• Journal of Microbiology and Biotechnology
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• 제34권8호
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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.

• 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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• 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.