• Journal of Microbiology and Biotechnology
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• v.34 no.8
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• pp.1599-1608
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• 2024

Yersinia enterocolitica is a globally distributed food-borne gastrointestinal pathogen. The O-antigen variation-determined serotype is an important characteristic of Y. enterocolitica, allowing intraspecies classification for diagnosis and epidemiology purposes. Among the 11 serotypes associated with human yersiniosis, O:3, O:5,27, O:8, and O:9 are the most prevalent, and their O-antigen gene clusters have been well defined. In addition to the O-antigen, several virulence factors are involved in infection and pathogenesis of Y. enterocolitica strains, and these are closely related to their biotypes, reflecting pathogenic properties. In this study, we identified the O-AGC of a Y. enterocolitica strain WL-21 of serotype O:10, and confirmed its functionality in O-antigen synthesis. Furthermore, we analyzed in silico the putative O-AGCs of uncommon serotypes, and found that the O-AGCs of Y. enterocolitica were divided into two genetic patterns: (1) O-AGC within the hemH-gsk locus, possibly synthesizing the O-antigen via the Wzx/Wzy dependent pathway, and (2) O-AGC within the dcuC-galU-galF locus, very likely assembling the O-antigen via the ABC transporter dependent pathway. By screening the virulence genes against genomes from GenBank, we discovered that strains representing different serotypes were grouped according to different virulence gene profiles, indicating strong links between serotypes and virulence markers and implying an interaction between them and the synergistic effect in pathogenicity. Our study provides a framework for further research on the origin and evolution of O-AGCs from Y. enterocolitica, as well as on differences in virulent mechanisms among distinct serotypes.

• Research in Plant Disease
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• v.7 no.3
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• pp.155-163
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• 2001

Two attenuated Cucumber mosaic virus (CMV) isolates, Paf-CMV and Rs2-CMV that had been selected from CMV isolates associated with satellite RNA (satRNA) were tested for cross-protection effect in pepper plants. The viruses selected as attenuated strains appeared to be identical serologically and physically to the challenge virus (Mf-CMV), but they were lower in the dilution end-point of infectivity of crude sap than Mf-CMV When symptoms were observed in several indicator plants after inoculation, Paf-CMV and Rs2-CMV were symptomless or showed mild mosaic symptoms while another satRNA isolate Ap-CMV developed severe mosaic symptoms on the leaves as Mf-CMV. The nucleotide sequences of the satRNAs were determined by sequencing full-length cDNA clones. Paf-, Rs2- and Ap-satRNAs were 386, 335, and 347 nucleotides long, respectively, The sequences were then compared with the other known Y-satRNA, revealing that nucleotide sequences of the satRNAs consisted of 5'- and 3'-terminal conserved regions. However variations occurred on the middle regions of the sequences, especially those related to symptom interference, showing significant differences between Paf-satRNA and other isolates. Infectious transcripts of Paf-satRNA and Rs2-satRNA induced mild mosaic symptoms in pepper plants when supported by genomic RNAs of Mf-CMV. Under greenhouse conditions, Paf-CMV and Rs2-CMV were tested for cross-protection effect in pepper and tobacco (Nicotiana tabacum cv, Xanthi nc) plants against Mf-CMV. No symptoms were developed on the plants vaccinated with Paf-CMV until 3 weeks after inoculation with the virulent strain; however another attenuated isolate, Rs2-CMV, showed less effectiveness in cross-protection. Depending on the concentration of the challenged virus, symptoms sometimes appeared later in the upper leaves. However, in plants challenged with low concentrations (below 0.2 mg/ml) of the challenge inoculum, symptoms caused by the virulent strain did not develop on the plants vaccinated with Paf-CMV. In the field experiments, the number of pepper plants with severe mosaic symptoms in the control plots was progressively increased after transplanting and reached approximately 50% after 50 days. On the other hand, the incidence of mosaic disease appeared very low on the plants that had received the protective inoculation with Paf-CMV.

