Showing papers on "Bacillus anthracis published in 1991"

Comparative analysis of Bacillus anthracis, Bacillus cereus, and related species on the basis of reverse transcriptase sequencing of 16S rRNA

Abstract: The primary structures of the 16S rRNAs of Bacillus anthracis, Bacillus cereus, Bacillus mycoides, and Bacillus thuringiensis were determined by using the reverse transcription-dideoxy sequencing method. All of the strains exhibited very high levels of sequence similarity T (T = type strain) by only a single nucleotide. The 16S rRNA sequences of B. mycoides and B. thuringiensis differed from each other and from the sequences of B. anthracis and B. cereus by four to nine nucleotides.

Contribution of individual toxin components to virulence of Bacillus anthracis.

Abstract: Three proteins, protective antigen (PA), lethal factor (LF), and edema factor (EF; a calmodulin-dependent adenylate cyclase), compose the lethal (PA + LF) and edema (PA + EF) toxins secreted by Bacillus anthracis. Mutant strains, each deficient in the production of one toxin component, were constructed, and their virulence was then studied. A kanamycin resistance cassette was inserted in each cya (encoding EF) and lef (encoding LF) gene, and the constructs were separately introduced into B. anthracis Sterne on a mobilizable shuttle plasmid. An EF- strain and an LF- strain were then isolated after homologous recombination with the resident toxin-encoding plasmid, pXO1. Spores from these mutants and from a previously constructed PA- mutant were used to inoculate mice, and the lethality and local edema formation were monitored. LF- or PA- mutants were not lethal even at high inocula, whereas the EF- mutant induced lethal infections. This indicates that LF in combination with PA is a key virulence factor required for lethality. Skin edema formation was observed with the LF- mutant, which produces only the combination of PA and EF. However, EF- and LF- mutants were significantly less efficient at inducing, respectively, lethality and edema than was the parental Sterne strain. These results suggest that the three toxin components might act synergistically in vivo to cause lethality and edema formation.

Antimicrobial Susceptibility of Bacillus Anthracis

Abstract: 22 Bacillus anthracis isolates were tested for susceptibility to 27 antimicrobial agents by agar dilution. All isolates were sensitive to penicillins and did not produce beta-lactamase. Although all isolates were sensitive to cefazolin, cephalothin, cephradine and cefoperazone 19 isolates were resistant to cefuroxime, 18 to cefotaxime, 18 to ceftizoxime, 9 to ceftriaxone and 21 to ceftazidime. All isolates were also found to be sensitive to other antimicrobials tested. The new antimicrobial agents, ofloxacin and ciprofloxacin showed very good activity with MICs of 0.03-0.06 mg/l.

Protection against anthrax with recombinant virus-expressed protective antigen in experimental animals.

Abstract: We previously described the cloning and expression of the protective antigen (PA) gene of Bacillus anthracis in both vaccinia virus and a baculovirus. The antigenicity of the PA products was characterized. PA expressed by the recombinant vaccinia viruses elicited a partial protective immune response against a lethal B. anthracis spore challenge in guinea pigs and mice. The WR strain vaccinia virus recombinant (WR-PA) protected 60% of male mice and 50% of guinea pigs. WR-PA elicited high anti-PA antibody titers in mice but not in guinea pigs. Connaught strain vaccinia virus recombinants failed to protect any immunized animals. PA purified from baculovirus recombinant-infected cultures plus adjuvant partially protected male CBA/J mice and completely protected female Hartley guinea pigs from challenge. Both the recombinant and nonrecombinant PA preparations combined with adjuvant elicited high anti-PA antibody titers in Hartley guinea pigs and CBA/J mice. These data demonstrate that the recombinant baculovirus- and vaccinia virus-produced PAs were immunogenic in both guinea pigs and mice, that the baculovirus-PA recombinant was a useful source of immunogenic PA, and that vaccinia virus-PA recombinants may be feasible live anthrax vaccine candidates worthy of consideration for further development as live vaccines.

Differentiation of Bacillus anthracis from Bacillus cereus by gas chromatographic whole-cell fatty acid analysis.

Abstract: Three strains of Bacillus anthracis and seven strains of Bacillus cereus were grown on complex medium and on synthetic medium Gas chromatographic analysis of whole-cell fatty acids of strains grown on complex medium gave nearly identical fatty acid patterns Fatty acid patterns of strains grown on synthetic medium showed a high content of branched-chain fatty acids Significant differences between the fatty acid patterns of the two species were found Odd iso/anteiso fatty acid ratios were about equal in B anthracis strains, whereas in B cereus strains the fractions of iso acids were at least twice as high as the fractions of anteiso acids The method described herein is used in our diagnostic laboratory to help differentiate between these two species

[An anthrax epidemic in Switzerland. Clinical, diagnostic and epidemiological aspects of a mostly forgotten disease].

