Microorganisms and Disease
The "A" subunit of diphtheria toxin

lysis macrophages with the release of cytokines
forms cAMP that leads to fluid accumulation
binds host cell receptors found on heart cells
cause ADP ribosylation of a factor involved in protein synthesis

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Microorganisms and Disease
Which of the following is common in the disease caused by Coryne-bacterium diphtheriae and Bacillus anthracis?

Diphtheria toxin and edema toxin are ADP ribosylating toxins
Both organisms cause skin and respiratory tract infections
The most serious disease symptoms are the direct result of toxin action
Both organisms are gram-positive spore formers

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Microorganisms and Disease
Type III secretion systems are used to inject "effector" proteins directly into a host cell. Salmonella uses a type III secretion system to help the pathogen to

survive within macrophages
activate T cells to proliferate and secrete cytokines
secrete LT (heat labile toxin) and ST (heat stable toxin) into the lumen of the intestine
survive the acid pH of the stomach

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Microorganisms and Disease
A major difference between EHEC and EPEC is

EPEC rearranges host cell actin and EHEC does not
EHEC possesses a type III secretion system and EPEC does not
EPEC passes through the placenta to infect the fetus and EHEC does not
EHEC secretes a Shiga-like toxin and EPEC does not

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