• Korean Journal of Veterinary Research
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• v.60 no.4
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• pp.195-202
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• 2020

Feline calicivirus (FCV) infection results in a common upper respiratory disease associated with oral ulceration in cats. Although FCV infection has been reported in cats worldwide, the biologic and genetic features of South Korean FCV are unclear. We aimed to investigate the biological and genetic features of South Korean FCV isolates. Crandell-Rees feline kidney (CRFK) cells were used to isolate FCV from 58 organ homogenate samples. The FCV isolates were confirmed by cytopathic effects, immunofluorescence, electron microscopy, and reverse transcription polymerase chain reaction assays. Viral genetic analysis was carried out with VP2 gene and complete genomes of FCVs. Five viruses propagated in CRFK cells were confirmed to be FCVs. The FCV17D283 isolate showed the highest viral titer of 107.2 TCID50/mL at 36 h post-inoculation. Korean FCV isolates did not grow well in Vero, BHK-21, A72, or Madin-Darby canine kidney cells. The FCV17D03 and FCV17D283 isolates had the highest genetic similarity (80.1% and 86.9%) with the UTCVM-H1 and 14Q315 strains, which were isolated in the United States and South Korea in 1995 and 2014, respectively. We isolated five FCVs from cats and detected important genetic differences among them. FCV isolates did not show any virulent effects in mice.

• Korean Journal of Veterinary Research
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• v.55 no.3
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• pp.163-167
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• 2015

Canine parvovirus (CPV) is a major diarrhea-causing agent in puppies. Since CPV type 2 (CPV-2) emerged in 1978, new antigenic variants including CPV-2a, CPV-2b, and CPV-2c have been identified in many countries. Two puppies died suddenly at a veterinary clinic in Gyeonggi province, South Korea. Two viruses were isolated in A72 cells, confirmed as CPV strains based on a CPV rapid kit and an indirect fluorescence test and designated QIACP1403 and QIACP1404. The nucleotide sequences of complete VP2 genes of QIACP1403 and QIACP1404 were determined, and the corresponding amino acid sequences were deduced. Molecular analyses revealed that the QIACP1403 and QIACP1404 isolates were type CPV-2b. Several mutated amino acids were detected on VP2 gene residues of the two isolates. Phylogenetic analyses showed that the two isolates were most closely related to strain CPV-BM11, which was isolated from Chinese dogs in 2011. Our results suggest that these isolates may be a candidate for a vaccine to prevent CPV infection in dogs after conducting passages of the isolates in an in vitro culture system.

• 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.

• Korean Journal of Veterinary Research
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• v.62 no.1
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• pp.10.1-10.9
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• 2022

Feline panleukopenia virus (FPV) causes fatal leukopenia and severe hemorrhagic diarrhea in cats. Although FPV isolates have been reported worldwide from several animals, the biological and genetic features of South Korean FPVs remain unclear. We characterized molecularly South Korean FPV isolates. Crandell-Rees feline kidney (CRFK) cells were used to isolate FPV from 60 organ homogenates. The isolates were confirmed to be FPVs via analyses of cytopathic effects, immunofluorescence studies, electron microscopy, and polymerase chain reaction. Viral genetic analyses used the full VP2 sequences. Eight isolates propagated in CRFK cells were confirmed to be FPVs. All isolates yielded viral titers ranging from 10^4.5 to 10^6.0 TCID₅₀/mL 5 days after inoculation into CRFK cells and exhibited hemagglutination titers ranging from 2⁷ to 2¹² (using pig erythrocytes). The Korean FPV isolates grew well in cat cells such as CRFK and Fcwf-4 cells. The FPV isolates were most similar to the KS42 strain isolated from a Korean cat in 2008. The FPV isolates will serve as useful antigens in future sero-epidemiological studies and will aid in the development of diagnostic tools.

• Korean Journal of Veterinary Service
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• v.37 no.2
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• pp.97-100
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• 2014

This study was performed in Korea to get serological information for bovine herpesvirus 1 (BoHV-1), most commonly found in cattle. Antibodies against BoHV-1 were examined by targeting infectious bovine rhinotracheitis (IBR) in unvaccinated and vaccinated cattle, using viral neutralization (VN) test. In 2013, among 261 sera collected from IBR-unvaccinated herds, 7 sera (2.7%) were found seropositive and their VN titers were ranging from 1:4 to 1:32. Among 315 sera collected from IBR-vaccinated herds in large capacity farms, 303 sera (96.2%) were found to be seropositive for BoHV-1 and their VN titers were in the range of 1:4 to 1:2048. It was found that the IBR-vaccinated herds had higher levels of VN titer than IBR-unvaccinated herds. The results indicated that it may be due to heavy vaccination in vaccinated herds and no or a little infection in unvaccinated herds. At the end of the study it was concluded that although the seropositivity in IBR-unvaccinated herds was low, the monitoring of IBR should be continuously practiced to control and prevent the disease because of exportation of living cattle causing its nationwide outbreaks.

