• Molecules and Cells
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• v.45 no.3
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• pp.148-157
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• 2022

Hepatitis C virus (HCV) is a major cause of chronic liver disease and is highly dependent on cellular proteins for viral propagation. Using protein microarray analysis, we identified 90 cellular proteins as HCV nonstructural 5A (NS5A) interacting partners, and selected telomere length regulation protein (TEN1) for further study. TEN1 forms a heterotrimeric complex with CTC and STN1, which is essential for telomere protection and maintenance. Telomere length decreases in patients with active HCV, chronic liver disease, and hepatocellular carcinoma. However, the molecular mechanism of telomere length shortening in HCV-associated disease is largely unknown. In the present study, protein interactions between NS5A and TEN1 were confirmed by immunoprecipitation assays. Silencing of TEN1 reduced both viral RNA and protein expression levels of HCV, while ectopic expression of the siRNA-resistant TEN1 recovered the viral protein level, suggesting that TEN1 was specifically required for HCV propagation. Importantly, we found that TEN1 is re-localized from the nucleus to the cytoplasm in HCV-infected cells. These data suggest that HCV exploits TEN1 to promote viral propagation and that telomere protection is compromised in HCV-infected cells. Overall, our findings provide mechanistic insight into the telomere shortening in HCV-infected cells.

• Korean Journal of Veterinary Research
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• v.61 no.2
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• pp.19.1-19.7
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• 2021

Feline panleukopenia virus (FPV) causes leukopenia and severe hemorrhagic diarrhea, killing 50% of naturally infected cats. Although intact FPV can serve as an antigen in the hemagglutination inhibition (HI) test, an accidental laboratory-mediated infection is concern. A non-infectious diagnostic reagent is required for the HI test. Here, we expressed the viral protein 2 (VP2) gene of the FPV strain currently prevalent in South Korea in a baculovirus expression system; VP2 protein was identified by an indirect immunofluorescence assay, electron microscopy (EM), Western blotting (WB), and a hemagglutination assay (HA). EM showed that the recombinant VP2 protein self-assembled to form virus-like particles. WB revealed that the recombinant VP2 was 65 kDa in size. The HA activity of the recombinant VP2 protein was very high at 1:2¹⁵. A total of 143 cat serum samples were tested using FPV (HI-FPV test) and the recombinant VP2 protein (HI-VP2 test) as HI antigens. The sensitivity, specificity, and accuracy of the HI-VP2 test were 99.3%, 88.9%, and 99.3%, respectively, compared to the HI-FPV test. The HI-VP2 and HI-FPV results correlated significantly (r = 0.978). Thus, recombinant VP2 can substitute for intact FPV as the serological diagnostic reagent of the HI test for FPV.

• The Journal of Korean Society of Virology
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• v.29 no.4
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• pp.221-233
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• 1999

Prospect Hill Virus (PHV) is the well known serotype of hantavirus, a newly established genus in family Bunyaviridae. Extensive studies have upheld the original view of PHV genetics with three genes such as nucleocapsid (N) protein, envelope proteins (G1, G2) and RNA dependent RNA polymerase. In this study, we report the existence of additional gene that is encoded in an overlapping reading frame of the N protein gene within S genome segment of PHV. This gene is expected to encode a nonstructural small (NSs) protein and it seems to be only found in PHV infected cell. The presence and synthesis of NSs protein could be demonstrated in the cell infected with PHV using anti-peptide sera specific to the predicted amino acid sequence deduced from the second open reading frame. Ribosomal synthesis of this protein appears to occur at AUG codon at the 83rd base of S genome segment, downstream of N protein initiation codon. This protein is small in size (10.4 KDa) and highly basic in nature. The expression strategy of NSs protein appears that a signal mRNA is used to translate both N and NSs protein in PHV infected cell. 10 KDa protein in virus infected cell lysates can bind to mimic dsRNA. This fact strongly suggests that NSs protein may be involved in virus replication on late phase of viral life cycle.

