• The Journal of Korean Society of Virology
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• v.29 no.4
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• pp.201-209
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• 1999

Results of the studies on the morphologic and molecular biologic characteristics of Hantaan virus (HTNV), one of the etiologic agents of Hemorrhagic fever with renal syndrome (HFRS), revealed that HTNV was a member of Family Bunyaviridae and its RNA divided into three segments. And the nucleotide sequences of these segments also were known and the differences in nucleotide sequences of HTNV from other members of genus Hantavirus were clearly evaluated. But the morphorgenesis, pathogenesis of HFRS and the replication time had not been clearly determined. In this study, to estimate the replication time of HTNV in Vero E-6 cells, Vero cells were infected with HTNV 76/118 strain, and cells were harvested from two hours post-infection up to 24 hours at two hours-intervals. Harvested cells were treated with ordinary techniques for electron microscopy and immune-electron microscopy. And then thin sections were observed under transmission electron microscope. HTNV particles were not found in the cytoplasm and in the extracellular space between $2{\sim}8$ hours after inoculation of virus, but virus particles were observed in extracellular space near the cell membrane of Vero-E6 cells 10 hours after infection. In immune electron microscopy, mature HTNV particles in extracellular spaces and immature virus labelled with gold particles in the cytoplasm of Vero E-6 cell 10 hours after infection of HTNV could be seen. This results suggest that the replication time of HTNV might be about 10 hours.

• Korean Journal of Veterinary Research
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• v.57 no.4
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• pp.209-214
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• 2017

Wild raccoon dogs (Nyctereutes procyonoides koreensis) may play a role transmitting several pathogens to humans and pet animals. Information concerning the incidence of rabies, canine distemper virus (CDV), canine parvovirus (CPV), canine adenovirus type 2 (CAdV-2), canine parainfluenza virus type 5 (CPIV-5), and canine herpesvirus (CHV) is needed in wild raccoon dogs. In total, 62 brain samples of raccoon dogs were examined for rabies virus (RABV) and CDV, and 49 lung samples were screened for CDV, CAdV-2, CPIV-5, and CHV. No RABV, CAdV-2, CPIV-5, or CHV was identified, but nine CDV antigens (8.1%, 9/111) were detected. Moreover, 174 serum samples from wild raccoon dogs were screened for antibodies against the five major viral pathogens. The overall sero-surveillance against CDV, CPV, CAdV-2, CPIV-5, and CHV in wild raccoon dogs was 60.3%, 52.9%, 59.8%, 23.6%, and 10.3%, respectively. Comparisons of the sero-surveillance of the five pathogens showed that raccoon dogs of Gyeonggi province have slightly higher sero-positive rates against CDV, CPV, and CHV than those of Gangwon province. These results indicate high incidences of CDV, CPV, and CAdV-2 in wild raccoon dogs of two Korean provinces and a latent risk of pathogen transmission to companion and domestic animals.

• Mycobiology
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• v.34 no.2
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• pp.61-66
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• 2006

Chestnut blight disease caused by Cryphonectria parasitica is widely distributed throughout chestnut tree plantations in Korea. We surveyed 65 sites located at 9 provinces in South Korea, and isolated 248 virulent and 3 hypovirulent strains of chestnut blight fungus. Hypovirulent strains had dsRNA virus in the cytoplasm, which is one of the typical characteristics of hypovirulent strains. In addition, they showed more characteristics of hypovirulent strains, i.e., suppressed conidiation, reduced pigmentation in colony color, and reduced phenol oxidase activity as well as reduced pathogenicity. Hypovirulent strains, KCPH-22, KCPH-135 and KCPH-136, had a genomic dsRNA band with the molecular weight of 12.7 kb, which is the L-dsRNA of CHV1. They also had a 2.7 kb defective dsRNA band. Single conidia isolated from hypovirulent strains were cultured and various phenotypes and absence of dsRNA bands were obtained from single conidial cultures, which means that hypovirulence transmission is unstable in asexual reproduction and variations in viral heredity by asexual reproduction. Biocontrol trial using hypovirulent strains was also carried out in the chestnut tree plantations, and canker expansion in the treated trees was stopped and healed by callus formation at the margin of the canker. These results show the potentials in successful biocontrol of chestnut blight if the vegetatively compatible hypovirulent strains could be directly used around the canker formed by compatible virulent strains.

