Switch from planktonic to sessile life: a major event in pneumococcal pathogenesis

作者：Marco Rinaldo Oggioni, Claudia Trappetti, Aras Kadioglu, Marco Cassone, Francesco Iannelli, Susanna Ricci, Peter William Andrew, Gianni Pozzi · 发表于：Molecular Microbiology · 年份：2006 · DOI：10.1111/j.1365-2958.2006.05310.x · 被引用次数：273 · 研究领域：Pneumonia and Respiratory Infections、Bacterial Infections and Vaccines、Inhalation and Respiratory Drug Delivery

Two main patterns of gene expression of Streptococcus pneumoniae were observed during infection in the host by quantitative real time RT-PCR; one was characteristic of bacteria in blood and one of bacteria in tissue, such as brain and lung. Gene expression in blood was characterized by increased expression of pneumolysin, pspA and hrcA, while pneumococci in tissue infection showed increased expression of neuraminidases, metalloproteinases, oxidative stress and competence genes. In vitro situations with similar expression patterns were detected in liquid culture and in a newly developed pneumococcal model of biofilm respectively. The biofilm model was dependent on addition of synthetic competence stimulating peptide (CSP) and no biofilm was formed by CSP receptor mutants. As one of the differentially expressed gene sets in vivo were the competence genes, we exploited competence-specific tools to intervene on pneumococcal virulence during infection. Induction of the competence system by the quorum-sensing peptide, CSP, not only induced biofilm formation in vitro, but also increased virulence in pneumonia in vivo. In contrast, a mutant for the ComD receptor, which did not form biofilm, also showed reduced virulence in pneumonia. These results were opposite to those found in a bacteraemic sepsis model of infection, where the competence system was downregulated. When pneumococci in the different physiological states were used directly for challenge, sessile cells grown in a biofil...