scholarly journals Attenuated Nontoxinogenic and Nonencapsulated Recombinant Bacillus anthracis Spore Vaccines Protect against Anthrax

2000 ◽  
Vol 68 (8) ◽  
pp. 4549-4558 ◽  
Author(s):  
S. Cohen ◽  
I. Mendelson ◽  
Z. Altboum ◽  
D. Kobiler ◽  
E. Elhanany ◽  
...  
Keyword(s):  
Bacillus Anthracis ◽  
Protective Immunity ◽  
Protective Antigen ◽  
Cell Vaccine ◽  
Lethal Challenge ◽  
Electrospray Mass Spectroscopy ◽  
Immunological Tests ◽  
Anthrax Spores ◽  
Biochemical Analyses ◽  
Recombinant Protective Antigen

ABSTRACT Several highly attenuated spore-forming nontoxinogenic and nonencapsulated Bacillus anthracis vaccines differing in levels of expression of recombinant protective antigen (rPA) were constructed. Biochemical analyses (including electrospray mass spectroscopy and N terminus amino acid sequencing) as well as biological and immunological tests demonstrated that the rPA retains the characteristics of native PA. A single immunization of guinea pigs with 5 × 107 spores of one of these recombinant strains, MASC-10, expressing high levels of rPA (≥100 μg/ml) from a constitutive heterologous promoter induced high titers of neutralizing anti-PA antibodies. This immune response was long lasting (at least 12 months) and provided protection against a lethal challenge of virulent (Vollum) anthrax spores. The recombinant B. anthracis spore vaccine appears to be more efficacious than the vegetative cell vaccine. Furthermore, while results clearly suggest a direct correlation between the level of expression of PA and the potency of the vaccine, they also suggest that some B. anthracisspore-associated antigen(s) may contribute in a significant manner to protective immunity.

scholarly journals Search for Correlates of Protective Immunity Conferred by Anthrax Vaccine

2001 ◽  
Vol 69 (5) ◽  
pp. 2888-2893 ◽  
Author(s):  
Shaul Reuveny ◽  
Moshe D. White ◽  
Yaakov Y. Adar ◽  
Yaron Kafri ◽  
Zeev Altboum ◽  
...  
Keyword(s):  
Antibody Titer ◽  
Neutralizing Antibodies ◽  
Protective Immunity ◽  
Protective Antigen ◽  
Surrogate Marker ◽  
Neutralizing Antibody ◽  
Enzyme Linked Immunosorbent Assay ◽  
Lethal Challenge ◽  
Anthrax Spores ◽  
Antibody Titers

ABSTRACT Vaccination by anthrax protective antigen (PA)-based vaccines requires multiple immunization, underlying the need to develop more efficacious vaccines or alternative vaccination regimens. In spite of the vast use of PA-based vaccines, the definition of a marker for protective immunity is still lacking. Here we describe studies designed to help define such markers. To this end we have immunized guinea pigs by different methods and monitored the immune response and the corresponding extent of protection against a lethal challenge with anthrax spores. Active immunization was performed by a single injection using one of two methods: (i) vaccination with decreasing amounts of PA and (ii) vaccination with constant amounts of PA that had been thermally inactivated for increasing periods. In both studies a direct correlation between survival and neutralizing-antibody titer was found (r 2 = 0.92 and 0.95, respectively). Most significantly, in the two protocols a similar neutralizing-antibody titer range provided 50% protection. Furthermore, in a complementary study involving passive transfer of PA hyperimmune sera to naive animals, a similar correlation between neutralizing-antibody titers and protection was found. In all three immunization studies, neutralization titers of at least 300 were sufficient to confer protection against a dose of 40 50% lethal doses (LD50) of virulent anthrax spores of the Vollum strain. Such consistency in the correlation of protective immunity with anti-PA antibody titers was not observed for antibody titers determined by an enzyme-linked immunosorbent assay. Taken together, these results clearly demonstrate that neutralizing antibodies to PA constitute a major component of the protective immunity against anthrax and suggest that this parameter could be used as a surrogate marker for protection.

scholarly journals Functional Analysis of Bacillus anthracis Protective Antigen by Using Neutralizing Monoclonal Antibodies

2004 ◽  
Vol 72 (11) ◽  
pp. 6313-6317 ◽  
Author(s):  
Fabien Brossier ◽  
Martine Lévy ◽  
Annie Landier ◽  
Pierre Lafaye ◽  
Michèle Mock
Keyword(s):  
Functional Analysis ◽  
Monoclonal Antibodies ◽  
Bacillus Anthracis ◽  
Protective Antigen ◽  
Lethal Factor ◽  
Cell Receptor ◽  
Lethal Challenge ◽  
Edema Factor

