Lecture 21 - Immunity to Viral Infection

Question 1

What is the typical structure of a virus (inner to outermost)

Answer 1

RNA
protein
envelopes (sometimes)

Question 2

define obligate intracellular pathogens

Answer 2

use host cells resources for replication and release of viral progeny

Question 3

Viruses are selected for what

Answer 3

their ability to evade the host’s immune system

Question 4

Animals are selected for what

Answer 4

their resistance to disease

Question 5

Anti-viral immunity includes

Answer 5

1. complement
2. antibodies
3. activated macrophages
4. cytotoxic and NK cells

Question 6

What is the general virus life cycle (3 steps)

Answer 6

1. attachment, entry & uncoating
2. gene expression & replication
3. release

Question 7

What virus skips viral RNA during their life cycle

Answer 7

RNA virus

Question 8

What virus uses reverse transcription in their life cycle

Answer 8

retrovirus

Question 9

What is an example of a cytosolic PRR

Answer 9

RIG-1

Question 10

What is an example of an cell surface PRR

Answer 10

TLR 2/4

Question 11

What is an example of an endosomal PRR

Answer 11

TLR 3/7/8/9

Question 12

What does NF-kB do in PRR signaling

Answer 12

vasodilation, increase in body temp, increase in inflammatory cytokines

Question 13

What do ISGs do to produce an antiviral state

Answer 13

act on neighboring cells

Question 14

What is the function of Interferons (IFNs)

Answer 14

interfere with viral replication
3 types, glycoproteins

Question 15

What is the function of IFN-stimulated genes (ISGs)

Answer 15

promote robust anti-viral state through multimodal mechanisms, genes/proteins

Question 16

Type I IFNs

Answer 16

alpha beta isoforms
produced in large quantities by plasmacytoid DCs

Question 17

T/F: IFN-b is expressed by all nucleated cells

Answer 17

FALSE - has to be a viral infected nucleated cell

Question 18

Type III IFNs

Answer 18

4 types
produced by epithelial cells at mucosal surfaces
receptors restricted to epithelial cells, neutrophils, and DCs

Question 19

Action of:

2’5’OAS

Answer 19

degrade RNA

Question 20

Action of:

Protein kinase R

Answer 20

prevents translation

Question 21

Action of:

MxGTPase

Answer 21

blocks viral assembly

Question 22

Action of:

ISG15

Answer 22

destroys viral proteins

Question 23

Action of:

viperin

Answer 23

blocks lipid rafts

Question 24

Action of:

tetherin

Answer 24

prevents viral release

Question 25

How do antibodies promote anti-viral immunity?

Answer 25

1. virus binds to receptor and receptor mediated endocytosis 2. acidification of endosome and entry of viral DNA 3. antibody blocks binding to virus receptor

Question 26

What is ADCC

Answer 26

antibodies-coated virus-infected cells can be killed by NK cells in antibody-dependent cell mediated cytotoxicity

Question 27

What are the 4 steps of ADCC

Answer 27

1. antibody binds antigens on target cell surface 2. Fc receptors on NK recognize bound antibody 3. cross-linking of Fc receptors signals killing 4. apoptosis

Question 28

T/F: antibodies are ineffective once a pathogen enters the cell

Answer 28

TRUE

Question 29

What are the 6 immune evasion strategies

Answer 29

1. antigenic variation 2. inhibition of antigen presentation 3. modulation of MHC I expression 4. cytokine targeting 5. prevention of apoptosis 6. latency

Question 30

Explain latency

Answer 30

virus hides in immune privileged site and is a reversible state/recurrent infection upon migration to epithelial cells

Question 31

Explain CTL and NK cell exhaustion

Answer 31

upregulation of inhibitory receptors that repress activation of the cytolytic machinery of these cells