Bacterial Pathogenesis (Exam 1)

Question 1

_______ is secreted by living bacteria with a specific activity against hos tissues.

Answer 1

exotoxin

Question 2

_______ is inside a bacterial cell envelope and is released when it disintegrates or dies.

Answer 2

endotoxin

Question 3

What are “superantigens”?

Answer 3

surface-acting exotoxins

Question 4

Superantigens bypass normal antigen presentation binding _______ to stimulate _______.

Answer 4

MHC
T cells

Question 5

Superantigens stimulate T cells which produces what major effect?

Answer 5

cytokine storm (excess IL-2 production)

Question 6

(T/F) Superantigens have an effect at a systemic but not a local level.

Answer 6

False - can be either

Question 7

Locally, superantigen effects are _______, while systemically, they lead to _______.

Answer 7

flesh-eating
toxic shock

Question 8

A-B exotoxins have A which is the ______ subunit and B which is the ______ subunit.

Answer 8

active
binding

Question 9

Direct, “door-to-door” delivery of toxins from a bacterial cytoplasm to a eukaryotic host uses what system?

Answer 9

Type III secretion system

Question 10

_______ is reversible variation while ________ is irreversible variation in terms of rearrangements of major surface protein genes in bacteria.

Answer 10

phase variation
mutation

Question 11

Term for small molecule secreted by pathogens which binds a host’s iron for import into bacteria.

Answer 11

siderophores

Question 12

Lethal pathogens have a (low/high) LD50 and ID50.

Answer 12

low

Question 13

LD50s are (higher/lower) than ID50s.

Answer 13

higher

Question 14

Term for adherence factors of bacteria which help them stick to host ligands.

Answer 14

adhesins

Question 15

What is an example of an adhesin on bacteria?

Answer 15

fimriae/pili

Question 16

Term for molecule which help bacteria into a host cell.

Answer 16

invasins

Question 17

Term for molecule on bacteria that binds to a host receptor which allows bacteria to internalize into a host cell after a signaling cascade occurs.

Answer 17

internalin

Question 18

What is the name of the mechanism bacteria use to internalize into a host cell using internalin?

Answer 18

zipper mechanism

Question 19

List the 2 strategies pathogens use to evade a host’s immune system.

Answer 19

1. form capsules, S-layers, biofilms
2. antigen/phase variation

Question 20

Antigenic variation is a strategy used by pathogens to evade a host’s immune system which leads to (low/high) frequency mutations in (specific/random) genes.

Answer 20

high
specific

Question 21

Term for bacteria that can replicate both inside and outside a host cell.

Answer 21

facultative intracellular

Question 22

Term for bacteria that cannot replicate outside a host cell.

Answer 22

obligate intracellular

Question 23

(T/F) All intracellular bacteria replicate within the host cytoplasm.

Answer 23

False - cytoplasm or vacuoles

Question 24

List 4 ways a host defends itself against intracellular pathogens.

Answer 24

1. ROS
2. antimicrobial peptides
3. apoptosis
4. lysozyme

Question 25

What mechanism do intracellular pathogens use to evade host defenses which contain virulence factors for protection?

Answer 25

pathogenicity islands

Question 26

Two molecules hosts make that bind iron and prevent pathogens from acquiring it.

Answer 26

lactoferrin transferrin

Question 27

Two membrane disrupting proteins pathogens have which can cause tissue damage to the host.

Answer 27

hemolysin leukotoxin

Question 28

Hemolysin is a pore-forming toxin of _______ while leukotoxin is a pore-forming toxin of ______.

Answer 28

RBCs WBCs