Liu Yanhong, Yoo Brian B, Hwang Cheng-An, Suo Yujuan, Sheen Shiowshuh, Khosravi Parvaneh, Huang Lihan
Molecular Characterization of Foodborne Pathogens Research Unit, Eastern Regional Research Center, Agricultural Research Service, United States Department of Agriculture, WyndmoorPA, United States.
Clinical and Environmental Microbiology Branch, Division of Healthcare Quality and Promotion, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, AtlantaGA, United States.
Front Microbiol. 2017 Aug 29;8:1611. doi: 10.3389/fmicb.2017.01611. eCollection 2017.
is a foodborne pathogen that causes listeriosis, which is a major public health concern due to the high fatality rate. , and encode for fructose-specific EIIABC components of phosphotransferase transport system (PTS) permease that is responsible for sugar transport. In previous studies, in-frame deletion mutants of a putative fructose-specific PTS permease (, and ) were constructed and analyzed. However, the virulence potential of these deletion mutants has not been studied. In this study, two methods were used to analyze the virulence potential of these deletion mutants. First, invasion assays were used to measure the invasion efficiencies to host cells using the human HT-29 cell line. Second, plaque forming assays were used to measure cell-to-cell spread in host cells. Our results showed that the deletion mutant Δ had reduced invasion and cell-to-cell spread efficiencies in human cell line compared to the parental strain , indicating that encoding for a fructose specific PTS permease IIA may be required for virulence in strain F2365. In addition, the gene expression levels of 15 virulence and stress-related genes were analyzed in the stationary phase cells of the deletion mutants using RT-PCR assays. Virulence-related gene expression levels were elevated in the deletion mutants Δ compared to the wild type parental strain , indicating the down-regulation of virulence genes by this PTS permease in . Finally, stress-related gene expression levels were also increased in all of the deletion mutants, suggesting the involvement of this PTS permease in stress response. Furthermore, these deletion mutants displayed the same pressure tolerance and the same capacity for biofilm formation compared to the wild-type parental strain . In summary, our findings suggest that the gene can be used as a potential target to develop inhibitors for new therapeutic and pathogen control strategies for public health.
是一种食源性病原体，可导致李斯特菌病，由于其高致死率，这是一个主要的公共卫生问题。 、 和 编码磷酸转移酶运输系统（PTS）通透酶的果糖特异性EIIABC组分，该通透酶负责糖的运输。在先前的研究中，构建并分析了假定的果糖特异性PTS通透酶（ 、 和 ）的框内缺失突变体。然而，尚未研究这些缺失突变体的毒力潜力。在本研究中，使用两种方法分析这些 缺失突变体的毒力潜力。首先，侵袭试验用于使用人HT-29细胞系测量对宿主细胞的侵袭效率。其次，噬菌斑形成试验用于测量宿主细胞中的细胞间传播。我们的结果表明，与亲本菌株 相比，缺失突变体Δ 在人细胞系中的侵袭和细胞间传播效率降低，这表明编码果糖特异性PTS通透酶IIA可能是菌株F2365毒力所必需的。此外，使用RT-PCR试验分析了缺失突变体的稳定期细胞中15个毒力和应激相关基因的基因表达水平。与野生型亲本菌株 相比，缺失突变体Δ 中的毒力相关基因表达水平升高，表明该PTS通透酶在 中下调了毒力基因。最后，所有缺失突变体中的应激相关基因 表达水平也增加，表明该PTS通透酶参与应激反应。此外，与野生型亲本菌株相比，这些缺失突变体表现出相同的压力耐受性和相同的生物膜形成能力。总之，我们的研究结果表明， 基因可作为开发新型治疗和公共卫生病原体控制策略抑制剂的潜在靶点。
