Flashcards in Pathogens Host Defenses Deck (103)
What inactivates exotoxins? Exotoxins are highly what?
Antibody response inactivates exotoxins. They are highly immunogenic (produce an immune response)
What are exotoxins categorized by? Give 5 examples.
1. Neurotoxins (nerve tissue)
2. Enterotoxins (GI tract)
3. Nephrotoxins (kidney)
4. Hepatotoxins (liver)
5. Cardiotoxins (heart)
What are 2 examples of extracellular exotoxins?
What type of toxin are AB toxins?
What do AB toxins do? What 2 subunits are they made up of?
They modify host cells. Enzymatic subunit A + binding/cell entry B
What does Subunit A of AB toxins do?
It modifies a target inside the host cell, leading to damage to the host.
What is an example of an enzymatic subunit A of an AB toxin?
What does Subunit B of AB toxins do? What does this provide?
It binds to specific cell receptors providing tissue/cell type specificity
What is an example of an AB toxin? What category of an AB toxin does it fall under?
Clostridium botulinum, a neurotoxin
What does the Botulinum neurotoxin block? What is the effect?
Blocks acetylcholine release in neuromuscular junction, leading to Flaccid paralysis (this inhibits muscle contractions)
What organisms does the AB neurotoxin Botulunim affect?
In what silly way do humans use the Botulinum toxin?
What does BOTOX do?
- Reduces wrinkles / frown
- Controls muscle spasms
- treats for hyperhydrolysis (excessive sweating)
What does the acetylcholine neurotransmitter normally do? How does the botulism toxin affect this?
It induces contraction of muscle fibers.
Botulism toxin blocks the release of A, inhibiting contraction
What is an example of an AB5 toxin?
Cholera toxin (Vibrio cholerae)
What is an infection by the cholera toxin Vibrio cholerae characterized by?
Massive loss of fluid from the GI tract
In the cholera toxin (Vibrio cholerae), what is the function of the A subunit? B subunit?
A: Adenylate cyclase, produces cAMP
B: binds to intestinal cells
When is lipid A of LPS from gram-neg bacterial pathogens released?
During multiplication of lysis of bacterial cells
Can endotoxins be inactivated? Why?
No, heat stable
Are endotoxins strongly or weekly immunogenic? How?
Weakly - no antibody are produced agains LPS
Endotoxins are very effective activators of what? What do they produce?
The immune system. They produce general systemic effects such as pyrogenic (heat) fever, shock, weakness, inflammation, diarrhea, septic shock
Endotoxins are an important cause of symptoms in what type of bacterial infections? What are 2 exmples?
In all gram-neg
Exotoxins stimulate the host defense system to produce what? This makes them highly what?
Antibodies that can neutralize the toxin.
When you get a vaccine, what is actually injected into your body?
Can exotoxins or endotoxins become toxoids?
What are toxoids?
ENXOtoxins inactivated by heat or formaldehyde
What characteristic of exotoxins do toxoids still possess?
Toxoids are no longer toxic, but are still antigenic (induce antibody response)
Why can endotoxins not be converted into toxoids?
They cannot be inactivated by heat or formaldehyde
Are there any vaccines against endotoxins?
No, because can not be transformed into toxoids