V.cholera

Question 1

What are some common characteristics of the Genus Vibrio?

Answer 1

Curved, gram- rods, oxidase positve, Mostly Halophilic

Question 2

Describe vibrio cholerae.

Answer 2

Caustive agent of cholera; Polar flagella; NOT halophilic

Question 3

What are V. cholerae’s virulence factors?

Answer 3

Flagella, Mucinase, Zot, adhesins, chloera toxin.

Question 4

Elaborate on the adhesins of V. cholerae.

Answer 4

TCP pili, hemagglutinin, neuraminidase, accessory colonization factor.

Question 5

Discuss cholera toxin

Answer 5

AB subunit exotoxin;Produced by cholera-causing strains encoded on a lysogenic phage. TCP is phage recpetor on bacteria, secreted by Type 2 secretion system.

Question 6

Explain the regulation of cholera toxin.

Answer 6

Expression is regulated with expression of other virulence factors like TCP by ToxT via ToxR. Also a globlal regulatory system that responds to environmental signals like pH, temp, osmolarity and cell density.

Question 7

What does cholera toxin do?

Answer 7

ADP-ribosylates and inactivates a G-protein; A regulatory protein that regulates production of adenylate cyclase.

Question 8

What are the cellular effects of cholera toxin?

Answer 8

1. Persistent activation of adenylate cyclase.
2. Elevated cAMP levels
3. Hyper secretion of water and chloride ion and blocked absorption of Sodium
4. Hypermotility and watery diarrhea.

Question 9

How is V.cholera transmitted? Resevoir?

Answer 9

Oral-fecal; Need ingestion of organism, NOT toxin. Its resevoir is contaminated water or food.

Question 10

Describe the pathogenesis of V.cholera.

Answer 10

Motile cells move toward intestinal walls and penetrate mucus; Attach to epithelium via pili aand multipley on epithelial surface.

Question 11

Talk through the AB subunit action of cholera toxin.

Answer 11

Subunit B binds GM1 receptor, Subunit A enters the cell and ADP-ribosylates a G protein that regulates production of adenylate cyclase. Elevates cAMP and causes nutrient loss.

Question 12

Is the intestinal epithelium damaged?

Answer 12

NO; just loss of fluids due to watery diarrhea.

Question 13

How is V. cholera infection diagnosed?

Answer 13

Stool is mucus flecked, watery with no blood or leuckocytes; culture

Question 14

How is V. cholera treated?

Answer 14

Replacement of fluids and electrolytes; Prevented by improved sanitation