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Goossens PL. Bacillus anthracis, "la maladie du charbon", Toxins, and Institut Pasteur. Toxins (Basel) 2024; 16:66. [PMID: 38393144 PMCID: PMC10891547 DOI: 10.3390/toxins16020066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Revised: 12/25/2023] [Accepted: 12/30/2023] [Indexed: 02/25/2024] Open
Abstract
Institut Pasteur and Bacillus anthracis have enjoyed a relationship lasting almost 120 years, starting from its foundation and the pioneering work of Louis Pasteur in the nascent fields of microbiology and vaccination, and blooming after 1986 following the molecular biology/genetic revolution. This contribution will give a historical overview of these two research eras, taking advantage of the archives conserved at Institut Pasteur. The first era mainly focused on the production, characterisation, surveillance and improvement of veterinary anthrax vaccines; the concepts and technologies with which to reach a deep understanding of this research field were not yet available. The second period saw a new era of B. anthracis research at Institut Pasteur, with the anthrax laboratory developing a multi-disciplinary approach, ranging from structural analysis, biochemistry, genetic expression, and regulation to bacterial-host cell interactions, in vivo pathogenicity, and therapy development; this led to the comprehensive unravelling of many facets of this toxi-infection. B. anthracis may exemplify some general points on how science is performed in a given society at a given time and how a scientific research domain evolves. A striking illustration can be seen in the additive layers of regulations that were implemented from the beginning of the 21st century and their impact on B. anthracis research. B. anthracis and anthrax are complex systems that raise many valuable questions regarding basic research. One may hope that B. anthracis research will be re-initiated under favourable circumstances later at Institut Pasteur.
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Kandari D, Joshi H, Tanwar N, Munde M, Bhatnagar R. Delineation of the Residues of Bacillus anthracis Zinc Uptake Regulator Protein Directly Involved in Its Interaction with Cognate DNA. Biol Trace Elem Res 2021; 199:3147-3158. [PMID: 33052530 DOI: 10.1007/s12011-020-02427-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Accepted: 10/05/2020] [Indexed: 12/13/2022]
Abstract
Zinc uptake regulator (Zur) is a negative transcriptional regulator of bacteria that belongs to the FUR superfamily of proteins and regulates zinc (Zn) homeostasis under extreme Zn conditions. The Zur protein of Bacillus anthracis (BaZur) was though characterized previously, but the residues of this transcriptional regulator, crucial for binding to the consensus Zur box in the cognate DNA, remain unexplored. In this study, we reveal the essential residues of the protein that govern the specific interaction with the cognate DNA, through mutational and binding studies. In silico predicted model of the BaZur protein with the promoter region of one of the regulon candidates was utilized to identify specific residues of the N-terminal domain (NTD), constituting the DNA-binding recognition helix. Our results suggest that two phenylalanine residues, a non-polar aliphatic leucine and a positively charged arginine residue of NTD, are predominantly involved in DNA binding of BaZur. Among these, the arginine residue (Arg58) is conserved among all the Zur proteins and the two Phe residues, namely Phe53 and Phe63, are conserved in the Zur proteins of Staphylococcus aureus and Listeria monocytogenes. Taken together, the current study represents an in-depth investigation into the key DNA-binding residues involved in the BaZur-DNA interaction.
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Affiliation(s)
- Divya Kandari
- Molecular Biology and Genetic Engineering Laboratory, School of Biotechnology, Jawaharlal Nehru University, New Delhi, 110067, India
| | - Hemant Joshi
- Molecular Biology and Genetic Engineering Laboratory, School of Biotechnology, Jawaharlal Nehru University, New Delhi, 110067, India
| | - Neetu Tanwar
- School of Physical Sciences, Jawaharlal Nehru University, New Delhi, 110067, India
| | - Manoj Munde
- School of Physical Sciences, Jawaharlal Nehru University, New Delhi, 110067, India
| | - Rakesh Bhatnagar
- Molecular Biology and Genetic Engineering Laboratory, School of Biotechnology, Jawaharlal Nehru University, New Delhi, 110067, India.
- Banaras Hindu University, Banaras, Uttar Pradesh, 221005, India.
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Transcriptional Regulators in Bacillus anthracis: A Potent Biothreat Agent. RECENT DEVELOPMENTS IN MICROBIAL TECHNOLOGIES 2021. [DOI: 10.1007/978-981-15-4439-2_17] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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Benn JS, Chaki SP, Xu Y, Ficht TA, Rice-Ficht AC, Cook WE. Protective antibody response following oral vaccination with microencapsulated Bacillus Anthracis Sterne strain 34F2 spores. NPJ Vaccines 2020; 5:59. [PMID: 32685200 PMCID: PMC7351773 DOI: 10.1038/s41541-020-0208-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Accepted: 06/05/2020] [Indexed: 11/30/2022] Open
Abstract
An oral vaccine against anthrax (Bacillus anthracis) is urgently needed to prevent annual anthrax outbreaks that are causing catastrophic losses in free-ranging livestock and wildlife worldwide. The Sterne vaccine, the current injectable livestock vaccine, is a suspension of live attenuated B. anthracis Sterne strain 34F2 spores (Sterne spores) in saponin. It is not effective when administered orally and individual subcutaneous injections are not a practical method of vaccination for wildlife. In this study, we report the development of a microencapsulated oral vaccine against anthrax. Evaluating Sterne spore stability at varying pH's in vitro revealed that spore exposure to pH 2 results in spore death, confirming that protection from the gastric environment is of main concern when producing an oral vaccine. Therefore, Sterne spores were encapsulated in alginate and coated with a protein shell containing poly-L-lysine (PLL) and vitelline protein B (VpB), a non-immunogenic, proteolysis resistant protein isolated from Fasciola hepatica. Capsule exposure to pH 2 demonstrated enhanced acid gel character suggesting that alginate microcapsules provided the necessary protection for spores to survive the gastric environment. Post vaccination IgG levels in BALBc/J mouse serum samples indicated that encapsulated spores induced anti-anthrax specific responses in both the subcutaneous and the oral vaccination groups. Furthermore, the antibody responses from both vaccination routes were protective against anthrax lethal toxin in vitro, suggesting that further optimization of this vaccine formulation may result in a reliable oral vaccine that will conveniently and effectively prevent anthrax in wildlife populations.