• The Plant Pathology Journal
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• v.36 no.3
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• pp.280-288
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• 2020

RNA interference (RNAi) has attracted attention as a promising approach to control plant viruses in their insect vectors. In the present study, to suppress replication of the rice stripe virus (RSV) in its vector, Laodelphax striatellus, using RNAi, dsRNAs against L. striatellus genes that are strongly upregulated upon RSV infection were delivered through a rice leaf-mediated method. RNAi-based silencing of peroxiredoxin, cathepsin B, and cytochrome P450 resulted in significant down regulation of the NS3 gene of RSV, achieving a transcriptional reduction greater than 73.6% at a concentration of 100 ng/μl and, possibly compromising viral replication. L. striatellus genes might play crucial roles in the transmission of RSV; transcriptional silencing of these genes could suppress viral replication in L. striatellus. These results suggest effective RNAi-based approaches for controlling RSV and provide insight into RSV-L. striatellus interactions.

• Korean Journal of Veterinary Research
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• v.40 no.4
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• pp.719-727
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• 2000

A study was conducted to determine the susceptibility of swine to Korean foot-and-mouth disease virus (FMDV; subtype O, isolated from Chungju province) in April, 2ooo. One holstein cow was inoculated intradermolingually with suspension of homogenized tissue from a Korean native cow naturally infected with Korean FMDY. Infected cow was housed with one susceptible cow and one susceptible pig (contact sentinels). Four additional susceptible pigs were housed in the same room but caged separately (non-contacted sentinels). The contacted pig and cow as well as non-contact pigs developed typical clinical signs after 2, 3, and 7 days post exposure, respectively. We compared neutralizing antibody from the animals to FMDV $O_1$ Lombardy, O Taiwan, $O_1$ Campos, and $O_1$ Manisa after 0, 4, 7, 10, 14, 21, 28 days post challenge and post-exposure. The highest viral neutralization titer could be interpreted that serotype O Korea (Chungju isolate) is antigenically more related to $O_1$ Manisa. In addition, immunohistochemistry was used to further characterize Korean FMDV from tissues of infected pigs. Korean FMDV antigen was observed in the tongue, hoof, esophagus, and tonsil tissues of sentinel pigs. These findings suggest that Korean FMD virus isolated from cattle can be rapidly transmitted to pigs both directly and indirectly contrast field observation in which only cattle were clinically ill.

• Applied Microscopy
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• v.35 no.1
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• pp.23-30
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• 2005

Many studies have been performed on the bovine leukemia virus (BLV) since bovine leukosis had been reported in 1968 in Korea. However, there was no report on the ultrastructural examination of BLV. An attempt to detect C-type viral particles in the cultured peripheral blood lymphocytes of Holstein-Friesian dairy cattle, was made to determine whether in vitro viral expression might be used as a reliable method to identify the cow which is likely to transmit BLV. In transmission electron microscopic (TEM) examination, the virus particles were found predominantly outside of the lymphocytes even though a few particles were also observed within the membrane bound cytoplasmic vacuoles. All of them were C-type particles consisting of a central, electron-dense core separated by a clear area from a limiting envelope with a unit membrane structure. Virus particles were easily detected in the lymphocyte which was cultured with medium supplemented with either T-lymphocyte mitogen (conconavalin A) or B-lymphocyte mitogen (lipopolysaccharide). Identical viral particles, although fewer, were also consistently present in the lymphocytes cultured with medium which was containing foetal bovine serum (FBS) only and which was containing neither FBS or mitogen. By contrast, no virus particle was detected in extensive examination of lymphocytes before culture. In conclusion, the BLV cultivation and detection methods established in this study could be used as a tool to identify and eliminate the cattle which can transmit the BLV.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.3 no.1
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• pp.56-62
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• 2000

Purpose: The aim of this study was to evaluate the efficacy and histologic changes of interferon-alfa therapy on chronic hepatitis B virus infection in children. Patients and Methods: Thirty five children aged 3~16 years who were seropositive for HBV DNA, HBsAg and HBeAg were enrolled. Interferon-alfa 2a ($3.4\;MU/m^2$) were given for 6 months. Serologic markers of viral replication was evaluated 1 year after therapy. Post treatment liver biopsy was performed in 18 patients who showed serologic response. Results: Serum HBeAg and viral DNA became negative in 22 (63%) of treated children at 12 months after therapy. Serum aminotransferase levels normalized in all of the responders and HBsAg became negative in one responder. Horizontal transmission, serum aminotransferase levels more than twice normal, and active inflammation on liver biopsy were predictive factors for response to interferon therapy. Periportal piecemeal necrosis, lobular activity, portal inflammation, fibrosis, and total histologic activity index were reduced in responders. Conclusion: In children with chronic hepatitis B, interferon alfa promotes loss of viral replication and improves aminotransferase. Serologic response is associated with improvement in hepatic histology.

