• The Journal of the Korean Society for Microbiology
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• v.22 no.1
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• pp.1-8
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• 1987

Hantaan virus(HV) 76-118 strain was inoculated into suckling ICR mice by intra-nasal route with an inoculum of $10LD_{50}$. Mortality was 65% at the 3rd week after inoculation, but declined to 35% at the 4th week. Infectivity was determined by the measuring immuno-fluorescent antibody in sera. The peak of infectivity was 80% at the 4'th week after inoculation. Viremia was reached peak level of $1.7{\times}10^4\;PFU/ml$ by day 10. Immunofluorescent antibody and neutralizing antibody appeared by 2 weeks and 15-17 days respectively, but achieved similar titer by 35 days. By using a monoclonal antibody to HV 76-118, viral antigens were initially detected in inguinal and axillary lymph node by 2 days. Viral antigens in bone marrow and lung were delayed much more than in those of lymph node. These were similar with those of intra-peritoneal and intra-muscular route. Immune complex against IgG, IgM and C3 appeared by 16 days, 14 days, and 18 days respectively. The pattern of immunofluorescence in the basement membrane of glomeruli was diffuse membranous. Spotted pattern was also observed in the tissue stained with anti-mouse C3 antibody. By 20 days, control tissue was also shown immune complex in the glomeruli.

• 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.

• Parasites, Hosts and Diseases
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• v.42 no.2
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• pp.85-89
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• 2004

Cryptosporidium parvum oocysts were isolated from a child suffering from acute gastroenteritis and successfully passaged in a calf and mice (designated hereafter SNU-H1) in the Republic of Korea; its molecular genotype has been analyzed. The GAG microsatellite region was amplified by a polymerase chain reaction (PCR), with a 238 base pair product, which is commonly displayed in C. parvum. The isolate was shown to be a mixture of the genotypes 1 (anthroponotic) and 2 (zoonotic). To study its infectivity in animals, 2 calves and 3 strains of mice were infected with the SNU-H1; in these animals, the propagation of both genotypes was successful. In immunosup-pressed (ImSP) BALB/c and C57BU6 mice the number of oocysts decreased after day 10 post-infection (PI); but in ImSP ICR mice, they remained constant until day 27 PI. The results show that both the C. parvum genotypes 1 and 2 can be propagated in calves and ImSP mice.

• KSBB Journal
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• v.14 no.4
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• pp.396-402
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• 1999

To verify enchancing effect of polycation of polycation on the retroviral infecivity, we directly measured the binding affinity of retroviruses to the target cells in the presence or in the absence of polybrene with R18 fluorescence assay and examined the effect of the polymers on the relationship between the host cell and the retroviral infecity. There was no difference in the effect of the types of charge of the polymer on the binding affinity. However, polycations, in general, show effect on the retrovirus infecity. This results suggest that the enhancing effect of polybrene and other polycations on the infecity is not due to the binding step but due to the post-binding steps, especially the internalization step. With the result of the internalization of FITC-labeled poly-L-lysine into the host cells, it is suggested that the uptake of polycations into the host cells would play a crucial role in the intermalization of retroviruses.

• Korean Journal of Veterinary Research
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• v.25 no.2
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• pp.155-165
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• 1985

Effects of binary ethylenimine (BEI) treatment on the inactivation of infectivity and hemagglutinin of Newcastle disease virus (NDV) were studied in comparison with those of formalin treatment. Immune responses of chickens vaccinated with BEI-inactivated NDV vaccines were also investigated. The results were summarized as followings; 1. Complete loss of infectivity of NDV (Bl) was observed at 3, 7, and 24 hours after the treatment at $37^{\circ}C$ with BEI concentrations of 0.01M, 0.005M and 0.001M, respectively. 2. The hemagglutinin activity of NDV (Bl) remained constant when treated with 0.01M BEI at $37^{\circ}C$. However, it gradually decreased when treated with 0.1% or 0.2% formalin at $37^{\circ}C$. 3. When 4-week-old chickens were vaccinated with NDV vaccines prepared from Bl or Miyadera strains of NDV, inactivated with 0.1M BEI and adsorbed to aluminium hydroxide gel, favorable immune responses were observed throughout the 8 weeks of observation period. 4. When these chickens were revaccinated at 8 weeks after the first vaccination, strong anamnestic responses were evoked and the immunity maintained for 4 weeks of the observation. Though slightly bettor immune responses were observed after primary vaccination in chickens vaccinated with Bl vaccine compared with those vaccinated with Miyadera vaccine, the differences were not significant. 5. On the electron microscopy, BEI (0.01M) gave least effect to the envelope as well as capsid of NDV.

