| the 17 kda lipoprotein and encoding gene of francisella tularensis lvs are conserved in strains of francisella tularensis. | a t-cell-stimulating 17 kda protein of the vaccine strain francisella tularensis lvs has previously been cloned, sequenced and shown to be a lipoprotein. in the present study, it was investigated whether the protein, denoted tul4, and its gene are present in various strains of the genus francisella. by western blot analysis, it was demonstrated that a tul4-specific monoclonal antibody bound to a protein present in each of the francisella strains. the immunoreactive proteins had an m(r) of 17 kda ... | 1992 | 1291846 |
| molecular cloning of the reca gene and construction of a reca strain of francisella novicida. | a gene locus that is functionally analogous to the reca gene of escherichia coli was molecularly cloned from francisella novicida. the cloned gene was found to suppress the sensitivity of an e. coli strain to dna-damaging agents and to support genetic recombination in e. coli. after transposon mutagenesis, the reca-like gene locus was returned to f. novicida and a uv-sensitive f. novicida strain was isolated. in contrast to the wild-type strain, this uv-sensitive strain could not be transformed ... | 1992 | 1309722 |
| identification of francisella species and discrimination of type a and type b strains of f. tularensis by 16s rrna analysis. | tularemia is a zoonotic disease, occurring throughout the northern hemisphere. the causative agent, the bacterium francisella tularensis, is represented by two main types. type a is found in north america, whereas type b is mainly found in asia and europe and to a minor extent in north america. no routine technique for rapid diagnosis of tularemia has been generally applied. we have partially sequenced 16s rrnas of two f. tularensis strains, as well as the closely related francisella novicida. o ... | 1990 | 1692676 |
| [construction and analysis of the tularemia pathogen gene library in escherichia coli]. | the library of tularemia causative agent genes cloned on the phc79 plasmid and the partial clonotek of these agents genes in escherichia coli cells have been constructed. the immunochemical analysis has revealed seven clones of escherichia coli harbouring the recombinant plasmids and expressing francisella antigens. the cloned sequences of francisella dna as well as the recombinant plasmids containing them and coding for francisella antigens are capable of specific hybridization with the dna fro ... | 1990 | 2185419 |
| francisella philomiragia comb. nov. (formerly yersinia philomiragia) and francisella tularensis biogroup novicida (formerly francisella novicida) associated with human disease. | over a 12-year period, 16 human strains of a gram-negative, catalase-positive, halophilic, aerobic, nonmotile, small coccoid bacterium were received for identification. on the bases of biochemical characteristics and cellular fatty acid profiles, 14 of these strains were similar to the "philomiragia" bacterium (yersinia philomiragia, species incertae sedis). additional characteristics were growth on thayer-martin agar but no growth or sparse, delayed growth on macconkey agar; oxidase positive; a ... | 1989 | 2671019 |
| transformation of pasteurella novicida. | deoxyribonucleic acid from a streptomycin-resistant mutant of pasteurella novicida transformed portions of p. novicida streptomycin-sensitive populations to streptomycin-resistant. similarly, mutants auxotrophic for tryptophan or purine biosynthesis were also transformed to nutritional independence. | 1969 | 5359612 |
| serum-sensitive mutation of francisella novicida: association with an abc transporter gene. | francisella novicida is a facultative intracellular pathogen that can survive and grow in macrophages by preventing phagolysosomal fusion. in this study in vitro cassette mutagenesis was used to generate a library of insertion mutants of f.novicida. two related mutants, km14 and km14s, initially identified as defective for growth in macrophages, were found to be sensitive to serum. these mutants were also found to grow approximately 1000-fold less well in the livers and spleens of infected mice. ... | 1994 | 7881549 |
| [isolation and molecular-genetic characteristic of a cryptic plasmid from the francisella novicida like f6168 strain]. | a 4 kb plasmid dna has been isolated from francisella novicida like strain f6168. restriction map of the plasmid was constructed for restriction endonucleases hindiii, xbai, ecorv, bgiii. the plasmid pfn10 has been shown to be stably inherited by f. tularensis. the use of pfn10 for the construction of plasmid vectors for microorganisms of the genus francisella is discussed. | 1994 | 8065386 |
| analysis of 16s ribosomal dna sequences of francisella strains and utilization for determination of the phylogeny of the genus and for identification of strains by pcr. | the 16s ribosomal dnas (rdnas) of two strains of francisella tularensis and one strain of francisella philomiragia were sequenced. on the basis of phylogenetic analysis data, the genus francisella was placed in the gamma subclass of the proteobacteria. the most closely related organism was the intracellular bacterium wolbachia persica. the sequenced 16s rdna molecules of the francisella species exhibited very high levels of similarity (98.5 to 99.9%). two variable regions, comprising 390 to 450 ... | 1994 | 8123561 |
| cryptic plasmid pfnl10 from francisella novicida-like f6168: the base of plasmid vectors for francisella tularensis. | the plasmid pfnl1oo was created by ligation of escherichia coli plasmid pbr328 and plasmid pfnl1o from francisella novicida-like strain f6168. this plasmid was able to replicate and to express the genes for chloramphenicol and tetracycline resistance in both e. coli and f. tularensis. the origin of replication of pfnl1o, needed for the replication of pfnl1oo in f. tularensis, was mapped. a sau3a-deletion derivative of pfnl1oo, designated pfnl2oo, was constructed. this plasmid could replicate onl ... | 1996 | 8861039 |
| suppression of francisella tularensis growth in the rat by co-infection with f. novicida. | we have previously shown that when cultured in vitro, peritoneal rat macrophages infected with francisella novicida spontaneously release nitric oxide in sufficient quantities to inhibit bacterial growth. however, it is not known whether f. novicida can have a similar antimicrobial effect in vivo. here we show that a co-infection of f. novicida with francisella tularensis can suppress the number of f. tularensis cells in rat spleens by as much as 100-fold. | 1997 | 9252574 |
| temperature-sensitive lesions in the francisella novicida vala gene cloned into an escherichia coli msba lpxk mutant affecting deoxycholate resistance and lipopolysaccharide assembly at the restrictive temperature. | the valab locus of francisella novicida has previously been found to be highly similar at the deduced amino acid level to msba lpxk of escherichia coli. both vala and msba are members of the superfamily of abc transporters, and they appear to have similar functions. in this study we describe the isolation of a temperature-sensitive valab locus. dna sequence analysis indicates that the only changes to the valab deduced amino acid sequence are changes of s453 to an f and t458 to an i in vala. e. c ... | 1997 | 9401020 |
| mgla and mglb are required for the intramacrophage growth of francisella novicida. | francisella novicida is a facultative intracellular pathogen capable of growing in macrophages. a spontaneous mutant of f. novicida defective for growth in macrophages was isolated on lb media containing the chromogenic phosphatase substrate 5-bromo-4-chloro-3-indolyl phosphate (x-p) and designated gb2. using an in cis complementation strategy, four strains were isolated that are restored for growth in macrophages. a locus isolated from one of these strains complements gb2 for both the intracell ... | 1998 | 9701818 |
