23. Shigella

Question 1

Disease caused by Shigella infection?

Answer 1

Bacillary dysentery (shigellosis)

Question 2

3 species of Shigella that cause shigellosis?

Answer 2

S. dysenteriae, S. flexneri, S. sonnei

Question 3

Shigella is a gram-______, ________cellular pathogen

Answer 3

Gram-negative

Intracellular pathogen

Question 4

Which other studied pathogenic bacteria is Shigella similar to? How?

Answer 4

Salmonella

Actively invasive

Question 5

Infectious dose of Shigella?

Answer 5

10-200 organisms

Question 6

3 ways Shigella has features common to Salmonella/Listeria/pathogenic E.coli?

Answer 6

Uses T3SS effectors to control gap junctions

Causes active invasion

Causes membrane ruffling to invade host cells

Question 7

What do Shigella hijack to cause the release of ATP from host cells?

Answer 7

Connexin 26 gap junction hemichannels

Question 8

Purpose of causing ATP release?

Answer 8

Further increases bacterial invasion

Question 9

What do Shigella use to control gap junctions?

Answer 9

T3SS effectors

Question 10

Name of effector Shigella generates? What is it similar to?

Answer 10

IcsA

ActA in Listeria

Question 11

Purpose of IcsA?

Answer 11

Recruits actin to propel bacteria around cytoplasm (huge comet tails)

Question 12

4 F’s of the fecal-oral route?

Answer 12

Food, fingers, feces, flies

Question 13

Where does Shigella replicate?

Answer 13

Cytoplasm

Question 14

How does the shiga toxin function?

Answer 14

A subunit can bind to host ribosomes => inhibits protein synthesis

Question 15

What can the shiga toxin cause to the host?

Answer 15

Watery diarrhea (w/ blood, mucus, pus)

Question 16

Shigella is resistant to many _______

Answer 16

antibiotics

Question 17

Is there a vaccine against Shigella?

Answer 17

No

Question 18

Which lab animal model is not susceptible to Shigella? Which will develop shigellosis? Which gives similar disease as in humans?

Answer 18

Not susceptible = mice

Develop shigellosis = young guinea pigs

Similar to humans = monkeys

Question 19

What part of cells do Shigella target for efficient cell-to-cell spreading?

Answer 19

Tricellular junctions

Question 20

What are tricellular junctions?

Answer 20

Junctions between multiple cells

Question 21

Tricellular junctions use what protein to fuse adjacent membranes?

Answer 21

Tricellulin

Question 22

How does Shigella move from cell to cell?

Answer 22

Couples tricellulin identification and clathrin-mediated endocytosis

Question 23

Shigella is a gram-_____, ____cellular pathogen

Answer 23

gram-negative

INTRAcellular pathogen

Question 24

Is shigella aerobic or anaerobic?

Answer 24

Anaerobic

Question 25

What does Shigella do to host cells to allow themselves to enter?

Answer 25

Cause membrane ruffling