• IMMUNE NETWORK
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• v.21 no.5
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• pp.32.1-32.14
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• 2021

Over two hundred twenty-eight million cases of coronavirus disease 2019 (COVID-19) in the world have been reported until the 21^st of September 2021 after the first rise in December 2019. The virus caused the disease called severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Over 4 million deaths blame COVID-19 during the last one year and 8 months in the world. Currently, four SARS-CoV-2 variants of concern are mainly focused by pandemic studies with limited experiments to translate the infectivity and pathogenicity of each variant. The SARS-CoV-2 α, β, γ, and δ variant of concern was originated from United Kingdom, South Africa, Brazil/Japan, and India, respectively. The classification of SARS-CoV-2 variant is based on the mutation in spike (S) gene on the envelop of SARS-CoV-2. This review describes four SARS-CoV-2 α, β, γ, and δ variants of concern including SARS-CoV-2 ε, ζ, η, ι, κ, and B.1.617.3 variants of interest and alert. Recently, SARS-CoV-2 δ variant prevails over different countries that have 3 unique mutation sites: E156del/R158G in the N-terminal domain and T478K in a crucial receptor binding domain. A particular mutation in the functional domain of the S gene is probably associated with the infectivity and pathogenesis of the SARS-CoV-2 variant.

• Journal of Microbiology and Biotechnology
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• v.33 no.12
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• pp.1587-1594
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• 2023

Since its first report in 2019, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has posed a grave threat to public health. Virus-specific countermeasures, such as vaccines and therapeutics, have been developed and have contributed to the control of the viral pandemic, which has become endemic. Nonetheless, new variants continue to emerge and could cause a new pandemic. Consequently, it is important to comprehensively understand viral evolution and the roles of mutations in viral infectivity and transmission. SARS-CoV-2 beta variant encode mutations (D614G, N501Y, E484K, and K417N) in the spike which are frequently found in other variants as well. While their individual role in viral infectivity has been elucidated against various therapeutic antibodies, it still remains unclear whether those mutations may act additively or synergistically when combined. Here, we report that N501Y mutation shows differential effect on two therapeutic antibodies tested. Interestingly, the relative importance of E484K and K417N mutations in antibody evasion varies depending on the antibody type. Collectively, these findings suggest that continuous efforts to develop effective antibody therapeutics and combinatorial treatment with multiple antibodies are more rational and effective forms of treatment.

• Journal of Chest Surgery
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• v.37 no.12
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• pp.1022-1024
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• 2004

Pulmonary aspergillosis is the most common disease of fungal infection and has lower infectivity. Pulmonary asergillosis is classified by aspergilloma, bronchopulmonary aspergillosis, necrotic and invasive aspergillosis. Invasive aspergillosis is found in immune compromised host, immunosuppressive treatment after organ transplantation, anticancerous chemotherapy, blood abnormality, AIDS patients etc. We reported a case of invasive aspergillosis in an immunocompetent host, with review of literatures.

• Biomolecules & Therapeutics
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• v.7 no.4
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• pp.385-389
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• 1999

The injibitory effect of Bacillus licheniformis AJ isolated from genitourinary normal flora as a new probiotics on the growth of diarrheal pathogens was studied. This B. licheniformis AJ inhibited the growth of E.coli O-157. Salmonella typhi and Shigella sonnei as well as the infectivity of rotavirus. However, it did not inhibit the growth of Helicobacter pyloriand human intestinal bacteria although it inhibited the harmful enzyme activity of human intestinal bacteria. B. licheniformis AJ seems to excret heat-lable growth-inhibitory protein, bacteriocin, into the media. These results suggest that B. lichenoformis AJ could be used as a new type of probiotics.

• Journal of applied mathematics & informatics
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• v.29 no.5_6
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• pp.1097-1115
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• 2011

We consider the global stability of a general tuberculosis model with two differential infectivity, n classes of latent individuals and mass action incidence. This system exhibits the traditional threshold behavior. There is always a globally asymptotically stable equilibrium state. Depending on the value of the basic reproduction ratio $\mathcal{R}_0$, this state can be either endemic ($\mathcal{R}_0$ > 1), or infection-free ($\mathcal{R}_0{\leq}1$). The global stability of this model is derived through the use of Lyapunov stability theory and LaSalle's invariant set theorem. Both the analytical results and numerical simulations suggest that patients should be strongly encouraged to complete their treatment and sputum examination.