| an erythromycin resistance cassette and mini-transposon for constructing transcriptional fusions to cat. | a new cassette (er-cm cassette) and mini-transposon (mtn) (tnmaxercm) based on the previously described mtn, tnmax2 [haas et al., gene 130, 23-31.], have been constructed. the cassette and mtn make use of an erythromycin resistance (err) marker encoded by ermc'. both the er-cm cassette and tnmaxercm also carry a promoterless cat gene to allow the construction of transcriptional fusions and the measurement of transcriptional activity by assaying for chloramphenicol acetyltransferase. we show the ... | 1999 | 10095104 |
| the respiratory burst-inhibiting acid phosphatase acpa is not essential for the intramacrophage growth or virulence of francisella novicida. | acid phosphatases capable of inhibiting the respiratory burst of neutrophils have been identified in certain intracellular pathogens. here we evaluate the role of acpa, a respiratory burst-inhibiting acid phosphatase of francisella, in the virulence and intracellular growth of this organism. an f. novicida acpa null mutant was created and found to exhibit wild-type growth kinetics in both cell-line and inflammatory mouse macrophages. the acpa mutant also shows wild-type replication in the spleen ... | 1999 | 10418134 |
| isolation and characterization of francisella novicida mutants defective in lipopolysaccharide biosynthesis. | in order to identify genes involved in lps biosynthesis we isolated random mutants generated by transposon insertion in francisella novicida. the resulting mutant bank yielded mutants with three distinct lps phenotypes, and three representative mutants were chosen for further study. one mutant that had short o-antigen chains was sensitive to serum; this mutant and one other were more sensitive to killing by deoxycholate than control strains. the third mutant was resistant to deoxycholate killing ... | 2000 | 10612732 |
| detection of francisella tularensis in biological specimens using a capture enzyme-linked immunosorbent assay, an immunochromatographic handheld assay, and a pcr. | the early detection of francisella tularensis, the causative agent of tularemia, is important for adequate treatment by antibiotics and the outcome of the disease. here we describe a new capture enzyme-linked immunosorbent assay (celisa) based on monoclonal antibodies specific for lipopolysaccharide (lps) of francisella tularensis subsp. holarctica and francisella tularensis subsp. tularensis. no cross-reactivity with francisella tularensis subsp. novicida, francisella philomiragia, and a panel ... | 2000 | 10618283 |
| comparison of different pcr approaches for typing of francisella tularensis strains. | in this study, we evaluated three pcr methods for epidemiological typing of francisella tularensis: repetitive extragenic palindromic element pcr (rep-pcr), enterobacterial repetitive intergenic consensus sequence pcr (eric-pcr), and random amplified polymorphic dna (rapd) assay with both m13 and t3-t7 primers. the analysis was performed with 40 strains of f. tularensis isolated from hares, humans, ticks, and a vole. on the basis of the combination of rep, eric, and rapd fingerprints, f. tularen ... | 2000 | 10698989 |
| purified lipopolysaccharide from francisella tularensis live vaccine strain (lvs) induces protective immunity against lvs infection that requires b cells and gamma interferon. | previous results have demonstrated that nonspecific protective immunity against lethal francisella tularensis live vaccine strain (lvs) or listeria monocytogenes infection can be stimulated either by sublethal infection with bacteria or by treatment with bacterial dna given 3 days before lethal challenge. here we characterize the ability of purified lipopolysaccharide (lps) from f. tularensis lvs to stimulate similar early protective immunity. treatment of mice with surprisingly small amounts of ... | 2000 | 10722593 |
| evaluation of pcr-based methods for discrimination of francisella species and subspecies and development of a specific pcr that distinguishes the two major subspecies of francisella tularensis. | previous studies have demonstrated that the four subspecies of the human pathogen francisella tularensis, despite showing marked variations in their virulence for mammals and originating from different regions in the northern hemisphere, display a very close phylogenetic relationship. this property has hampered the development of generally applicable typing methods. to overcome this problem, we evaluated the use of pcr for discrimination of the subspecies using various forms of long arbitrary pr ... | 2000 | 11060087 |
| francisella tularensis strain typing using multiple-locus, variable-number tandem repeat analysis. | francisella tularensis, the etiological agent of tularemia, is found throughout the northern hemisphere. after analyzing the f. tularensis genomic sequence for potential variable-number tandem repeats (vntrs), we developed a multilocus vntr analysis (mlva) typing system for this pathogen. variation was detected at six vntr loci in a set of 56 isolates from california, oklahoma, arizona, and oregon and the f. tularensis live vaccine strain. pcr assays revealed diversity at these loci with total a ... | 2001 | 11526148 |
| nucleotide sequence, structural organization, and functional characterization of the small recombinant plasmid pom1 that is specific for francisella tularensis. | pom1 is a recombinant 4442-bp plasmid that includes the replicon of the francisella novicida-like strain f6168 cryptic plasmid pfnl10 and the tetracycline resistance gene (tetc) of plasmid pbr328. pom1 can stably replicate and is maintained in francisella tularensis biovars tularensis, palaearctica, and palaearctica var. japonica. the replicon of pom1 includes the ori region and the repa gene. the ori region, located upstream of the repa gene includes two sets of 31- and 13-bp direct repeats (dr ... | 2001 | 11591134 |
| comparative biology of incq and incq-like plasmids. | plasmids belonging to escherichia coli incompatibility group q are relatively small (approximately 5 to 15 kb) and able to replicate in a remarkably broad range of bacterial hosts. these include gram-positive bacteria such as brevibacterium and mycobacterium and gram-negative bacteria such as agrobacterium, desulfovibrio, and cyanobacteria. these plasmids are mobilized by several self-transmissible plasmids into an even more diverse range of organisms including yeasts, plants, and animal cells. ... | 2001 | 11729261 |
| genetic organization of the francisella plasmid pfnl10. | we report here the molecular characterization of pfnl10, a 3990-bp cryptic plasmid of francisella novicida-like f6168. the plasmid was maintained in f. novicida utah 112 and f. tularensis lvs strains. we sequenced the entire plasmid and found six open reading frames (orfs)-orf1, orf2, orf3, orf4, orf5, and orfm. orf3, orf4, orf5, and orfm are located on the same strand, and we designated it the plus strand. orf1 and orf2 are on the complementary strand. the orfs appear to be arranged in two oper ... | 2001 | 11735370 |
| identification and characterization of a brucella abortus atp-binding cassette transporter homolog to rhizobium meliloti exsa and its role in virulence and protection in mice. | brucella abortus is a facultative intracellular bacterial pathogen that causes abortion in domestic animals and undulant fever in humans. the mechanism of virulence of brucella spp. is not fully understood yet. furthermore, genes that allow brucella to reach the intracellular niche and to interact with host cells need to be identified. using the genomic survey sequence (gss) approach, we identified the gene encoding an atp-binding cassette (abc) transporter of b. abortus strain s2308. the deduce ... | 2002 | 12183550 |