Abstract: On average in Switzerland there is only one case of human anthrax every two years, and this is almost exclusively caused through contact with sick animals in agriculture. However, within less than 3 years, 25 workers in one textile factory have contracted this anthropo-zoonosis. 24 cases had cutaneous and one inhalation anthrax. The infection was imported in goat's hair from Pakistan. This almost unique industrial epidemic was due to various circumstances. In particular, the rarity of the illness contributed to a general lack of experience and therefore hindered recognition of the clinical symptoms. In addition, repeated attempts failed to identify the pathogenic agent conclusively. In most cases, the diagnosis was only confirmed retrospectively using the Russian allergen "Anthraxin"--an intracutaneous test unknown up to that time in human medicine in the West--and later also by EIA. All the patients recovered. The clinical picture, diagnosis and epidemiology of cutaneous anthrax are described in detail. The typical features are, in the beginning, a pruritic insect-bite-like pimple, then a painless ulcer surrounded by serous-hemorrhagic, often rapidly confluent vesicles and non-pitting edema. On the ground of the ulcer a black necrosis develops which is never colliquative but is transformed into the typical pitch-black firmly adherent eschar. Lymphadenitis and lymphangitis are concomitant manifestations. The bacteriological findings and occupational history are decisive for the diagnosis. Anthrax spores can survive many decades. The vegetative organisms are highly susceptible to almost all antibiotics. The latter prevent the invasion of the anthrax bacilli and the toxinemia if administered in time, but they do not influence the development of the local lesions. For the detection of anthrax bacillus, sterile swabs should be soaked in the fluid of the vesicles. It must be done before beginning of any antibiotic treatment. For the examination of animal products, preparatory procedures are necessary to destroy contaminants that may be antagonistic to or overgrow Bacillus anthracis.

Protective and other biological properties of Bacillus anthracis soluble antigens.

Abstract: The soluble antigens were explored of the culture filtrate (CF) derived during static growth of B. anthracis vaccine strain 34F2 on a medium containing casein hydrolysate. Electrofocusing of CF preparations revealed that the protective activity was distributed over a wide range of pH 3-7. The most pronounced and stable protective activity was observed at pH 4.6-4.8. Following toxin factors were isolated and identified: protective antigen (87 kD), oedema factor (87 kD) and lethal factor (78-81 kD). The greatest protective activity was associated with antigens characterized by a molecular weight of 78-87 kD and toxic activity. Preparations of the oedema and lethal factors had the same protective activity as protective antigen (PA) preparations. Other CF soluble antigens protected about 30% of immunized guinea pigs. A protein was isolated with a molecular weight of 80 kD and isoelectric point at pH 5.3-5.7 which was not toxic and did not form toxic mixtures in association with other toxin factors; this protein featured a high immunogenic activity, however, it protected only 31% of immunized animals. Factors are analyzed which determine differences in the protective effects of live and chemical vaccines.

The prostaglandin and cyclic nucleotide levels in the organs of mice with experimental anthrax intoxication

Abstract: In this work the influence of Bacillus anthracis toxin, introduced intraperitoneally in a dose of LD100, on the content of prostaglandins E and F2 alpha, 6-ketoprostaglandin F1 alpha, thromboxane, cAMP and cGMP in the lungs, heart, liver and spleen of BALB/c mice in the time course of experimental intoxication has been studied. The concentration and proportion of prostaglandins and cyclic nucleotides have been shown to undergo-sharp changes in all organs under study in the process of intoxication. The level and proportion of prostaglandins in the lungs ensures the development of vaso- and bronchodilatation processes even at early stages of the action of the toxin. B. anthracis toxin sharply increases the content of cGMP in the organs under study and cAMP in the liver. The activating effect on the adenylate cyclase system of tissue cells is not linked with the action of the edematous factor of the toxin. The role of cyclic nucleotides and prostaglandins in the development of pulmonary edema in intoxication with B. anthracis toxin is discussed.

The molecular nature of Bacillus anthracis toxin

Abstract: The biochemical nature of the three-component toxin of Bacillus anthracis is described as well as the molecular structure and regulation of the genetical determinants coding for its synthesis. The mechanism of toxin affect on animal cells is presented. The role of every of the toxin components in realization of Bacillus anthracis pathogenic properties is discussed.

Contribution ofIndividual ToxinComponents toVirulence of Bacillus anthracis

Abstract: Threeproteins, protective antigen (PA), lethal factor (LF), andedemafactor (EF;acalmodulin-dependent adenylate cyclase), compose thelethal (PA+LF)andedema(PA+EF)toxins secreted byBacillus anthracis. Mutant strains, eachdeficient intheproduction ofonetoxin component, wereconstructed, andtheir virulence wasthenstudied. Akanamycin resistance cassette wasinserted ineachcya(encoding EF)andlef (encoding LF) gene, andtheconstructs wereseparately introduced into B.anthracis Sterne onamobilizable shuttle plasmid. An EF-strain andanLF-strain werethenisolated after homologous recombination withtheresident toxin-encoding plasmid, pXO1.Spores fromthese mutants andfromapreviously constructed PA-mutant wereusedtoinoculate mice, andthelethality andlocal edemaformation weremonitored. LF-orPA-mutants werenotlethal evenathighinocula, whereas theEF-mutant induced lethal infections. Thisindicates that LF incombination withPAisakeyvirulence factor required forlethality. Skinedemaformation wasobserved withtheLF-mutant, whichproduces onlythecombination ofPAandEF.However, EF-andLF-mutants weresignificantly less efficient atinducing, respectively, lethality andedemathanwastheparental Sterne strain. Theseresults suggest that thethree toxin components mightactsynergistically invivotocause lethality andedemaformation.