Showing papers on "Bacillus anthracis published in 1998"

Proteolytic Inactivation of MAP-Kinase-Kinase by Anthrax Lethal Factor

Abstract: Anthrax lethal toxin, produced by the bacterium Bacillus anthracis, is the major cause of death in animals infected with anthrax. One component of this toxin, lethal factor (LF), is suspected to be a metalloprotease, but no physiological substrates have been identified. Here it is shown that LF is a protease that cleaves the amino terminus of mitogen-activated protein kinase kinases 1 and 2 (MAPKK1 and MAPKK2) and that this cleavage inactivates MAPKK1 and inhibits the MAPK signal transduction pathway. The identification of a cleavage site for LF may facilitate the development of LF inhibitors.

PCR analysis of tissue samples from the 1979 Sverdlovsk anthrax victims: The presence of multiple Bacillus anthracis strains in different victims

Abstract: An outbreak of human anthrax occurred in Sverdlovsk, Union of Soviet Socialists Republic (now Ekaterinburg, Russia) in April 1979. Officials attributed this to consumption of contaminated meat, but Western governments believed it resulted from inhalation of spores accidentally released from a nearby military research facility. Tissue samples from 11 victims were obtained and methods of efficiently extracting high-quality total DNA from these samples were developed. Extracted DNA was analyzed by using PCR to determine whether it contained Bacillus anthracis-specific sequences. Double PCR using “nested primers” increased sensitivity of the assay significantly. Tissue samples from 11 persons who died during the epidemic were examined. Results demonstrated that the entire complement of B. anthracis toxin and capsular antigen genes required for pathogenicity were present in tissues from each of these victims. Tissue from a vaccination site contained primarily nucleic acids from a live vaccine, although traces of genes from the infecting organisms were also present. PCR analysis using primers that detect the vrrA gene variable region on the B. anthracis chromosome demonstrated that at least four of the five known strain categories defined by this region were present in the tissue samples. Only one category is found in a single B. anthracis strain.

The pathology of experimental anthrax in rabbits exposed by inhalation and subcutaneous inoculation.

Abstract: ○ Objective. Although rhesus monkeys are considered to be an appropriate model for inhalational anthrax in humans, an alternative for vaccine and therapeutic efficacy studies is desirable. This study characterized the pathology of lethal anthrax in rabbits challenged by subcutaneous inoculation and aerosol exposure. Materials and Methods.--New Zealand white rabbits were exposed by subcutaneous inoculation or aerosol to lethal doses of Bacillus anthracis spores. Results. The pathology of anthrax in rabbits exposed by either route was similar, with principal findings occurring in the spleen, lymph nodes, lungs, gastrointestinal tract, and adrenal glands. The cardinal changes were hemorrhage, edema, and necrosis, with bacilli and limited leukocytic infiltration. Features that depended on the route of exposure included mediastinitis in aerosol-exposed rabbits, a primary dermal lesion after subcutaneous inoculation, and differences in the pattern of lymph node involvement. Lesions observed in rabbits were comparable to those of inhalational anthrax in humans and rhesus monkeys. Noteworthy differences included the lack of leukocytic infiltration in brain and meningeal lesions, the relatively mild mediastinal lesions, and a lower incidence of anthrax-related pneumonia in rabbits compared with humans. These differences may be attributed to the greater susceptibility of rabbits to anthrax. Increased susceptibility is associated with both reduced leukocytic response to the bacilli and a more rapid progression to death, which further limits development of leukocytic infiltrates in response to the basic lesions of hemorrhage and necrosis. Primary pneumonic foci of inhalational anthrax, which may be influenced by preexisting pulmonary lesions in humans, were not observed in our rabbits, which were free of preexisting pulmonary disease. Conclusion. Anthrax in rabbits may provide a useful model for evaluating prophylaxis and therapy against inhalational anthrax in humans.

Anthrax Pathogenesis and Host Response

Abstract: Anthrax has been both a scourge and a fundamental model for infectious disease studies for over a century. Death associated with systemic anthrax is mimicked in animals challenged with anthrax lethal toxin, a virulence factor believed to affect only macrophages. Animals depleted of macrophages become resistant to the toxin, while reintroduction of cultured macrophages into depleted animals restores sensitivity. These studies and others implicate an active role for the innate immune system in the demise of the anthrax victim. Many of the molecular factors and events in the cascade of lethal events during anthrax infections have now been identified. Other recent overviews of anthrax pathogenesis and toxins include those by Stephen (1986), Friedlander (1990), Leppla (1995), and Hanna and Collier (1997).

