• IMMUNE NETWORK
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• v.11 no.6
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• pp.309-323
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• 2011

MicroRNAs (miRNAs) are a class of naturally occurring small non-coding RNAs of about 22 nucleotides that have recently emerged as important regulators of gene expression at the posttranscriptional level. Recent studies provided clear evidence that microRNAs are abundant in the lung, liver and kidney and modulate a diverse spectrum of their functions. Moreover, a large number of studies have reported links between alterations of miRNA homeostasis and pathological conditions such as infectious diseases, sickle cell disease and endometrium diseases as well as lung, liver and kidney diseases. As a consequence of extensive participation of miRNAs in normal functions, alteration and/or abnormalities in miRNAs should have importance in human diseases. Beside their important roles in patterning and development, miRNAs also orchestrated responses to pathogen infections. Particularly, emerging evidence indicates that viruses use their own miRNAs to manipulate both cellular and viral gene expression. Furthermore, viral infection can exert a profound impact on the host cellular miRNA expression profile, and several RNA viruses have been reported to interact directly with cellular miRNAs and/or to use these miRNAs to augment their replication potential. Here I briefly summarize the newly discovered roles of miRNAs in various human diseases including infectious diseases, sickle cell disease and enodmetrium diseases as well as lung, liver and kidney diseases.

• Journal of Microbiology and Biotechnology
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• v.12 no.4
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• pp.674-678
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• 2002

Yersinia enterocolitica causes various diseases in humans, including enteritis. The onset of such diseases is closely related with the expression of important virulence factors, particularly outer membrane proteins (OMPs). The expression of OMPs depends on several factors, including temperature, and origin, biotype and serotype of the bacteria. Recently, concerns over food safety have increased along with the demand for the development of sensitive, rapid, and pathogen-specific detection methods. To develop a suitable detection method for Y. enterocolitica isolated from Korean moutainspring water and pig feces, the OMP expression patterns were analyzed phenotypically and immunologically using 12 representative strains from 51 Y. enterocolitica Korean isolates. A 38-kDa OMP was commonly observed in all strains. However, additional OMPs were also observed in different biotypes and serotypes as well as bacterial origins, by incubating Y. enterocolitica at a low temperature. The specificity of the 38-kDa OMP was confirmed by a Western blot analysis with antisera against Y. enterocolitica and Brucella abortus. The results, therefore, indicate that the 38-kDa OMP could be used as a marker for detecting Y. enterocolitica in the environment or for seromonitoring.

• Proceedings of the Microbiological Society of Korea Conference
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• 2003.05a
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• pp.83-86
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• 2003

Major advances in positive-sense RNA virus research have been facilitated by the development of reverse genetics systems. These systems consist of an infectious cDNA clone that encompasses the genome of the virus in question. This clone is then used as a template for the subsequent synthesis of infectious RNA for the generation of synthetic viruses. However, the construction of infectious cDNA for the Japanese encephalitis virus (JEV) has been repeatedly thwarted by the instability of its cDNA. As JEV is an important human pathogen that causes permanent neuropsychiatric sequelae and even fatal disease, a reliable reverse genetics system for this virus is highly desirable. The availability of this tool would greatly and the development of effective vaccines as well as facilitate studies into the basic biology of the virus, including the molecular mechanisms of viral replication, neurovirulence, and pathogenesis. We have successfully constructed a genetically stable infectious JEV cDNA containing full-length viral RNA genome. Synthetic RNA transcripts generated in vitro from the cDNA were highly infectious upon transfection into susceptible cells, and the cDNA remained stable after it had been propagated in E. coli for 180 generations. Using this infectious JEV cDNA, we have successfully expressed a variety of reporter genes from the full-length genomic and various subgenomic RNAs in vitro transcribed from functional JEV cDNAS. In summary, we have developed a reverse genetics system for JEV that will greatly facilitate the research on this virus in a variety of different fields. It will also be useful as a heterologous gene expression vector and aid the development of a vaccine against JEV.

