Journal of Microbiology

Research Support, Non-U.S. Gov'ts

Identification of Conserved Surface Proteins as Novel Antigenic Vaccine Candidates of Actinobacillus pleuropneumoniae: Xiabing Chen , Zhuofei Xu , Lu Li , Huanchun Chen , Rui Zhou; J. Microbiol. 2012;50(6):978-986. Published online December 30, 2012; DOI: https://doi.org/10.1007/s12275-012-2214-2

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Abstract: Actinobacillus pleuropneumoniae is an important swine respiratory pathogen causing great economic losses worldwide. Identification of conserved surface antigenic proteins is helpful for developing effective vaccines. In this study, a genome-wide strategy combined with bioinformatic and experimental approaches, was applied to discover and characterize surface-associated immunogenic proteins of A. pleuropneumoniae. Thirty nine genes encoding outer membrane proteins (OMPs) and lipoproteins were identified by comparative genomics and gene expression profiling as beinghighly conserved and stably transcribed in the different serotypes of A. pleuropneumoniae reference strains. Twelve of these conserved proteins were successfully expressed in Escherichia coli and their immunogenicity was estimated by homologous challenge in the mouse model, and then three of these proteins (APJL_0126, HbpA and OmpW) were further tested in the natural host (swine) by homologous and heterologous challenges. The results showed that these proteins could induce high titers of antibodies, but vaccination with each protein individually elicited low protective immunity against A. pleuropneumoniae. This study gives novel insights into immunogenicity of the conserved OMPs and lipoproteins of A. pleuropneumoniae. Although none of the surface proteins characterized in this study could individually induce effective protective immunity against A. pleuropneumoniae, they are potential candidates for subunit vaccines in combination with Apx toxins.

Structural and Functional Importance of Outer Membrane Proteins in Vibrio cholerae Flagellum: Wasimul Bari , Kang-Mu Lee , Sang Sun Yoon; J. Microbiol. 2012;50(4):631-637. Published online August 25, 2012; DOI: https://doi.org/10.1007/s12275-012-2116-3

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Abstract: Vibrio cholerae has a sheath-covered monotrichous flagellum that is known to contribute to virulence. Although the structural organization of the V. cholerae flagellum has been extensively studied, the involvement of outer membrane proteins as integral components in the flagellum still remains elusive. Here we show that flagella produced by V. cholerae O1 El Tor strain C6706 were two times thicker than those from two other Gram-negative bacteria. A C6706 mutant strain (SSY11) devoid of two outer membrane proteins (OMPs), OmpU and OmpT, produced thinner flagella. SSY11 showed significant defects in the flagella-mediated motility as compared to its parental strain. Moreover, increased shedding of the flagella-associated proteins was observed in the culture supernatant of SSY11. This finding was also supported by the observation that culture supernatants of the SSY11 strain induced the production of a significantly higher level of IL-8 in human colon carcinoma HT29 and alveolar epithelial A549 cells than those of the wild-type C6706 strain. These results further suggest a definite role of these two OMPs in providing the structural integrity of the V. cholerae flagellum as part of the surrounding sheath.

Journal Article

Proteomic Analysis of Outer Membrane Proteins from Acinetobacter baumannii DU202 in Tetracycline Stress Condition: Sung-Ho Yun , Chi-Won Choi , Soon-Ho Park , Je Chul Lee , Sun-Hee Leem , Jong-Soon Choi , Soohyun Kim , Seung Il Kim; J. Microbiol. 2008;46(6):720-727. Published online December 24, 2008; DOI: https://doi.org/10.1007/s12275-008-0202-3

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Abstract: Acinetobacter baumannii readily developed antimicrobial resistance to clinically available antibiotics. A. baumannii DU202 is a multi-drug resistant strain, and is highly resistant to tetracycline (MIC>1,024μg/ml). The surface proteome of A. baumannii DU202 in response to the sub-minimal inhibitory concentration (subMIC) of tetracycline was analyzed by 2-DE/MS-MS and 1-DE/LC/MS-MS to understand the pathways that form barriers for tetracycline. Membrane expression of major outer membrane proteins (Omps) was significantly decreased in response to the subMIC of tetracycline. These Omps with sizes of 38, 32, 28, and 21 kDa were identified as OmpA38, OmpA32, CarO, and OmpW, respectively. However, transcription level of these Omps was not significantly changed. 1-DE/LC/MS-MS analysis of secreted proteins showed that OmpA38, CarO, OmpW, and other Omps were increasingly secreted at tetracycline condition. This result suggests that A. baumannii actively regulates the membrane expression and the secretion of Omps to overcome antibiotic stress condition.

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