• Proceedings of the Microbiological Society of Korea Conference
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• 2002.10a
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• pp.118-120
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• 2002

Genetic materials including DNA plasmid are effective delivery vehicle to express interesting gene efficiently and safely not to generate replication competent virus. Moreover, it has advantages to design a better vector and to simplify manufacturing and storage condition. To understand a possible pathogenic mechanism by a flavivirus, West Nile virus (WNV), WNV genome sequence was aligned to other pathogenic viral genome. Interestingly, WNV capsid (Cp) amino acid sequence has some homology to HIV-l Vpr protein. These proteins induce apoptosis in human cell lines as well as in vivo and cell cycle arrest. Therefore, DNA plasmid carrying apoptosis-inducing and cell cycle arresting viral proteins including a HIV-1 Vpr and a WNV Cp protein can be useful for anti-cancer therapeutic applications. This WNV Cp protein is an early expressed protein which can be a reasonable target antigen (Ag) for vaccine design. Immunization of a DNA construct encoding WNV Cp protein induces a strong Ag-specific humoral and Th1-type immune responses in animal. Therefore, DNA plasmid encoding apoptotic viral proteins can be useful tool for therapeutic and prophylactic applications.

• Molecules and Cells
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• v.43 no.5
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• pp.469-478
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• 2020

Hepatitis C virus (HCV) propagation is highly dependent on cellular proteins. To identify the host factors involved in HCV propagation, we previously performed protein microarray assays and identified the LIM and SH3 domain protein 1 (LASP-1) as an HCV NS5A-interacting partner. LASP-1 plays an important role in the regulation of cell proliferation, migration, and protein-protein interactions. Alteration of LASP-1 expression has been implicated in hepatocellular carcinoma. However, the functional involvement of LASP-1 in HCV propagation and HCV-induced pathogenesis has not been elucidated. Here, we first verified the protein interaction of NS5A and LASP-1 by both in vitro pulldown and coimmunoprecipitation assays. We further showed that NS5A and LASP-1 were colocalized in the cytoplasm of HCV infected cells. NS5A interacted with LASP-1 through the proline motif in domain I of NS5A and the tryptophan residue in the SH3 domain of LASP-1. Knockdown of LASP1 increased HCV replication in both HCV-infected cells and HCV subgenomic replicon cells. LASP-1 negatively regulated viral propagation and thereby overexpression of LASP-1 decreased HCV replication. Moreover, HCV propagation was decreased by wild-type LASP-1 but not by an NS5A binding-defective mutant of LASP-1. We further demonstrated that LASP-1 was involved in the replication stage of the HCV life cycle. Importantly, LASP-1 expression levels were increased in persistently infected cells with HCV. These data suggest that HCV modulates LASP-1 via NS5A in order to regulate virion levels and maintain a persistent infection.

• The Journal of Korean Society of Virology
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• v.27 no.2
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• pp.209-216
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• 1997

Three dimensional structures of envelope protein from Korean isolates and Nakayama-NIH strain of Japanese encephalitis virus (JEV) were deduced by a computer program (HyperChem 4.0 Chemplus 1.0) based on the data of the three dimentional structure of Tick-borne encephalitis virus. In the three dimensional structure of envelope protein, neutralizing epitope and T-helper cell recognition site of C-terminal region of Korean isolates were structually similar to those of Nakayama-NIH but the N-terminal region was not. Korean JE isolates were compared with Nakayama-NIH strain by using cross-neutralization antibody test. Neutralizing activities of Korean isolates derived from guinea pigs were higher than those of Nakayama-NIH strain against Korean isolates, although the polyclonal antibody titers of Nakayama-NlH showed 1:160 to 1:640 against Korean isolates. According to the results from three dimentional structures and cross-neutralization analyses, the antigenic difference between Korean JE isolates and Nakayama-NIH strain may be dependent on structural difference of envelope protein.

• Journal of Microbiology and Biotechnology
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• v.21 no.2
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• pp.170-175
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• 2011