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Affiliation(s)
- Jamie S. Benn
- Texas A&M University, Department of Veterinary Pathobiology, College Station, TX 77843 USA
| | - Sankar P. Chaki
- Texas A&M University, Department of Veterinary Pathobiology, College Station, TX 77843 USA
| | - Yi Xu
- Center for Infectious and Inflammatory Diseases, Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, TX 77030 USA
| | - Thomas A. Ficht
- Texas A&M University, Department of Veterinary Pathobiology, College Station, TX 77843 USA
| | - Allison C. Rice-Ficht
- Texas A&M University, Department of Veterinary Pathobiology, College Station, TX 77843 USA
- Texas A&M Health Science Center, Department of Molecular and Cellular Medicine, College Station, TX 77843 USA
| | - Walter E. Cook
- Texas A&M University, Department of Veterinary Pathobiology, College Station, TX 77843 USA
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Seid K, Shiferaw AM, Yesuf NN, Derso T, Sisay M. Livestock owners' anthrax prevention practices and its associated factors in Sekota Zuria district, Northeast Ethiopia. BMC Vet Res 2020; 16:39. [PMID: 32013973 PMCID: PMC6998812 DOI: 10.1186/s12917-020-2267-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Accepted: 01/27/2020] [Indexed: 11/21/2022] Open
Abstract
BACKGROUND In Ethiopia, the second most prioritized of the zoonotic diseases next to rabies is anthrax. About 50.6% of anthrax cases and 33.3% of deaths of livestock have been reported from Wag-Himra Zone, where appropriate anthrax prevention practices are not implemented by the owners of the animals. Thus, the aim of this study was to determine the extent of appropriate anthrax prevention practices of livestock owners and associated factors in Sekota Zuria district, northwest Ethiopia. RESULTS Twenty-five percent (95% CI: 25.2, 26.1%) of the livestock owners implemented appropriate anthrax prevention. Three quarters (74%) of the owners consumed infected meat; more than three quarters (78%) used the skins and hides of animals found dead with anthrax. The odds of appropriate anthrax prevention practices were higher among livestock owners with positive attitude (AOR = 4.16, 95% CI: 2.72, 6.37), who received health education (AOR = 2.00, 95% CI: 1.21, 3.28) and owners who lived in urban areas (AOR = 2.62, 95% CI: 1.43, 4.77) compared to their counterparts. Ability to read and write (AOR = 2.76, 95% CI: 1.74, 4.37), and primary (AOR = 3.6, 95% CI: 1.74, 4.37) or secondary school and above education (AOR = 4.24, 95% CI: 1.61, 11.13) were significantly associated with appropriate anthrax prevention practices. CONCLUSION In Sekota Zuria district, only one quarter of the livestock owners were aware of appropriate anthrax prevention practices. Thus, implementing effective health education and creating positive attitude are vital to improve anthrax prevention practices in the area.
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Affiliation(s)
- Kibeb Seid
- Sekota Town agricultural office, Sekota Zuria district, Wag-Himra Zone, northeast, Amhara Region State, Ethiopia
| | - Atsede Mazengia Shiferaw
- Department of Health Informatics, Institute of Public Health, College of Medicine and Health Sciences, University of Gondar, Gondar, Ethiopia
| | - Nurhusien Nuru Yesuf
- Department of Surgical Nursing, School of Nursing, College of Medicine and Health Sciences, University of Gondar, Gondar, Ethiopia
| | - Terefe Derso
- Department of Human Nutrition, Institute of Public Health, College of Medicine and Health Sciences, University of Gondar, Gondar, Ethiopia
| | - Mekonnen Sisay
- Department of Human Nutrition, Institute of Public Health, College of Medicine and Health Sciences, University of Gondar, Gondar, Ethiopia
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Manzulli V, Fasanella A, Parisi A, Serrecchia L, Donatiello A, Rondinone V, Caruso M, Zange S, Tscherne A, Decaro N, Pedarra C, Galante D. Evaluation of in vitro antimicrobial susceptibility of Bacillus anthracis strains isolated during anthrax outbreaks in Italy from 1984 to 2017. J Vet Sci 2019; 20:58-62. [PMID: 30541185 PMCID: PMC6351761 DOI: 10.4142/jvs.2019.20.1.58] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Revised: 10/10/2018] [Accepted: 10/30/2018] [Indexed: 12/04/2022] Open
Abstract
Anthrax, caused by Bacillus anthracis, is a non-contagious infectious disease that affects a wide range of animal species (primarily ruminants) including humans. Due to the often-fatal outcome in humans, quick administration of definitely effective antimicrobials is crucial either as prophylaxis or as a clinical case therapy. In this study, 110 B. anthracis strains, temporally, geographically, and genetically different, isolated during anthrax outbreaks in Italy from 1984 to 2017, were screened using a broth microdilution method to determine their susceptibility to 16 clinically relevant antimicrobial agents. The strains were isolated from various matrices (human, animal, and environmental samples) and were representative of thirty distinct genotypes previously identified by 15-loci multiple-locus variable-number of tandem repeats analysis. The antimicrobials tested were gentamicin, ceftriaxone, streptomycin, penicillin G, clindamycin, chloramphenicol, vancomycin, linezolid, cefotaxime, tetracycline, erythromycin, rifampin, amoxicillin, ciprofloxacin, doxycycline, and trimethoprim. All isolates were susceptible to most of the tested antimicrobials, with the exception of trimethoprim for which all of them showed high minimal inhibitory concentration values. An intermediate level of susceptibility was recorded for ceftriaxone and cefotaxime. Although the Centers for Disease Control and Prevention recommend the use of doxycycline, ciprofloxacin, penicillin G, and amoxicillin for treatment of human cases and for post-exposure prophylaxis to anthrax spores, this study shows a high degree of in vitro susceptibility of B. anthracis to many other antimicrobials, suggesting the possibility of an alternative choice for prophylaxis and therapy.
