• Journal of Microbiology
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• v.38 no.4
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• pp.255-259
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• 2000

For rapid and sensitive measurement of antiviral activities, application of a recombinant virus containing firefly luciferase gene was attempted. Recombinant human cytomegalovirus (HCMV) containing luciferase gene driven by HCMV late gene pp28 promoter (HCMV/pp28-luc) was used to test the antiviral activities of three known compounds and the result was compared with results from the conventional plaque assay for measuring the production of infectious viruses. When human fibroblast cells were infected with HCMV/pp28-luc, luciferase activity was observed at 2 days after infection and reached maximum at 6 days after infection, whereas the production of infectious virus was maximal at 4 days after infection. The antiviral activities of ganciclovir, acyclovir, and papaverine were measured in HFF cells infected with HCMV/PP28-luc and the luciferase activity was compared with the infectious virus titers. Luciferase activity decreased as the concentration of ganciclovir or papaverine increased, while there was a slight decrease in luciferase activity with acyclovir. The level of the decrease in Luciferase activity was comparable to the level of decrease in the production of infectious virus. Therefore, the antiviral assay using recombinant virus HCMV/pp28-luc resulted in sensitivity similar to the conventional plaque assay with a significant reduction in assay time.

• Natural Product Sciences
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• v.5 no.2
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• pp.107-111
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• 1999

To investigate less toxic antiviral agents from Basidiomycetes, EA, the water soluble substance, was isolated from the carpophores of Elfvingia applanata (pers.) Karst. Anti-varicella zoster virus (Oka strain; anti-VZV/Oka) activity of EA was examined in MRC-5 cells by plaque reduction assay in vitro. And the combined antiviral effects of EA with nucleoside anti-VZV agents, acyclovir and vidarabine, were examined on the multiplication of VZV/Oka. EA exhibited a concentration-dependent reduction in the plaque formation of VZV/Oka with a 50% effective concentration $(EC_{50})$ of $464.14\;{\mu}g/ml$. The results of combination assay were evaluated by the combination index (CI) that was calculated by the multiple drug effect analysis. The combination of EA with acyclovir showed more potent synergism with CI values of $0.18{\sim}0.62$ for $50{\sim}90%$ effective levels than that of EA with vidarabine with CI values of $0.67{\sim}1.04$.

• Korean Journal of Pharmacognosy
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• v.30 no.1
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• pp.25-33
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• 1999

In order to find less toxic antiviral agents from basidiomycetes, EA, the water soluble substance, was prepared from the carpophores of Elfvingia applanata (Pers.) Karst. EA was examined for antiviral activity against five strains of pathogenic viruses such as encephalomyocarditis virus (EMCV), vesicular stomatitis virus (VSV) Indiana and New Jersey strains, influenza A virus (Flu A), and varicella zoster virus (VZV) in vitro. Antiviral activity was evaluated by plaque reduction assay. Among five strains of viruses tested, EA exhibited the most potent antiviral activity against VSV Indiana strain with 50% effective concentration $(EC_{50})$ of 0.104 mg/ml in Vero cells, and its selectivity index (SI) was 36.5. EA was also examined for the virucidal activity, antiviral activity in preincubation on VSV Indiana strain in order to examine possible mode of antiviral activity. Preincubation of Vero cells with EA did not confer protection against VSV, however, prolonged exposure of cells to EA inhibited the replication of virus dose-dependently. In virucidal activity, the titer of infectious virus did not decrease significantly.

• The Korean Journal of Mycology
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• v.27 no.3 s.90
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• pp.237-241
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• 1999

To search for less toxic antiviral agents from Basidiomycetes, the water soluble components (=EA), were isolated from the carpophores of Elfvingia applanata (Pers.) Karst. Anti-varicella zoster virus (Oka strain; anti-VZV/Oka) activity of EA was examined in MRC-5 cells by plaque reduction assay in vitro. And the combined antiviral effects of EA with interferon (IFN) alpha or IFN gamma were examined on the multiplication of VZV/Oka. EA exhibited a dose-dependent reduction in the plaque formation of VZV/Oka with 50% effective concentration $(EC_{50})$ of $464.14\;{\mu}g/ml$. The results of the combination assay were evaluated by the combination index (CI) that was calculated by the multiple drug effect analysis. The combination of EA with IFN alpha showed partially synergistic or additive effects with CI values of $0.83{\sim}1.09$ for 50%, 70%, 90% effective levels, and those with IFN gamma showed antagonism with CI values of $1.20{\sim}1.24$.

• Korean Journal of Veterinary Service
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• v.20 no.2
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• pp.195-203
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• 1997

Fecal samples were collected from 47 calves with diarrhea and 12 clinically normal co-h-abitants, and tested for virus using MDBK cell cultures. Three cytopathic viruses were isolated from 8 fecal samples obtained from diarrheic calves. The isolated viruses were neutralized by bovine coronavirus hyperimmune serum In plaque reduction assay and were detected in the cytoplasm of MDBK cell by bovine coronavirus hyperimmune serum using immunofluorescence staining. The viruses agglutinated mouse erythrocytes only among the various animal erythrocytes tested and new isolates were identified as bovine coronavirus.

