• Journal of Environmental Health Sciences
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• v.26 no.4
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• pp.45-48
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• 2000

Reverse osmosis filtration(RO) system and ultrafiltration(UF) system are principally use for domestic home drinking water treatment systems. The object of this study is to make a comparison between two systems in terms of theirs abilities to remove RNA coilphage QB as an indicator of pathogenic enteroviruses. The virus removal ratio of RO system was 99.999%, which was higher than EPA virus treatment guideline(99.99%). In the course of filtration, removal ratios of sediment filter, pre-carbon filter, reverse osmosis membrane and post-carbon filter were 75.000%, 93.208%, 99.997% and 99.999%, repectively. In case of UF system, virus removal ratio was 99.708%. Removal ratios of sediment filter, pre-carbon filter, post-carbon filter and ultrafiltration membration membrane were 71.038%, 91.530%, 98.283% and 99.708%, respecively, in UF steps. Therefore, RO system is more effective than UF system in virus removal.

• Journal of Microbiology and Biotechnology
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• v.14 no.1
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• pp.140-147
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• 2004

Urokinase is an enzyme with fibrinolytic activity (plasminogen activator) isolated from fresh urine of healthy men. Viral safety is an important prerequisite for clinical preparation of the protein from urine. In order to increase the viral safety of a high purity urokinase in regard to non-enveloped viruses, a virus removal process using a novel polyvinylidene fluoride membrane filter (Viresolve NFP) has been optimized. Urokinase was able to pass through the filter with recoveries of 95% in the production scale process. No substantial changes were observed in physical and biochemical characteristics of the filtered urokinase in comparison with those of the enzyme before filtration. A 47-mm disk membrane filter was used to simulate the process performance of the production scale cartridges and tested if it could remove several experimental model viruses for human pathogenic viruses, including porcine parvovirus (PPV), human hepatitis A virus (HAV), murine encephalomyocarditis virus (EMCV), bovine viral diarrhoea virus (BVDV), and bovine herpes virus (BHV). Non-enveloped viruses (PPV, HAV, and EMCV) as well as enveloped viruses (BVDV and BHV) were completely removed during filtration. The log reduction factors achieved were $\geq$4.86 for PPV, $\geq$4.60 for HAV, $\geq$6.87 for EMCV, $\geq$4.60 for BVDV, and $\geq$5.44 for BHV. These results indicate that the virus filtration process successfully improved the viral safety of the final products.

• Journal of Plant Biotechnology
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• v.49 no.3
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• pp.222-229
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• 2022

Apples are the most grown fruit crops in the fruit industry of Korea. However, virus or viroid infection such as apple mosaic virus (ApMV), apple stem grooving capillovirus (ASGV), apple stem pitting virus (ASPV), apple chlorotic leaf spot virus (ACLSV), apple scar skin viroid (ASSVd) causes fruit yield reduction and poor fruit quality. Therefore, in this study, we examined to established an efficient virus-free system to eliminate the most infected ASGV virus in domestic apple orchard. We investigated that the shoot growth rate and the virus removal rate in ASGV infected potted apples that were treated with heat treatment in a growth chamber (constant temperature/humidity device) maintained at 36℃, 38℃ and 40℃ for 4 weeks. Here we found that the shoot growth rate was the highest in the heat treatment group (36℃) and the virus was removed in the middle and top of the shoot but not in the bottom. The virus was did not removed in the 38℃ and 40℃ heat treatment group in all section of shoots, and the heat treatment group (40℃) died after 4 weeks of heat treatment without growth of shoots. We performed in vivo shoot-tip grafting using the shoot-tip of potted apple heat-treated at 36 ℃, and we also investigated the viability and virus removal rate, which showed 94% viability and 20% virus removal rate. Collectively, our results suggest that it would be possible to produce the virus-free apple plants through heat treatment and shoot-tip grafting.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.615-618
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• 2000