| tularemia. | francisella tularensis is the etiological agent of tularemia, a serious and occasionally fatal disease of humans and animals. in humans, ulceroglandular tularemia is the most common form of the disease and is usually a consequence of a bite from an arthropod vector which has previously fed on an infected animal. the pneumonic form of the disease occurs rarely but is the likely form of the disease should this bacterium be used as a bioterrorism agent. the diagnosis of disease is not straightforwa ... | 2002 | 12364373 |
| the identification of five genetic loci of francisella novicida associated with intracellular growth. | five transposon mutants of francisella novicida were isolated that are compromised in their ability to grow in mouse macrophages in vitro. sequence analysis of the dna flanking the transposon insertions identified the genes that were interrupted in these mutants. one of the inactivated loci corresponds to the francisella tularensis gene that encodes a 23-kda protein that is the most prominently induced protein following macrophage infection. another insertion was localised to approximately 2 kb ... | 2002 | 12393200 |
| detection of francisella tularensis within infected mouse tissues by using a hand-held pcr thermocycler. | the diagnosis of human cases of tularemia often relies upon the demonstration of an antibody response to francisella tularensis or the direct culturing of the bacteria from the patient. antibody response is not detectable until 2 weeks or more after infection, and culturing requires special media and suspicion of tularemia. in addition, handling live francisella poses a risk to laboratory personnel due to the highly infectious nature of this pathogen. in an effort to develop a rapid diagnostic a ... | 2003 | 12574268 |
| francisella novicida lps has greater immunobiological activity in mice than f. tularensis lps, and contributes to f. novicida murine pathogenesis. | to further understand the role of lps in the pathogenesis of francisella infection, we characterized murine infection with f. novicida, and compared immunobiological activities of f. novicida lps and the lps from f. tularensis live vaccine strain (lvs). f. novicida had a lower intradermal ld(50) in balb/cbyj mice than f. tularensis lvs, and mice given a lethal f. novicida dose intraperitoneally died faster than those given the same lethal f. tularensis lvs dose. however, the pattern of in vivo d ... | 2003 | 12737995 |
| francisella strains express hemolysins of distinct characteristics. | historically, francisella strains have been described as nonhemolytic. in this study, we show by use of solid and liquid hemolysis assays that some francisella strains have hemolytic properties. the francisella novicida type strain u112 is hemolytic to horse erythrocytes and francisella philomiragia type strain fsc144 is hemolytic towards both human and horse erythrocytes. the f. novicida strain u112 released a protein (novilysin a) into the culture supernatant which cross-reacted with antiserum ... | 2003 | 12855173 |
| [is pasteurella novicida n. sp. a variation of pasteurella tularensis]. | | 1957 | 13425102 |
| comparative studies of francisella tularensis and francisella novicida. | owen, c. r. (u.s. public health service, rocky mountain laboratory, hamilton, mont.), e. o. buker, w. l. jellison, d. b. lackman, and j. f. bell. comparative studies of francisella tularensis and francisella novicida. j. bacteriol. 87:676-683. 1964.-comparative studies of various properties of francisella tularensis (= pasteurella tularensis) and f. novicida were performed. the two organisms are very similar morphologically. growth of both was markedly enhanced by addition of cystine to media, b ... | 1964 | 14127585 |
| allelic exchange in francisella tularensis using pcr products. | we describe here a technique for allelic exchange in francisella tularensis subsp. novicida utilizing polymerase chain reaction (pcr) products. linear pcr fragments containing gene deletions with an erythromycin resistance cassette insertion were transformed into f. tularensis. the subsequent ermr progeny were found to have undergone allelic exchange at the correct location in the genome; the minimum flanking homology necessary was 500 bp. this technique was used to create mgla, iglc, bla, and t ... | 2003 | 14680699 |
| clpb, a novel member of the listeria monocytogenes ctsr regulon, is involved in virulence but not in general stress tolerance. | clp-hsp100 atpases are a widespread family of ubiquitous proteins that occur in both prokaryotes and eukaryotes and play important roles in the folding of newly synthesized proteins and refolding of aggregated proteins. they have also been shown to participate in the virulence of several pathogens, including listeria monocytogenes. here, we describe a member of the clp-hsp100 family of l. monocytogenes that harbors all the characteristics of the clpb subclass, which is absent in the closely rela ... | 2004 | 14762012 |
| characterization of the lipopolysaccharide o-antigen of francisella novicida (u112). | francisella novicida (u112), a close relative of the highly virulent bacterium f. tularensis, was shown to produce a lipopolysaccharide in which the antigenic o-polysaccharide component was found by chemical, 1h and 13c nmr and ms analyses to be an unbranched neutral linear polymer of a repeating tetrasaccharide unit composed of 2-acetamido-2-deoxy-d-galacturonamide (d-galnacan) and 2,4-diacetamido-2,4,6-trideoxy-d-glucose (d-qui2nac4nac, di-n-acetylbacillosamine) residues (3:1) and had the stru ... | 2004 | 15013402 |
| characterisation of the core part of the lipopolysaccharide o-antigen of francisella novicida (u112). | francisella novicida (u112), a close relative of the highly virulent bacterium f. tularensis, is known to produce a lipopolysaccharide that is significantly different in biological properties from the lps of f. tularensis. here we present the results of the structural analysis of the f. novicida lps core part, which is found to be similar to that of f. tularensis, differing only by one additional alpha-glc residue:where r is an o-chain, linked via a beta-bacillosamine (2,4-diamino-2,4,6-trideoxy ... | 2004 | 15183739 |
| protection afforded by heat shock protein 60 from francisella tularensis is due to copurified lipopolysaccharide. | heat shock proteins (hsps) have attracted significant attention as protective antigens against a range of diseases caused by bacterial pathogens. however, more recently there have been suggestions that the protective response is due to the presence of peptide components other than hsps. we have shown that mice that had been immunized with purified heat shock protein 60 (hsp60) isolated from francisella tularensis were protected against a subsequent challenge with some strains of the bacterium. h ... | 2004 | 15213156 |
| mice sublethally infected with francisella novicida u112 develop only marginal protective immunity against systemic or aerosol challenge with virulent type a or b strains of f. tularensis. | the current study determined the ability of francisella novicida to act as a live vaccine against the much more virulent, but closely related pathogen, francisella tularensis. live attenuated strains of the latter are effective vaccines against human tularemia. however, the molecular cause of their attenuation remains unknown, and this is a regulatory barrier for licensing such vaccines. moreover, f. tularensis is exceptionally difficult to manipulate genetically. this is hampering the developme ... | 2004 | 15312850 |