This study was carried out for the molecular level identification of recombinant protein vaccine efficacy, by oral feeding against white spot syndrome virus infection, with the comparison of viral mRNA transcriptional levels in shrimp cells. For the determination of WSSV dilution ratio for the vaccination experiment by oral feeding, in vivo virus titration was carried out using different virus dilutions of virus stock ($1{\times}10^2$, $2{\times}10^2$, and $1{\times}10^3$). Among the dilution ratios, $2{\times}10^2$ diluted WSSV stock was chosen as the optimal condition because this dilution showed 90% mortality at 10 days after virus injection. Recombinant viral proteins, rVP19 and rVP28, produced as protein vaccines were delivered in shrimps by oral feeding. The cumulative mortalities of the shrimps vaccinated with rVP19 and rVP28 at 21 days after the challenge with WSSV were 66.7% and 41.7%, respectively. This indicates that rVP28 showed a better protective effect against WSSV in shrimp than rVP19. Through the comparison of mRNA transcriptional levels of viral genes from collected shrimp organ samples, it was confirmed that viral gene transcriptions of vaccinated shrimps were delayed for 4~10 days compared with those of unvaccinated shrimps. Protection from WSSV infection in shrimp by the vaccination with recombinant viral proteins could be accomplished by the prevention of entry of WSSV due to the shrimp immune system activated by recombinant protein vaccines.

• The Journal of the Korean Society for Microbiology
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• v.3 no.1
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• pp.51-65
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• 1968

The site of the synthesis of Japanese encephalitis virus(JEV) in the actinomycin-treated and infecter PS Y15 cells(a porcine kidney stable cell line) was observed by the immunofluorescent antibody technique, acridine orange staining, and the autoradiographic analysis. In the parallel studies by immunofluorescent technique and acridine orange staining it the infected cells, Viral protein(as an antigen) and viral RNA were detected at the same site of cytoplasm. In the autoradiographic analysis, the cytoplasmic labeling of $^3H$-uridine was due to the synthesis of JEV-RNA, while the nucleolus and nucleus were not involved. In the autoradiographic studies on the secton of infected cells, the $^3H$-uridine was frequently incorporated around the cytoplasmic vacuoles. This localization of labeling agreed with the site of acridine orange positive granules. The results suggest that the syntheses of the viral RNA and viral protein occurred in the similar site of cytoplasm of the infected cells, and also the virus particles seem to be assembled in the sites of the viral RNA and protein syntheses.

• BMB Reports
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• v.32 no.1
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• pp.82-85
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• 1999

The movement protein of cucumber mosaic virus (CMV) is required for cell-to-cell movement of viral RNA. The movement of viral RNA occurs through the plant intercellular connection, the plasmodesmata. The viral movement protein was known to be multi-functional. In this work, a series of deletion mutants of CMV movement protein gene were created to identify the functional domains. The mutated movement proteins were produced as inclusion body in E. coli, and purified and renatured. A polyclonal antibody was raised against the CMV-Kor strain (Korean isolate) movement protein expressed in E. coli. The ability of the truncated proteins to bind to ssRNA was assayed by UV cross-linking and gel retardation analyses. The results indicate that the domain between amino acids 118 and 160 of CMV movement protein is essential for ssRNA binding.

• The Plant Pathology Journal
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• v.28 no.1
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• pp.40-48
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• 2012

$Potato$ $virus$ $X$ (PVX) replication is precisely regulated by regulatory viral sequences and by viral and/or host proteins. In a previous study, we identified a 54-kDa cellular tobacco protein that bound to a region within the first 46 nucleotides (nt) of the 5' non-translated region (NTR) of the viral genome. Optimal binding was dependent upon the presence of an ACCA sequence at nt 10-13. To identify host factors that bind to 5' NTR elements including AC-rich sequences as well as stemloop 1 (SL1), we used northwestern blotting and matrixassisted laser desorption/ionization time-of-flight mass spectrometry for peptide mass fingerprinting. We screened several host factors that might affect PVX replication and selected a candidate protein, $Nicotiana$ $tabacum$ WRKY transcription factor 1 (NtWRKY1). We used a $Tobacco$ $rattle$ $virus$ (TRV)-based virus-induced gene silencing (VIGS) system to investigate the role of NtWRKY1 in PVX replication. Silencing of $WRKY1$ in $Nicotiana$ $benthamiana$ caused lethal apical necrosis and allowed an increase in PVX RNA accumulation. This result could reflect the balancing of PVX accumulation in a systemic $N.$ $benthamiana$ host to maintain PVX survival and still produce a suitable appearance of mosaic and mottle symptoms. Our results suggest that PVX may recruit the WRKY transcription factor, which binds to the 5' NTR of viral genomic RNA and acts as a key regulator of viral infection.