The Capsule and S-Layer: Two Independent and Yet Compatible Macromolecular Structures in Bacillus anthracis

Abstract: Bacillus anthracis, a gram-positive spore-forming bacterium, is the causative agent of anthrax. This disease, to which many animals, including humans, are susceptible, involves toxemia and septicemia. In the mammalian host, B. anthracis bacilli synthesize two toxins (lethal and edema toxins) (31) and a capsule (18) encoded by two large plasmids, pXO1 and pXO2, respectively (12, 21). The capsule is composed of poly-γ-d-glutamic acid and has antiphagocytic properties (13, 31, 37). Although unusual, a similar capsule is also found on Bacillus licheniformis bacilli (9). In the absence of pXO2 or the inducer bicarbonate, the cell does not produce a capsule and the cell wall appears layered. These layers are composed of fragments displaying a highly patterned ultrastructure (10, 16). This type of cell surface is now referred to as the surface layer (S-layer). S-layers are present on the surfaces of many archaea and bacteria (for reviews, see references 29 and 30). Most are formed by noncovalent, entropy-driven assembly of a single (glyco)protein protomer on the bacterial surface, giving rise to proteinaceous paracrystalline layers. Generally, a single S-layer is present, constituting 5 to 10% of total cell protein. Its synthesis is thus presumably energy consuming for the bacterium. Numerous bacteria have S-layers, suggesting that they play important roles in the interaction between the cell and its environment. Various functions have been proposed for S-layers, including shape maintenance and molecular sieving, and they can serve in phage fixation. The S-layer may be a virulence factor, protecting pathogenic bacteria against complement killing, facilitating binding of bacteria to host molecules, or enhancing their ability to associate with macrophages (for reviews, see references 27 and 29). Some bacteria, such as cyanobacteria or Azotobacter spp., possess both a capsule and an S-layer; however, to our knowledge, their structural relationships have not been analyzed through simultaneous genetic and cytologic studies. Both of these features have been independently described for the surface of the pathogenic bacterium B. anthracis. The components of the B. anthracis S-layer are two abundant surface proteins, EA1 and Sap (6, 20). Previous analyses of the B. anthracis S-layer used plasmid-cured strains; consequently, the interaction, if any, between the capsule and the S-layer could not be studied. Temporal or environmental regulation could be such that only one or the other structure is ever present at the cell surface. However, we show that S-layer proteins are synthesized under conditions where the bacilli are capsulated. We determined the localizations of capsule and S-layer components and analyzed whether the S-layer is necessary for proper capsulation. Finally, the assembly of the S-layer proteins in a two-dimensional crystal was examined in the presence of the capsule.

Molecular Characterization of Bacillus Strains Involved in Outbreaks of Anthrax in France in 1997

Abstract: Outbreaks of anthrax zoonose occurred in two regions of France in 1997. Ninety-four animals died, and there were three nonfatal cases in humans. The diagnosis of anthrax was rapidly confirmed by bacteriological and molecular biological methods. The strains of Bacillus anthracis in animal and soil samples were identified by a multiplex PCR assay. They all belonged to the variable-number tandem repeat (VNTR) group (VNTR)3. A penicillin-resistant strain was detected. Nonvirulent bacilli related to B. anthracis, of all VNTR types, were also found in the soil.

Fermentation, Purification, and Characterization of Protective Antigen from a Recombinant, Avirulent Strain of Bacillus anthracis