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Affiliation(s)
- Viviana Manzulli
- Anthrax Reference Institute of Italy, Experimental Zooprophylactic Institute of Puglia and Basilicata Regions, Foggia 71121, Italy
| | - Antonio Fasanella
- Anthrax Reference Institute of Italy, Experimental Zooprophylactic Institute of Puglia and Basilicata Regions, Foggia 71121, Italy
| | - Antonio Parisi
- Anthrax Reference Institute of Italy, Experimental Zooprophylactic Institute of Puglia and Basilicata Regions, Foggia 71121, Italy
| | - Luigina Serrecchia
- Anthrax Reference Institute of Italy, Experimental Zooprophylactic Institute of Puglia and Basilicata Regions, Foggia 71121, Italy
| | - Adelia Donatiello
- Anthrax Reference Institute of Italy, Experimental Zooprophylactic Institute of Puglia and Basilicata Regions, Foggia 71121, Italy
| | - Valeria Rondinone
- Anthrax Reference Institute of Italy, Experimental Zooprophylactic Institute of Puglia and Basilicata Regions, Foggia 71121, Italy
| | - Marta Caruso
- Anthrax Reference Institute of Italy, Experimental Zooprophylactic Institute of Puglia and Basilicata Regions, Foggia 71121, Italy
| | - Sabine Zange
- Bundeswehr Institute of Microbiology, Munich 80937, Germany
| | - Alina Tscherne
- Bundeswehr Institute of Microbiology, Munich 80937, Germany
| | - Nicola Decaro
- Department of Veterinary Medicine, University of Bari, Valenzano 70010, Italy
| | - Carmine Pedarra
- Anthrax Reference Institute of Italy, Experimental Zooprophylactic Institute of Puglia and Basilicata Regions, Foggia 71121, Italy
| | - Domenico Galante
- Anthrax Reference Institute of Italy, Experimental Zooprophylactic Institute of Puglia and Basilicata Regions, Foggia 71121, Italy
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Kandari D, Gopalani M, Gupta M, Joshi H, Bhatnagar S, Bhatnagar R. Identification, Functional Characterization, and Regulon Prediction of the Zinc Uptake Regulator ( zur) of Bacillus anthracis - An Insight Into the Zinc Homeostasis of the Pathogen. Front Microbiol 2019; 9:3314. [PMID: 30687290 PMCID: PMC6336718 DOI: 10.3389/fmicb.2018.03314] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 12/19/2018] [Indexed: 11/29/2022] Open
Abstract
Zinc has an abounding occurrence in the prokaryotes and plays paramount roles including catalytic, structural, and regulatory. Zinc uptake regulator (Zur), a Fur family transcriptional regulator, is connoted in maintaining zinc homeostasis in the pathogenic bacteria by binding to zinc and regulating the genes involved in zinc uptake and mobilization. Zinc homeostasis has been marginally scrutinized in Bacillus anthracis, the top-rated bio-terror agent, with no decipherment of the role of Zur. Of the three Fur family regulators in B. anthracis, BAS4181 is annotated as a zinc-specific transcriptional regulator. This annotation was further substantiated by our stringent computational and experimental analyses. The residues critical for zinc and DNA binding were delineated by homology modeling and sequence/structure analysis. ba zur existed as a part of a three-gene operon. Purified BaZur prodigiously existed in the dimeric form, indicated by size exclusion chromatography and blue native-polyacrylamide gel electrophoresis (PAGE). Computational and manual strategies were employed to decipher the putative regulon of ba zur, comprising of 11 genes, controlled by six promoters, each harboring at least one Zur box. The DNA binding capability of the purified BaZur to the upstream regions of the ba zur operon, yciC, rpmG, znuA, and genes encoding a GTPase cobalamine synthesis protein and a permease was ascertained by electrophoretic mobility shift assays. The regulon genes, implicated in zinc uptake and mobilization, were mostly negatively regulated by BaZur. The ba zur expression was downregulated upon exposure of cells to an excess of zinc. Conversely, it exhibited a marked upregulation under N, N, N', N'-Tetrakis (2-pyridylmethyl) ethylenediamine (TPEN) mediated zinc-depleted environment, adding credence to its negative autoregulation. Moreover, an increase in the transcript levels of the regulon genes znuA, rpmG, and yciC upon exposure of cells to TPEN connoted their role in combating hypo-zincemic conditions by bringing about zinc uptake and mobilization. Thus, this study functionally characterizes Zur of B. anthracis and elucidates its role in maintaining zinc homeostasis.
