1.4.2 Immune Responses to Viruses I

Question 1

What are the 3 general mechanisms by which the immune system controls or eliminates viruses?

Answer 1

1. Soluble extracellular factors that:
   
   • Damage viral structures
   • Inhibit virus binding to, entry into or un-coating in host cells
   • Promote clearance, uptake and elimination by phagocytic cells
2. Inhibition of intracellular virus replication by:
3. Immune-mediated recognition and lysis of virus-infected host cells by NK cells and CTL

Question 2

Describe the role of interferons, complement and NK cells in antiviral immunity.

Answer 2

Question 3

Answer 3

A, D, E

Question 4

What are the 3 ways that innate immune cells recognize viruses?

Answer 4

Cell surface PRR

Endosomal PRR: Toll-like receptors

Cytosolic PRR: Nod-like receptors

Question 5

What are the main roles of interferons (5)

Answer 5

Question 6

What are the important facts about complement?

Answer 6

All 3 pathways of complement recognize patterns at some level

All pathways lead to the production of a C3 Convertase

C3b/iC3b acts a potent opsonin

Question 7

What are the 3 ways that complement disrupts the pathogenesis of viruses?

Answer 7

Question 8

What is the role of NK cells in innate immunity?

Answer 8

Kill, Kill, Kill everything that doesn’t express MHC class I

Question 9

Describe 3 major protective mechanisms of immune protection against viruses provided by the adaptive immune system. Explain the role of antibody, CTL and Th cells.

Answer 9

Question 13

What is the role of Th cells?

Answer 13

Question 14

What is the role of Cytotoxic T cells in adaptive immunity?

Answer 14

Question 15

Answer 15

C

Question 16

What are some of the host innate/adaptive techniques to fight off viruses?

Answer 16

Question 17

What some ways that viruses try to evade the immune system?

Answer 17

Question 21

Answer 21

Question 22

Answer 22

B. Inhibition of MHC Class I expression

Question 23

Answer 23

B. Antigenic variation

Question 26

Which type of Ig is more effective at mucosal surfaces in preventing host cell attachement to epithelium?

Answer 26

IgA

Question 27

What Ig is important in facilitating clearnace from infected tissues -> opsonophagocytosis?

Answer 27

IgG > IgM

Question 28

What is seroconversion? How can it be important in diagnosis?

Answer 28

A rise in serum Ab titers.

IgM implies a recent, primary infection

IgG implies either a more chronic or repeat infection

Question 34

What what might the recurrence of infection by a virus that had previously gone latent?

Answer 34

Cellular immune defects exist

Question 35

What are some ways that viruses try to alter MHC expression and Ag presentation?

Answer 35

1. Disrupts peptide transport and loading of MHC I
2. Degradation of MHC I
3. Binds MHC class II and prevents peptide loading

Question 36

What some mechanisms that viruses employ to alter cytokines/growth factors?

Answer 36

1. produce immunosuppressive IL-10-like mimic
2. encode soluble receptors
3. encode EGF-like mimic that promotes epithelial cell growth and viral replication

Question 40

What are some of the pathogen immune evasion mechanisms that evade the important host protective mechanisms?

Answer 40

Persistance (waiting for immunosuppression), antigenic variation, decreased MHC-I, immune suppression

Question 41

What are the 3 general immune mechanisms for eliminating viruses that involve innate and adaptive immunity?

Answer 41

Innate: complement, interferon, NK cells Adaptive: Ab (neutralizing clearance, ADCC) and CTLs

Question 42

More cards need to be made using the supplemental materials!