ABSTRACT Protective antigen (PA) is central to the action of the lethal and edema toxins produced by Bacillus anthracis. It is the common cell-binding component, mediating the translocation of the enzymatic moieties (lethal factor [LF] and edema factor) into the cytoplasm of the host cell. Monoclonal antibodies (MAbs) against PA, able to neutralize the activities of the toxins in vitro and in vivo, were screened. Two such MAbs, named 7.5 and 48.3, were purified and further characterized. MAb 7.5 binds to domain 4 of PA and prevents the binding of PA to its cell receptor. MAb 48.3 binds to domain 2 and blocks the cleavage of PA into PA63, a step necessary for the subsequent interaction with the enzymatic moieties. The epitope recognized by this antibody is in a region involved in the oligomerization of PA63; thus, MAb 48.3 does not recognize the oligomer form. MAbs 7.5 and 48.3 neutralize the activities of anthrax toxins produced by B. anthracis in mice. Also, there is an additive effect between the two MAbs against PA and a MAb against LF, in protecting mice against a lethal challenge by the Sterne strain. This work contributes to the functional analysis of PA and offers immunotherapeutic perspectives for the treatment of anthrax disease.

scholarly journals Human Monoclonal Antibody AVP-21D9 to Protective Antigen Reduces Dissemination of the Bacillus anthracis Ames Strain from the Lungs in a Rabbit Model

2007 ◽  
Vol 75 (7) ◽  
pp. 3414-3424 ◽  
Author(s):  
Johnny W. Peterson ◽  
Jason E. Comer ◽  
Wallace B. Baze ◽  
David M. Noffsinger ◽  
Autumn Wenglikowski ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Bacillus Anthracis ◽  
Protective Antigen ◽  
Human Monoclonal Antibody ◽  
Rabbit Model ◽  
Concomitant Treatment ◽  
Dependent Manner ◽  
Lethal Challenge ◽  
Tissue Sections ◽  
Inhalation Anthrax

ABSTRACT Dutch-belted and New Zealand White rabbits were passively immunized with AVP-21D9, a human monoclonal antibody to protective antigen (PA), at the time of Bacillus anthracis spore challenge using either nasal instillation or aerosol challenge techniques. AVP-21D9 (10 mg/kg) completely protected both rabbit strains against lethal infection with Bacillus anthracis Ames spores, regardless of the inoculation method. Further, all but one of the passively immunized animals (23/24) were completely resistant to rechallenge with spores by either respiratory challenge method at 5 weeks after primary challenge. Analysis of the sera at 5 weeks after primary challenge showed that residual human anti-PA levels decreased by 85 to 95%, but low titers of rabbit-specific anti-PA titers were also measured. Both sources of anti-PA could have contributed to protection from rechallenge. In a subsequent study, bacteriological and histopathology analyses revealed that B. anthracis disseminated to the bloodstream in some naïve animals as early as 24 h postchallenge and increased in frequency with time. AVP-21D9 significantly reduced the dissemination of the bacteria to the bloodstream and to various organs following infection. Examination of tissue sections from infected control animals, stained with hematoxylin-eosin and the Gram stain, showed edema and/or hemorrhage in the lungs and the presence of bacteria in mediastinal lymph nodes, with necrosis and inflammation. Tissue sections from infected rabbits dosed with AVP-21D9 appeared comparable to corresponding tissues from uninfected animals despite lethal challenge with B. anthracis Ames spores. Concomitant treatment with AVP-21D9 at the time of challenge conferred complete protection in the rabbit inhalation anthrax model. Early treatment increased the efficacy progressively and in a dose-dependent manner. Thus, AVP-21D9 could offer an adjunct or alternative clinical treatment regimen against inhalation anthrax.

scholarly journals Killed but Metabolically Active Bacillus anthracis Vaccines Induce Broad and Protective Immunity against Anthrax

2009 ◽  
Vol 77 (4) ◽  
pp. 1649-1663 ◽  
Author(s):  
Justin Skoble ◽  
John W. Beaber ◽  
Yi Gao ◽  
Julie A. Lovchik ◽  
Laurie E. Sower ◽  
...  
Keyword(s):  
Bacillus Anthracis ◽  
Neutralizing Antibodies ◽  
Protective Immunity ◽  
Protective Antigen ◽  
Excision Repair ◽  
Uv Light ◽  
Lethal Factor ◽  
Point Mutations ◽  
Anthrax Vaccine ◽  
Edema Factor

ABSTRACTBacillus anthracisis the causative agent of anthrax. We have developed a novel whole-bacterial-cell anthrax vaccine utilizingB. anthracisthat is killed but metabolically active (KBMA). Vaccine strains that are asporogenic and nucleotide excision repair deficient were engineered by deleting thespoIIEanduvrABgenes, renderingB. anthracisextremely sensitive to photochemical inactivation with S-59 psoralen and UV light. We also introduced point mutations into thelefandcyagenes, which allowed inactive but immunogenic toxins to be produced. Photochemically inactivated vaccine strains maintained a high degree of metabolic activity and secreted protective antigen (PA), lethal factor, and edema factor. KBMAB. anthracisvaccines were avirulent in mice and induced less injection site inflammation than recombinant PA adsorbed to aluminum hydroxide gel. KBMAB. anthracis-vaccinated animals produced antibodies against numerous anthrax antigens, including high levels of anti-PA and toxin-neutralizing antibodies. Vaccination with KBMAB. anthracisfully protected mice against challenge with lethal doses of toxinogenic unencapsulated Sterne 7702 spores and rabbits against challenge with lethal pneumonic doses of fully virulent Ames strain spores. Guinea pigs vaccinated with KBMAB. anthraciswere partially protected against lethal Ames spore challenge, which was comparable to vaccination with the licensed vaccine anthrax vaccine adsorbed. These data demonstrate that KBMA anthrax vaccines are well tolerated and elicit potent protective immune responses. The use of KBMA vaccines may be broadly applicable to bacterial pathogens, especially those for which the correlates of protective immunity are unknown.