• Journal of Microbiology
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• v.40 no.3
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• pp.183-192
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• 2002

Cells infected With equine herpesvirus type-1 (EHV-1) Produced both infectious and non-infectious Virus-related particles. Compared to the whole virion, non-infectious particles termed L-particles were deter-mined to lack 150 kDa protein, commonly known as nucleocapsid protein. The potential of L-particles to induce immune responses was studied in mice and foals. Intranasal immunization with L-particles or whole virions induced poor IgG antibody responses in mice. Interestingly, despite the poor antibody response, the conferred immunity protected the host from challenge infections. This was indicated by a significant reduction in virus titers in line with recovery towards normal body weight. Subsequently, the test on the usefulness of L-particles as immunizing agents was extended to foals. Immunization of specific-pathogen-free (SPF) foals resulted in similar results. As determined by a complement-fixing-antibody test (CFT), foals seroconverted when they were immunized either with inactivated L-particles or whole virions via intramuscular (i.m.) injections. The presence of the antibody correlated with the degree of protection. Beyond day 1 post challenge infection (p.i.), there was no virus shedding in the nasal mucus of foals immunized with whole EHV-1 virions. Virus shedding was observed in foals Immunized with L-particles but limited to days 6 to 8 p.i. only. In contrast, extended vim shedding was observed in non-immunized foals and it was well beyond day 14 p.i. Viremia was not detected for more than four days except in non-immunized foals. Immunization in mice via intranasal (i.n.) conferred good protection. However, compared to the i.n. route, a greater degree of protection was obtained in foals following immunization via i.m. route. Despite variation in the degree of protection due to different routes of immunization in the two animal species, our results have established significant evidence that immunization with L-particles confers protection in the natural host. It is suggested that non-infectious L-particles should be used as immunizing agents for vaccination of horses against EHV-1 infection.

• The Plant Pathology Journal
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• v.37 no.2
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• pp.162-172
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• 2021

Soybean mosaic virus (SMV) is the predominant viral pathogen that affects the yield and quality of soybean. The natural host range for SMV is very narrow, and generally limited to Leguminosae. However, we found that SMV can naturally infect Pinellia ternata and Atractylodes macrocephala. In order to clarify the molecular mechanisms underlying the cross-family infection of SMV, we used double-stranded RNA extraction, rapid amplification of cDNA ends polymerase chain reaction and Gibson assembly techniques to carry out SMV full-length genome amplification from susceptible soybeans and constructed an infectious cDNA clone for SMV. The genome of the SMV Shanxi isolate (SMV-SX) consists of 9,587 nt and encodes a polyprotein consisting of 3,067 aa. SMV-SX and SMV-XFQ008 had the highest nucleotide and amino acid sequence identities of 97.03% and 98.50%, respectively. A phylogenetic tree indicated that SMV-SX and SMV-XFQ018 were clustered together, sharing the closest relationship. We then constructed a pSMV-SX infectious cDNA clone by Gibson assembly technology and used this clone to inoculate soybean and Ailanthus altissima; the symptoms of these hosts were similar to those caused by the virus isolated from natural infected plant tissue. This method of construction not only makes up for the time-consuming and laborious defect of traditional methods used to construct infectious cDNA clones, but also avoids the toxicity of the Potyvirus special sequence to Escherichia coli, thus providing a useful cloning strategy for the construction of infectious cDNA clones for other viruses and laying down a foundation for the further investigation of SMV cross-family infection mechanisms.

• Molecules and Cells
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• v.26 no.5
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• pp.415-426
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• 2008

The interactions between the host and microbial pathogen largely dictate the onset, progression, and outcome of infectious diseases. Pathogens subvert host components to promote their pathogenesis and, among these, cell surface heparan sulfate proteoglycans are exploited by many pathogens for their initial attachment and subsequent cellular entry. The ability to interact with heparan sulfate proteoglycans is widespread among viruses, bacteria, and parasites. Certain pathogens also use heparan sulfate proteoglycans to evade host defense mechanisms. These findings suggest that heparan sulfate proteoglycans are critical in microbial pathogenesis, and that heparan sulfate proteoglycan-pathogen interactions are potential targets for novel prophylactic and therapeutic approaches.