• Journal of Microbiology
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• v.44 no.5
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• pp.548-555
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• 2006

FaeG is the key factor in the infection process of K88ad enterotoxigenic Escherichia coli (ETEC) fimbrial adhesin. In an attempt to determine the possibility of expressing recombinant FaeG with immunogenicity for a new safe and high-production vaccine in E. coli, we constructed the recombinant strain, BL21 (DE3+K88), which harbors an expression vector with a DNA fragment of faeG, without a signal peptide. Results of 15% SDS-polyacrylamide slab gel analysis showed that FaeG can be stably over-expressed in BL21 (DE3+K88) as inclusion bodies without FaeE. Immunoglobulin G (IgG) and M (IgM) responses in pregnant pigs, with boost injections of the purified recombinant FaeG, were detected 4 weeks later in the sera and colostrum. An in vitro villius-adhesion assay verified that the elicited antibodies in the sera of vaccinated pigs were capable of preventing the adhesion of K88ad ETEC to porcine intestinal receptors. The protective effect on the mortality rates of suckling piglets born to vaccinated mothers was also observed one week after oral challenge with the virulent ETEC strain, $C_{83907}$ (K88ad, $CT^+,\;ST^+$). The results of this study proved that the adhesin of proteinaceous bacterial fimbriae or pili could be overexpressed in engineered E. coli strains, with protective immune responses to the pathogen.

• Applied Biological Chemistry
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• v.48 no.3
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• pp.201-206
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• 2005

The development of microbial inoculant was conducted using a by-product of oriental herbal medicine. The constituent of the by-product, which was high in organic matter, was 11.3% of crude protein, 5.1% of crude lipid, 49.7% of NDF (neutral detergent fiber), and 33.8% of ADF (acid detergent fiber). Microorganisms isolated from the by-product of oriental herbal medicine were 35 species. Among them, 6 bacterial species, 4 fungal species, 2 actnomycetes species, and 1 yeast species were effective in the utilization of the by-products. The 13 strains screened were tested for the plant growth-promoting effect in soybean seedling. BL-333 strain was found to increase the soybean yield by about 23% as compared with control. The strain BL-333 was identified as Paenibacillus marcerans. P. marcerans BL-333 showed high anti-fungal activities against virulent fungi, especially Fusarium sp. and Collectotrichum sp. Yields of plants which were inoculated with microbial inoculant prepared with P. marcerans BL-333 and by-product of oriental herbal medicine were found to be higher than control by $3{\sim}24%$. The yield was especially promoted in lettuce, radish, chinese cabbage and cucumber plants.

• Parasites, Hosts and Diseases
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• v.26 no.3
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• pp.155-162
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• 1988

Surface membrane proteins of virulent RH strain and tissue cyst-forming Fukaya strain of Toxoplasma gondii were analysed by SDS-polyacrylamide gel electrophoresis after LPO-catalyzed surface iodination and lectin blotting, then identified the zoite-specific antigens. Prior to the analyses, purification of RH tachyzoites from mouse peritoneal exudate and of Fukaya bradyzoites from mouse brain tissues were performed by centrifugation - on the discontinuous Percoll density-gradient. Ta- chysoites were obtained at the interface of 50U and 60% Percoll solution and brain cysts were harvested at the interfaces of 40-50% and 50-60%, then bradyzoites were obtained by treating the cysts with hypertonic solution. The LPO-catalyzed iodination detected 15 KDa and 14 KDa proteins o( brady- zoites and 30 KDa protein of tachysoites as major bands with several other minor bands. But Con A blotting revealed some bands of 200 K∼50 KDa glycoproteins of bradyzoites and 52 KDa band as major and minor bands of 33 K∼20 KDa of tachyzoites. Phytohemagglutinin did not detect any band in the two forms. EITB with anti- Fukaya antibody and anti-RH antibody revealed cross-reactivities between the two forms. Despite the cross-reactivity, anti-Fukaya antibody reacted with 15 KDa band of bradyzoites specifically and, anti-RH antibody with 52 KDa, 30 KDa, and 25 KDa bands of tachyzoites, respectively. It was identified that 15 KDa protein in bradyzoite, which was not a glycoprotein, was a major membrane protein with sufficient antigenicity, and in the case of tacky- zoite, 52 KDa surface glycoprotein (gp52) with specific antigenicity might be added to the major surface protein, p30.