The purpose of present study was to examine the efficacy of PAB (para-amino benzamidine) affinity column chromatography, pasteurization ($60^{\circ}C$ heat treatment for 10 h), and lyophilization steps, employed in the manufacture of urokinase from human urine, in the removal and/or inactivation of urine-born viruses. Bovine herpes virus (BHV) and Murine encephalomyocarditis virus (EMCV) were selected for this study. Samples from the relevant stages of the production process were spiked with the viruses and the amount of virus in each fraction was quantified by 50% tissue culture infectious dose ($TCID_{50}$). BHV and EMCV were effectively partitioned from urokinase during PAB chromatography with the log reduction factors of 6.71 and 5.27, respectively. Pasteurization was a robust and effective step in inactivating BHV and EMCV, of which titers were reduced from initial titers of $8.65\;log_{10}\;TCID_{50}$ and $7.81\;log_{10}\;TCID_{50}$, respectively, to undetectable levels within 1 hour of treatment. The log reduction factors achieved during lyophilization were 2.06 for BHV and 4.54 for EMCV. These results indicate that the production process for urokinase has sufficient virus reducing capacity to achieve a high margin of virus safety.

• Journal of Microbiology and Biotechnology
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• v.18 no.7
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• pp.1317-1325
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• 2008

Viral safety is an important prerequisite for clinical preparations of plasma-derived pharmaceuticals. One potential way to increase the safety of therapeutic biological products is the use of a virus-retentive filter. In order to increase the viral safety of human antihemophilic factor IX, particularly in regard to non-enveloped viruses, a virus removal process using a polyvinylidene fluoride membrane filter (Viresolve NFP) has been optimized. The most critical factor affecting the filtration efficiency was operating pH and the optimum pH was 6 or 7. Flow rate increased with increasing operating pressure and temperature. Recovery yield in the optimized production-scale process was 96%. No substantial changes were observed in the physical and biochemical characteristics of the filtered factor IX in comparison with those before filtration. A 47-mm disk membrane filter was used to simulate the process performance of the production-scale cartridges and to test if it could remove several experimental model viruses for human pathogenic viruses, including human hepatitis A virus (HAV), porcine parvovirus (PPV), murine encephalomyocarditis virus (EMCV), human immunodeficiency virus type 1 (HIV), bovine viral diarrhea virus (BVDV), and bovine herpes virus (BHV). Non-enveloped viruses (HAV, PPV, and EMCV) as well as enveloped viruses (HIV, BVDV, and BHV) were completely removed during filtration. The log reduction factors achieved were $\geq$6.12 for HAV, $\geq$4.28 for PPV, $\geq$5.33 for EMCV, $\geq$5.51 for HIV, $\geq$5.17 for BVDV, and $\geq$5.75 for BHV. These results indicate that the virus filtration process successfully improved the viral safety of factor IX.

• Biotechnology and Bioprocess Engineering:BBE
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• v.7 no.6
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• pp.340-346
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• 2002

The purpose of the present study was to examine the efficacy and mechanism of the PAB (para-amino benzamidine) affinity column chromatography, Viresolve NFP virus filtration, pasteurization (60$\^{C}$ heat treatment for 10 h), and lyophilization steps employed in the manufacture of urokinase from human urine as regards the removal and/or inactivation of the hepatitis A virus (HAV). Samples from the relevant stages of the production process were spiked with HAV and subjected to scale-down processes mimicking the manufacture of urokinase Samples were collected at each step, immediately titrated using a 50% tissue culture infectious dose (TCID$\_$50/), and the virus reduction factors evaluated. PAB chromatography was found to be an effective step for removing HAV with a log reduction factor of 3.24. HAV infectivity was rarely detected in the urokinase fraction, while most of the HAV infectivity was recovered in the unbound and wash fractions. HAV was completely removed during the Viresolve NFP filtration with a log reduction factor of $\geq$ 4.60. Pasteurization was also found to be an effective step in inactivating HAV where the titers were reduced from an initial titer of 7.18 log$\_$10/ TCID$\_$50/ to undetectable levels within 10 h of treatment. The log reduction factor achieved during pasteurization was $\geq$ 4.76. Lyophilization revealed the lowest efficacy for inactivating HAV with a log reduction factor of 1.48. The cumulative log reduction factor was $\geq$ 14.08. Accordingly, these results indicate that the production process for urokinase exhibited a sufficient HAV reducing capacity to achieve a high margin of virus safety.