• Infection and chemotherapy
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• v.50 no.4
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• pp.362-366
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• 2018

Millerozyma farinosa (formerly Pichia farinosa) is halotolerant yeast mainly found in food and ubiquitous in the environment. It was a rare yeast pathogen, but it has recently emerged as a cause of fungemia in immunocompromised patients. Optimal therapy for invasive fungal infection by this pathogen remains unclear. We report a case of catheter related blood stream infection caused by M. farinosa in a 71-year-old patient who recovered successfully after removal of the central venous catheter and treatment with micafungin.

• Journal of Medicine and Life Science
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• v.20 no.1
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• pp.43-47
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• 2023

Streptococcus suis (S. suis) is an emerging zoonotic pathogen that causes bacterial meningitis in humans. S. suis is an encapsulated gram-positive facultative anaerobic bacterium and is an important pathogen in pigs. This infectious disease usually manifests in humans as meningitis, endocarditis, septicemia, and arthritis. Most cases originate in Southeast Asia, and human S. suis infections are often reported in countries with a high density of pigs. Meningitis is a common clinical manifestation of S. suis infection. Moreover, hearing loss is a common complication that can be bilateral, profound, and/or permanent. This report presents two cases of bacterial meningitis and hearing loss caused by S. suis in patients without a history of direct exposure to pigs in an intensive pork industry region.

• Molecules and Cells
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• v.27 no.1
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• pp.5-14
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• 2009

The availability of effective vaccines has had the most profound positive effect on improving the quality of public health by preventing infectious diseases. Despite many successful vaccines, there are still old and new emerging pathogens against which there is no vaccine available. A better understanding of how vaccines work for providing protection will help to improve current vaccines as well as to develop effective vaccines against pathogens for which we do not have a proper means to control. Recent studies have focused on innate immunity as the first line of host defense and its role in inducing adaptive immunity; such studies have been an intense area of research, which will reveal the immunological mechanisms how vaccines work for protection. Toll-like receptors (TLRs), a family of receptors for pathogen-associated molecular patterns on cells of the innate immune system, play a critical role in detecting and responding to microbial infections. Importantly, the innate immune system modulates the quantity and quality of long-term T and B cell memory and protective immune responses to pathogens. Limited studies suggest that vaccines which mimic natural infection and/or the structure of pathogens seem to be effective in inducing long-term protective immunity. A better understanding of the similarities and differences of the molecular and cellular events in host responses to vaccination and pathogen infection would enable the rationale for design of novel preventive measures against many challenging pathogens.

• Journal of Microbiology and Biotechnology
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• v.21 no.10
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• pp.1026-1035
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• 2011

Vibrio parahaemolyticus, which owes its origin to the marine environment, is considered as one of the most common causes of infectious diarrhea worldwide. The present study investigated the pathogenicity of V. parahaemolyticus against the model organism, Caenorhabditis elegans. Infection in the host was localized with GFP-tagged V. parahaemolyticus using confocal laser scanning microscopy. The times required for causing infection, bacterial load in intestine, chemotactic response, and alteration in pharyngeal pumping were analyzed in the host system. In addition, the regulation of innate immune-related genes, lys-7, clec- 60, and clec-87, was analyzed using real-time PCR. The role of immune-responsible pmk-1 was studied using mutant strains. The pathogenicity of environmental strain CM2 isolated from the Gulf of Mannar, India was compared with that of a reference strain obtained from ATCC. The pathogen infected animals appeared to ward off infection by up-regulating candidate antimicrobial genes for a few hours after the exposure, before succumbing to the pathogen. For the first time, the pathogenicity of V. parahaemolyticus at both the physiological and molecular levels has been studied in detail using the model organism C. elegans.