| msba transporter-dependent lipid a 1-dephosphorylation on the periplasmic surface of the inner membrane: topography of francisella novicida lpxe expressed in escherichia coli. | the lipid a anchor of francisella tularensis lipopolysaccharide (lps) lacks both phosphate groups present in escherichia coli lipid a. membranes of francisella novicida (an environmental strain related to f. tularensis) contain enzymes that dephosphorylate lipid a and its precursors at the 1- and 4'-positions. we now report the cloning and characterization of a membrane-bound phosphatase of f. novicida that selectively dephosphorylates the 1-position. by transferring an f. novicida genomic dna l ... | 2004 | 15339914 |
| use of transposon-transposase complexes to create stable insertion mutant strains of francisella tularensis lvs. | francisella tularensis is a highly virulent zoonotic bacterial pathogen capable of infecting numerous different mammalian species, including humans. elucidation of the pathogenic mechanisms of f. tularensis has been hampered by a lack of tools to genetically manipulate this organism. herein we describe the use of transposome complexes to create insertion mutations in the chromosome of the f. tularensis live vaccine strain (lvs). a tn5-derived transposon encoding kanamycin resistance and lacking ... | 2004 | 15528561 |
| comparison of enzyme-linked immunosorbent assay, western blotting, microagglutination, indirect immunofluorescence assay, and flow cytometry for serological diagnosis of tularemia. | the serodiagnostic efficiencies of five different approaches to detecting antibodies (immunoglobulins g, a, and m) developed in clinically proven infections with francisella tularensis have been assessed. fifty serum samples from patients suffering from tularemia during an outbreak in sweden were compared with samples from 50 healthy blood donors (controls) by using an enzyme-linked immunosorbent assay (elisa), microagglutination (ma), western blotting (wb), an indirect immunofluorescence assay ... | 2004 | 15539498 |
| intranasal interleukin-12 treatment promotes antimicrobial clearance and survival in pulmonary francisella tularensis subsp. novicida infection. | francisella tularensis is a highly virulent facultative intracellular bacterium and is considered a potential biological warfare agent. inhalation tularemia can lead to the development of bronchopneumonia, which is frequently fatal without medical intervention. treatment strategies that directly target the respiratory mucosa may extend the efficacy of therapy, particularly for the medical management of acute aerosol exposure. to this end, we describe an intranasal (i.n.) strategy for the treatme ... | 2004 | 15561819 |
| construction and characterization of a highly efficient francisella shuttle plasmid. | francisella tularensis is a facultative intracellular pathogen that infects a wide variety of mammals and causes tularemia in humans. it is recognized as a potential agent of bioterrorism due to its low infectious dose and multiple routes of transmission. to date, genetic manipulation in francisella spp. has been limited due to the inefficiency of dna transformation, the relative lack of useful selective markers, and the lack of stably replicating plasmids. therefore, the goal of this study was ... | 2004 | 15574954 |
| intranasal interleukin-12 treatment for protection against respiratory infection with the francisella tularensis live vaccine strain. | francisella tularensis is a gram-negative intracellular bacterium that can induce lethal respiratory infection in humans and rodents. however, little is known about the role of innate or adaptive immunity in protection from respiratory tularemia. in the present study, the role of interleukin-12 (il-12) in inducing protective immunity in the lungs against intranasal infection of mice with the live vaccine strain (lvs) of f. tularensis was investigated. it was found that gamma interferon (ifn-gamm ... | 2005 | 15784575 |
| a novel 3-deoxy-d-manno-octulosonic acid (kdo) hydrolase that removes the outer kdo sugar of helicobacter pylori lipopolysaccharide. | the lipid a domain anchors lipopolysaccharide (lps) to the outer membrane and is typically a disaccharide of glucosamine that is both acylated and phosphorylated. the core and o-antigen carbohydrate domains are linked to the lipid a moiety through the eight-carbon sugar 3-deoxy-d-manno-octulosonic acid known as kdo. helicobacter pylori lps has been characterized as having a single kdo residue attached to lipid a, predicting in vivo a monofunctional kdo transferase (waaa). however, using an in vi ... | 2005 | 15866922 |
| modulation of biogenesis of the francisella tularensis subsp. novicida-containing phagosome in quiescent human macrophages and its maturation into a phagolysosome upon activation by ifn-gamma. | francisella tularensis is a highly virulent facultative intracellular pathogen that has been categorized as a class a bioterrorism agent, and is classified into four subsp, tularensis, holarctica, mediasiatica and novicida. although the ability of f. tularensis subsp. novicida to cause tularemia in mice is similar to the virulent subsp. tularensis and holarctica, it is attenuated in humans. it is not known whether attenuation of f. tularensis subsp. novicida in humans is resulting from a differe ... | 2005 | 15953028 |
| the francisella tularensis pathogenicity island protein iglc and its regulator mgla are essential for modulating phagosome biogenesis and subsequent bacterial escape into the cytoplasm. | the francisella tularensis subsp. novicida-containing phagosome (fcp) matures into a late endosome-like stage that acquires the late endosomal marker lamp-2 but does not fuse to lysosomes, for the first few hours after bacterial entry. this modulation in phagosome biogenesis is followed by disruption of the phagosome and bacterial escape into the cytoplasm where they replicate. here we examined the role of the francisella pathogenicity island (fpi) protein iglc and its regulator mgla in the intr ... | 2005 | 15953029 |
| internalization and phagosome escape required for francisella to induce human monocyte il-1beta processing and release. | macrophage responses to francisella infection have been characterized previously by subdued proinflammatory responses; however, these studies have generally focused on macrophage cell lines or monocyte-derived macrophages. therefore, we studied the ability of fresh human blood monocytes to engulf and respond to francisella by using the live vaccine strain variant and francisella novicida. because francisella organisms have been reported to escape from the phagolysosome into the cytosol, we hypot ... | 2006 | 16373510 |
| internalization and phagosome escape required for francisella to induce human monocyte il-1beta processing and release. | macrophage responses to francisella infection have been characterized previously by subdued proinflammatory responses; however, these studies have generally focused on macrophage cell lines or monocyte-derived macrophages. therefore, we studied the ability of fresh human blood monocytes to engulf and respond to francisella by using the live vaccine strain variant and francisella novicida. because francisella organisms have been reported to escape from the phagolysosome into the cytosol, we hypot ... | 2006 | 16373510 |
| virulence comparison in mice of distinct isolates of type a francisella tularensis. | francisella tularensis subspecies tularensis (type a f. tularensis) is considered to be one of the most virulent of all bacterial pathogens. mice are extremely susceptible to infection with this subspecies (ld100 via various inoculation routes is <10 cfu). however, it has not been established whether overt virulence differences exist amongst type a strains of f. tularensis. to this end, the present study compared the virulence of two distinct type a strains, fsc033 and schu s4, for naïve mice an ... | 2006 | 16448801 |