• Korean Journal of Microbiology
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• v.38 no.4
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• pp.255-255
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• 2002

For rapid and sensitive measurement of antiviral activities, application of a recombinant virus containing firefly luciferase gene was attempted. Recombinant human cytomegalovirus (HCMV) containing luciferase gene driven by HCMV late gene pp28 promoter (HCMV/pp28-luc) was used to test the antiviral activities of three known compounds and the result was compared with results from the conventional plaque assay for measuring the production of infectious viruses. When human fibroblast cells were infected with HCMV/pp28-luc, luciferase activity was observed at 2 days after infection and reached maximum at 6 days after infection, whereas the production of infectious virus was maximal at 4 days after infection. The antiviral activities of ganciclovir, acyclovir, and papaverine were measured in HFF cells infected with HCMV/PP28-luc and the luciferase activity was compared with the infectious virus titers. Luciferase activity decreased as the concentration of ganciclovir or papaverine increased, while there was a slight decrease in luciferase activity with acyclovir. The level of the decrease in Luciferase activity was comparable to the level of decrease in the production of infectious virus. Therefore, the antiviral assay using recombinant virus HCMV/pp28-luc resulted in sensitivity similar to the conventional plaque assay with a significant reduction in assay time.

• Biomedical Science Letters
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• v.8 no.4
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• pp.269-273
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• 2002

Dengue fever (DF) is an acute febrile illness caused by dengue viruses in the family Flaviviridae, genus Flavivirus. DF has so far posed any problem in Korea, however it has been recently believed to be associated with oversea's traveler infected with dengue virus. Antibody titers of sera from DF patients against dengue virus were measured by indirect immunofluorescence assay (IFA) and plaque reduction neutralization test (PRNT), including the haematologic test. Three of patients with DF showed highly fluorescent and neutralizing antibody titers by IFA and PRNT assay. Two of them showed higher, remarkably. Meanwhile, one of them was tested and resulted in severe tirombocytopenia, elevated serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT) activities as well as mild leucopenia, increased monocytes and basophils and depressed lymphocytes in haematological differential count.

• Archives of Pharmacal Research
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• v.15 no.3
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• pp.242-245
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• 1992

Two triterpenes 1 and 2 with antiviral activity against Herpes simplex virus type 1 in vitro were isolated from Prunella vulgaris. Each compound caused a significant reduction in viral cytopathic effect when vero cells were exposed to them for 72 hours after viral challenge. They were identified as betulinic acid (1) and $2\alpha, 3\alpha$-dihydroxyurs-12-en-28-oic acid(2) on the basis of their spectroscopic properties. The antiviral activity of them was estimated as $EC_{50}=30\;\mu$g/ml(1) and $8\;\mu$g/ml(2), respectively by plaque reduction assay.

• Journal of Microbiology and Biotechnology
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• v.14 no.1
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• pp.121-127
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• 2004

Amphotericin B (AmB), an amphipathic polyene macrolide, is an antifungal drug produced by Streptomyces nodosus. Recently, AmB has been shown to exert antiviral activity against rubella virus and human immunodeficiency virus by different mechanisms. In this study, we evaluated the antiviral effect of AmB against Japanese encephalitis virus (JEV) and investigated which step of the viral life cycle was inhibited by AmB to understand the mechanism of antiviral action of AmB. AmB reduced both plaque size and number in the infected cells in a dose-dependent manner. In addition, a 200-fold reduction of infectious virus titer was observed by treatment of infected cells with $5\mug/ml$ of AmB. AmB acted at the post virus-infection step, but not during adsorption of virus to host cells. Western blot analysis revealed that the accumulated level of JEV envelope protein dramatically decreased in the infected cells by treatment with $5-10\mug/ml$ of AmB. Our results indicate that AmB inhibits the replication of JEV at the postinfection step by interfering with viral replication and/or by inhibiting the synthesis of viral proteins.

• Journal of Microbiology and Biotechnology
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• v.14 no.4
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• pp.745-750
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• 2004

The objective of this collaborative study was to establish a Korean standard of Japanese encephalitis (JE) vaccine (mouse brain-derived, formalin-inactivated) for potency assay. A candidate preparation proposed as a Korean standard was provided by GreenCross Vaccine, and six laboratories, including one national control laboratory and five manufacturers of JE vaccine, participated in the study. The potency of the candidate preparation and a reference standard obtained from Japan was estimated by mouse immunogenicity assay using the in vitro plaque reduction neutralization test (PRNT). The results of 72 assays conducted by the 6 laboratories showed that the overall mean potency estimate of the candidate preparation was 2.455 log median plaque reduction neutralization antibody titer per 0.5-ml dosage administered twice in mice at 7-day intervals, and that the mean potency ratio of the candidate preparation relative to the reference standard was 1.074. The potency estimates were quite variable among laboratories irrespective of the preparation. The variability of assays assessed by Z scores and coefficient of variation (CV) were in general within the level of acceptance (Z scores within $\pm3$ and $CV\;\leq\;15%$). Therefore, we concluded that the candidate preparation would be suitable as a national standard for testing the potency of JE vaccine (inactivated).