• Parasites, Hosts and Diseases
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• v.53 no.3
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• pp.259-263
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• 2015

The increasing prevalence of Toxoplasma gondii infection in the human population in the Republic of Korea (= Korea) is due to various reasons such as an increase in meat consumption. However, the importance of cats in transmitting T. gondii infection through oocysts to humans has seldom been assessed. A total of 300 fecal samples of stray cats captured around Seoul from June to August 2013 were examined for T. gondii B1 gene (indicating the presence of oocysts) using nested-PCR. Fourteen (4.7%) of 300 cats examined were positive for B1 gene. Female cats (7.5%) showed a higher prevalence than male cats (1.4%). Cats younger than 3 months (5.5%) showed a higher prevalence than cats (1.5%) older than 3 months. For laboratory passage of the positive samples, the fecal suspension (0.2 ml) of B1 gene positive cats was orally inoculated into experimental mice. Brain tissues of the mice were obtained after 40 days and examined for the presence of tissue cysts. Two isolates were successfully passaged (designated KNIH-1 and KNIH-2) and were molecularly analyzed using the SAG5D and SAG5E gene sequences. The SAG5D and SAG5E gene sequences showed high homologies with the ME49 strain (less virulent strain). The results indicated the importance of stray cats in transmitting T. gondii to humans in Korea, as revealed by detection of B1 gene in fecal samples. T. gondii isolates from cats were successfully passaged in the laboratory for the first time in Korea.

• Korean Journal of Veterinary Research
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• v.46 no.2
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• pp.107-117
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• 2006

This paper described the epidemiological characteristics of 2002 outbreak of classical swine fever (CSF) in Korea. A total of thirteen CSF-infected farms could be classified into two clusters according to the location and time of outbreak. Two farms located in the same county of Gangwon province and 11 farms located in several different districts of Incheon metropolitan/Gyeonggi province were identified as CSF-infected from April 16 to 30 and from October 7 to December 21 in 2002, respectively. As the result of epidemiological analysis, the two clusters of outbreaks were turned out to be independent epidemics which had different sources of virus introduction. Three farms were found to have been infected primarily; one located in Cheolwon county of Gangwon province and two located in Kangwha county of Incheon metropolitan area. The most likely factors of virus introduction into these primary infected farms were considered to be direct or indirect contact by foreign workers and/or owners of the infected farms who had come back from traveling in China before outbreaks. This was supported by the genetic typing of CSF viruses isolated from the pigs of infected farms. All the virus isolates of 2002 outbreak were found to be genetic type 2, whereas the viruses isolated before 2000 were type 3 and the reference strains, such as attenuated live vaccine virus (LOM strain) and high virulent challenge virus (ALD strain), were type 1. Accordingly, we concluded that the 2002 CSF outbreak must have been caused by a newly introduced virus from overseas and the type 3 virus must have been eradicated after the last outbreak of 1999 by the national CSF eradication campaign which were implemented since 1996. Based on the combined analysis of epidemiological data and genetic typing, the transmission routes of classical swine fever virus were found to be the movement of vehicles (60%) and persons (10%), neighbourhood spread (20%) and unknown (10%). It is expected that the analyzed data and findings of classical swine fever outbreak epidemic could be very useful to establish the disease control and eradication program for the country in the future.

