Showing papers on "Bacillus anthracis published in 1986"

Differences in susceptibility of inbred mice to Bacillus anthracis.

Abstract: Animal species differ in their resistance both to infection by Bacillus anthracis and to anthrax toxin. A mouse model was developed to study the basis of the host differences and the pathogenesis of infection. When mice were infected with the virulent B. anthracis strain Vollum 1B, low 50% lethal dose (LD50) values (5 to 30 spores) were found for all 10 strains of inbred mice tested. However, analysis of time-to-death data revealed significant differences among the strains, which could be divided into three groups: most susceptible (A/J and DBA/2J); least susceptible (CBA/J, BALB/cJ, and C57BR/cdJ); and intermediate (the remaining five strains). In contrast, the mice were distinctly susceptible or resistant to lethal infection by the toxigenic, nonencapsulated Sterne vaccine strain. The LD50 for the susceptible A/J and DBA/2J mice was approximately 10(3) spores of the Sterne strain, whereas the remaining eight relatively resistant strains were killed only by 10(6) or more spores. F1 hybrid and backcross studies suggested that resistance to the Sterne strain is determined by a single dominant gene or gene complex. Mice lethally infected with B. anthracis showed an acute course of infection, characterized by extensive gelatinous edema and large concentrations of bacilli in the blood and organs (e.g., 10(9) CFU/g of spleen). The susceptibility of A/J and CBA/J mice to intravenously injected anthrax toxin components appeared to differ from their susceptibility to infection. The toxin LD50 values for both strains were similar. However, CBA/J mice died sooner than did A/J mice, with mean time to death of 0.9 and 3.7 days, respectively, in mice given 4 LD50 of toxin. The mouse model appears to be useful in studies on host resistance to anthrax and on the pathogenesis of the infection.

Comparative efficacy of Bacillus anthracis live spore vaccine and protective antigen vaccine against anthrax in the guinea pig.

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. Confirmation of previously reported studies (which used only protective antigen vaccines) was made with the identification of 9 of the 27 challenge isolates as being vaccine resistant. However, guinea pigs immunized with the live Sterne strain spore vaccine were fully protected against these nine isolates. In experiments designed to determine the basis of vaccine resistance, guinea pigs which were immunized with individual toxin components and which demonstrated enzyme-linked immunosorbent assay antibody titers comparable to those induced by Sterne strain vaccine were not protected when challenged with a vaccine-resistant isolate. We 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.

Development of antibodies to protective antigen and lethal factor components of anthrax toxin in humans and guinea pigs and their relevance to protective immunity.

Abstract: A competitive inhibition enzyme-linked immunosorbent assay (ELISA) was developed to detect antibodies in serum to the protective antigen (PA) and lethal factor (LF) components of anthrax toxin. Current human vaccination schedules with an acellular vaccine induce predictable and lasting antibody titers to PA and, when present in the vaccine, to LF. Live spore vaccine administered to guinea pigs in a single dose conferred significantly better protection than the human vaccines (P less than 0.001), although they elicited significantly lower (P less than 0.0005) anti-PA and anti-LF titers at time of challenge with virulent Bacillus anthracis. Substantial anti-PA and anti-LF titers may not, therefore, indicate solid protective immunity against anthrax infection. The ELISA system was also shown to be capable of detecting anti-PA and anti-LF antibodies in the sera of individuals with histories of clinical anthrax. The advantage of ELISA over the Ouchterlony gel diffusion test and indirect microhemagglutination assay are demonstrated. There was a highly significant degree of correlation between ELISA and the indirect microhemagglutination assay (P less than 0.0005); but ELISA was markedly superior in terms of reproducibility, reliability, specificity, and simplicity in performance and stability of the bound antigen.

Immunization studies with attenuated strains of Bacillus anthracis

Abstract: Live, attenuated strains of Bacillus anthracis lacking either the capsule plasmid pXO2, the toxin plasmid pXO1, or both were tested for their efficacy as vaccines against intravenous challenge with anthrax toxin in Fischer 344 rats and against aerosol or intramuscular challenge with virulent anthrax spores in Hartley guinea pigs. Animals immunized with toxigenic, nonencapsulated (pXO1+, pXO2-) strains survived toxin and spore challenge and demonstrated postimmunization antibody titers to the three components of anthrax toxin (protective antigen, lethal factor, and edema factor). Immunization with two nontoxigenic, encapsulated (pXO1-, pXO2+), Pasteur vaccine strains neither provided protection nor elicited titers to any of the toxin components. Therefore, to immunize successfully against anthrax toxin or spore challenge, attenuated, live strains of B. anthracis must produce the toxin components specified by the pXO1 plasmid.

Production and purification of anthrax toxin.

Abstract: Publisher Summary This chapter describes the production and purification of anthrax toxin. Bacillus anthracis secretes three proteins that are collectively known as anthrax toxin. The protective antigen (PA, 85 kDa), lethal factor (LF, 83 kDa), and edema factor (EF, 89 kDa) proteins individually have no known toxic activities. Simultaneous injection of PA and LF causes death of rats, while PA and EF together produce edema in skin. Thus, “anthrax toxin” is actually two toxins, each of which is like staphylococcal leukocidin and botulinum C 2 toxin in having receptor-binding and effecter domains on separate proteins. The PA protein appears to play a dual role as the B moiety for two different A proteins. Binding studies have shown that PA must be present in order for EF to bind to cells. Study of anthrax toxin is essential in improving for understanding of the virulence of B. anthracis and in design of improved vaccines. In addition, study of the anthrax toxins may show them to be useful tools in cell biology.

