Showing papers on "Bacillus anthracis published in 1985"
TL;DR: Proof that pXO2 is involved in capsule synthesis came from experiments in which the plasmid was transferred by CP-51-mediated transduction and by a mating system in which plasmids transfer is mediated by a Bacillus thuringiensis fertility plasmide, pXo12.
Abstract: Virulent and certain avirulent strains of Bacillus anthracis harbor a plasmid, designated pXO2, which is involved in the synthesis of capsules. Two classes of rough, noncapsulated (Cap-) variants were isolated from the capsule-producing (Cap+) Pasteur vaccine strains ATCC 6602 and ATCC 4229. One class was cured of pXO2, and the other class still carried it. Reversion to Cap+ was demonstrable only in rough variants which had retained pXO2. Proof that pXO2 is involved in capsule synthesis came from experiments in which the plasmid was transferred by CP-51-mediated transduction and by a mating system in which plasmid transfer is mediated by a Bacillus thuringiensis fertility plasmid, pXO12. Cells of Bacillus cereus and a previously noncapsulated (pXO2-) strain of B. anthracis produced capsules after the acquisition of pXO2.
486 citations
TL;DR: Two of the protein components of anthrax toxin, edema factor and protective antigen, increase host susceptibility to infection by suppressing polymorphonuclear neutrophil function and impairing host resistance.
Abstract: The virulence of Bacillus anthracis has been attributed to a tripartite toxin composed of three proteins designated protective antigen, lethal factor, and edema factor. The effects of the toxin components on phagocytosis and chemiluminescence of human polymorphonuclear neutrophils were studied in vitro. Initially, it was determined that the avirulent Sterne strain of B. anthracis (radiation killed) required opsonization with either serum complement or antibodies against the Sterne cell wall to be phagocytized. Phagocytosis of the opsonized Sterne cells was not affected by the individual anthrax toxin components. However, a combination of protective antigen and edema factor inhibited Sterne cell phagocytosis and blocked both particulate and phorbol myristate acetate-induced polymorphonuclear neutrophil chemiluminescence. These polymorphonuclear neutrophil effects were reversible upon removal of the toxin components. The protective antigen-edema factor combination also increased intracellular cyclic AMP levels. These studies suggest that two of the protein components of anthrax toxin, edema factor and protective antigen, increase host susceptibility to infection by suppressing polymorphonuclear neutrophil function and impairing host resistance.
214 citations
TL;DR: This mating system provides an efficient method for interspecies transfer of a large range of Bacillus plasmid transfer among strains of B. anthracis, B. cereus, and B. thuringiensis by a conjugation-like process.
Abstract: To facilitate the analysis of genetic determinants carried by large resident plasmids of Bacillus anthracis, a mating system was developed which promotes plasmid transfer among strains of B. anthracis, B. cereus, and B. thuringiensis. Transfer of the selectable tetracycline resistance plasmid pBC16 and other plasmids from B. thuringiensis to B. anthracis and B. cereus recipients occurred during mixed incubation in broth. Two plasmids, pXO11 and pXO12, found in B. thuringiensis were responsible for plasmid mobilization. B. anthracis and B. cereus transcipients inheriting either pXO11 or pXO12 were, in turn, effective donors. Transcipients harboring pXO12 were more efficient donors than those harboring pXO11; transfer frequencies ranged from 10(-4) to 10(-1) and from 10(-8) to 10(-5), respectively. Cell-to-cell contact was necessary for plasmid transfer, and the addition of DNase had no effect. The high frequencies of transfer, along with the fact that cell-free filtrates of donor cultures were ineffective, suggested that transfer was not phage mediated. B. anthracis and B. cereus transcipients which inherited pXO12 also acquired the ability to produce parasporal crystals (Cry+) resembling those produced by B. thuringiensis, indicating that pXO12 carries a gene(s) involved in crystal formation. Transcipients which inherited pXO11 were Cry-. This mating system provides an efficient method for interspecies transfer of a large range of Bacillus plasmids by a conjugation-like process.
155 citations
TL;DR: Virulent strains of B. anthracis were easily separated from the closely related Bacillus species by most of the test methods; but separation of slightly virulent and avirulent strain could be done only by API and phage-sensitivity tests.
Abstract: API and morphological tests were examined for their ability to distinguish between 37 Bacillus anthracis strains (virulent and avirulent) and 194 strains of closely related Bacillus species (B. cereus, B. mycoides and B. thuringiensis). In addition, 34 strains of B. anthracis and four of B. cereus were tested by several other methods that included capsule formation, ability to grow on a selective medium, and sensitivity to phage. It was found that virulent strains of B. anthracis were easily separated from the closely related Bacillus species by most of the test methods; but separation of slightly virulent and avirulent strains of B. anthracis from the closely related species could be done only by API and phage-sensitivity tests.
47 citations
Journal Article•
TL;DR: There was no difference in the survival of mice and the distribution of the bacilli in various tissues between the penicillin treated mouse and the peniillin plus anti-anthrax serum treated group of mice.
Abstract: In this study penicillin alone versus penicillin combined with anti-anthrax serum were compared in the treatment of experimental anthrax of mice. Three groups of mice were inoculated intraperitoneally with the same suspension of Bacillus anthracis. Ten hours after the onset of infection the control group received no treatment, to the second group penicillin-G was injected every day, and the 3 rd group received penicillin-G plus anti-anthrax serum. The survival rate of the latter two groups was significantly higher than that of the control group. But, there was no difference in the survival of mice and the distribution of the bacilli in various tissues between the penicillin treated mice and the penicillin plus anti-anthrax serum treated group of mice.
4 citations
13 Nov 1985
TL;DR: It is concluded that antibodies to toxin components may not be sufficient to provide protection against all strains of B. anthracis, and that other antigens may play a role in active immunity and the efficacy of anthrax vaccines must be tested by using vaccine-resistant isolates if protection againstall possible challenge strains is to be assured.
Abstract: : Several strains of Bacillus anthracis have been reported previously to cause fatal infection in immunized guinea pigs. In this study, guinea pigs were immunized with either a protective antigen vaccine or a live Sterne strain spore vaccine, then challenged with virulent B. anthracis strains isolated from various host species from the United States and foreign sources. The authors concluded that antibodies to toxin components may not be sufficient to provide protection against all strains of B. anthracis, and that other antigens may play a role in active immunity. As a practical matter, it follows that the efficacy of anthrax vaccines must be tested by using vaccine-resistant isolates if protection against all possible challenge strains is to be assured.
1 citations
01 Jan 1985
TL;DR: It was found that virulent strains of B. anthracis were easily separated from the closely related Bacillus species by most of the test methods; but of slightly virulent and avirulent strain could be done only by API and phage-sensi tivi ty tests.
Abstract: SUMMARY. API and morphological tests were examined for their ability to distinguish between 37 Bacillus anthracis strains (virulent and avirulent) and 194 strains of closely related Bacillus species (B. cereus, B. mycoides and B. thuringiensis). In addition, 34 strains of B. anthracis and four of B. cereus were tested by several other methods that included capsule formation, ability to grow on a selective medium, and sensitivity to phage. It was found that virulent strains of B. anthracis were easily separated from the closely related Bacillus species by most of the test methods; but separation of slightly virulent and avirulent strains of B. anthracis from the closely related species could be done only by API and phage-sensi tivi ty tests.