• Research in Plant Disease
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• v.10 no.4
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• pp.324-330
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• 2004

This studies were investigated the occurrence of sclerotinia rot at the crisphead lettuce field in Uiryeong-Gun, Gyeongsangnam-Do from January to May in 2003. Average incidence rates of sclerotinia rot on crisphead lettuce was up to 21.9% at the five plastic houses. A total of 140 isolates of Sclerotinia sp. were obtained from diseased leaves of crisphead lettuce. Among them, the fungi YR-1 was isolated, which showed highly virulent on the whole plant. the YR-1 was identified as Sclerotinia sclerotiorum based on the formation, color, shape and size of sclerotium and apothecium. For the pathogenicity test, the most suitable inoculum quantity of YR-1 strain was selected as the triturated mycelial suspension of $A_{550}$=0.8, 40 ml showing disease incidence of 94%, and the symptom showed as same as at the fields, the leaves and stem had rotten and developed white downy mycelial at the diseased lesion on the leaves and stems, and produced black and irregular sclerotinia. This is the first report on the pathogenicity test using by triturated mycelial suspension-inoculum of the pathogen for the sclerotinia rot of crisphead lettuce.

• Korean Journal of Veterinary Research
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• v.47 no.3
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• pp.291-298
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• 2007

Olive flounder, Paralichthys olivaceus is one of the most important cultured fish in Korea, its farming has been negatively impacted by viral, bacterial and parasitic diseases. Streptococcal infection was considered as a serious problem because of significant economic losses in olive flounder farm industry. The development and evaluation of vaccine for protection against infection by this agent were required. We evaluated the safety and efficacy of ${\beta}$-hemolytic Streptococcus (S.) iniae vaccine on olive flounder Three hundreds of flounders (weight $119.8{\pm}20.7g$, body length $22.6{\pm}1.4cm$) were reared in 0.5 tons aquaria in land-marine tank system. Seawater was provided from the sea of Inchon in Korea, and water temperature was set to $22^{\circ}C$ and $25^{\circ}C$ in the vaccination and challenge test, respectively. We used the formalin-inactivated ${\beta}$-hemolytic S. iniae (F2K) vaccine (M VAC INIAE; Kyoritsu seiyaku, Japan) originated in Japan. The vaccine was intraperitoneally administered to fish. Both of vaccinated group and control group were challenged with intraperitoneally injection by virulent S. iniae SI-36 isolates with $1.0{\times}10^7CFU/fish$ at 3 weeks after vaccination. Difference on mortality of control and vaccinated group (90.0 and 15.0%, 76.5 and 8.0% respectively) at two trials were found significant (p<0.05), and relative percent survival were 83.4% and 89.5%, respectively. The dead fishes were showed dark pigmentation of skin, abdominal extension, hemorrhagic ascites, and liver necrosis, and isolated the S. iniae strain from ascites, liver and kidney. We confirmed the safety and efficacy of ${\beta}$-hemolytic S. iniae vaccine by determinations of the optimal management condition and artificial challenge test in olive flounder.

• Korean journal of applied entomology
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• v.45 no.1 s.142
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• pp.67-74
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• 2006

Korean entomopathogenic nematodes were introduced into cultural management of turfgrasses to enhance white grub control in golf courses for saving labour and expenses and contribution to giving safe playing and working places for golfers and superintendents by environmentally friendly control strategy. The turfgrass height influenced efficacy of entomopathogenic nematodes. Efficacy was higher at short turfgrass both in pot using Galleria mellonella larvae and in golf courses using 2nd instar of Exomala orientalis and Ectinohoplia rufipes as baits. Aeration increased the efficacy of entomopathogenic nematodes which were lower virulent. Pre-aeration was more effective than post-aeration. Exomala orientalis larval population was reduced 80.4 and 66.0% in the pre-aeration and post-aeration with entomopathogenic nematode, Steinernema carpocapsae Pocheon strain compared to 35.4% in the no aeration treatment.