| expression cloning and periplasmic orientation of the francisella novicida lipid a 4'-phosphatase lpxf. | francisella tularensis and related intracellular pathogens synthesize lipid a molecules that differ from their escherichia coli counterparts. although a functional orthologue of lpxk, the gene encoding the lipid a 4'-kinase, is present in francisella, no 4'-phosphate moiety is attached to francisella lipid a. we now demonstrate that a membrane-bound phosphatase present in francisella novicida u112 selectively removes the 4'-phosphate residue from tetra- and pentaacylated lipid a molecules. a clo ... | 2006 | 16467300 |
| in vivo himar1-based transposon mutagenesis of francisella tularensis. | francisella tularensis is the intracellular pathogen that causes human tularemia. it is recognized as a potential agent of bioterrorism due to its low infectious dose and multiple routes of entry. we report the development of a himar1-based random mutagenesis system for f. tularensis (himarft). in vivo mutagenesis of f. tularensis live vaccine strain (lvs) with himarft occurs at high efficiency. approximately 12 to 15% of cells transformed with the delivery plasmid result in transposon insertion ... | 2006 | 16517634 |
| intranasal vaccination with a defined attenuated francisella novicida strain induces gamma interferon-dependent antibody-mediated protection against tularemia. | francisella tularensis is an intracellular gram-negative bacterium that is the causative agent of tularemia and a potential bioweapon. we have characterized the efficacy of a defined f. novicida mutant (deltaiglc) as a live attenuated vaccine against subsequent intranasal challenge with the wild-type organism. animals primed with the f. novicida deltaiglc (kkf24) mutant induced robust splenic gamma interferon (ifn-gamma) and interleukin-12 (il-12) recall responses with negligible il-4 production ... | 2006 | 16552035 |
| factors affecting transformation of pasteurella novicida. | the requirements and characteristics of pasteurella novicida transformations in liquid suspensions were studied. transformation frequencies of 0.1 to 0.3% were routinely obtained when recipient cells were harvested from 16-hr agar plates and higher than 1% when logarithmic-phase broth-grown cells were used. calcium ions were essential for transformations. the deoxyribonucleic acid dose response curve, kinetics of transformation, and ph optimum for transformations were similar to those of other b ... | 1970 | 16559109 |
| francisella tularensis: taxonomy, genetics, and immunopathogenesis of a potential agent of biowarfare. | tularemia is a zoonosis of humans caused by infection with the facultative intracellular bacterium francisella tularensis. interest in f. tularensis has increased markedly in the past few years because of its potential use as an agent of bioterrorism. five subspecies of this organism are found in the northern hemisphere, but only f. tularensis subsp. tularensis and subsp. holarctica cause disease in humans. this review summarizes what is known about the pathogenesis of tularemia with a focus on ... | 2006 | 16704343 |
| the lipid a 1-phosphatase of helicobacter pylori is required for resistance to the antimicrobial peptide polymyxin. | modification of the phosphate groups of lipid a with amine-containing substituents, such as phosphoethanolamine, reduces the overall net negative charge of gram-negative bacterial lipopolysaccharide, thereby lowering its affinity to cationic antimicrobial peptides. modification of the 1 position of helicobacter pylori lipid a is a two-step process involving the removal of the 1-phosphate group by a lipid a phosphatase, lpxehp (hp0021), followed by the addition of a phosphoethanolamine residue ca ... | 2006 | 16740959 |
| characterization of the lipopolysaccharide and beta-glucan of the fish pathogen francisella victoria. | lipopolysaccharide (lps) and beta-glucan from francisella victoria, a fish pathogen and close relative of highly virulent mammal pathogen francisella tularensis, have been analyzed using chemical and spectroscopy methods. the polysaccharide part of the lps was found to contain a nonrepetitive sequence of 20 monosaccharides as well as alanine, 3-aminobutyric acid, and a novel branched amino acid, thus confirming f. victoria as a unique species. the structure identified composes the largest oligos ... | 2006 | 16759227 |
| identification of francisella tularensis genes affected by iron limitation. | cells of an attenuated live vaccine strain (lvs) of f. tularensis grown under iron-restricted conditions were found to contain increased quantities of several proteins relative to cells of this same strain grown under iron-replete conditions. mass spectrometric analysis identified two of these proteins as iglc and pdpb, both of which are encoded by genes located in a previously identified pathogenicity island in f. tularensis lvs. regions with homology to the consensus fur box sequence were loca ... | 2006 | 16790797 |
| differential infection of mononuclear phagocytes by francisella tularensis: role of the macrophage mannose receptor. | francisella tularensis (ft) is a gram-negative bacterium and the causative agent of tularemia. it is well established that this organism replicates inside macrophages, but we are only beginning to understand this interface at the molecular level. herein, we compared directly the ability of ft subspecies holarctica live-vaccine strain to infect freshly isolated human peripheral blood monocytes, monocyte-derived macrophages (mdm), and cells of the murine macrophage cell line j774a.1 (j774). we now ... | 2006 | 16816147 |
| macrophage pro-inflammatory response to francisella novicida infection is regulated by ship. | francisella tularensis, a gram-negative facultative intracellular pathogen infecting principally macrophages and monocytes, is the etiological agent of tularemia. macrophage responses to f. tularensis infection include the production of pro-inflammatory cytokines such as interleukin (il)-12, which is critical for immunity against infection. molecular mechanisms regulating production of these inflammatory mediators are poorly understood. herein we report that the sh2 domain-containing inositol ph ... | 2006 | 16848641 |
| attenuated francisella novicida transposon mutants protect mice against wild-type challenge. | francisella tularensis is the bacterial pathogen that causes tularemia in humans and a number of animals. to date, there is no approved vaccine for this widespread and life-threatening disease. the goal of this study was to identify f. tularensis mutants that can be used in the development of a live attenuated vaccine. we screened f. novicida transposon mutants to identify mutants that exhibited reduced growth in mouse macrophages, as these cells are the preferred host cells of francisella and a ... | 2006 | 16926401 |
| characterization of the receptor-ligand pathways important for entry and survival of francisella tularensis in human macrophages. | inhalational pneumonic tularemia, caused by francisella tularensis, is lethal in humans. f. tularensis is phagocytosed by macrophages followed by escape from phagosomes into the cytoplasm. little is known of the phagocytic mechanisms for francisella, particularly as they relate to the lung and alveolar macrophages. here we examined receptors on primary human monocytes and macrophages which mediate the phagocytosis and intracellular survival of f. novicida. f. novicida association with monocyte-d ... | 2006 | 16926403 |
