A5015240920- Bacillus and Francisella bacterial research
- Bacteriophages and microbial interactions
- Bacterial Genetics and Biotechnology
- Yersinia bacterium, plague, ectoparasites research
- SARS-CoV-2 and COVID-19 Research
- Viral Infections and Outbreaks Research
- Poxvirus research and outbreaks
- Vibrio bacteria research studies
- Legionella and Acanthamoeba research
- Immune Response and Inflammation
- Microbial Inactivation Methods
- Heat shock proteins research
- Influenza Virus Research Studies
- Hepatitis B Virus Studies
- Viral gastroenteritis research and epidemiology
- Antibiotic Resistance in Bacteria
- Inflammasome and immune disorders
- Nuclear Issues and Defense
- Bacterial biofilms and quorum sensing
- Microbial infections and disease research
- interferon and immune responses
Umeå University
2011-2023
University of Washington
2004
Swedish Defence Research Agency
1995-1997
Walter Reed Army Institute of Research
1997
Institute of Immunological Engineering
1995-1996
Francisella tularensis is a highly infectious, facultative intracellular bacterium which causes epidemics of tularemia in both humans and mammals at regular intervals. The natural reservoir the largely unknown, although it has been speculated that protozoa may harbor it. To test this hypothesis, Acanthamoeba castellanii was cocultured with strain F. engineered to produce green fluorescent protein (GFP) nutrient-rich medium. GFP fluorescence within A. then monitored by flow cytometry...
The facultative intracellular bacterium Francisella tularensis is a highly virulent and contagious organism, little known about its survival mechanisms. We studied the localization of attenuated human vaccine strain, F. LVS, in adherent mouse peritoneal cells, macrophage-like cell line J774A.1, macrophage THP-1. Confocal microscopy infected J774A.1 cells indicated that during first hour infection bacteria colocalized with late endosomal-lysosomal glycoprotein LAMP-1, but within 3 h this...
Microbial ligands, including lipopolysaccharide (LPS) and bacterial lipoproteins, activate Toll-like receptors (TLR) of mononuclear phagocytes, thereby inducing proinflammatory cytokines antimicrobial activity. We show that Francisella tularensis, an intracellular pathogen, is capable inhibiting this macrophage response. Infection with the live vaccine strain F. tularensis LVS rendered cells murine macrophage-like cell line J774A.1 incapable secreting TNF-α or IL-1β mobilizing activity in...
A vector for mutagenesis of Francisella tularensis was constructed based on the pUC19 plasmid. By inserting sacB gene Bacillus subtilis, oriT plasmid RP4, and a chloramphenicol resistance Shigella flexneri, vector, pPV, obtained that allowed specific mutagenesis. protocol developed introduction into live vaccine strain, LVS, F. by conjugation. As proof principle, we aimed to develop mutant defective in expression 23-kDa protein (iglC) previously have shown be prominently upregulated during...
ABSTRACT The murine macrophage-like cell line J774.A1 ingests and allows intracellular growth of Francisella tularensis . We demonstrate that, after 24 h infection, a pronounced cytopathogenicity resulted the J774 cells were undergoing apoptosis. Despite this host apoptosis, no decrease in bacterial numbers was observed. When internalization bacteria prevented or intracellularly located F. eradicated within 12 h, progression apoptosis prevented.
The highly virulent bacterium Francisella tularensis is well adapted to the intracellular habitat but mechanisms behind its survival have been elusive. Recently, it was shown that capable of escaping from phagosome human and mouse monocytic cells. Here this escape affected by gamma interferon (IFN-gamma) treatment peritoneal exudate cells since in treated proportion escaped significantly lower (80%) than untreated (97%) as determined transmission electron microscopy. By contrast, < 1% mutant...
Francisella tularensis subsp. (type A) strain SCHU S4 is a prototypic of the pathogen that highly virulent for humans and other mammals. Its intradermal (i.d.) 50% lethal dose (LD50) mice <10 CFU. We discovered spontaneous mutant, designated FSC043, with an i.d. LD50 >10(8) FSC043 effectively vaccinated against challenge type A strain, protective efficacy was at least as good F. LVS, empirically attenuated which has been used efficacious human vaccine. Comparative proteomics to identify two...
The adaptation of facultative intracellular bacteria to host macrophages involves regulation the synthesis bacterial proteins. We analyzed protein Francisella tularensis LVS growing intracellularly in macrophage-like murine cell line J774 and extracellularly culture medium. After pulse-labeling with [35S] methionine separation by one- two-dimensional polyacrylamide gel electrophoresis, induction a few proteins during growth was demonstrated. One them, 23-kDa protein, prominently induced also...
The Francisella tularensis live vaccine strain (LVS), in contrast to its iglC mutant, replicates the cytoplasm of macrophages. We studied outcome infection murine macrophagelike cell line J774A.1 with LVS and iglC, iglD, mglA mutants, latter which is deficient a global regulator. Compared LVS, all mutants showed impaired intracellular replication up 72 h, number mutant bacteria even decreased. Colocalization LAMP-1 was significantly increased for compared indicating an ability escape into...