• Research in Plant Disease
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• v.20 no.3
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• pp.206-210
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• 2014

Korean ginseng (Panax ginseng) is the most popular herb for medical purpose in Korea. Recently, viral diseases from Korean ginseng showing various degrees of severe mottling, variegation and mosaic symptoms have caused quantity losses of Korean ginseng in a large number of farms. Watermelon mosaic virus (named WMV-gin) was identified as a causal agent for the disease of Korean ginseng. Interestingly, WMV-gin failed to infect both Korean ginseng plant and susceptible host species including cucurbitaceous plants by mechanical inoculation. However, WMV-gin could successfully infect Korean ginseng by transmission of two aphid species (Myzus persicae and Aphis gossypii). It is likely that transmission of WMV-gin was done by both the aphid species during feeding behavior of the two aphid species on Korean ginseng, though the aphids dislike feeding in Korea ginseng. Similarly, a strain of WMV (WMV-wm) isolated from watermelon was transmitted successfully to Korean ginseng plant by the two aphid species, but not by mechanical inoculations. Transmission assays using M. persicae and A. gossypii clearly showed both WMV-gin and WMV-wm were not transmitted from infected Korean ginseng plant to cucurbit species that are good host species for WMV. These results suggest WMV disease occurring in Korean ginseng plant can be controlled by ecological approaches.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.122-123
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• 2003

Apple stem grooving virus (ASGV) belongs to Capillovirus and infects pome fruits. Transmission mode of ASGV is known by grafting and mechanical inoculation into susceptible hosts, not by any other natural vectors. But we have observed the spread of ASGV in the field without mechanical inoculation or grafting. Transmission seems to be occurred from tree-to-tree and tree-to-susceptible herbaceous plants along but not across ditches in the field. In order to ascertain this possibility, various fungi were isolated and cultured from ASGV-infected plants and 69 isolates were characterized. By means of RNA dot-blot hybridization and PCR analysis, 3 isolates were sorted out for further studies. The isolates were identified to Tataromyces sp. and belonged to Phenicillium by morphological characteristics and molecular markers. As an experimental host, 10 kidney beans (Phaseolus vulgaris) were screened and Kyunggi-5 was selected for virus amplification and symptom development. Kyunggj-5 infected by fungi which seemed to carry ASGV showed the typical disease symptoms and viral coat protein genes were detected from all tested plants. To confirm the Koch's rule, fungi cultured from inoculation origins of kidney bean were grown on PDA media and re-inoculated to hosts. The fungi isolated from inoculation origins induced the typical disease symptoms on hosts. However virus free fungi did not induce any symptom on the experimental hosts. This bioassay showed that these typical symptoms were caused by virus, not fungi.

• Research in Community and Public Health Nursing
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• v.13 no.3
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• pp.503-512
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• 2002

Purpose: This study was conducted to develop educational materials for preventing type B viral hepatitis infection. Prior to this study, a survey had been conducted to define the educational needs of persons with hepatitis B antigen. Method: Based on the results of the former study and a review of the literature, the content of the educational materials was confined to the transmission cycle and its prevention in type B hepatitis. A professional team that consisted of writers and producers videotaped the lectures provided by professors and instructors in a nursing school. A professional graphic designer produced the leaflet to enhance the visual effects. Results: The contents of the educational materials for type B hepatitis were composed of six parts: (1) the prevalence rate (or morbidity) of type B hepatitis antigen positive and its recent trend, (2) transformation of hepatitis. (3) transmission cycle of hepatitis infection, (4) persons who are susceptible to hepatitis and need a vaccination, (5) preventive approach hepatitis vaccination and the guideline for patients' daily lives for preventing infection and (6) questions and answers. The materials were delivered in the form of lectures, visual charts, graphics, and multi-media. Conclusion: The educational materials developed in this study may provide practical information and knowledge on strategies to prevent type B hepatitis. The educational materials may be utilized in primary health care centers or school health services.