| identification of a francisella tularensis lvs outer membrane protein that confers adherence to a549 human lung cells. | francisella tularensis is a highly pathogenic bacterium; however, little is known about its initial interactions with mucosal surfaces of the human respiratory tract. to investigate these interactions, we tested whether two francisella strains could adhere to a549 human lung epithelial cells. we found that lvs adhered well to these cells while francisella novicida adhered poorly. we used surface biotinylation to identify bacterial proteins that might mediate this adherence. we report the identif ... | 2006 | 16958857 |
| lack of in vitro and in vivo recognition of francisella tularensis subspecies lipopolysaccharide by toll-like receptors. | francisella tularensis is an intracellular gram-negative bacterium that is highly infectious and potentially lethal. several subspecies exist of varying pathogenicity. infection by only a few organisms is sufficient to cause disease depending on the model system. lipopolysaccharide (lps) of gram-negative bacteria is generally recognized by toll-like receptor 4 (tlr4)/md-2 and induces a strong proinflammatory response. examination of human clinical f. tularensis isolates revealed that human virul ... | 2006 | 16982824 |
| potential source of francisella tularensis live vaccine strain attenuation determined by genome comparison. | francisella tularensis is a bacterial pathogen that causes the zoonotic disease tularemia and is important to biodefense. currently, the only vaccine known to confer protection against tularemia is a specific live vaccine strain (designated lvs) derived from a virulent isolate of francisella tularensis subsp. holarctica. the origin and source of attenuation of this strain are not known. to assist with the design of a defined live vaccine strain, we sought to determine the genetic basis of the at ... | 2006 | 17000723 |
| identification of mgla-regulated genes reveals novel virulence factors in francisella tularensis. | the facultative intracellular bacterium francisella tularensis causes the zoonotic disease tularemia. f. tularensis resides within host macrophages in vivo, and this ability is essential for pathogenesis. the transcription factor mgla is required for the expression of several francisella genes that are necessary for replication in macrophages and for virulence in mice. we hypothesized that the identification of mgla-regulated genes in the francisella genome by transcriptional profiling of wild-t ... | 2006 | 17000729 |
| role of the wbt locus of francisella tularensis in lipopolysaccharide o-antigen biogenesis and pathogenicity. | francisella tularensis is a highly infectious bacterial pathogen, responsible for the zoonotic disease tularemia. we screened a bank of transposon insertion mutants of f. tularensis subsp. holarctica lvs for colony morphology alterations and selected a mutant with a transposon insertion in wbta, the first gene of the predicted lipopolysaccharide o-antigen gene cluster. inactivation of wbta led to the complete loss of o antigen, conferred serum sensitivity, impaired intracellular replication, and ... | 2007 | 17030571 |
| role of the wbt locus of francisella tularensis in lipopolysaccharide o-antigen biogenesis and pathogenicity. | francisella tularensis is a highly infectious bacterial pathogen, responsible for the zoonotic disease tularemia. we screened a bank of transposon insertion mutants of f. tularensis subsp. holarctica lvs for colony morphology alterations and selected a mutant with a transposon insertion in wbta, the first gene of the predicted lipopolysaccharide o-antigen gene cluster. inactivation of wbta led to the complete loss of o antigen, conferred serum sensitivity, impaired intracellular replication, and ... | 2007 | 17030571 |
| akt/protein kinase b modulates macrophage inflammatory response to francisella infection and confers a survival advantage in mice. | the gram-negative bacterium francisella novicida infects primarily monocytes/macrophages and is highly virulent in mice. macrophages respond by producing inflammatory cytokines that confer immunity against the infection. however, the molecular details of host cell response to francisella infection are poorly understood. in this study, we demonstrate that f. novicida infection of murine macrophages induces the activation of akt. inhibition of akt significantly decreases proinflammatory cytokine p ... | 2006 | 17056562 |
| acpa is a francisella acid phosphatase that affects intramacrophage survival and virulence. | acpa of francisella spp. is a respiratory-burst-inhibiting acid phosphatase that also exhibits phospholipase c activity. to better understand the molecular basis of acpa in virulence, a deletion of acpa was constructed in francisella novicida. the phosphatase and lipase activities were reduced 10-fold and 8-fold, respectively, in the acpa mutant compared to the wild type and were found mostly associated with the outer membrane. the acpa mutant was more susceptible to intracellular killing than t ... | 2007 | 17060465 |
| acpa is a francisella acid phosphatase that affects intramacrophage survival and virulence. | acpa of francisella spp. is a respiratory-burst-inhibiting acid phosphatase that also exhibits phospholipase c activity. to better understand the molecular basis of acpa in virulence, a deletion of acpa was constructed in francisella novicida. the phosphatase and lipase activities were reduced 10-fold and 8-fold, respectively, in the acpa mutant compared to the wild type and were found mostly associated with the outer membrane. the acpa mutant was more susceptible to intracellular killing than t ... | 2007 | 17060465 |
| the immunologically distinct o antigens from francisella tularensis subspecies tularensis and francisella novicida are both virulence determinants and protective antigens. | we have determined the sequence of the gene cluster encoding the o antigen in francisella novicida and compared it to the previously reported o-antigen cluster in francisella tularensis subsp. tularensis. immunization with purified lipopolysaccharide (lps) from f. tularensis subsp. tularensis or f. novicida protected against challenge with francisella tularensis subsp. holarctica and f. novicida, respectively. the lps from f. tularensis subsp. tularensis did not confer protection against challen ... | 2007 | 17074846 |
| the immunologically distinct o antigens from francisella tularensis subspecies tularensis and francisella novicida are both virulence determinants and protective antigens. | we have determined the sequence of the gene cluster encoding the o antigen in francisella novicida and compared it to the previously reported o-antigen cluster in francisella tularensis subsp. tularensis. immunization with purified lipopolysaccharide (lps) from f. tularensis subsp. tularensis or f. novicida protected against challenge with francisella tularensis subsp. holarctica and f. novicida, respectively. the lps from f. tularensis subsp. tularensis did not confer protection against challen ... | 2007 | 17074846 |
| proteolytic adaptor for transfer-messenger rna-tagged proteins from alpha-proteobacteria. | we have identified an analog of sspb, the proteolytic adaptor for transfer-messenger rna (tmrna)-tagged proteins, in caulobacter crescentus. c. crescentus sspb shares limited sequence similarity with escherichia coli sspb but binds the tmrna tag in vitro and is required for optimal proteolysis of tagged proteins in vivo. | 2007 | 17085560 |
| proteolytic adaptor for transfer-messenger rna-tagged proteins from alpha-proteobacteria. | we have identified an analog of sspb, the proteolytic adaptor for transfer-messenger rna (tmrna)-tagged proteins, in caulobacter crescentus. c. crescentus sspb shares limited sequence similarity with escherichia coli sspb but binds the tmrna tag in vitro and is required for optimal proteolysis of tagged proteins in vivo. | 2007 | 17085560 |
