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Black Death
- 14th century Europe
- Typically thought to be Y. pestis
- Medical records show people were dying too quickly (3-4 days) w/out buboes or fever
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Murrain
- Anthrax in cows
- Cattle boom in 14th century
- Infected meat sold in market places
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Connection between Murrain and Black Plauge
- Anthrax spores found in pits of plague victims
- 1340 evidence of spores jumping from cows to humans
- Early stages of plague and anthrax look the same
- Black Death was most likely more anthrax than plague
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Bacillus anthracis
- Anthrax bacterium
- rod shaped, prefers lymph
- Bacillaceae: Gram +
- Discovered by Koch 1876
- Spore forming (very hardy)
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Bacillus anthracis life cycle
- Usually cow parasite (human infection are incidental)
- Cows eat spores in grass
- Bacteria multiply, produce toxin, kill host
- Carcass opens, spores form
- Liquid leaches into soil
- Liquid dries, spores are left
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Anthrax Toxins
- Exotoxins: released outside of cell
- 3 main toxins
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Protective Antigen
- Not actually a toxin--> precursor to other toxins
- 2 parts
- 83kD (764 amino acid)
- Used in vaccine
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PA steps of Activity
- 1) Binds to host receptor
- -ATR (anthrax toxin receptor)
- -CMG2 (capillary morphogenesis protein 2)
- -capillary formation
- 2) Cleaved by host cell protease to be 63kD
- 3) Repeats 6 times
- 4) 7 parts bind together (heptamerize) to form pore on cell surface
- 5) Pore binds to one of the other 2 toxins to allow entry into cell
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Edema Factor (EF)
- 800 amino acids
- Causes cAMP level to rise
- -messes with cell energy level
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Lethal Factor
- 809 amino acids
- Cleaves MAPKK: interferes with cell signals and energy
- Macrophages hit especially hard (causes cell lysis)
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Transmission
- Cutaneous (wool sorter's disease, soil, biting flies: vegetative not spore)
- Gastrointestinal
- Inhalation
- No person-to-person
- Incubation ~7 days
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