Abstract: Bacillus anthracis, the etiologic agent for anthrax, produces two bipartite, AB-type exotoxins, edema toxin and lethal toxin. The B subunit of both exotoxins is an Mr 83,000 protein termed protective antigen (PA). The human anthrax vaccine currently licensed for use in the United States consists primarily of this protein adsorbed onto aluminum oxyhydroxide. This report describes the production of PA from a recombinant, asporogenic, nontoxigenic, and nonencapsulated host strain of B. anthracis and the subsequent purification and characterization of the protein product. Fermentation in a high-tryptone, high-yeast-extract medium under nonlimiting aeration produced 20 to 30 mg of secreted PA per liter. Secreted protease activity under these fermentation conditions was low and was inhibited more than 95% by the addition of EDTA. A purity of 88 to 93% was achieved for PA by diafiltration and anion-exchange chromatography, while greater than 95% final purity was achieved with an additional hydrophobic interaction chromatography step. The purity of the PA product was characterized by reversed-phase high-pressure liquid chromatography, sodium dodecyl sulfate (SDS)-capillary electrophoresis, capillary isoelectric focusing, native gel electrophoresis, and SDS-polyacrylamide gel electrophoresis. The biological activity of the PA, when combined with excess lethal factor in the macrophage cell lysis assay, was comparable to previously reported values.

Ltx1, a mouse locus that influences the susceptibility of macrophages to cytolysis caused by intoxication with Bacillus anthracis lethal factor, maps to chromosome 11

Abstract: The lethal factor (LF) toxin that is produced by Bacillus anthracis plays an important role in the pathogenesis of anthrax. LF has mononuclear phagocyte-specific intoxicating effects that are not well understood. We have identified genetic differences in inbred mouse strains that determine whether their cultured macrophages are susceptible to the cytolytic effect of LF intoxication. Our identification of resistant and susceptible mouse strains enabled us to analyse crosses between these strains and to map a single responsible gene (called Ltx1 ) to chromosome 11. Ltx1 probably influences intoxication events that occur after the delivery of LF to the cytosol, as all mouse macrophages are killed by polypeptides containing the catalytic domain of Diphtheria toxin fused to the domain of LF required for cytosolic transport. Furthermore, the susceptibility phenotype is dominant to resistance, suggesting that resistance is caused by an absence of or polymorphism in a molecule that acts jointly with, or downstream of, the activity of LF. Our mapping of Ltx1 is a crucial first step in its positional cloning, which will provide more information about the mechanism of LF intoxication.

Study of Immunization against Anthrax with the Purified Recombinant Protective Antigen of Bacillus anthracis

Abstract: Protective antigen (PA) of anthrax toxin is the major component of human anthrax vaccine. Currently available human vaccines in the United States and Europe consist of alum-precipitated supernatant material from cultures of toxigenic, nonencapsulated strains of Bacillus anthracis. Immunization with these vaccines requires several boosters and occasionally causes local pain and edema. We previously described the biological activity of a nontoxic mutant of PA expressed in Bacillus subtilis. In the present study, we evaluated the efficacy of the purified mutant PA protein alone or in combination with the lethal factor and edema factor components of anthrax toxin to protect against anthrax. Both mutant and native PA preparations elicited high anti-PA titers in Hartley guinea pigs. Mutant PA alone and in combination with lethal factor and edema factor completely protected the guinea pigs from B. anthracis spore challenge. The results suggest that the mutant PA protein may be used to develop an effective recombinant vaccine against anthrax.

Internalization of a bacillus anthracis protective antigen-c-myc fusion protein mediated by cell surface anti-c-myc antibodies

Abstract: Anthrax toxin, secreted by Bacillus anthracis, consists of protective antigen (PA) and either lethal factor (LF) or edema factor (EF). PA, the receptor-binding component of the toxin, translocates LF or EF into the cytosol, where the latter proteins exert their toxic effects. We hypothesized that anthrax toxin fusion proteins could be used to kill virus-infected cells and tumor cells, if PA could be redirected to unique receptors found only on these cells. To test this hypothesis in a model system, amino acids 410–419 of the human p62c-myc epitope were fused to the C-terminus of PA to redirect PA to the c-Myc-specific hybridoma cell line 9E10. The PA-c-Myc fusion protein killed both mouse macrophages and 9E10 hybridoma cells when administered with LF or an LF fusion protein (FP59), respectively. Similar results were obtained with PA, which suggests that PA-c-Myc used the endogenous PA receptor to enter the cells. By blocking the endogenous PA receptors on 9E10 cells with the competitive inhibitor PA SNKEΔFF, the PA-c-Myc was directed to an alternate receptor, i.e., the anti-c-Myc antibodies presented on the cell surface. The c-Myc IgG were proven to act as receptors because the addition of a synthetic peptide containing the c-Myc epitope along with PA SNKEΔFF further reduced the toxicity of PA-c-Myc + FP59. This study shows that PA can be redirected to alternate receptors by adding novel epitopes to the C-terminus of PA, enabling the creation of cell-directed toxins for therapeutic purposes.