• Korean Journal of Veterinary Research
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• v.57 no.1
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• pp.37-42
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• 2017

Getah virus (GETV) infection causes sporadic outbreaks of mild febrile illness in horses and reproductive failure in pigs. In this study, we established a reverse transcription polymerase chain reaction (RT-PCR) method to detect GETV from suspected virus-infected samples. The reaction conditions were optimized and validated by using RNA extracted from GETV propagated in cell culture. A GETV-specific GED4 primer set was designed and used to amplify a 177 bp DNA fragment from a highly conserved region of the E1 glycoprotein gene in the GETV genome. RT-PCR performed with this primer set revealed high sensitivity and specificity. In the sensitivity test, the GED4 primer set detected GETV RNA at the level of $10^{2.0}\;TCID_{50}/mL$. In the specificity test, the GED4 primer set amplified only a single band of PCR product on the GETV RNA template, without non-specific amplification, and exhibited no cross-reactivity with other viral RNAs. These results suggest that this newly established RT-PCR method is useful for accurate identification of GETV infection in animals.

• 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.

• Clinical and Experimental Pediatrics
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• v.64 no.12
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• pp.652-660
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• 2021

Background: Viral load and shedding duration are highly associated with the transmission of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection. However, limited studies have reported on viral load or shedding in children and adolescents infected with sudden acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Purpose: This study aimed to investigate the natural course of viral load in asymptomatic or mild pediatric cases. Methods: Thirty-one children (<18 years) with confirmed SARS-CoV-2 infection were hospitalized and enrolled in this study. Viral loads were evaluated in nasopharyngeal swab samples using real-time reverse transcription polymerase chain reaction (E, RdRp, N genes). cycle threshold (Ct) values were measured when patients met the clinical criteria to be released from quarantine. Results: The mean age of the patients was 9.8 years, 18 (58%) had mild disease, and 13 (42%) were asymptomatic. Most children were infected by adult family members, most commonly by their mothers. The most common symptoms were fever and sputum (26%), followed by cough and runny nose. Nine patients (29%) had a high or intermediate viral load (Ct value≤30) when they had no clinical symptoms. Viral load showed no difference between symptomatic and asymptomatic patients. Viral rebounds were found in 15 cases (48%), which contributed to prolonged viral detection. The mean duration of viral detection was 25.6 days. Viral loads were significantly lower in patients with viral rebounds than in those with no rebound (E, P=0.003; RdRp, P=0.01; N, P=0.02). Conclusion: Our study showed that many pediatric patients with coronavirus disease 2019 (COVID-19) experienced viral rebound and showed viral detection for more than 3 weeks. Further studies are needed to investigate the relationship between viral rebound and infectiousness in COVID-19.

• BMB Reports
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• v.40 no.5
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• pp.662-669
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• 2007

Although the function of cellular prion protein (PrP$^C$) and the pathogenesis of prion diseases have been widely described, the mechanisms are not fully clarified. In this study, increases of the portion of non-glycosylated prion protein deposited in the hamster brains infected with scrapie strain 263K were described. To elucidate the pathological role of glycosylation profile of PrP, wild type human PrP (HuPrP) and two genetic engineering generated non-glycosylated PrP mutants (N181Q/N197Q and T183A/T199A) were transiently expressed in human astrocytoma cell line SF126. The results revealed that expressions of non-glycosylated PrP induced significantly more apoptosis cells than that of wild type PrP. It illustrated that Bcl-2 proteins might be involved in the apoptosis pathway of non-glycosylated PrPs. Our data highlights that removal of glycosylation of prion protein provokes cells apoptosis.

• The Journal of Korean Society of Virology
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• v.28 no.4
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• pp.327-335
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• 1998

Hantaan (HTN) and Seoul (SEO) viruses, murid rodent-borne hantaviruses, are known to causes hemorrhagic fever with renal syndrome (HFRS) in Korea. To determine the genomic diversity and molecular phylogeny of HTN and SEO viruses found in Korea, we amplified for part of M and S genomic segments of hantaviruses from sera of HFRS patients and lung tissues of hantavirus seropositive striped-field mice. Both M and S segment of 16 HTN and 2 SEO viruses were amplified by nested reverse transcription-polymerase chain reaction. Based on 324 nucleotides in the M genomic segment, the HTN and SEO strains showed $93.8{\sim}100%$ and $99.1{\sim}99.4%$ homologies, respectively. Similarly, based on 230 nucleotides in the S genomic segment, HTN and SEO strains showed $90.9{\sim}100%$ and 100% homologies, respectively. Phylogenetic analysis of M and S segments indicated that HTN strains could be divided into at least two main groups in M and S trees and the sequence differences detected among the Sand M genomic segments of HTN viruses are consistent with reassortment having taken place between HTN virus strains.