ABSTRACT Francisella tularensis is a facultative intracellular bacterial pathogen capable of proliferating within host macrophages. The mechanisms that explain the differences in virulence between various strains species are not well characterized. In present study, we show both attenuated (strain LVS) and virulent (strains FSC200 SCHU S4) replicate at similar rates resting murine peritoneal exudate cells (PEC). However, when PEC were activated by exposure to gamma interferon (IFN-γ), they...
Francisella tularensis is a highly virulent human pathogen. The most strains belong to subspecies and these cause sometimes fatal disease. Despite an intense recent research effort, there very limited information available that explains the unique features of distinguish them from other F. explain their high virulence. Here we report use targeted mutagenesis investigate roles various genes or pathways for virulence strain SCHU S4, type tularensis.The S4 mutants was assessed by following...
Summary Intracellular bacterial pathogens generally express chaperones such as Hsp100s during multiplication in host cells, allowing them to survive potentially hostile conditions. Francisella tularensis is a highly infectious bacterium causing the zoonotic disease tularaemia. The ability of F. multiply and macrophages considered essential for its virulence. Although previous mutant screens have identified Hsp100 chaperone ClpB important intracellular survival, no detailed study has been...
The intracellular bacterium Francisella tularensis survives in mammals, arthropods, and freshwater amoeba. It was previously established that the conventional media used for vitro propagation of this microbe do not yield bacteria mimic those harvested from infected mammals; whether these vitro-cultivated resemble arthropod- or amoeba-adapted is unknown. As a foundation our goal identifying F. outer membrane proteins which are expressed during mammalian infection, we first sought to identify...
A disadvantage of several old vaccines is that the genetic events resulting in attenuation are often largely unknown and reversion to virulence cannot be excluded. In 1950s, a live vaccine strain, LVS, was developed from type B strain Francisella tularensis, causative agent tularemia. which highly attenuated for humans but still virulent mice by some infection routes, has been extensively studied found protect staff laboratory-acquired The efforts improve biopreparedness have identified...
Guanylate binding proteins (GBPs) are interferon-inducible involved in the cell-intrinsic immunity against numerous intracellular pathogens. The molecular mechanisms underlying potent antibacterial activity of GBPs still unclear. have been functionally linked to NLRP3, AIM2 and caspase-11 inflammasomes. Two opposing models currently proposed explain GBPs-inflammasome link: i) would target bacteria or bacteria-containing vacuoles increase cytosolic PAMPs release ii) directly facilitate...
We analysed diverse strains of Francisella tularensis subsp. holarctica to assess if its division into biovars I and II is associated with specific mutations previously linked erythromycin resistance determine the distribution this trait across subspecies. Three-hundred fourteen F. were tested for susceptibility whole-genome sequences these examined SNPs in genes resistance. Each strain was assigned a global phylogenetic framework using genome-wide canonical SNPs. The contribution SNP...
Francisella tularensis subsp. is a highly virulent pathogen for humans especially if inhaled. Consequently, it considered to be potential biothreat agent. An experimental vaccine, F. live vaccine strain, derived from the less holarctica, was developed more than 50 years ago, but remains unlicensed. Previously, we novel by deleting chaperonin clpB gene SCHU S4. S4ΔclpB mice LVS and effective against respiratory challenge with wild type In current study, were interested determine whether...
Cytokine expression was determined in the livers of mice inoculated subcutaneously with Francisella tularensis LVS. During first 48 h infection, there a logarithmic increase bacteria liver, doubling time 2.5 h. Within h, tumor necrosis factor alpha (TNF-alpha), interleukin 10 (IL-10), IL-12, and gamma interferon (IFN-gamma) mRNAs were expressed, production TNF-alpha IFN-gamma demonstrated. There no within 96 mRNA from IL-2, IL-3, or IL-4. After subcutaneous inoculation heat-killed LVS, any...
All four Francisella tularensis subspecies possess gene clusters with potential to express type IV pili (Tfp). These include putative pilin genes, as well pilB, pilC and pilQ, required for secretion assembly of Tfp. A hallmark Tfp is the ability retract pilus upon surface contact, a property mediated by ATPase PilT. Interestingly, out two major human pathogenic only highly virulent strains have functional pilT gene.In previous study, we were able show that one gene, pilA, was essential...
Tularemia, a disease caused by the environmental bacterium Francisella tularensis , is characterized acute febrile illness. F. highly infectious: as few 10 organisms can cause human disease. Tularemia not known to be spread from person person.
The groE operon of Francisella tularensis LVS, encoding the heat shock proteins chaperone-10 (Cpn10) and Cpn60, was sequenced characterized, T-cell response LVS-vaccinated individuals to two third major chaperone, Ft-DnaK, assayed. cpn10 cpn60 genes were amplified by PCR with degenerate oligonucleotides derived from N-terminal sequence proteins. analysis revealed expected open reading frames, estimated Mrs 10,300 57,400. deduced amino acid sequences closely resembled Cpn10 Cpn60 other...