Cloning and expression of the Bacillus anthracis protective antigen gene in Bacillus subtilis

Abstract: The gene encoding the protective antigen (PA) moiety of the tripartite exotoxin of Bacillus anthracis was cloned from the recombinant plasmid pSE36 into Bacillus subtilis 1S53 by using the plasmid vector pUB110. Two clones, designated PA1 and PA2, were identified which produced PA in liquid cultures at levels of 20.5 to 41.9 micrograms/ml. This PA was identical to B. anthracis Sterne PA with respect to migration on sodium dodecyl sulfate-polyacrylamide gels and to Western blot antigenic reactivity. Addition of lethal factor or edema factor to PA1 and PA2 supernatants generated biologically active anthrax lethal toxin or edema-producing toxin, respectively. The recombinant plasmid in PA1 (pPA101) was 7.8 kilobases, whereas the PA2 strain plasmid (pPA102) was 6.1 kilobases. Both plasmids had deletions extending into the insert sequence but not into the DNA encoding the PA protein. Immunization with the live recombinant strains protected guinea pigs from lethal challenge with virulent B. anthracis spores, and the immunization partially or completely protected rats from intravenous challenge with anthrax lethal toxin.

Virulence and immunogenicity in experimental animals of Bacillus anthracis strains harbouring or lacking 110 MDa and 60 MDa plasmids.

Abstract: Summary: A comparative study was made of the virulence and immunogenicity in mice or guinea pigs of Bacillus anthracis strains harbouring 110 MDa and/or 60 MDa plasmids. Strains cured of the 110 MDa or the 60 MDa plasmid were more than 100-fold less virulent to mice than were the parental strains harbouring these plasmids. Guinea-pigs immunized with plasmid-free derivatives of the non-encapsulated vaccine strain 34F2 showed no resistance to challenge with strain 17JB, which harbours both 110 MDa and 60 MDa plasmids, suggesting that the derivative strains had lost their immunizing ability against anthrax.

Anthrax toxin blocks priming of neutrophils by lipopolysaccharide and by muramyl dipeptide.

Abstract: We studied the pretreatment of human polymorphonuclear neutrophils (PMN) with purified preparations of the anthrax toxin components--protective antigen (PA), edema factor (EF), and lethal factor (LF)--and their effects on release of superoxide anion (O-2) after stimulation with the chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine (FMLP). PMN isolated in the absence of lipopolysaccharide (LPS) (less than 0.1 ng/ml) released only small amounts of O-2 after FMLP stimulation; pretreatment with anthrax toxin had little effect. The release of O-2 was increased fivefold by prior treatment with 3 ng/ml LPS for 1 h at 37 degrees C, an effect referred to as priming. PMN were primed to an equivalent extent by treatment with 100 ng/ml N-acetyl-muramyl-L-alanyl-D-isoglutamine (muramyl dipeptide [MDP]). Pretreatment of PMN with anthrax toxin components PA plus EF or PA plus LF inhibited priming by LPS or MDP, as shown by the reduction in the release of O-2 up to 90% relative to controls not treated with toxin; single toxin components were inactive. The inhibition was markedly reduced when priming with LPS or MDP was carried out before exposure to toxin. O-2 release after stimulation by phorbol myristate acetate was not increased by priming, and pretreatment with toxin did not inhibit O-2 release after this stimulus. Evidently, anthrax toxin inhibits the priming that is normally induced in PMN by bacterial products and is necessary for the full expression of antimicrobial effects.

Photoreactivation of ultraviolet-irradiated, plasmid-bearing, and plasmid-free strains of Bacillus anthracis.

Abstract: The effects of toxin- and capsule-encoding plasmids on the kinetics of UV inactivation of various strains of Bacillus anthracis were investigated. Plasmids pXO1 and pXO2 had no effect on bacterial UV sensitivity or photoreactivation. Vegetative cells were capable of photoreactivation, but photo-induced repair of UV damage was absent in B. anthracis Sterne spores.

Treatment of anthrax in man: history and current concepts.

Abstract: : A critical evaluation of the currently recommended treatments of cutaneous, inhalation, and gastrointestinal anthrax is presented with an historical perspective The importance of early diagnosis and specific, vigorous therapy, started on suspicion alone, is emphasized Although Bacillus anthracis is sensitive to sulfonamides and many broad-spectrum antibiotics, the drug of choice is currently penicillin For the treatment of septicemic anthrax, this study recommends the use of specific anti-anthrax serum to neutralize circulating toxin, as an adjunct to bactericidal antibiotics It is also recommended that in cases of known anthrax exposure, penicillin prophylaxis should be coupled with with vaccination to prevent latent infection

Induced release of Bacillus spores from sporangia by sodium sulphate

Abstract: Incubation of sporulating cultures of Bacillus anthracis, B. cereus, B. subtilis and B. thuringiensis in 1.0 mol/l sodium sulphate markedly increased the release of free spores from sporangia. It is postulated that the release of spores is due to activation of latent autolysins which hydrolyse sporangial cell walls. Sodium sulphate-induced lysis of sporangia represents a novel and highly effective method for the recovery of spores from cultures of Bacillus species.

Sporicidal Activity of Alcide Exspor and Sodium Hypochlorite on Bacillus anthracis Spores

Abstract: : Exspor, a commercial disinfectant, was completely sporicidal to Bacillus anthracis spores and was active in the presence of 5% (wt/vol) brain heart infusion, 5% (vol/vol) whole sheep blood, and 50% (wt/vol) plant materials. Sodium hypochlorite, 0.5% (wt/vol), although highly sporicidal, was inhibited significantly by the presence of organic material. Alcide, Exspor, Spore, Anthrax, Sodium hypochlorite, Disinfectant, Decontamination, Infectious diseases.