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Affiliation(s)
- Divya Kandari
- Laboratory of Molecular Biology and Genetic Engineering, School of Biotechnology, Jawaharlal Nehru University, New Delhi, India
| | - Monisha Gopalani
- Laboratory of Molecular Biology and Genetic Engineering, School of Biotechnology, Jawaharlal Nehru University, New Delhi, India
| | - Manish Gupta
- Laboratory of Molecular Biology and Genetic Engineering, School of Biotechnology, Jawaharlal Nehru University, New Delhi, India
| | - Hemant Joshi
- Laboratory of Molecular Biology and Genetic Engineering, School of Biotechnology, Jawaharlal Nehru University, New Delhi, India
| | - Sonika Bhatnagar
- Computational and Structural Biology Laboratory, Division of Biotechnology, Netaji Subhas Institute of Technology, University of Delhi, New Delhi, India
| | - Rakesh Bhatnagar
- Laboratory of Molecular Biology and Genetic Engineering, School of Biotechnology, Jawaharlal Nehru University, New Delhi, India
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Joon S, Gopalani M, Rahi A, Kulshreshtha P, Gogoi H, Bhatnagar S, Bhatnagar R. Biochemical characterization of the GTP-sensing protein, CodY of Bacillus anthracis. Pathog Dis 2018; 75:3791465. [PMID: 28472295 DOI: 10.1093/femspd/ftx048] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 04/22/2017] [Indexed: 12/30/2022] Open
Abstract
The pleiotropism of the GTP-sensing transcriptional regulator CodY is evident by the gamut of processes that it regulates in almost all low G+C Gram-positive bacteria, including general metabolism, biosynthesis of some amino acids and transport systems, nitrogen uptake, sporulation, biofilm formation, motility and virulence. The role of CodY in virulence has been established in Bacillus anthracis, the top rated bioterrorism agent. In this study, we investigated the biochemical attributes of this global regulator. Homology modeling and sequence/structure analysis revealed putative GTP-binding residues in CodY of B. anthracis. CodY exhibited an interaction with the GTP as tested by ultraviolet cross-linking experiments. It could autophosphorylate itself at a conserved Ser215 residue. This was further corroborated by the impairment of autophosphorylation activity in the CodYS215A mutant. Autophosphorylation may be speculated as an additional mechanism regulating CodY activity in the cell. The protein could also hydrolyze GTP, albeit weakly, as indicated by thin- layer chromatography and spectrophotometric quantification of its kinetic parameters. Altogether, these observations provide us an insight into the mechanism of action of this global regulator and a better understanding of its functional regulation.
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Affiliation(s)
- Shikha Joon
- Laboratory of Molecular Biology and Genetic Engineering, School of Biotechnology, Jawaharlal Nehru University, Munirka, New Delhi 110067, India.,Structural and Computational Biology Laboratory, Department of Biotechnology, Netaji Subhas Institute of Technology, New Delhi 110078, India
| | - Monisha Gopalani
- Laboratory of Molecular Biology and Genetic Engineering, School of Biotechnology, Jawaharlal Nehru University, Munirka, New Delhi 110067, India
| | - Amit Rahi
- Laboratory of Molecular Biology and Genetic Engineering, School of Biotechnology, Jawaharlal Nehru University, Munirka, New Delhi 110067, India
| | | | - Himanshu Gogoi
- Laboratory of Molecular Biology and Genetic Engineering, School of Biotechnology, Jawaharlal Nehru University, Munirka, New Delhi 110067, India
| | - Sonika Bhatnagar
- Structural and Computational Biology Laboratory, Department of Biotechnology, Netaji Subhas Institute of Technology, New Delhi 110078, India
| | - Rakesh Bhatnagar
- Laboratory of Molecular Biology and Genetic Engineering, School of Biotechnology, Jawaharlal Nehru University, Munirka, New Delhi 110067, India
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Gopalani M, Dhiman A, Rahi A, Kandari D, Bhatnagar R. Identification, Functional Characterization and Regulon Prediction of a Novel Two Component System Comprising BAS0540-BAS0541 of Bacillus anthracis. PLoS One 2016; 11:e0158895. [PMID: 27392063 PMCID: PMC4938410 DOI: 10.1371/journal.pone.0158895] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2015] [Accepted: 06/23/2016] [Indexed: 12/22/2022] Open
Abstract
Two component systems (TCSs) can be envisaged as complex molecular devices that help the bacteria to sense its environment and respond aptly. 41 TCSs are predicted in Bacillus anthracis, a potential bioterrorism agent, of which only four have been studied so far. Thus, the intricate signaling network contributed by TCSs remains largely unmapped in B. anthracis and needs comprehensive exploration. In this study, we functionally characterized one such system composed of BAS0540 (Response regulator) and BAS0541 (Histidine kinase). BAS0540-BAS0541, the closest homolog of CiaRH of Streptococcus in B. anthracis, forms a functional TCS with BAS0541 displaying autophosphorylation and subsequent phosphotransfer to BAS0540. BAS0540 was also found to accept phosphate from physiologically relevant small molecule phosphodonors like acetyl phosphate and carbamoyl phosphate. Results of qRT-PCR and immunoblotting demonstrated that BAS0540 exhibits a constitutive expression throughout the growth of B. anthracis. Regulon prediction for BAS0540 in B. anthracis was done in silico using the consensus DNA binding sequence of CiaR of Streptococcus. The predicted regulon of BAS0540 comprised of 23 genes, which could be classified into 8 functionally diverse categories. None of the proven virulence factors were a part of the predicted regulon, an observation contrasting with the regulon of CiaRH in Streptococci. Electrophoretic mobility shift assay was used to show direct binding of purified BAS0540 to the upstream regions of 5 putative regulon candidates- BAS0540 gene itself; a gene predicted to encode cell division protein FtsA; a self–immunity gene; a RND family transporter gene and a gene encoding stress (heat) responsive protein. A significant enhancement in the DNA binding ability of BAS0540 was observed upon phosphorylation. Overexpression of response regulator BAS0540 in B. anthracis led to a prodigious increase of ~6 folds in the cell length, thereby conferring it a filamentous phenotype. Furthermore, the sporulation titer of the pathogen also decreased markedly by ~16 folds. Thus, this study characterizes a novel TCS of B. anthracis and elucidates its role in two of the most important physiological processes of the pathogen: cell division and sporulation.
