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Submitted to: Applied and Environmental Microbiology
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 2/28/2007 Publication Date: 5/10/2007 Citation: Malik-Kale, P., Rapheal, B., Parker, C., Joens, L., Klena, J., Quinones, B., Keech, A., Konkel, M. 2007. Characterization of genetically-matched isolates of campylobacter jejuni reveals mutations in genes involved in flagellar biosynthesis alter the organism's virulence potential. Applied and Environmental Microbiology. 73(10) 3123-3136 Interpretive Summary: Campylobacter jejuni is a leading cause of bacterial gastroenteritis worldwide. While C. jejuni isolates can be recovered from a variety of animals including chickens, phenotypic evidence suggests that not all isolates are pathogenic to humans. We defined pathogenic C. jejuni isolates as those capable of invading laboratory cultured human intestinal epithelial cells and secreting a set of defined proteins, the Campylobacter invasion antigens (Cia). We reasoned that differences in gene content or gene expression alter the degree of pathogenicity of C. jejuni isolates. A C. jejuni isolate from a turkey (Turkey) and a second C. jejuni isolate from a chicken (CS) differed in their virulence potential as judged by their in vitro phenotypes; the C. jejuni Turkey isolate was hypothesized to be a more pathogenic isolate than C. jejuni isolate CS as it invaded human epithelial cells and secreted Cia proteins. Additionally, the C. jejuni Turkey and CS isolates were found to be genetically indistinguishable from one another by molecular biological methods. Additional work revealed that flagellin was absent in whole-cell and outer-membrane protein extracts prepared from the CS isolate. Microarray analysis revealed that flagellar genes were expressed at a greater level in the C. jejuni Turkey strain when compared to the C. jejuni CS strain. Finally, newborn piglets inoculated with the C. jejuni Turkey strain developed more severe clinical signs of campylobacteriosis than piglets inoculated with the C. jejuni CS strain. Collectively, these findings support the hypothesis that critical differences in gene expression can alter the pathogenic potential of C. jejuni strains. Technical Abstract: Campylobacter jejuni is a leading cause of bacterial gastroenteritis worldwide. While C. jejuni isolates can be recovered from a variety of animals including chickens, phenotypic evidence suggests that not all isolates are pathogenic to humans. We defined pathogenic C. jejuni isolates as those capable of invading laboratory cultured human intestinal epithelial cells and secreting a set of defined proteins, the Campylobacter invasion antigens (Cia). We reasoned that differences in gene content or gene expression alter the degree of pathogenicity of C. jejuni isolates. A C. jejuni isolate from a turkey (Turkey) and a second C. jejuni isolate from a chicken (CS) differed in their virulence potential as judged by their in vitro phenotypes; the C. jejuni Turkey isolate was hypothesized to be a more pathogenic isolate than C. jejuni isolate CS as it invaded human epithelial cells and secreted Cia proteins. Additionally, the C. jejuni Turkey and CS isolates were found to be genetically indistinguishable from one another by molecular biological methods. Additional work revealed that flagellin was absent in whole-cell and outer-membrane protein extracts prepared from the CS isolate. Microarray analysis revealed that flagellar genes were expressed at a greater level in the C. jejuni Turkey strain when compared to the C. jejuni CS strain. Finally, newborn piglets inoculated with the C. jejuni Turkey strain developed more severe clinical signs of campylobacteriosis than piglets inoculated with the C. jejuni CS strain. Collectively, these findings support the hypothesis that critical differences in gene expression can alter the pathogenic potential of C. jejuni strains. |