| characterization of francisella tularensis outer membrane proteins. | francisella tularensis is a gram-negative coccobacillus that is capable of causing severe, fatal disease in a number of mammalian species, including humans. little is known about the proteins that are surface exposed on the outer membrane (om) of f. tularensis, yet identification of such proteins is potentially fundamental to understanding the initial infection process, intracellular survival, virulence, immune evasion and, ultimately, vaccine development. to facilitate the identification of put ... | 2007 | 17114266 |
| characterization of francisella tularensis outer membrane proteins. | francisella tularensis is a gram-negative coccobacillus that is capable of causing severe, fatal disease in a number of mammalian species, including humans. little is known about the proteins that are surface exposed on the outer membrane (om) of f. tularensis, yet identification of such proteins is potentially fundamental to understanding the initial infection process, intracellular survival, virulence, immune evasion and, ultimately, vaccine development. to facilitate the identification of put ... | 2007 | 17114266 |
| preparation of monoclonal antibodies for detection and identification of francisella tularensis. | monoclonal antibodies (mabs) against francisella tularensis were obtained. three mabs specifically reacted with f. tularensis, while four mabs reacted with other members of the genus francisella as well. fluorescent isothiocyanate-conjugated mabs unequivocally stained bacterial cells in specimens from experimentally infected mice. two mabs agglutinated f. tularensis antigen in the agglutination tests. these mabs should improve methods for detection and identification of f. tularensis. | 2007 | 17121981 |
| preparation of monoclonal antibodies for detection and identification of francisella tularensis. | monoclonal antibodies (mabs) against francisella tularensis were obtained. three mabs specifically reacted with f. tularensis, while four mabs reacted with other members of the genus francisella as well. fluorescent isothiocyanate-conjugated mabs unequivocally stained bacterial cells in specimens from experimentally infected mice. two mabs agglutinated f. tularensis antigen in the agglutination tests. these mabs should improve methods for detection and identification of f. tularensis. | 2007 | 17121981 |
| structure and biosynthesis of free lipid a molecules that replace lipopolysaccharide in francisella tularensis subsp. novicida. | francisella tularensis subsp. novicida u112 phospholipids, extracted without hydrolysis, consist mainly of phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine, and two lipid a species, designated a1 and a2. these lipid a species, present in a ratio of 7:1, comprise 15% of the total phospholipids, as judged by 32pi labeling. although lipopolysaccharide is detectable in f. tularensis subsp. novicida u112, less than 5% of the total lipid a is covalently linked to it. a1 and a2 were ... | 2006 | 17128982 |
| coactivating signals for the hepatic lymphocyte gamma interferon response to francisella tularensis. | the facultative intracellular bacterium francisella tularensis is capable of causing systemic infections in various hosts, including mice and humans. the liver is a major secondary site of f. tularensis infection, but hepatic immune responses to the pathogen remain poorly defined. immune protection against the pathogen is thought to depend on the cytokine gamma interferon (ifn-gamma), but the cellular basis for this response has not been characterized. here we report that natural killer cells fr ... | 2007 | 17178781 |
| coactivating signals for the hepatic lymphocyte gamma interferon response to francisella tularensis. | the facultative intracellular bacterium francisella tularensis is capable of causing systemic infections in various hosts, including mice and humans. the liver is a major secondary site of f. tularensis infection, but hepatic immune responses to the pathogen remain poorly defined. immune protection against the pathogen is thought to depend on the cytokine gamma interferon (ifn-gamma), but the cellular basis for this response has not been characterized. here we report that natural killer cells fr ... | 2007 | 17178781 |
| a comprehensive transposon mutant library of francisella novicida, a bioweapon surrogate. | francisella tularensis, the causative agent of tularemia, is one of the most infectious bacterial pathogens known and is a category a select agent. we created a sequence-defined, near-saturation transposon mutant library of f. tularensis novicida, a subspecies that causes a tularemia-like disease in rodents. the library consists of 16,508 unique insertions, an average of >9 insertions per gene, which is a coverage nearly twice that of the greatest previously achieved for any bacterial species. i ... | 2007 | 17215359 |
| the francisella pathogenicity island protein igla localizes to the bacterial cytoplasm and is needed for intracellular growth. | francisella tularensis is a gram negative, facultative intracellular bacterium that is the etiological agent of tularemia. f. novicida is closely related to f. tularensis but has low virulence for humans while being highly virulent in mice. igla is a 21 kda protein encoded by a gene that is part of an iglabcd operon located on the francisella pathogenicity island (fpi). | 2007 | 17233889 |
| characterization of lipid a acylation patterns in francisella tularensis, francisella novicida, and francisella philomiragia using multiple-stage mass spectrometry and matrix-assisted laser desorption/ionization on an intermediate vacuum source linear ion trap. | lipopolysaccharide (lps) is a major component of the outer membrane of gram-negative bacteria. the lipid a region of lps stimulates the immune system in a structure-dependent manner. we have previously identified the two major lipid a species from francisella tularensis as asymmetric tetraacylated structures containing four long acyl chains (16 and 18 carbons) and a single phosphate group that is partially modified by galactosamine (phillips, n. j.; schilling b.; mclendon, m. k.; apicella, m. a. ... | 2007 | 17263332 |
| attenuated virulence of a francisella mutant lacking the lipid a 4'-phosphatase. | francisella tularensis causes tularemia, a highly contagious disease of animals and humans, but the virulence features of f. tularensis are poorly defined. f. tularensis and the related mouse pathogen francisella novicida synthesize unusual lipid a molecules lacking the 4'-monophosphate group typically found in the lipid a of gram-negative bacteria. lpxf, a selective phosphatase located on the periplasmic surface of the inner membrane, removes the 4'-phosphate moiety in the late stages of f. nov ... | 2007 | 17360489 |
| lipid a modification systems in gram-negative bacteria. | the lipid a moiety of lipopolysaccharide forms the outer monolayer of the outer membrane of most gram-negative bacteria. escherichia coli lipid a is synthesized on the cytoplasmic surface of the inner membrane by a conserved pathway of nine constitutive enzymes. following attachment of the core oligosaccharide, nascent core-lipid a is flipped to the outer surface of the inner membrane by the abc transporter msba, where the o-antigen polymer is attached. diverse covalent modifications of the lipi ... | 2007 | 17362200 |
| modulation of virulence factors in francisella tularensis determines human macrophage responses. | francisella tularensis, the causative agent of tularemia and category a biodefense agent, is known to replicate within host macrophages, though the pathogenesis of this organism is incompletely understood. we have isolated a variant of f. tularensis live vaccine strain (lvs) based on colony morphology and its effect on macrophages. human monocyte-derived macrophages produced more tumor necrosis factor alpha (tnfalpha), interleukin (il)-1beta, il-6, and il-12 p40 following exposure to the variant ... | 2007 | 17369012 |