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Affiliation(s)
- Monisha Gopalani
- Laboratory of Molecular Biology and Genetic Engineering, School of Biotechnology, Jawaharlal Nehru University, New Delhi-110067, India
| | - Alisha Dhiman
- Laboratory of Molecular Biology and Genetic Engineering, School of Biotechnology, Jawaharlal Nehru University, New Delhi-110067, India
| | - Amit Rahi
- Laboratory of Molecular Biology and Genetic Engineering, School of Biotechnology, Jawaharlal Nehru University, New Delhi-110067, India
| | - Divya Kandari
- Laboratory of Molecular Biology and Genetic Engineering, School of Biotechnology, Jawaharlal Nehru University, New Delhi-110067, India
| | - Rakesh Bhatnagar
- Laboratory of Molecular Biology and Genetic Engineering, School of Biotechnology, Jawaharlal Nehru University, New Delhi-110067, India
- * E-mail:
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D'Amelio E, Gentile B, Lista F, D'Amelio R. Historical evolution of human anthrax from occupational disease to potentially global threat as bioweapon. ENVIRONMENT INTERNATIONAL 2015; 85:133-146. [PMID: 26386727 DOI: 10.1016/j.envint.2015.09.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Revised: 09/03/2015] [Accepted: 09/04/2015] [Indexed: 06/05/2023]
Abstract
PURPOSE Anthrax is caused by Bacillus anthracis, which can naturally infect livestock, wildlife and occupationally exposed humans. However, for its resistance due to spore formation, ease of dissemination, persistence in the environment and high virulence, B. anthracis has been considered the most serious bioterrorism agent for a long time. During the last century anthrax evolved from limited natural disease to potentially global threat if used as bioweapon. Several factors may mitigate the consequences of an anthrax attack, including 1. the capability to promptly recognize and manage the illness and its public health consequences; 2. the limitation of secondary contamination risk through an appropriate decontamination; and 3. the evolution of genotyping methods (for microbes characterization at high resolution level) that can influence the course and/or focus of investigations, impacting the response of the government to an attack. METHODS A PubMed search has been done using the key words “bioterrorism anthrax”. RESULTS Over one thousand papers have been screened and the most significant examined to present a comprehensive literature review in order to discuss the current knowledge and strategies in preparedness for a possible deliberate release of B. anthracis spores and to indicate the most current and complete documents in which to deepen. CONCLUSIONS The comprehensive analysis of the two most relevant unnatural anthrax release events, Sverdlovsk in the former Soviet Union (1979) and the contaminated letters in the USA (2001), shows that inhalational anthrax may easily and cheaply be spread resulting in serious consequences. The damage caused by an anthrax attack can be limited if public health organization, first responders, researchers and investigators will be able to promptly manage anthrax cases and use new technologies for decontamination methods and in forensic microbiology.
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Affiliation(s)
| | - Bernardina Gentile
- Histology and Molecular Biology Section, Army Medical Research Center, Via Santo Stefano Rotondo 4, 00184 Rome, Italy
| | - Florigio Lista
- Histology and Molecular Biology Section, Army Medical Research Center, Via Santo Stefano Rotondo 4, 00184 Rome, Italy
| | - Raffaele D'Amelio
- Sapienza University of Rome, Department of Clinical and Molecular Medicine, S. Andrea University Hospital, Via di Grottarossa 1039, 00189 Rome, Italy.
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Abstract
ABSTRACT
The family
Bacillaceae
constitutes a phenotypically diverse and globally ubiquitous assemblage of bacteria. Investigation into how evolution has shaped, and continues to shape, this family has relied on several widely ranging approaches from classical taxonomy, ecological field studies, and evolution in soil microcosms to genomic-scale phylogenetics, laboratory, and directed evolution experiments. One unifying characteristic of the
Bacillaceae
, the endospore, poses unique challenges to answering questions regarding both the calculation of evolutionary rates and claims of extreme longevity in ancient environmental samples.
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12
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Addae E, Dong X, McCoy E, Yang C, Chen W, Yang L. Investigation of antimicrobial activity of photothermal therapeutic gold/copper sulfide core/shell nanoparticles to bacterial spores and cells. J Biol Eng 2014; 8:11. [PMID: 24963345 PMCID: PMC4068869 DOI: 10.1186/1754-1611-8-11] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Accepted: 05/16/2014] [Indexed: 02/03/2023] Open
Abstract
BACKGROUND Au/CuS core/shell nanoparticles (NPs) were designed as a new type of transducer agent for photothermal therapy (PTT), with attractive features of easy preparation, low cost and small size for targeting. This paper studied for the first time the intrinsic antimicrobial activity of Au/CuS NPs to B. anthracis spores and cells in addition to its PTT effect. RESULTS It was found that Au/CuS NPs were highly efficient in inactivating B. anthracis cells, but not effective to the spores. Treatment with NPs at ~0.83 μM for 30 min achieved a 7 log reduction in viable cells. The antimicrobial effect was both NPs concentration and treatment time dependent. SEM imaging and the efflux of DNA test demonstrated the damage of cell membrane after NPs treatment, yet further research is necessary to fully understand the precise inactivation mechanism. CONCLUSIONS The Au/CuS NPs had strong antimicrobial activity to B. anthracis cells, which showed a great potential to be an effective antimicrobial agent to bacterial cells.
