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Sem 3: Viro > Host Response to Viral Infection > Flashcards

Host Response to Viral Infection Flashcards

1
Q

What physical and chemical defenses are part of innate immunity?

A
  1. Skin
  2. Mucous membranes
  3. GI tract
  4. Resp tract
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2
Q

___________ cells synthesize and release a variety of cytokines, including type II IFN

A

NK cells

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3
Q

What recognizes PAMPS on viruses?

A

PRRs on surface of host cells (Ex: TLR)

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4
Q

What occurs when PRR on macrophage binds to PAMP on virus cell?

A

Stimulates

  1. Phagocytosis
  2. Chemotaxis
  3. Inflamm mediators
  4. Interferons
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5
Q

_________ (DNA/RNA) viruses are stronger inducers of interferon than _______ (DNA/RNA) viruses

A

RNA is stronger inducer of interferon than DNA viruses

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6
Q

Interferons are known to have anti-cancer properties, how should they ideally be administered?

A

Parenteral route (Injection)

** interferons are orally inactive bc its a glycoprotein

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7
Q

True or False: Interferons are virus specific

A

FALSE - no virus specificity

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8
Q

What are examples of Type 1 interferons?

A

IFN-a

IFN-b

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9
Q

How is IFN-a produced and what kind of interferon is it?

A

Leukocyte interferon - Type 1

Produced in large quantities by plasmacytoid dendritic cells

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10
Q

How is IFN-b produced and what kind of interferon is it?

A

Fibroblast interferon - Type 1

Secreted by virus infected fibroblasts

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11
Q

How do type 1 interferons inhibit virus replication?

A
  1. Activates latent RNAase to degrade viral RNA
  2. Synthesizes Mx proteins that bind and trap viral nucleocapsid and inhibit virus assembly
  3. Synthesizes Protein Kinase R (PKR) which prevents translation of viral RNA
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12
Q

What roles do type 1 IFNs have?

A
  1. Inhibits viral rep
  2. Activates NK cells
  3. Increases Ag presentation and MHC I expression
  4. Stimulates differentiation of monocytes into dendritic cells
  5. Maturation of DCs
  6. Memory T cell proliferation
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13
Q

Example of a type II interferon?

A

IFN-y

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14
Q

How is IFN-y produced?

A

Type II interferon produced by Ag-stimulated T cells and NK cells

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15
Q

Examples of Type III interferons?

A

IFN-λ1

IFN-λ2

IFN-λ3

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16
Q

When are Type III interferons expressed?

A

In response to viral infections and activation of TLRs

Functions as immunoregulator

17
Q

_______ interferons were recently discovered

A

Type III interferons- IFN-λ1, IFN-λ2, IFN-λ3

18
Q

_________ antigens elicit a protective Cell mediated immune response

A

Internal viral Ag

19
Q

________ antigens elicit a protective humoral AND CMI response

A

Surface Ag

20
Q

In humoral immunity, Ab can be directed against ?

A

Viral proteins on free virions (capsid or nucleocapsid)

OR against viral proteins on surface of infected cells

21
Q

What is virus neutralization?

A

Ab neutralizes virus by preventing attachment and entry into host cell

Ab binds to viral capsid or host envelope

22
Q

What are antiviral effects of antibodies?

A
  1. Virus Neutralization
  2. Opsonization
  3. Clumping of viruses (Immunocomplex formation)
  4. Complement activation
  5. ADCC pathway
23
Q

What is opsonization?

A

Coating of virions with Ab which is then detected and phagocytosed by macrophages and neutrophils

** Ab puts a sticker on virus infected cell which attracts host cells to come kill

24
Q

What are ways viruses evade the immune system? (9)

A
  1. Ag plasticity
  2. Antigenic multiplicity
  3. Negative cytokine regulation
  4. Down reg of MHC I pathway
  5. Inhibition of complement
  6. Evasion of neutralizing Ab
  7. Latency
  8. Cell to cell spread
  9. Inhibition of apoptosis
25
Q

What is antigenic plasticity?

A
  • Method viruses use to hide from IR
  • rapid changes in structure of Viral Ag, may be a result of mutation (Ag drift) , reassortment, or recombination (Ag shift)
26
Q

What is antigenic multiplicity?

A
  • Antigenic variants with little or no cross reactivity
  • Immune system can’t recognize variants
27
Q

How do viruses evade the immune system by negative cytokine regulation?

A
  1. Virokines are made by the virus which mimics host cytokines
  2. Viroceptors are made by the virus which mimic host receptors and is able to encode proteins (down reg)
28
Q

True or False: Rapid changes in structure of a viral Ag of a virus over time due to mutations is known as antigenic multiplicity

A

FALSE - Antigenic plasticity

Sem 3: Viro (17 decks)

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