• 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.

• BMB Reports
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• v.42 no.7
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• pp.444-449
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• 2009

Different neurodegenerative disorders like prion disease, is caused by protein misfolding conformers. Reverse-transfected cytosolic prion protein (PrP) and PrP expressed in the cytosol have been shown to be neurotoxic. To investigate the possible mechanism of neurotoxicity due to accumulation of PrP in cytosol, a PrP mutant lacking the signal and GPI (CytoPrP) was introduced into the SH-SY5Y cell. MTT and trypan blue assays indicated that the viability of cells expressing CytoPrP was remarkably reduced after treatment of MG-132. Obvious apoptosis phenomena were detected in the cells accumulated with CytoPrP, including loss of mitochondrial transmembrane potential, increase of caspase-3 activity, more annexin V/PI-double positive-stained cells and reduced Bcl-2 level. Moreover, DNA fragmentation and TUNEL assays also revealed clear evidences of late apoptosis in the cells accumulated CytoPrP. These data suggest that the accumulation of CytoPrP in cytoplasm may trigger cell apoptosis, in which mitochondrial relative apoptosis pathway seems to play critical role.

• Molecules and Cells
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• v.27 no.2
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• pp.143-148
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• 2009

EBV-transformed lymphoblastoid cell lines (LCLs) are used as a resource for human genetic, immunological, and pharmacogenomic studies. We investigated the biological activity of 20 LCL strains during continuous long-term subculture up to a passage number of 160. Out of 20 LCL strains, 17 proliferated up to a passage number of 160, at which point LCLs are generally considered as "immortalized". The other three LCL strains lost the ability to proliferate at an average passage number of 41, during which these LCLs may have undergone cellular crisis. These non-immortal LCL strains exhibited no telomerase activity, decreased EBV gene expression, and a lower copy number of the EBV genome and mitochondrial DNA when compared with immortal LCLs. Thus, this study suggests that sustained EBV viral activity as well as telomerase activity may be required for complete LCL immortalization.

• The Journal of the Korean Society for Microbiology
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• v.16 no.1
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• pp.57-64
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• 1981

The clinical need for agents to modify immune response in the treatment of viral infection has lead to an increased interest in cellular and biochemical mechanisms regulating the immune response and to the development of a variety of biological and chemical substance with immunomodulatory activity. Inosiplex has shown antiviral activity in tissue culture, animal models and huamn studies through augmentation of immune response. However, the effect of inosiplex on immune response in animal has not been extensively analyzed, and the effect of inosiplex on immune response has been paradoxical depending on the time of administration of inosiplex in relation to that of antigen. Therefore, this study was undertaken to assess the effect of inosiplex on the immune response to sheep red blood cells(SRBC) in normal and viral infected mice. Inosiplex increased cellular immune response and plaque forming lymphocyte response to SRBC, decreased the recovery of S. typhimurium from infected mice spleen, and restored the depressed cellular immune response by measle and newcastle disease virus infections. All of the above results were observed only when inosiplex was given after immunization but did not when given before immunization. These results indicate that inosiplex stimulate the efferent are of immune response and may even block the afferent are, and suggest that inosiplex is a very promising drug in therapy of many viral infections.

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.237.3-238
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• 2003

Carbonucleosides has extensively been studied as a promising anti-viral agents having chemical and metabolical stability. As yet there are no rules relating the structures of carbocyclic nucleosides to their therapeutic activity. although trends among certain kinds of structure have been tentatively put forward. In our research program for discovery of anti-viral drugs, the novel cyclobutyl nucleosides can be expected to be potential antiviral drugs as analogues of cyclobut-A, anti-HBV agent. (omitted)

• The Journal of Dong Guk Oriental Medicine
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• v.1
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• pp.209-236
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• 1992

The microculture XTT antiviral assay method is used to quantitate HIV-1 induced cytopathic effects as modulated by test substances. This relatively simple assay facilitated the safe and rapid determination of in vitro antiviral activity of selected chemicals as well as direct cytotoxicity. This experiment also confirmed that this system measures infection and subsequent viral replication in target cells and XTT formazan formations correlated with the accumulation of extracellular virions, as measured by quantitative HIV-1 induced syncytium foramtion. The present results with Glycyrrhizin using this in vitro culture system demonstrated that effective dose, EC50(the concentration at which increases XTT formazan production in infected cultures to 50% of that in untreated, uninfected controls) was 250ml. As comparison, AZT was included in this experiment and demonstrated that EC50 AZT of was 0.05g/ml, approximately 5,000 times more potent than Glycyrrhizin based on EC50 ratio's alone. However, this potency is limited by severe cytotoxicity of AZT, while Glycyrrhizin is approximately 16 times less toxic(IC50 of Glycyrrhizin 800 and AZT 51 g/ml). While AZT's anti-HIV-1 viral activity is mediated by inhibition of reverse transcriptase of the virus, Glycyrrhizin faild to demonstrate any inhibitory activity against reverse transcriptase. Further study is necessary in order to understand the precise mechanisms of Glycyrrhizin action against HIV-1 viruses. Althouth Glycyrrhizin is less effective antiviral agent than AZT, much less toxicity of Glycyrrhizin is desirable in terms of chronic treatment. Combination treatment of AZT and Glycyrrhizin may be therapeutically beneficial. Clinical effectiveness of two drug combination therapy for AIDS patient is unknown at this time. However, this experimental investigation presents the scientific rational basis for such therapeutic approach.

