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Flashcards in Pathogens Host Defenses Deck (103)
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61

What inactivates exotoxins? Exotoxins are highly what?

Antibody response inactivates exotoxins. They are highly immunogenic (produce an immune response)

62

What are exotoxins categorized by? Give 5 examples.

Their target.
1. Neurotoxins (nerve tissue)
2. Enterotoxins (GI tract)
3. Nephrotoxins (kidney)
4. Hepatotoxins (liver)
5. Cardiotoxins (heart)

63

What are 2 examples of extracellular exotoxins?

Hyaluronidase, collagenase

64

What type of toxin are AB toxins?

Exotoxins

65

What do AB toxins do? What 2 subunits are they made up of?

They modify host cells. Enzymatic subunit A + binding/cell entry B

66

What does Subunit A of AB toxins do?

It modifies a target inside the host cell, leading to damage to the host.

67

What is an example of an enzymatic subunit A of an AB toxin?

ADP-ribosyltransferase

68

What does Subunit B of AB toxins do? What does this provide?

It binds to specific cell receptors providing tissue/cell type specificity

69

What is an example of an AB toxin? What category of an AB toxin does it fall under?

Clostridium botulinum, a neurotoxin

70

What does the Botulinum neurotoxin block? What is the effect?

Blocks acetylcholine release in neuromuscular junction, leading to Flaccid paralysis (this inhibits muscle contractions)

71

What organisms does the AB neurotoxin Botulunim affect?

Humans
Cattle
Horses
Ducks

72

In what silly way do humans use the Botulinum toxin?

BOTOX!

73

What does BOTOX do?

- Reduces wrinkles / frown
- Controls muscle spasms
- treats for hyperhydrolysis (excessive sweating)

74

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

75

What is an example of an AB5 toxin?

Cholera toxin (Vibrio cholerae)

76

What is an infection by the cholera toxin Vibrio cholerae characterized by?

Severe diarrhea
Massive loss of fluid from the GI tract

77

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

78

When is lipid A of LPS from gram-neg bacterial pathogens released?

During multiplication of lysis of bacterial cells

79

Can endotoxins be inactivated? Why?

No, heat stable

80

Are endotoxins strongly or weekly immunogenic? How?

Weakly - no antibody are produced agains LPS

81

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

82

Endotoxins are an important cause of symptoms in what type of bacterial infections? What are 2 exmples?

In all gram-neg

Salmonella, E.coli

83

Exotoxins stimulate the host defense system to produce what? This makes them highly what?

Antibodies that can neutralize the toxin.

Highly antigenic

84

When you get a vaccine, what is actually injected into your body?

Toxoids

85

Can exotoxins or endotoxins become toxoids?

Exotoxins only

86

What are toxoids?

ENXOtoxins inactivated by heat or formaldehyde

87

What characteristic of exotoxins do toxoids still possess?

Toxoids are no longer toxic, but are still antigenic (induce antibody response)

88

Why can endotoxins not be converted into toxoids?

They cannot be inactivated by heat or formaldehyde

89

Are there any vaccines against endotoxins?

No, because can not be transformed into toxoids

90

What are the chemical properties of exotoxins?

Proteins excreted by certain gram-positive or gram-negative bacteria; generally heat-liable