Francisella tularensis is a highly infectious bacterium with the potential to cause high fatality rates if infections are untreated. To aid in the development of rapid and accurate detection assays, we have sequenced and annotated the genomes of 18 F. tularensis and Francisella philomiragia strains. ...[more]
Project description:We used an inhalation mouse model of infection to query a collection of 2149 mutants in a Francisella tularensis subsp. novicida background for genes required for growth, survival and systemic dissemination. A microarray-based genome-wide negative selection screen (Microarray tracking of transposon mutants = MATT) allowed us to monitor the behavior of transposon insertions in 1371 unique genes. Interestingly most of these genes persisted in lung and colonized liver and spleen. We found 44 (35%) genes negatively selected in lung and 81 (65%) genes negatively selected in liver and/or spleen. If negative selection in lung occurred, the attenuated mutants in general persisted at 24h after infection, disseminated to liver and/or spleen and appeared to be lost in lung after 48 to 72h of infection. These genes with a strong phenotype in lung but also potential for dissemination might be attractive vaccine or drug candidates. Keywords: Genome-Wide Negative Selection Screen 185 arrays, no duplicates/replicates Filtered data (per organ/timepoint) provided as a supplementary file
Project description:Prior aerosol exposure to F. tularensis subsp. tularensis, but not the live attenuated strain (LVS) of F. tularensis subsp. holarctica or F. novicida, significantly antagonized the transcriptional response in the lungs of infected mice exposed to aerosolized TLR4 ligand E. coli LPS. Overall design: The ability of a Toll-like receptor 4 (TLR4) agonist to induce a pulmonary inflammatory response in Francisella-infected animals was examined to distinguish between these two possible mechanisms, and also to investigate potential differences between three Francisella strains that exhibit varying levels of virulence in humans.
Project description:Differential expression in human peripheral blood monocytes between F. novicida-infected and uninfected, and between Francisella tularensis tularensis isolate Schu S4 and uninfected. The goal was to examine genomewide transcriptional reponses to these two strains, and identify differentially-regulated genes that may help explain the virulence of Schu S4. Keywords: Immune Response, Human Monocytes, Bacteria, Francisella Overall design: Human monocytes were infected with the Schu S4 isolate of Francisella tularensis tularensis (n=4), with F. tularensis subspecies novicida isolate U112 (n=4) or were left uninfected (n=6). Gene expression values were calculated using the gcrma package in R and BioConductor, and limma to identify differentially expressed genes. Submitted here are expression values calculated using R 2.7.1 and BioConductor 2.2 (FreeBSD/amd64) but the original were done using R 2.6.1 and BioConductor 2.1 (FreeBSD/amd64). Twelve other chips were pooled with these 14 for preprocessing.
Project description:These samples are part of an experiment comparing the expression profiles of Francisella tularensis novicida grown in chemically defined medium and bacteria isolated 24 hours post infection of J774 macrophages to identify virulence factors Custom microarray submitted previously was used as the platform (GPL20119). The samples submitted here were compared with samples submitted previously (GSM1673555-57 in GSE68478) and differentially expressed genes during the intra-macrophage growth were identified.