptamers. These results suggest that the isolated aptamers are strongly expected to be new therapeutic agents against influenza infection.

• The Plant Pathology Journal
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• v.39 no.5
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• pp.449-465
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• 2023

Plants are challenged by various pathogens throughout their lives, such as bacteria, viruses, fungi, and insects; consequently, they have evolved several defense mechanisms. In addition, plants have developed localized and systematic immune responses due to biotic and abiotic stress exposure. Animals are known to activate DNA damage responses (DDRs) and DNA damage sensor immune signals in response to stress, and the process is well studied in animal systems. However, the links between stress perception and immune response through DDRs remain largely unknown in plants. To determine whether DDRs induce plant resistance to pathogens, Arabidopsis plants were treated with bleomycin, a DNA damage-inducing agent, and the replication levels of viral pathogens and growth of bacterial pathogens were determined. We observed that DDR-mediated resistance was specifically activated against viral pathogens, including turnip crinkle virus (TCV). DDR increased the expression level of pathogenesis-related (PR) genes and the total salicylic acid (SA) content and promoted mitogen-activated protein kinase signaling cascades, including the WRKY signaling pathway in Arabidopsis. Transcriptome analysis further revealed that defense-and SA-related genes were upregulated by DDR. The atm-2atr-2 double mutants were susceptible to TCV, indicating that the main DDR signaling pathway sensors play an important role in plant immune responses. In conclusion, DDRs activated basal immune responses to viral pathogens.

• Journal of fish pathology
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• v.11 no.2
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• pp.129-136
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• 1998

In March 1997, a new rhabdovirus was isolated from moribund cultured Japanese flounder Paralichthys olivaceus in sea water tank and cage culture systems in Kyung-Nam and Chun-Nam province, Korea. At temperature $15^{\circ}C$ the virus replicated and induced cytopathic effects (CPE), which progressed to eventual cytolysis, in susceptible cell lines, including RTG-2 and EPC. The CHES-214 cell line was refractory. Virus particles were bullet-shaped and measured $70nm{\times}100$ to 150 nm in size. The isolate was sensitive to pH 3, to diethyl ether, and to heat ($50^{\circ}C$ 5 min, $60^{\circ}C$ 1 min). Viral replication was not inhibited by $10^{-4}$ M 5-iododeoxyuridine. Virus infectivity was reduced by anti-HRV (8401-H) rabbit serum, but can not reduced by antisera against infectious hematopoietic necrosis virus (IHNV), chum salmon reovirus (CSV), retrovirus of salmonid (RVS) and infectious pancreatic necrosis virus (IPNV). HRV virus antigen was detected by fluorescent antibody test (FAT) in the cytoplasm of infected EPC cell. Purified isolates virions were composed of: polymerase (L), glycoprotein (G), nucleoprotein (N) and 2 matrix proteins (M1 and M2). Based upon their relative mobilities, the estimated molecular weights of the proteins were: L, 160 kDa; G, 55 kDa; N, 45 kDa; M1, 26 kDa; and M2, 22 kDa.

• The Journal of Korean Society of Virology
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• v.30 no.1
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• pp.39-49
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• 2000

The genome of Hantaan virus, the prototype of the hantavirus genus, is composed of three segmented, single stranded negative sense RNA genome. The 5' and 3' termini of the Hantaan virus RNA genome contain noncoding regions (NCRs) that are highly conserved and complementary to form panhandle structures. There are some reports that these NCRs seems to control gene expression and viral replication in influenza virus and vesicular stomatitis virus. In this study, we examined whether NCRs in Hantaan virus playa role in expression of the viral nucleocapsid protein (Np) and foreign (luciferase) gene. The 5' and/or 3' NCR-deleted mutants were constructed and analysed. The Np expression of 5' NCR-deleted clone was similar to that of the clone containing full S genome. In the case of 3' NCR-deleted clone, it showed 40% reduction. To investigate the role of NCR in foreign gene expression, the clones which are replaced ORF of Hantaan viral Np gene with that of luciferase gene were constructed. The results were similar to those of the experiments using Np gene. These results suggest that 3' NCR is more important than 5' NCR in protein expression. To find out a critical region of 3' NCR in protein expression, several clones with a deleted part of 3' NCR were constructed and analyzed. The deletion of the conserved region in 3' NCR showed $20{\sim}30%$ decrease in Np expression. However there were no change in luciferase activities between clones with or without non-conserved region of 3' NCR. These results suggest that the 3' NCR of Hantaan virus S genome, especially conserved region in 3' NCR, plays an important role in the expression of Hantaan viral Np and foreign genes.