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Affiliation(s)
- Ebenezer Addae
- Department of Pharmaceutical Sciences, Biomanufacturing Research Institute and Technology Enterprises (BRITE), North Carolina Central University, Durham, NC 27707, USA
| | - Xiuli Dong
- Department of Pharmaceutical Sciences, Biomanufacturing Research Institute and Technology Enterprises (BRITE), North Carolina Central University, Durham, NC 27707, USA
| | - Eric McCoy
- Department of Pharmaceutical Sciences, Biomanufacturing Research Institute and Technology Enterprises (BRITE), North Carolina Central University, Durham, NC 27707, USA
| | - Chang Yang
- Department of Physics, University of Texas at Arlington, Arlington, TX 76019, USA ; Guizhou Provincial Key Laboratory of Pharmaceutics, School of Pharmacy, Guiyang Medical College, Guiyang, Guizhou 550004, China
| | - Wei Chen
- Department of Physics, University of Texas at Arlington, Arlington, TX 76019, USA
| | - Liju Yang
- Department of Pharmaceutical Sciences, Biomanufacturing Research Institute and Technology Enterprises (BRITE), North Carolina Central University, Durham, NC 27707, USA
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Gorantala J, Grover S, Rahi A, Chaudhary P, Rajwanshi R, Sarin NB, Bhatnagar R. Generation of protective immune response against anthrax by oral immunization with protective antigen plant-based vaccine. J Biotechnol 2014; 176:1-10. [PMID: 24548460 DOI: 10.1016/j.jbiotec.2014.01.033] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Revised: 12/30/2013] [Accepted: 01/29/2014] [Indexed: 01/04/2023]
Abstract
In concern with frequent recurrence of anthrax in endemic areas and inadvertent use of its spores as biological weapon, the development of an effective anthrax vaccine suitable for both human and veterinary needs is highly desirable. A simple oral delivery through expression in plant system could offer promising alternative to the current methods that rely on injectable vaccines extracted from bacterial sources. In the present study, we have expressed protective antigen (PA) gene in Indian mustard by Agrobacterium-mediated transformation and in tobacco by plastid transformation. Putative transgenic lines were verified for the presence of transgene and its expression by molecular analysis. PA expressed in transgenic lines was biologically active as evidenced by macrophage lysis assay. Intraperitoneal (i.p.) and oral immunization with plant PA in murine model indicated high serum PA specific IgG and IgA antibody titers. PA specific mucosal immune response was noted in orally immunized groups. Further, antibodies indicated lethal toxin neutralizing potential in-vitro and conferred protection against in-vivo toxin challenge. Oral immunization experiments demonstrated generation of immunoprotective response in mice. Thus, our study examines the feasibility of oral PA vaccine expressed in an edible plant system against anthrax.
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Affiliation(s)
- Jyotsna Gorantala
- Laboratory of Molecular Biology and Genetic Engineering, School of Biotechnology, Jawaharlal Nehru University, New Delhi, India
| | - Sonam Grover
- Molecular Technology Laboratory, School of Biotechnology, Jawaharlal Nehru University, New Delhi, India
| | - Amit Rahi
- Laboratory of Molecular Biology and Genetic Engineering, School of Biotechnology, Jawaharlal Nehru University, New Delhi, India
| | - Prerna Chaudhary
- School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Ravi Rajwanshi
- School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Neera Bhalla Sarin
- School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Rakesh Bhatnagar
- Laboratory of Molecular Biology and Genetic Engineering, School of Biotechnology, Jawaharlal Nehru University, New Delhi, India.
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14
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Arévalo MT, Navarro A, Arico CD, Li J, Alkhatib O, Chen S, Diaz-Arévalo D, Zeng M. Targeted silencing of anthrax toxin receptors protects against anthrax toxins. J Biol Chem 2014; 289:15730-8. [PMID: 24742682 DOI: 10.1074/jbc.m113.538587] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Anthrax spores can be aerosolized and dispersed as a bioweapon. Current postexposure treatments are inadequate at later stages of infection, when high levels of anthrax toxins are present. Anthrax toxins enter cells via two identified anthrax toxin receptors: tumor endothelial marker 8 (TEM8) and capillary morphogenesis protein 2 (CMG2). We hypothesized that host cells would be protected from anthrax toxins if anthrax toxin receptor expression was effectively silenced using RNA interference (RNAi) technology. Thus, anthrax toxin receptors in mouse and human macrophages were silenced using targeted siRNAs or blocked with specific antibody prior to challenge with anthrax lethal toxin. Viability assays were used to assess protection in macrophages treated with specific siRNA or antibody as compared with untreated cells. Silencing CMG2 using targeted siRNAs provided almost complete protection against anthrax lethal toxin-induced cytotoxicity and death in murine and human macrophages. The same results were obtained by prebinding cells with specific antibody prior to treatment with anthrax lethal toxin. In addition, TEM8-targeted siRNAs also offered significant protection against lethal toxin in human macrophage-like cells. Furthermore, silencing CMG2, TEM8, or both receptors in combination was also protective against MEK2 cleavage by lethal toxin or adenylyl cyclase activity by edema toxin in human kidney cells. Thus, anthrax toxin receptor-targeted RNAi has the potential to be developed as a life-saving, postexposure therapy against anthrax.
