Bacillus anthracis as a Bioterrorism Agent: Difference between revisions
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== | ==Description and Methods of Infection== | ||
<br> | <br><b>Biology of Bacillus anthracis</b> | ||
<br><i>Bacillus anthracis</i> is the organism which causes the disease of anthrax. It is a large Gram positive aerobic, rod shaped, bacillus bacterium. It ranges from 1-1.5 x 3-10 µm in size and is the only obligate pathogen within the genus bacillus.<sup>1</sup> | |||
Two virulence plasmids pXO1 and pXO2 encode the major virulence factors for<br><i>B. anthracis</i>.<sup>2</sup> Plasmid pXO1 codes for three toxins which cause hemorrhage, edema, and necrosis. It is 184.5 kilobase pairs (kbp) in size. The exotoxins it codes for are binary, so that the protective antigen acta as a binding domain on the host thus permitting entry of the toxin. pXO2 is a smaller capsule bearing plasmid than pXO1 that is 95.3 kbp in size.It encodes three genes (cap A, cap B, and cap C) which is involved in the synthesis of the polyglutamyl capsule. The capsule prevents the bacteria from phagocytosis and is poorly recognized by the immune system of the host.<sup>3</sup> Both pXO1 and pXO2 plasmids are necessary to provide the anthrax toxin and capsule respectively for <br><i>B. anthracis</i> to have full virulence. An attenuated strain results when either plasmid is lost.<sup>4</sup> | |||
<br><b>Anthrax has three routes of infection</b> | |||
Anthrax has three forms in which virulence occurs as cutaneous anthrax, gastrointestinal anthrax, and inhalational anthrax. Cutaneous anthrax comprises over 90% of all human cases. It is obtained via a lesion on the skin in which infection occurs through an abrasion, cut, or insect bite.<sup>5</sup> This type of anthrax manifests itself through a black eschar associated with edema. Gastrointestinal anthrax results for the ingestion of undercooked meat from animals who have <br><i>B. anthracis</i>. This form of the disease has a high mortality rate because it is difficult to make an early diagnosis due to its’ non specific presentation. Inhalation anthrax is the third way in which anthrax can be contracted. It is of utmost concern for its use as an agent of bioterrorism. Inhalation anthrax was traditionally associated with industrial exposure as spores in the textile, meat packing, leather-tanning, bone meal processing, and hair/wool-sorting industries until its use as a bioterrorism agent in 2001. Beginning with “flu-like” symptoms of mild fever, fatigue, malaise, myalgia, and non-productive cough from two to five days after initial exposure, it develops into an acute illness characterized by acute illness characterized by dyspnea, stridor, fever, cyanosis, and pleural effusion. If not treated by multidrug antibiotic regimens and supported care, the disease is more likely to result in coma and death. | |||
==Section 2== | ==Section 2== | ||
Revision as of 08:09, 26 March 2013
Introduction
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Legend/credit: Electron micrograph of the Ebola Zaire virus. This was the first photo ever taken of the virus, on 10/13/1976. By Dr. F.A. Murphy, now at U.C. Davis, then at the CDC.
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Description and Methods of Infection
Biology of Bacillus anthracis
Bacillus anthracis is the organism which causes the disease of anthrax. It is a large Gram positive aerobic, rod shaped, bacillus bacterium. It ranges from 1-1.5 x 3-10 µm in size and is the only obligate pathogen within the genus bacillus.1
Two virulence plasmids pXO1 and pXO2 encode the major virulence factors for
B. anthracis.2 Plasmid pXO1 codes for three toxins which cause hemorrhage, edema, and necrosis. It is 184.5 kilobase pairs (kbp) in size. The exotoxins it codes for are binary, so that the protective antigen acta as a binding domain on the host thus permitting entry of the toxin. pXO2 is a smaller capsule bearing plasmid than pXO1 that is 95.3 kbp in size.It encodes three genes (cap A, cap B, and cap C) which is involved in the synthesis of the polyglutamyl capsule. The capsule prevents the bacteria from phagocytosis and is poorly recognized by the immune system of the host.3 Both pXO1 and pXO2 plasmids are necessary to provide the anthrax toxin and capsule respectively for
B. anthracis to have full virulence. An attenuated strain results when either plasmid is lost.4
Anthrax has three routes of infection
Anthrax has three forms in which virulence occurs as cutaneous anthrax, gastrointestinal anthrax, and inhalational anthrax. Cutaneous anthrax comprises over 90% of all human cases. It is obtained via a lesion on the skin in which infection occurs through an abrasion, cut, or insect bite.5 This type of anthrax manifests itself through a black eschar associated with edema. Gastrointestinal anthrax results for the ingestion of undercooked meat from animals who have
B. anthracis. This form of the disease has a high mortality rate because it is difficult to make an early diagnosis due to its’ non specific presentation. Inhalation anthrax is the third way in which anthrax can be contracted. It is of utmost concern for its use as an agent of bioterrorism. Inhalation anthrax was traditionally associated with industrial exposure as spores in the textile, meat packing, leather-tanning, bone meal processing, and hair/wool-sorting industries until its use as a bioterrorism agent in 2001. Beginning with “flu-like” symptoms of mild fever, fatigue, malaise, myalgia, and non-productive cough from two to five days after initial exposure, it develops into an acute illness characterized by acute illness characterized by dyspnea, stridor, fever, cyanosis, and pleural effusion. If not treated by multidrug antibiotic regimens and supported care, the disease is more likely to result in coma and death.
Section 2
Include some current research in each topic, with at least one figure showing data.
Section 3
Include some current research in each topic, with at least one figure showing data.
Conclusion
Overall paper length should be 3,000 words, with at least 3 figures.
References
Edited by Alison Lerner, a student of Nora Sullivan in BIOL187S (Microbial Life) in The Keck Science Department of the Claremont Colleges Spring 2013.
