3.9

Question 1

Cell death
Lysis of host cells
1. growth of pathogen within host cells

Answer 1

• Cell membrane
damage causes cell
death (free radicalinduced lipid
peroxidation).
• Damage is
proportional to number
of bacteria inside cell.

Question 2

1. Cell death (continued)
   Lysis of host cells
2. cell-mediated immunity

Answer 2

activated CD8+ cell encounters infected cell displaying pMHC class 1
reactivated CD8+ cell proliferated and makes contact with other cells that display the same pMHC class 1
CTL use perforin and granzymes to kill cells displaying appropriate pMHC class 1

Question 3

1. Cell death (continued)
   Lysis of host cells
2. Membrane-damaging toxins

Answer 3

Apoptosis (programmed cell death)

Question 4

Damage caused by host responses
Uncontrolled inflammation
due to

Answer 4

exaggerated adaptive immune response = hypersensitivities

Question 5

Inflammation (3)

Answer 5

– healthy response
- increased blood supply (redness)
- increased vascular permeability (edema)
- chemotaxis (infiltration by phagocytes and
lymphocytes)

Question 6

Type I hypersensitivity =

Answer 6

allergy but can lead to

anaphylaxis and shock

Question 7

Type II hypersensitivity =

Answer 7

bound
antibodies leading to complement
and leukocyte activation to surfaces

Question 8

Type III hypersensitivity =

Answer 8

bound antibodies
leading to complement and leukocyte
activation to soluble molecules, then immune
complex deposition (e.g in glomeruli)

Question 9

Type IV hypersensitivity =

Answer 9

inflammation by purely CMI

responses (not antibodies)

Question 10

Alteration of the metabolism of host cells

caused by —

Answer 10

toxins

Question 11

Toxins

Answer 11

Microbial product or component that can injure another

cell or organism at low concentrations

Question 12

Toxins act in different ways: (3)

Answer 12

Modulation of targets inside a host cell
Action in the extracellular matrix
Action on surface of a host cell

Question 13

Toxin production and disease consequences vary widely

among

Answer 13

pathogenic bacteria

Question 14

Like transposons, many toxin-encoding genes are carried

on

Answer 14

plasmids or temperate bacteriophage genomes (easy to

transfer to other, non-toxigenic bacteria).

Question 15

ctxA and ctxB encode the

proteins that comprise

Answer 15

cholera toxin

Question 16

Modulation of targets inside a host cell

Exotoxins -

Answer 16

secreted by pathogens

Question 17

Modulation of targets inside a host cell

Type III cytotoxins -

Answer 17

injected into host cells

contact-dependent

Question 18

Exotoxins are secreted

by

Answer 18

Type I or II secretion

systems

Question 19

Common features of exotoxins (3)

Answer 19

1. A-B toxins (2 components)
2. Require activation (proteolysis or reduction of disulfides)
3. Many are ADP-ribosyltransferases

Question 20

Action of diphtheria toxin (an exotoxin)

Inhibits

Answer 20

translocation reaction

of protein synthesis

Question 21

Action on surface of a host cell

3

Answer 21

Membrane-damaging toxins
Superantigens
Endotoxin

Question 22

Membrane-damaging toxins

Answer 22

lipases, pore-forming toxins, hemolysins

Question 23

Endotoxin

=

Answer 23

LPS of gram negative bacteria

Question 24

Active toxin

part =

Answer 24

Lipid A

Question 25

Exoenzymes collagenases, hyaluronidases, DNases streptokinase (Streptococcus pyogenes) activates

Answer 25

plasminogen (converts to plasmin) | help microbes spread

Question 26

Protection against exotoxins (2)

Answer 26

A. Immunization with toxoids B. Treatment with antitoxins passive immunization