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Affiliation(s)
- Maria T Arévalo
- From the Center of Excellence for Infectious Diseases, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center, El Paso, Texas 79905
| | - Ashley Navarro
- From the Center of Excellence for Infectious Diseases, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center, El Paso, Texas 79905
| | - Chenoa D Arico
- From the Center of Excellence for Infectious Diseases, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center, El Paso, Texas 79905
| | - Junwei Li
- From the Center of Excellence for Infectious Diseases, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center, El Paso, Texas 79905
| | - Omar Alkhatib
- From the Center of Excellence for Infectious Diseases, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center, El Paso, Texas 79905
| | - Shan Chen
- From the Center of Excellence for Infectious Diseases, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center, El Paso, Texas 79905
| | - Diana Diaz-Arévalo
- From the Center of Excellence for Infectious Diseases, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center, El Paso, Texas 79905
| | - Mingtao Zeng
- From the Center of Excellence for Infectious Diseases, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center, El Paso, Texas 79905
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15
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Liu S, Moayeri M, Leppla SH. Anthrax lethal and edema toxins in anthrax pathogenesis. Trends Microbiol 2014; 22:317-25. [PMID: 24684968 DOI: 10.1016/j.tim.2014.02.012] [Citation(s) in RCA: 113] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Revised: 02/23/2014] [Accepted: 02/26/2014] [Indexed: 10/25/2022]
Abstract
The pathophysiological effects resulting from many bacterial diseases are caused by exotoxins released by the bacteria. Bacillus anthracis, a spore-forming bacterium, is such a pathogen, causing anthrax through a combination of bacterial infection and toxemia. B. anthracis causes natural infection in humans and animals and has been a top bioterrorism concern since the 2001 anthrax attacks in the USA. The exotoxins secreted by B. anthracis use capillary morphogenesis protein 2 (CMG2) as the major toxin receptor and play essential roles in pathogenesis during the entire course of the disease. This review focuses on the activities of anthrax toxins and their roles in initial and late stages of anthrax infection.
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Affiliation(s)
- Shihui Liu
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA.
| | - Mahtab Moayeri
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA.
| | - Stephen H Leppla
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA.
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Milhomme O, Dhénin SG, Djedaïni-Pilard F, Moreau V, Grandjean C. Synthetic studies toward the anthrax tetrasaccharide: alternative synthesis of this antigen. Carbohydr Res 2012; 356:115-31. [DOI: 10.1016/j.carres.2012.01.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2011] [Revised: 01/15/2012] [Accepted: 01/17/2012] [Indexed: 10/14/2022]
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17
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Hardiman CA. From structure to solutions: the role of basic research in developing anthrax countermeasures: Microbiology Graduate Program Seminar: Anthrax toxin. THE YALE JOURNAL OF BIOLOGY AND MEDICINE 2012; 85:285-92. [PMID: 22737057 PMCID: PMC3375657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Dr. John Collier traced the discoveries that elucidated the structure and function of the anthrax toxin in his talk "Anthrax Toxin," which was part of the Microbiology Graduate Program Seminar Series at Yale School of Medicine on February 23, 2012. Dr. Collier, Professor of Microbiology and Immunobiology at Harvard University, began by noting the advantages to studying anthrax pathogenesis in a biosafety level-1 lab. This designation does not merely facilitate his research, but also reflects a larger trend of basic research being leveraged to develop translational applications. Basic research on toxin structure has led to the development of a vaccine by Dr. Collier's group. Next-generation prophylactics also may stem from recent discoveries uncovering a role for cellular cofactors that mediate toxin function. Finally, basic research into the toxin substructure has facilitated efforts to change the receptor tropism to target dysregulated cells for therapeutic purposes. The urgency around biodefense agents makes the choice of research priorities a salient issue. As such, this author submits that basic research occupies a unique and lucrative niche driving clinical applications.
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Bishop BL, Lodolce JP, Kolodziej LE, Boone DL, Tang WJ. The role of anthrolysin O in gut epithelial barrier disruption during Bacillus anthracis infection. Biochem Biophys Res Commun 2010; 394:254-9. [PMID: 20188700 DOI: 10.1016/j.bbrc.2010.02.091] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2010] [Accepted: 02/15/2010] [Indexed: 01/13/2023]
Abstract
Gastrointestinal (GI) anthrax, caused by the bacterial infection of Bacillus anthracis, posts a significant bioterrorism threat by its relatively high mortality rate in humans. Different from inhalational anthrax by the route of infection, accumulating evidence indicates the bypass of vegetative bacteria across GI epithelium is required to initiate GI anthrax. Previously, we reported that purified anthrolysin O (ALO), instead of tripartite anthrax edema and lethal toxins, is capable of disrupting gut epithelial tight junctions and barrier function in cultured cells. Here, we show that ALO can disrupt intestinal tissue barrier function in an ex vivo mouse model. To explore the effects of ALO in a cell culture model of B. anthracis infection, we showed that anthrax bacteria can effectively reduce the monolayer integrity of human Caco-2 brush-border expressor (C2BBE) cells based on the reduced transepithelial resistance and the increased leakage of fluorescent dye. This disruption is likely caused by tight junction dysfunction observed by the reorganization of the tight junction protein occludin. Consequently, we observe significant passage of vegetative anthrax bacteria across C2BBE cells. This barrier disruption and bacterial crossover requires ALO since ALO-deficient B. anthracis strains fail to induce monolayer dysfunction and allow the passage of anthrax bacteria. Together these findings point to a pivotal role for ALO within the establishment of GI anthrax infection and the initial bypass of the epithelial barrier.