• Food Science of Animal Resources
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• v.28 no.4
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• pp.512-516
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• 2008

To search for anit-H5N1 influenza virus agent, the anti-viral activity of methanol and aqueous extracts from thirty medicinal plants were examined in this study. The plant material (30 g) was extracted with methanol (300 mL) for 24 hr at room temperature. Methanol extracts were filtered and evaporated, then freeze-dried. Aqueous extracts were prepared with dried plant material (30 g) and hot distilled water (300 mL). After 3 hr, the aqueous extracts were filtered and evaporated, then lyophilized. Extracts prepared from different plants were tested the antiviral activity against influenza viruses [A/vietnam/1194/04 (H5N1)-NIBRG-14] using the hemagglutination (HA) assay. Among the test plants, Asarum sieboldii was found to be a potent inhibitor of H5N1 influenza virus in MDCK cell culture. Virus titers were 7 log, whereas with methanol extract of Asarum sieboldii for 48 hr titers were 3 log, indicating that methanol extract of Asarum sieboldii inhibited the H5N1 influenza viruses from the infected cells.

• Biomolecules & Therapeutics
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• v.26 no.3
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• pp.242-254
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• 2018

Defensins are antimicrobial peptides that participate in the innate immunity of hosts. Humans constitutively and/or inducibly express ${\alpha}$- and ${\beta}$-defensins, which are known for their antiviral and antibacterial activities. This review describes the application of human defensins. We discuss the extant experimental results, limited though they are, to consider the potential applicability of human defensins as antiviral agents. Given their antiviral effects, we propose that basic research be conducted on human defensins that focuses on RNA viruses, such as human immunodeficiency virus (HIV), influenza A virus (IAV), respiratory syncytial virus (RSV), and dengue virus (DENV), which are considered serious human pathogens but have posed huge challenges for vaccine development for different reasons. Concerning the prophylactic and therapeutic applications of defensins, we then discuss the applicability of human defensins as antivirals that has been demonstrated in reports using animal models. Finally, we discuss the potential adjuvant-like activity of human defensins and propose an exploration of the 'defensin vaccine' concept to prime the body with a controlled supply of human defensins. In sum, we suggest a conceptual framework to achieve the practical application of human defensins to combat viral infections.

• Korean Journal of Veterinary Service
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• v.36 no.2
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• pp.87-93
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• 2013

This study was conducted to investigate the antimicrobial, antivirus properties of Saururus chinensis extracts. The n-hexane extracts from Saururus chinensis showed the active antimicrobial activity against gram-positive bacteria. Minimum inhibitory concentration (MIC) of Saururus chiensis n-hexane extracts was 1.25 mg/ml against B. subtilis and 2.5 mg/ml against S. aureus. The cytotoxicity effects on MDBK (Madin-Darby bovine kidney) cell were observed at the various n-hexane extract concentrations. In $TCID_{50}$ assay, 0.6 mg/ml of n-hexane extracts decreased BVD (bovine viral diarrhea) virus by 1.4 log, whereas other extracts did not show antiviral activity. In this study, The results suggested that n-hexane extracts and fractions of Saururus chinensis can be a candidate materal of feed additive to chemical antibiotics and antivirus substances.

• BMB Reports
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• v.56 no.11
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• pp.606-611
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• 2023

The main protease (Mpro) of SARS-CoV-2 cleaves 11 sites of viral polypeptide chains and generates essential non-structural proteins for viral replication. Mpro is an important drug target against COVID-19. In this study, we developed a real-time fluorometric turn-on assay system to evaluate Mpro proteolytic activity for a substrate peptide between NSP4 and NSP5. It produced reproducible and reliable results suitable for HTS inhibitor assays. Thus far, most inhibitors against Mpro target the active site for substrate binding. Mpro exists as a dimer, which is essential for its activity. We investigated the potential of the Mpro dimer interface to act as a drug target. The dimer interface is formed of domain II and domain III of each protomer, in which N-terminal ten amino acids of the domain I are bound in the middle as a sandwich. The N-terminal part provides approximately 39% of the dimer interface between two protomers. In the real-time fluorometric turn-on assay system, peptides of the N-terminal ten amino acids, N10, can inhibit the Mpro activity. The dimer interface could be a prospective drug target against Mpro. The N-terminal sequence can help develop a potential inhibitor.