• Journal of Microbiology
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• 제45권1호
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• pp.69-74
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• 2007

Escherichia coli is a clonal species, and occurs as both commensal and pathogenic strains, which are normally classified on the basis of their O, H, and K antigens. The O-antigen (O-specific polysaccharide), which consists of a series of oligosaccharide (O-unit) repeats, contributes major antigenic variability to the cell surface. The O-antigen gene cluster of E. coli O66 was sequenced in this study. The genes putatively responsible for the biosynthesis of dTDP-6-deoxy-L-talose and GDP-mannose, as well as those responsible for the transfer of sugars and for O-unit processing were identified based on their homology. The function of the wzy gene was confirmed by the results of a mutation test. Genes specific for E. coli O66 were identified via PCR screening against representatives of 186 E. coli and Shigella O type strains. The comparison of intergenic sequences located between galF and the O-antigen gene cluster in a range of E. coli and Shigella showed that this region may perform an important function in the homologous recombination of the O-antigen gene clusters.

• Journal of Microbiology and Biotechnology
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• 제18권12호
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• pp.1890-1894
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• 2008

Apoemulsan is a biopolymer with potent emulsification activity, produced by Acinetobacter venetian us RAG-1 (RAG-1). The wee gene cluster is responsible for apoemulsan biosynthesis. The analysis of (i) a putative polysaccharide copolymerase mutant (${\Delta}wzc$), (ii) a putative polymerase mutant (${\Delta}wzy$), and (iii) an apoemulsan-deficient variant (${\Delta}2$) indicated that the wee gene cluster controls the synthesis of two polysaccharides: high molecular weight (HMW) and low molecular weight (LMW). LMW polysaccharide of wee origin was present in LPS isolated from RAG-1 cells, suggesting a link to the Lipid A-core of LPS molecules. SDS-PAGE analysis indicated that apoemulsan is copurified with LPS polysaccharide, with implications in the emulsification activity of RAG-1 polymer.

• Journal of Microbiology and Biotechnology
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• 제31권4호
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• pp.520-528
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• 2021

Plesiomonas shigelloides, a member of the family Vibrionaceae, is a gram-negative, rod-shaped, facultative anaerobic bacterium with flagella. P. shigelloides has been isolated from such sources as freshwater, surface water, and many wild and domestic animals. P. shigelloides contains 102 O-antigens and 51 H-antigens. The diversity of O-antigen gene clusters is relatively poorly understood. In addition to O1 and O17 reported by other laboratories, and the 12 O serogroups (O2, O10, O12, O23, O25, O26, O32, O33, O34, O66, O75, and O76) reported previously by us, in the present study, nine new P. shigelloides serogroups (O8, O17, O18, O37, O38, O39, O44, O45, and O61) were sequenced and annotated. The genes for the O-antigens of these nine groups are clustered together in the chromosome between rep and aqpZ. Only O38 possesses the wzm and wzt genes for the synthesis and translocation of O-antigens via the ATP-binding cassette (ABC) transporter pathway; the other eight use the Wzx/Wzy pathway. Phylogenetic analysis using wzx and wzy showed that both genes are diversified. Among the nine new P. shigelloides serogroups, eight use wzx/wzy genes as targets. In addition, we developed an O-antigen-specific PCR assay to detect these nine distinct serogroups with no cross reactions among them.

• Journal of Microbiology and Biotechnology
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• 제31권9호
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• pp.1191-1199
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• 2021

Enteropathogenic Escherichia coli (EPEC), which belongs to the attaching and effacing diarrheagenic E. coli strains, is a major causative agent of life-threatening diarrhea in infants in developing countries. Most EPEC isolates correspond to certain O serotypes; however, many strains are non-typeable. Two EPEC strains, EPEC001 and EPEC080, which could not be serotyped during routine detection, were isolated. In this study, we conducted an in-depth characterization of their putative O-antigen gene clusters (O-AGCs) and also performed constructed mutagenesis of the O-AGCs for functional analysis of O-antigen (OAg) synthesis. Sequence analysis revealed that the occurrence of O-AGCs in EPEC001 and E. coli O132 may be mediated by recombination between them, and EPEC080 and E. coli O2/O50 might acquire each O-AGC from uncommon ancestors. We also indicated that OAg-knockout bacteria were highly adhesive in vitro, except for the EPEC001 wzy derivative, whose adherent capability was less than that of its wild-type strain, providing direct evidence that OAg plays a key role in EPEC pathogenesis. Together, we identified two EPEC O serotypes in silico and experimentally, and we also studied the adherent capabilities of their OAgs, which highlighted the fundamental and pathogenic role of OAg in EPEC.

• Pediatric Infection and Vaccine
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• 제22권2호
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• pp.97-105
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• 2015

목적: 폐구균의 혈청형 분석은 백신의 효능을 평가하고 감시하는데 매우 중요하다. 그러나 폐구균의 혈청형 분석이 힘들기 때문에 최근 라텍스 구슬과 흐름세포측정기를 이용한 다중구슬 혈청형 분석법이 소개되었다. 이 연구에서는 새로운 혈청형 분석법을 이화백신연구센터에서 구축하고 실제 임상 검체들에 적용해보았다. 방법: 라텍스 구슬 3종과 폐구균 피막다당 특이 단클론항체 1가지, 시동체 2종을 Univerisity of Alabama at Birmingham에서 제공 받았다. 이 시료들을 이용하여 단클론항체와 wzy 다중 PCR을 이용한 다중구슬 혈청형 분석법을 확립하였다. 그리고 75개의 혈청형이 알려져 있는 검체를 이용하여 이화백신효능연구센터에 확립된 다중구슬 혈청형 분석법의 정확도를 보았고 이를 토대로 528개의 임상 검체를 분석해 보았다. 결과: 다중구슬 혈청형 분석법은 이화백신효능연구센터에 안정적으로 확립되었다. 75종의 이미 혈청형이 알려져 있는 검체를 암호화하여 분석한 결과 전부 일치하여 정확도가 높음을 보여 주었고 실제 임상 검체에도 적용한 결과 94.3% (498/528)에서 혈청형을 확인할 수 있었다. 결론: 다중구슬 분석법은 다수의 혈청형을 쉽고 빠르게 한번에 많은 수의 검체를 확인할 수 있는 객관적인 검사 방법으로 향후 임상적 진단과 역학연구 등의 폐구균의 혈청형 분석에 유용하게 사용될 수 있을 것이다.