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Affiliation(s)
- Brian L Bishop
- Ben May Department for Cancer Research, University of Chicago, 929 E., 57th St., Chicago, IL 60637, USA
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Fasanella A, Galante D, Garofolo G, Jones MH. Anthrax undervalued zoonosis. Vet Microbiol 2009; 140:318-31. [PMID: 19747785 DOI: 10.1016/j.vetmic.2009.08.016] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2009] [Revised: 08/03/2009] [Accepted: 08/11/2009] [Indexed: 11/19/2022]
Abstract
Anthrax is a non-contagious disease, known since ancient times. However, it became a matter of global public interest after the bioterrorist attacks in the U.S.A. during the autumn of 2001. The concern of politicians and civil authorities everywhere towards this emergency necessitated a significant research effort and the prevention of new bioterrorist acts. Anthrax is primarily a disease that affects livestock and wildlife; its distribution is worldwide; and it can represent a danger to humans but especially more so when it occurs in areas considered to be free and in atypical seasons and climatic conditions. The atypicality of the phenomenon may lead health workers to misdiagnose and, consequently, an inappropriately manage of affected carcasses with a consequent and inevitable increase in the risk of human infection. This article emphasises the importance of paying increasing attention to this zoonosis. The biggest risk is its underestimation.
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Affiliation(s)
- Antonio Fasanella
- Istituto Zooprofilattico Sperimentale della Puglia e della Basilicata, Anthrax Reference Institute of Italy, Foggia, Italy.
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Tonello F, Montecucco C. The anthrax lethal factor and its MAPK kinase-specific metalloprotease activity. Mol Aspects Med 2009; 30:431-8. [PMID: 19665472 DOI: 10.1016/j.mam.2009.07.006] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2009] [Accepted: 07/30/2009] [Indexed: 02/06/2023]
Abstract
The anthrax lethal factor is a multi-domain protein toxin released by Bacillus anthracis which enters cells in a process mediated by the protective antigen and specific cell receptors. In the cytosol, the lethal factor cleaves the N-terminal tail of many MAPK kinases, thus deranging a major cell signaling pathway. The structural features at the basis of these activities of LF are reviewed here with particular attention to the proteolytic activity and to the identification of specific inhibitors. A significant similarity between the metalloprotease domain of the lethal factor and of that of the clostridial neurotoxins has been noted and is discussed.
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Affiliation(s)
- Fiorella Tonello
- Dipartimento di Scienze Biomediche Sperimentali, Istituto CNR di Neuroscienze, Università di Padova, Viale G. Colombo 3, 35131 Padova, Italy
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Schwartz M. Dr. Jekyll and Mr. Hyde: a short history of anthrax. Mol Aspects Med 2009; 30:347-55. [PMID: 19577591 DOI: 10.1016/j.mam.2009.06.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2009] [Accepted: 06/29/2009] [Indexed: 10/20/2022]
Abstract
The anthrax letters crisis, following the discovery of a major bacterial warfare program in the USSR and the realization that Irak had been on the verge of using anthrax as a weapon during the first Gulf war, had the consequence of putting anthrax back on the agenda of scientists. Fortunately, although it was mostly unknown by the public before these events, it was far from unknown by microbiologists. Already mentioned in the bible as a disease of herbivores, it remained a major cause of death for animals all over the planet until the end of the 19th century, with occasional, sometimes extensive, contamination of human beings. The aetiological agent, Bacillus anthracis, was identified by French and German scientists in the 1860s and 1870s. This was the first time that a disease could be attributed to a specific microorganism. The discovery by Koch that this bacterium formed spores greatly contributed to the understanding of the disease epidemiology. Studies on the pathophysiology of anthrax led to the identification of two major virulence factors, the capsule, protecting the bacilli against phagocytosis, and a tripartite toxin. The latter consists of two toxins with a common component (protecting antigen, PA) that allows the binding to and penetration into cells of two enzymes, the oedema factor EF, a calmodulin dependent adenylate cyclase, and the lethal factor LF, a specific zinc metalloprotease. The primary targets of these toxins would seem to be cells of innate immunity that would otherwise impair multiplication of the bacilli. If detected early enough, B. anthracis infections can be stopped by using antibiotics such as ciprofloxacin. Infection of animals can be prevented by the administration of vaccines, the first of which was developed by Pasteur after an historical testing at Pouilly-le-Fort which marked the beginning of the science of vaccines.
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Affiliation(s)
- Maxime Schwartz
- Institut Pasteur, 25 Rue du Docteur Roux, 75015 Paris, France.
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Abstract
Bacillus anthracis represents a formidable bioterrorism and biowarfare threat for which new vaccines are needed with improved safety and efficacy over current options. Toward this end, we created recombinant adeno-associated virus type 1 (rAAV1) vectors containing synthetic genes derived from the protective antigen (PA) or lethal factor (LF) of anthrax lethal toxin (LeTx) and tested them for immunogenicity and induction of toxin-neutralizing antibodies in rabbits. Codon-optimized segments encoding activated PA (PA63), or LF, were synthesized and cloned into optimized rAAV1 vectors containing a human cytomegalovirus (hCMV) promoter and synthetic optimized leader. Serum from rabbits immunized intramuscularly with rAAV1/PA (monovalent), rAAV1/LF (monovalent), rAAV1/PA + rAAV1/LF (bivalent), or rAAV1/enhanced green fluorescent protein (control) exhibited substantial PA- and LF-specific antibody responses at 4 weeks by both western blot (> 1:10,000 dilution) and enzyme-linked immunosorbent assay (ELISA) (mean end-point titer: 32,000-260,000), and contained anthrax LeTx-neutralizing activity in vitro, with peak titers approximating those of a rabbit hyperimmune antisera raised against soluble PA and LF. Compared to the monovalent groups (rAAV1/PA or rAAV1/LF), the bivalent group (rAAV1/PA + rAAV1/LF) exhibited marginally higher ELISA and neutralization activity with dual specificity for both PA and LF. The finding of robust neutralizing antibody responses after a single injection of these rAAV1-based vectors supports their further development as candidate anthrax vaccines.
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