| francisella tularensis induces il-23 production in human monocytes. | francisella tularensis, the causative agent of tularemia, is phagocytosed by immune cells such as monocytes and macrophages. instead of being destroyed in the phagolysosome, the bacterium escapes the phagosome and replicates within the host cytosol. recent studies indicate that phagosomal escape may have a major impact on the nature of the inflammatory cytokine response to infection. to better understand the host cell response to francisella infection, we exposed human peripheral blood monocytes ... | 2007 | 17372002 |
| host-dependent trigger of caspases and apoptosis by legionella pneumophila. | the dot/icm system of legionella pneumophila triggers activation of caspase-3 during early stages of infection of human macrophages, but apoptosis is delayed until late stages of infection. during early stages of infection of mouse macrophages, the organism triggers rapid caspase-1-mediated cytotoxicity, which is mediated by bacterial flagellin. however, it is not known whether caspase-1 is triggered by l. pneumophila in human macrophages or whether caspase-3 is activated in permissive or nonper ... | 2007 | 17420236 |
| structural heterogeneity and environmentally regulated remodeling of francisella tularensis subspecies novicida lipid a characterized by tandem mass spectrometry. | the structural characterization of environmentally-regulated lipid a derived from francisella tularensis subspecies novicida (fn) u112 is described using negative electrospray ionization with a linear ion trap fourier transform ion cyclotron resonance (it-ft-icr) hybrid mass spectrometer. the results indicate that a unique profile of lipid a molecular structures are synthesized in response to fn growth at 25 degrees c versus 37 degrees c. molecular species were found to be tetra-acylated, sharin ... | 2007 | 17446084 |
| identification of an orphan response regulator required for the virulence of francisella spp. and transcription of pathogenicity island genes. | francisella tularensis is a category a agent of biowarfare/biodefense. little is known about the regulation of virulence gene expression in francisella spp. comparatively few regulatory factors exist in francisella, including those belonging to two-component systems (tcs). however, orphan members of typical tcs can be identified. to determine if orphan tcs members affect francisella gene expression, a gene encoding a product with high similarity to the salmonella pmra response regulator (ftt1557 ... | 2007 | 17452468 |
| development of novel plasmid vectors and a promoter trap system in francisella tularensis compatible with the pfln10 based plasmids. | francisella tularensis is a category a bioterror pathogen which in some cases can cause a severe and fatal human infection. very few virulence factors are known in this species due to the difficulty in working with it as well as the lack of tools for genetic manipulation. this work describes the construction of a shuttle vector that can replicate in escherichia coli and f. tularensis as well as two distinct promoter trap constructs based on the shuttle vector backbone. replication in f. tularens ... | 2007 | 17459476 |
| comparison of francisella tularensis genomes reveals evolutionary events associated with the emergence of human pathogenic strains. | francisella tularensis subspecies tularensis and holarctica are pathogenic to humans, whereas the two other subspecies, novicida and mediasiatica, rarely cause disease. to uncover the factors that allow subspecies tularensis and holarctica to be pathogenic to humans, we compared their genome sequences with the genome sequence of francisella tularensis subspecies novicida u112, which is nonpathogenic to humans. | 2007 | 17550600 |
| twin rna polymerase-associated proteins control virulence gene expression in francisella tularensis. | the mgla protein is the only known regulator of virulence gene expression in francisella tularensis, yet it is unclear how it functions. f. tularensis also contains an mgla-like protein called sspa. here, we show that mgla and sspa cooperate with one another to control virulence gene expression in f. tularensis. using a directed proteomic approach, we show that both mgla and sspa associate with rna polymerase (rnap) in f. tularensis, and that sspa is required for mgla to associate with rnap. fur ... | 2007 | 17571921 |
| mgla regulates francisella tularensis subsp. novicida (francisella novicida) response to starvation and oxidative stress. | mgla is a transcriptional regulator of genes that contribute to the virulence of francisella tularensis, a highly infectious pathogen and the causative agent of tularemia. this study used a label-free shotgun proteomics method to determine the f. tularensis subsp. novicida (f. novicida) proteins that are regulated by mgla. the differences in relative protein amounts between wild-type f. novicida and the mgla mutant were derived directly from the average peptide precursor ion intensity values mea ... | 2007 | 17644593 |
| identification of lpxl, a late acyltransferase of francisella tularensis. | lipopolysaccharide (lps) is a major component of the outer membrane of gram-negative bacteria, and the lipid a region of lps mediates stimulation of the immune system in a structure-dependent manner. unlike the lps of many other gram-negative bacteria, the lps of francisella tularensis isolated from in vitro cultures is not proinflammatory. this observed lack of proinflammatory prowess may reflect structural features of the lipid a, such as the number and length of the acyl chains and the single ... | 2007 | 17724076 |
| generation and characterization of hybridoma antibodies for immunotherapy of tularemia. | tularemia is caused by the gram-negative facultative intracellular bacterium francisella tularensis, which has been classified as a category a select agent-a likely bioweapon. the high virulence of f. tularensis and the threat of engineered antibiotic resistant variants warrant the development of new therapies to combat this disease. we have characterized 14 anti-francisella hybridoma antibodies derived from mice infected with f. tularensis live vaccine strain (lvs) for potential use as immunoth ... | 2007 | 17764754 |
| attenuation and protective efficacy of an o-antigen-deficient mutant of francisella tularensis lvs. | francisella tularensis is a zoonotic, gram-negative coccobacillus that causes tularemia in humans and animals. f. tularensis subspecies tularensis (type a) and f. tularensis subspecies holarctica (type b) are antigenically similar and more virulent than francisella novicida in humans. the genetic locus that encodes the lps o antigen was found to be substantially different between the type b live vaccine strain (lvs) and f. novicida. one lvs-specific gene with homology to a galactosyl transferase ... | 2007 | 17768257 |
| a 55 kda hypothetical membrane protein is an iron-regulated virulence factor of francisella tularensis subsp. novicida u112. | iron is an important nutritional requirement for bacteria due to its conserved role in many essential metabolic processes. as a consequence of the lack of freely available iron in the mammalian host, bacteria upregulate a range of virulence factors during infection. transcriptional analysis of francisella tularensis subsp. novicida u112 grown in iron-deficient medium identified 21 genes upregulated in response to this condition, four of which were attributed to a siderophore operon. in addition, ... | 2007 | 17893160 |