Project description:This SuperSeries is composed of the following subset Series: GSE26473: Secreted bacterial effectors that inhibit host protein synthesis are critical for induction of the innate immune response to virulent Legionella pneumophila [exp1] GSE26490: Secreted bacterial effectors that inhibit host protein synthesis are critical for induction of the innate immune response to virulent Legionella pneumophila [exp2] Refer to individual Series
Project description:Legionella pneumophila is a Gram-negative facultative intracellular human pathogen with a distinct biphasic lifestyle. One of its primary environmental hosts in the free-living amoeba Acanthamoeba castellanii and its infection by L. pneumophila mimics that seen in human macrophages. Here we present analysis of strand specific sequencing of the transcriptional response of L. pneumophila in broth growth and in infection of A. castellanii.
Project description:Differential gene expression of Dictyostelium discoideum after infection with Legionella pneumophila was investigated using DNA microarrays. A detailed analysis of the 24 h time point post infection was performed in comparison to three controls, uninfected cells and co-incubation with Legionella hackeliae and L. pneumophila DeltadotA. One hundred and thirty-one differentially expressed D. discoideum genes were identified as common to all three experiments and are thought to be involved in the pathogenic response. Functional annotation of the differentially regulated genes revealed that apart from triggering a stress response Legionella apparently not only interferes with intracellular vesicle fusion and destination but also profoundly influences and exploits the metabolism of its host. The results provide the basis for a better understanding of the complex host-pathogen interactions and for further studies on the Dictyostelium response to Legionella infection.
Project description:Differential gene expression of Dictyostelium discoideum after infection with Legionella pneumophila was investigated using DNA microarrays. A detailed analysis of the 24 h time point post infection was performed in comparison to three controls, uninfected cells and co-incubation with Legionella hackeliae and L. pneumophila DeltadotA. One hundred and thirty-one differentially expressed D. discoideum genes were identified as common to all three experiments and are thought to be involved in the pathogenic response. Functional annotation of the differentially regulated genes revealed that apart from triggering a stress response, Legionella apparently not only interferes with intracellular vesicle fusion and destination but also profoundly influences and exploits the metabolism of its host. The results provide the basis for a better understanding of the complex host-pathogen interactions and for further studies on the Dictyostelium response to Legionella infection.
Project description:Differential gene expression of Dictyostelium discoideum after infection with Legionella pneumophila was investigated using DNA microarrays. A detailed analysis of the 24 h time point post infection was performed in comparison to three controls, uninfected cells and co-incubation with Legionella hackeliae and L. pneumophila DeltadotA. One hundred and thirty-one differentially expressed D. discoideum genes were identified as common to all three experiments and are thought to be involved in the pathogenic response. Functional annotation of the differentially regulated genes revealed that apart from triggering a stress response Legionella apparently not only interferes with intracellular vesicle fusion and destination but also profoundly influences and exploits the metabolism of its host. The results provide the basis for a better understanding of the complex host-pathogen interactions and for further studies on the Dictyostelium response to Legionella infection.
Project description:Legionella pneumophila is a Gram-negative facultative intracellular human pathogen with a distinct biphasic lifestyle. One of its primary environmental hosts in the free-living amoeba Acanthamoeba castellanii and its infection by L. pneumophila mimics that seen in human macrophages. Here we present analysis of strand specific sequencing of the transcriptional response of L. pneumophila in broth growth and in infection of A. castellanii. Examination of 2 infection and 3 broth growth time points
Project description:Legionella pneumophila are important opportunistic pathogens for which environmental reservoirs such as protists are crucial for the infection of humans. Free-living amoebae are considered key hosts providing nutrients and shelter for highly efficient intracellular proliferation of L. pneumophila, which eventually leads to lysis of the amoeba host cell. Yet, the significance of other bacterial players for L. pneumophila ecology is poorly understood. In this study we used a ubiquitous amoeba and their bacterial endosymbiont to investigate the impact of this common association on L. pneumophila infection. We demonstrate that Acanthamoeba castellanii harboring the chlamydial symbiont Protochlamydia amoebophila were able to erase L. pneumophila and, in contrast to symbiont-free amoebae, survived the infection and were able to resume growth. Environmental amoeba isolates harboring P. amoebophila were equally well-protected, and fresh environmental isolates of L. pneumophila were equally well-erased, suggesting ecological relevance of this symbiont-mediated protection. We further show that protection was not mediated by impaired L. pneumophila uptake. Instead, we observed reduced virulence of L. pneumophila released from symbiont-containing amoebae that is strongly supported by transcriptome data. Interference with transition to the transmissive phase is thus likely the basis for this protection. Finally, our data indicate that the defensive response of amoebae harboring P. amoebophila leaves the amoebae with superior fitness reminiscent of immunological memory. Given that mutualistic associations between bacteria and amoebae are widely distributed, P. amoebophila and potentially other amoeba endosymbionts could be key elements in shaping environmental survival, abundance and virulence of this important pathogen thereby affecting frequency of human infection.
Project description:Differential gene expression of Dictyostelium discoideum after infection with Legionella pneumophila was investigated using DNA microarrays. A detailed analysis of the 24 h time point post infection was performed in comparison to three controls, uninfected cells and co-incubation with Legionella hackeliae and L. pneumophila DeltadotA. One hundred and thirty-one differentially expressed D. discoideum genes were identified as common to all three experiments and are thought to be involved in the pathogenic response. Functional annotation of the differentially regulated genes revealed that apart from triggering a stress response Legionella apparently not only interferes with intracellular vesicle fusion and destination but also profoundly influences and exploits the metabolism of its host. The results provide the basis for a better understanding of the complex host-pathogen interactions and for further studies on the Dictyostelium response to Legionella infection. The bacterial strains used in this study were L. pneumophila Philadelphia I JR32, L. pneumophila Philadelphia I JR32 LELA 3118 (dotA3118:Tn903 DLL LacZ) and L. hackeliae (ATCC 35250). The Legionella strains were grown on buffered charcoal yeast extract agar (BCYE) at 37M-BM-0C with 5% CO2 atmosphere for 3 days. The D. discoideum wild-type strain AX2 was grown at 23M-BM-0C in 75 cm2 cell-culture flasks with 10 ml HL5 medium. For infection, Dictyostelium cells were harvested, resuspended in a 1:1 solution of HL5 medium and Soerensen buffer. Fifteen millilitres of a 1M-CM-^W10e6 cells/ml suspension were seeded into a 75 square-cm cell culture flask and the amoebae were inoculated with 10e7 bacteria/ml. Three different pairs of infection were compared: 1. AX2 infected with L. pneumophila JR32 versus uninfected cells; 19 microarrays of seven independent infections; 2. AX2 infected with L. pneumophila JR32 versus AX2 infected with L. pneumophila JR32 delta DotA; 4 microarrays of two independent infections; 3. AX2 infected with L. pneumophila JR32 versus AX2 infected with L. hackeliae; 4 microarrays of two independent infections. 24h post infection the RNA was isolated from 1.5M-CM-^W10e7 Dictyostelium cells and microarray analysis was performed as described (Farbrother et al., 2006).