Immune Responses to Virus I

Question 1

All viruses are

Answer 1

obligate IC pathogens

Question 2

What are some special challenges to the immune system posed by viruses?

Answer 2

Question 3

What are three general strategies for immune elimination of viruses?

Answer 3

Question 4

What are some innate immune components present in newborns that can protect against viruses?

Answer 4

Complement

NK cells

Interferons

Question 5

Innate immunity is involves recognition of

Answer 5

patterns (not epitopes)

Question 6

Is innate immunity affected by immunization?

Answer 6

No

However, adjuvants stimulate innate immune cells (dendritic cells) and are sometimes used with vaccines.

Question 7

Does innate immunity result in memory for the pathogen?

Answer 7

No

Question 8

Function of vaccines?

Answer 8

Induce population of memory cells.

Question 9

NOD-like receptors trigger

Answer 9

Apoptosis (suicidal)

Question 10

Pattern recognition receptors

Answer 10

Cell Surface PRR

Endosomal PRR

Cytosolic PRR

Question 11

Describe innate immune response to viruses

Answer 11

Question 12

Describe interferon’s role in innate immunity.

Answer 12

Question 13

Interferons limit

Answer 13

viral replication

Question 14

Type I Interferons play an important role in

Answer 14

T cell regulation (Induce expression of MHC-I)

Question 15

Complement Pathway

Answer 15

Recognizes Patterns

All three pathways lead to production of C3 convertase which cleaves C3 into two molecules: opsonin and anaphylatoxin

C3 is most important opsonin

Question 16

Describe Complement Pathway’s role in innate immunity.

Answer 16

Question 17

NK cells are activated when

Answer 17

Target cell no longer expresses MHC molecules

Question 18

NK cells have two receptors:

Answer 18

Activating Receptor: Recognizes viral components

Inhibitory Receptor (trumps activation)

Question 19

What happens to NK cell receptors when they see MHC-I?

Answer 19

Turn off

Question 20

NK cells can kill tumor cells b/c

Answer 20

Tumor cells sometimes inhibit MHC-I expression

Question 21

Describe NK cells role in innate immunity

Answer 21

Question 22

Describe adaptive immunity

Answer 22

Question 23

Blocking antibodies are

Answer 23

Primarily IgG but also IgA on mucosal surfaces

Question 24

Describe function of blocking antibodies

Answer 24

Block attachments to susceptible cells

Bind to viruses when they are EC to prepare them for opsonophagocytosis by phagocytic cells

Bind to virus-encoded host cell surface antigens to facilitate type of killing called antibody-dependent cytotoxicity (NK cell with Fc receptor can use this strategy to kill virus-infected cells).

Question 25

Describe antibody's role in adaptive immunity

Answer 25

Question 26

Seroconversion is

Answer 26

Rise in antibody titer

Question 27

IgM implies

Answer 27

Recent, primary infection

Question 28

IgG implies

Answer 28

chronic or recent repeat infection

Question 29

Describe T Helper Cells role in adaptive immunity

Answer 29

Question 30

Describe Cytotoxic T cells role in adaptive immunity

Answer 30

Question 31

Rotavirus

Answer 31

Question 32

Which is an important immune response to rotavirus that reduces infection and dirrheal disease?

Answer 32

Production of secretory IgA antibodies

Question 33

Host immunity selects for virus variants that

Answer 33

evade protective immune mechanisms

Question 34

Evolving viral evasion mechanisms select for

Answer 34

new host immune protective responses over time

Question 35

Complement-Mediated Lysis Interferon Production Activation of NK cells and lysis Cytokine production

Answer 35

Innate Immune Responses

Question 36

Antigen presentation to T cells Activation of B and T cells Neutralizing antibody Opsonophagocytosis and killing CTL-mediated lysis Resolution of infection

Answer 36

Adaptive Immune Responses

Question 37

Influenza has immune evasion strategy of

Answer 37

Antigenic variation

Question 38

Describe immune evasion by viruses

Answer 38

Question 39

Immune Evasion: Virus Persistence

Answer 39

Question 40

Immune Evasion: Antigenic Variation

Answer 40

Question 41

Immune Evasion: MHC expression and antigen presentation

Answer 41

Question 42

Main points of immune evasion through MHC expression and antigen presentation

Answer 42

Block peptide loading for MHC (essential for expression) or Degrade MHC molecules (sometimes virus encode products bind MHC)

Question 43

Describe immune evasion: Cytokines/growth factors

Answer 43

Question 44

Immune evasion by cytokines/growth factors: main points

Answer 44

Different viruses use different cytokine strategies directed at producing ligand mimics or inhbiting key receptor of cytokine

Question 45

Immune Evasion: Host Cell Death

Answer 45

Question 46

If host makes neutralizing antibody, virus escapes through

Answer 46

antigenic variation

Question 47

Activation of cytotoxic T-cells through antigen presentation to T cells results in virus escaping detection by

Answer 47

Virus inhibiting MHC expression (process involves transporter molecule TAP)

Question 48

If host is using activation of NK cells and lysis as a back-up system, virus may respond by

Answer 48

Inducing anti-apoptosis genes

Question 49

Which immune evasion mechanism best enables a virus to avoid immune elimination by cytotoxic T cells?

Answer 49

Inhibition of MHC-I expression

Question 50

Virus can escape immune system recognition by producing soluble Fc receptor mimic only in

Answer 50

EC Phase

Question 51

Viruses use evasion mechanisms that target

Answer 51

the most important protective host responses for that virus

Question 52

Viruses target both

Answer 52

innate and adaptive immunity

Question 53

Main points of lecture

Answer 53

Question 54

What is herpangina?

Answer 54

Small lesions on palate caused by Coxsackie A virus

Question 55

As a member of a first responder team prepared to assist in the event of a biowarfare attack, you are asked to consider being immunized for smallpox. The vaccine consists of a heterologous attenuated live virus, vaccinia, which is given at multiple puncture sites in the skin overlaying the deltoid muscle. What type of anti-viral immunity is intended to be induced by this form of vaccine?

Answer 55

Answer: Induction of serum antibodies and cytotoxic T cells The primary purpose immunization is to induce circulating antibodies and memory T and B cells, which can be rapidly mobilized upon a subsequent encounter with a pathogen. The smallpox virus can be cleared by circulating antibodies and cytotoxic T cells are also protective, although there is evidence that CTLs mediate much of the skin damage associated with the smallpox rash. A is Incorrect. While vaccines can induce interferons, these immune mediators are short-lived. B is Incorrect. Vaccines do not alter a host’s innate immune responses. C is Incorrect. Vaccines can induce neutralizing secretory IgA antibodies, but immunization must be by the mucosal route (eg., oral or respiratory). D is Incorrect. NK cells are a component of the innate immune system. There numbers and activity are not altered by vaccination.