Production and purification of recombinant protective antigen and protective efficacy against Bacillus anthracis.

Abstract: Recombinant protective antigen (rPA), expressed by Bacillus subtilis WB600 (pPA101), has been purified to homogeneity and the protective efficacy against a Bacillus anthracis challenge has been investigated. rPA was fractionated from culture supernatant fluid by ammonium sulphate, followed by anion exchange chromatography using DEAE Streamline™, anion-exchange chromatography on FPLC MonoQ HR 10/10 and finally, gel filtration chromatography on FPLC Superose 12 HR 10/30, to yield 7 mg rPA per litre of culture. The protective efficacy of rPA against an airborne challenge with the AMES strain of B. anthracis was determined in the presence of the adjuvants, alhydrogel and Ribi, and compared to that achieved by the current UK human vaccine in guinea pigs. rPA combined with the Ribi adjuvant was found to provide 100% protection against challenge.

The expression of the protective antigen of Bacillus anthracis in Bacillus subtilis.

Abstract: The expression of Bacillus anthracis protective antigen (PA) in B. subtilis from the pag gene in pPA101–Colour RGB 0,0,1281 was explored in different genetic backgrounds in an attempt to identify opportunities to maximize expression. Introduction of AtxA, which positively regulates PA expression in B. anthracis did not improve expression levels in the protease-deficient strain WB600. Plasmid pPA101–1 was found to carry a deletion which created a new fusion point between vector and insert sequence, and which removed part of the AtxA binding site. The deletion may have occurred as a consequence of recombination between TCTAT sequences within both the vector and insert. Host mutations could influence expression; PA levels from pPA101–1 are threefold higher in a ccpA mutant than in an otherwise isogenic parent, and eightfold higher in an abrB mutant. These data demonstrate that the introduction of mutations affecting catabolite repression and growth phase regulation results in an increase in the yield of PA in this host–vector system. Combining these mutations with a multiply protease-negative background could potentially allow further improvements in PA yield.

Expression and Purification of the Recombinant Lethal Factor of Bacillus anthracis

Abstract: The structural gene for the 90-kDa lethal factor (LF) isolated from Bacillus anthracis was expressed as a fusion protein with six histidine residues in Escherichia coli. Expression of LF in E. coli under the transcriptional regulation of the T5 promoter yielded a soluble cytosolic protein with an apparent molecular mass of 90 kDa, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Recombinant LF reacted with anti-LF antibodies. The protein was purified to homogeneity by nickel nitrilotriacetic acid affinity chromatography and gel filtration on a Sephacryl S-200 column followed by anion exchange on a fast-performance liquid chromatograph with a Resource-Q column. The yield of purified LF from this procedure was 1.5 mg/liter. In solution, trypsin cleaved protective antigen bound to native and recombinant LF with comparable affinities. In macrophage lysis assays, native and recombinant LF exhibited identical potencies. The results suggest that large amounts of biologically active LF can be purified by this procedure.

A heat‐inducible Bacillus subtilis bacteriophage Φ105 expression system for the production of the protective antigen of Bacillus anthracis

Abstract: The protective antigen of Bacillus anthracis is the major protective immunogen in the current human vaccine. A heat-inducible protective antigen expression system was constructed based on a derivative of Bacillus subtilis phage phi 105. The recombinant protein produced by this system protected immunised animals against challenge with spores of B. anthracis. Gene instability and protease activity of the host strain contributed to the low level of recoverable protein in culture supernatant (approximately 2 mg l-1).

Surgical management of cutaneous anthrax.

Abstract: Cutaneous anthrax in humans is a very rare disease caused by Bacillus anthracis. Humans become infected with this spore-forming bacterium when they come into contact with an infected animal. The disease usually develops on exposed sites like the hands and the face. The authors present 4 patients with cutaneous anthrax: 2 of the hands and 2 of the eyelids. All patients needed plastic surgical help via skin grafting after excision of the black eschar. No complications occurred after surgery. Because they are so rare in Europe and the United States, sporadic cases of anthrax are easily overlooked because the diagnosis often is not considered. Cutaneous anthrax should be considered in any patient with a painless ulcer or black eschar who has a history of exposure to animals.