• Journal of Microbiology and Biotechnology
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• v.31 no.8
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• pp.1088-1097
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• 2021

Grouper nervous necrosis virus (GNNV) infection causes mass grouper mortality, leading to substantial economic loss in Taiwan. Traditional methods of controlling GNNV infections involve the challenge of controlling disinfectant doses; low doses are ineffective, whereas high doses may cause environmental damage. Identifying potential methods to safely control GNNV infection to prevent viral outbreaks is essential. We engineered a virus-binding bacterium expressing a myxovirus resistance (Mx) protein on its surface for GNNV removal from phosphate-buffered saline (PBS), thus increasing the survival of grouper fin (GF-1) cells. We fused the grouper Mx protein (which recognizes and binds to the coat protein of GNNV) to the C-terminus of outer membrane lipoprotein A (lpp-Mx) and to the N-terminus of a bacterial autotransporter adhesin (Mx-AIDA); these constructs were expressed on the surfaces of Escherichia coli BL21 (BL21/lpp-Mx and BL21/Mx-AIDA). We examined bacterial surface expression capacity and GNNV binding activity through enzyme-linked immunosorbent assay; we also evaluated the GNNV removal efficacy of the bacteria and viral cytotoxicity after bacterial adsorption treatment. Although both constructs were successfully expressed, only BL21/lpp-Mx exhibited GNNV binding activity; BL21/lpp-Mx cells removed GNNV and protected GF-1 cells from GNNV infection more efficiently. Moreover, salinity affected the GNNV removal efficacy of BL21/lpp-Mx. Thus, our GNNV-binding bacterium is an efficient microparticle for removing GNNV from 10‰ brackish water and for preventing GNNV infection in groupers.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.6
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• pp.426-431
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• 2011

The objective of this study was to investigate the virus removal from artificial groundwater using Mg-Fe layered double hydroxide (LDH). Batch experiments were conducted under various experimental conditions to examine bacteriophage T7 removal with Mg-Fe LDH. Results showed that the removal of T7 by Mg-Fe LDH was a fast process, reaching equilibrium within 2~3 hrs. Mg-Fe LDH had the virus removal capacity of $1.57{\times}10^8pfu/g$ with a removal percent of 96%. Results also showed that the effect of solution pH on T7 removal was minimal between pH 6.2 and 9.1. The influence of anions ($SO_4^{2-}$, $CO_3^{2-}$, $HPO_4^{2-}$) on T7 removal was significant due to their competition with bacteriophage at the sorption sites on LDH, while the effect of $NO_3^-$ was negligible. This study demonstrated that Mg-Fe LDH could be applied as adsorbents for virus removal in water treatment.

• Biotechnology and Bioprocess Engineering:BBE
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• v.7 no.1
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• pp.6-9
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• 2002

In this work we have investigated the feasibility of virus clearance by flocculation and tangential flow microfiltration. Chinese hamster ovary cell feed streams were spiked with minute virus of mice and then flocculated using cationic polyelectrolytes prior to tangential flow microfiltration. Our results indicate that flocculation prior to microfiltration leads to more than 100 fold clearance of minute virus of mice particles in the permeate. Today, validation of virus clearance is a major concern in the manufacture of biopharmaceutical products. Frequently new unit operations are added simply to validate virus clearance thus increasing the manufacturing cost. The results obtained here suggest that virus clearance can be obtained during tangential flow microfiltration. Since tangential flow microfiltration is frequently used for bioreactor harvesting this could be a low cost method to validate virus clearance.

• Proceedings of the Membrane Society of Korea Conference
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• 1996.10a
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• pp.18-21
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• 1996

Virus and DNA removal in bio-drug manufacturing processes has received a great deal of attention in recent years. Removing of a virus using a membrane process is a promising method, because inactivated virus can be removed from the bio-drug and the process can be used as an additional and security inactivation after the method of general heat-inactivation of the virus in the bio-drug. The FDA and the biopharmaceutical industry have recently announced strict guidelines for impurities of virus and DNA contamination. The regulatory guidelines on residual amounts of DNA in mammalian cell culture products require DNA contamination of less than 100 pg/dose. Therefore, permeation and rejection of DNA through the porous membranes have become important in the application of DNA removal in bio-drug manufacturing using membrane technology. In this study, the permeation of DNA and chromatin through regenerated cellulose hollow fibers that have a mean pore diameter of 15 nm was investigated.