What is Anthrax?
Gram-positive bacterium,* Bacillus anthracis*
What are the two forms of Bacillus anthracis?
- Vegetative (non-motile rods, fragile)
- Spore (ovoid, long-lasting)
What are the requirements for sporulation of Bacillus anthracis?
- Oxygen
- Poor nutrient condition (eg outside host)
Can you perform an autopsy/post mortem on an animal that was infected with anthrax?
NO! The bacteria would sporulate.
What are the 3 main routes to anthrax infection?
- Cutaneous (skin abrasions)
- Gastrointestinal (contaminated food/soil)
- Oropharyngeal (aerosolized spores)
Of tthe 3 main routes to infection, which 2 routes can be lethal if untreated?
Gastrointestinal and Oropharyngeal
Anthrax can affect all mammals and birds, but what group of animals is especially at risk?
Ruminants
What are the 3 forms of systemic anthrax disease?
- Peracute
- Acute
- Subacute
Peracute/Acute Anthrax Infections primarily affects…?
Ruminants and horses
What are the symptoms of peracute/acute anthrax infection?
- Tremors
- Neck edema
- Dyspnea
- Asphyxiation
- Abortion
- Bloody discharge
Subacute infection can affect all mammals, but especially… ?
pigs, cats, dogs
Symptoms of Subacute Anthrax infection?
- Neck edema
- Dyspnea
- Asphyxiation
- Anorexia
- ovmiting
- Diarrhea
- necrosis of GI tract
The anthrax toxin is composed of what 3 proteins?
- Protective Antigen (PA)
- Lethal Factor (LF)
- Edemic Factor (EF)
True or False:
The anthrax toxin proteins are harmless individually.
True
Which of the 3 proteins in the anthrax toxin is absolutely necessary for toxic effects?
Protective Antigen (PA)
how does the anthrax toxin enter the cell?
Anthrax receptors (ANTXR1, ANTXR2) bind Protective Antigen (PA). PA then forms a heptamer with the anthrax receptors and binds LF and/or EF. This complex is then internalized into endosomes which will gradually become acidic. The acidic environment turns PA into a channel that releases EF and LF into the cytoplasm.
Once released into the cytoplasm Edemic Factor (EF) does what?
- Converts ATP into cAMP (requires Ca2+/calmodulin)
- Increases leakiness of the endothelial barrier
- Inhibits phagocytosis by inflammatory cells
Once released into the cytoplasm Lethal Factor (LF) does what?
- Protease activity cleaves protective MAPKKs
- Induces apoptosis (especially cardiovasular system)
What is the current treatment for anthrax?
Antibiotics (doxycycline, ciprofloxacin)
What are some potential treatments for Anthrax?
- Dominant negative PA protein (bind anthrax receptor but LF and EF can’t bind)
- Soluble anthrax receptors to bind PA (won’t be internalized)
- Anthrax receptor antgonists
- Anti-PA, EF, and LF antibodies (cocktail)
How is anthrax used as a bioweapon?
- PA+LF, no EF
- High expression
- Dispersable aerosol
- Delivery system