Oligonucleotides for detection of Bacillus cereus group bacteria harmful to mammals, and method of detection with the oligonucleotides

Abstract: A method of detection is provided that permits differentiation of each of Bacillus cereus, Bacillus thuringiensis, and Bacillus anthracis from other microorganisms, using oligonucleotide primers for amplification of the target nucleotide sequences characteristic to Bacillus cereus, Bacillus thuringiensis, and Bacillus anthracis, consisting of the oligonucleotide (A) having a nucleotide sequence obtained from SEQ ID NO:1 and containing at least one site that can amplify a nucleotide sequence characteristic to Bacillus cereus, the oligonucleotide (B) having a nucleotide sequence obtained from SEQ ID NO:3 and containing at least one site that can amplify a nucleotide sequence characteristic to Bacillus thuringiensis, and the oligonucleotide (C) having a nucleotide sequence obtained from SEQ ID NO:5 and containing at least one site that can amplify a nucleotide sequence characteristic to Bacillus anthracis. Also provided are a method of detection of Bacillus cereus, Bacillus thuringiensis, and Bacillus anthracis by polymerase chain reaction (PCR) using a primer specific to the DNA gyrase sub-unit B (gyrB) gene and a method of detection of Bacillus cereus, Bacillus thuringiensis, and Bacillus anthracis in a sample by differentiation on the genetic level.

Use of a photoactivatable lipid to probe the topology of PA63 of Bacillus anthracis in lipid membranes

Abstract: The protective antigen of Bacillus anthracis is a key protein that promotes the translocation of the enzymatic moieties of the two toxins of B. anthracis into the cell cytoplasm. The membrane topology of the active form of the protective antigen (PA63) was investigated by proteolysis of PA63 inserted into liposomes containing a photoactivatable, radioactive lipid, and characterization of the N-terminal moiety of the deeply-inserted (and therefore radiolabeled) peptides. A single sequence starting at residue Ala258 was identified. Fourier-transform infrared spectroscopy showed that the protected peptide was mainly adopting a beta-sheet structure whose orientation was compatible with a transmembrane organization.

PCR analysis of tissue samples from the 1979 Sverdlovsk anthrax victims: The presence of multiple Bacillus anthracis strains in different victims (vrrA geneyvariable number tandem repeats)

Abstract: An outbreak of human anthrax occurred in Sverdlovsk, Union of Soviet Socialists Republic (now Ekater- inburg, Russia) in April 1979. Officials attributed this to consumption of contaminated meat, but Western governments believed it resulted from inhalation of spores accidentally released from a nearby military research facility. Tissue samples from 11 victims were obtained and methods of efficiently extracting high-quality total DNA from these sam- ples were developed. Extracted DNA was analyzed by using PCR to determine whether it contained Bacillus anthracis- specific sequences. Double PCR using ''nested primers'' in- creased sensitivity of the assay significantly. Tissue samples from 11 persons who died during the epidemic were examined. Results demonstrated that the entire complement of B. an- thracis toxin and capsular antigen genes required for patho- genicity were present in tissues from each of these victims. Tissue from a vaccination site contained primarily nucleic acids from a live vaccine, although traces of genes from the infecting organisms were also present. PCR analysis using primers that detect the vrrA gene variable region on the B. anthracis chromosome demonstrated that at least four of the five known strain categories defined by this region were present in the tissue samples. Only one category is found in a single B. anthracis strain.

Method of bacillus anthracis nucleic acid preparing

Abstract: FIELD: biochemistry, biotechnology, bacteriology. SUBSTANCE: biomass is obtained at preliminary additional culturing microbe cells Bacillus anthracis under condition of the sealed flasks containing culture. Biomass is treated with lysozyme in presence of EDTA at concentration 20 mg/1 g biomass. The obtained suspension is frozen three times in liquid nitrogen followed by thawing at 60 C. Freezing time is 40-60 s. Then additional lysis with tris-SDS-buffer is carried out. Nucleic acids were purified with phenol and precipitated with cold ethanol. EFFECT: improved method of nucleic acid preparing. 3 tbln