scholarly journals Correlation between Lethal Toxin-Neutralizing Antibody Titers and Protection from Intranasal Challenge with Bacillus anthracis Ames Strain Spores in Mice after Transcutaneous Immunization with Recombinant Anthrax Protective Antigen

2006 ◽  
Vol 74 (1) ◽  
pp. 794-797 ◽  
Author(s):  
Kristina K. Peachman ◽  
Mangala Rao ◽  
Carl R. Alving ◽  
Robert Burge ◽  
Stephen H. Leppla ◽  
...  
Keyword(s):  
Bacillus Anthracis ◽  
Protective Antigen ◽  
Neutralizing Antibody ◽  
Lethal Toxin ◽  
Vaccine Strategy ◽  
Transcutaneous Immunization ◽  
Antibody Titers ◽  
Anthrax Protective Antigen ◽  
Ames Strain ◽  
Recombinant Protective Antigen

ABSTRACT Transcutaneous immunization of mice with recombinant protective antigen (rPA) of Bacillus anthracis resulted in significantly higher lethal toxin-neutralizing antibody titers than did intramuscular injection of alum-adsorbed rPA. Immunized mice were partially protected against intranasal challenge with 235,000 (10 50% lethal doses) Ames strain B. anthracis spores. A highly significant correlation was observed between toxin-neutralizing antibody titer and survival after challenge. Future experiments with rabbits and nonhuman primates should confirm the significance of protection by this vaccine strategy.

scholarly journals Development of Protective Immunity in New Zealand White Rabbits Challenged with Bacillus anthracis Spores and Treated with Antibiotics and Obiltoxaximab, a Monoclonal Antibody against Protective Antigen

2017 ◽  
Vol 62 (2) ◽  
Author(s):  
Lisa N. Henning ◽  
Sarah Carpenter ◽  
Gregory V. Stark ◽  
Natalya V. Serbina
Keyword(s):  
Monoclonal Antibody ◽  
New Zealand ◽  
Bacillus Anthracis ◽  
Protective Immunity ◽  
Protective Antigen ◽  
Lethal Dose ◽  
Survival Rates ◽  
Anamnestic Response ◽  
Content Type ◽  
Treatment Regimens

ABSTRACT The recommended management of inhalational anthrax, a high-priority bioterrorist threat, includes antibiotics and antitoxins. Obiltoxaximab, a chimeric monoclonal antibody against anthrax protective antigen (PA), is licensed under the U.S. Food and Drug Administration's (FDA's) Animal Rule for the treatment of inhalational anthrax. Because of spore latency, disease reemergence after treatment cessation is a concern, and there is a need to understand the development of endogenous protective immune responses following antitoxin-containing anthrax treatment regimens. Here, acquired protective immunity was examined in New Zealand White (NZW) rabbits challenged with a targeted lethal dose of Bacillus anthracis spores and treated with antibiotics, obiltoxaximab, or a combination of both. Survivors of the primary challenge were rechallenged 9 months later and monitored for survival. Survival rates after primary and rechallenge for controls and animals treated with obiltoxaximab, levofloxacin, or a combination of both were 0, 65, 100, and 95%, and 0, 100, 95, and 89%, respectively. All surviving immune animals had circulating antibodies to PA and serum toxin-neutralizing titers prior to rechallenge. Following rechallenge, systemic bacteremia and toxemia were not detected in most animals, and the levels of circulating anti-PA IgG titers increased starting at 5 days postrechallenge. We conclude that treatment with obiltoxaximab, alone or combined with antibiotics, significantly improves the survival of rabbits that received a lethal inhalation B. anthracis spore challenge dose and does not interfere with the development of immunity. Survivors of primary challenge are protected against reexposure, have rare incidents of systemic bacteremia and toxemia, and have evidence of an anamnestic response.

scholarly journals Two approaches for the stabilization of Bacillus anthracis recombinant protective antigen

2020 ◽  
pp. 1-6
Author(s):  
Ekaterina M. Ryabchevskaya ◽  
Ekaterina A. Evtushenko ◽  
Dmitry L. Granovskiy ◽  
Peter A. Ivanov ◽  
Joseph G. Atabekov ◽  
...  
Keyword(s):  
Bacillus Anthracis ◽  
Protective Antigen ◽  
Recombinant Protective Antigen
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