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Immunology > Immunity to Viruses (18) > Flashcards

Immunity to Viruses (18) Flashcards

1
Q

T/F: Viruses must infect a cell intracellularly

A

TRUE

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2
Q

What is the effector molecule for antibody-mediated?

A

antibody
complement activated by IgG or IgM

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3
Q

What is the activity in antibody-mediated response?

A

blocks binding of virus to host cell, fusion of viral envelope with host cell membrane
enhances phagocytosis (opsonization)
agglutinates viral particles
mediates opsonization and lysis

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4
Q

What is the effector molecule for cell-mediated response?

A

IFN-gamma secreted by T helped or cytotoxic T cells
NK cells and macrophages

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5
Q

What is the activity in cell-mediated response?

A

has direct antiviral activity
kills virus infected cells
kill virus infected cells by antibody-dependent cell-mediated cytotoxicity (ADCC)

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6
Q

Virus particles, called ______, consist of a ______ surrounded by a layer of proteins

A

virions
nucleic acid core

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7
Q

The virus protein layer is called a ______, with subcomponents called ______

A

capsid
capsomeres

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8
Q

An envelope containing _____ may also surround virions

A

lipoprotein

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9
Q

What are the 3 major steps in virus infection (or 4)

A

adsorption - virus binds to receptors on cells
Virion taken through endocytosis
capsid is dismantled called uncoating, nucleic acid released
viral genome uncoated and replication begins

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10
Q

Retroviruses use a [positive/negative] strand for reverse transcription to make viral DNA

A

negative

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11
Q

The innate response to viral infections include the induction of type [I/II] interferons and activation of ______

A

Type I interferons
NK cells

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12
Q

The adaptive immune response to viruses include generation of ______ and neutralizing antibodies, which confer the long-term protection against individual viruses

A

cytotoxic T cells

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13
Q

The earliest immune response of the host to viral infection is production of ______

A

type I interferons - alpha and beta

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14
Q

What produces type I interferons?

A

cells of the innate immune system, especially macrophages and also by virally-infected cells

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15
Q

Infected cells produce _____ by detecting components of viral replication within them by detecting the presence of virus through Toll-like receptors

A

interferons

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16
Q

Toll-like receptors can bind a diverse array of _______ (_____)

A

microbial molecules (PAMPs)

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17
Q

TLR 2, 3, 7, 8, 9 are for

A

recognizing viruses

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18
Q

What are the 3 major mechanisms of interference with viral replication by interferons?

A
  1. synthesis of double-stranded RNA-dependent protein kinase
  2. activation of latent cellular endonuclease
  3. production of Mx proteins
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19
Q

What does synthesis of double-stranded RNA dependent protein kinase do? It results in ______

A

inactivates initiation factor EIF2alpha
results in inhibition of ALL protein synthesis, viral and cellular

20
Q

In activation of latent cellular endonuclease, IFN signaling induce expression of ______. What does this in turn activate and degrade?

A

2’5’ OAS (oligadenylate synthetase)
activates a latent cellular ribonuclease, RNase L
RNase L degrades mRNA and ribosomal RNA

21
Q

In the production of Mx proteins, they are expressed in hepatocytes and endothelial cells to inhibit ________ of a range of RNA viruses (influenza)

A

viral transcription and assembly

22
Q

Some viruses down regulate _____ on host cells which limits cell’s ability to present viral antigen on surface. _____ cells can recognize and eliminate such virally infected cells

A

MHC 1
NK cells

23
Q

NK cells activate macrophages by producing ________

A

IFN-gamma

24
Q

_____ destroy infected cells through antibody-dependent cell mediated toxicity

A

NK cells

25
Q

Adaptive immunity is mediated by _____ which block virus binding and entry into host cells

A

antibodies

26
Q

What are the two main parts of adaptive immunity?

A

humoral immunity
cell-mediated immunity

27
Q

MHC type [I/II] is better at eliminating certain parasites (nematodes or tapeworms) and reaction to vaccines

A

MHC II

28
Q

MHC [I/II] type response is better at producing an immune response that is effective at targeting viruses, bacteria, & protozoa (cell-mediated)

A

MHC I

29
Q

Ab-mediated immunity is effective against viruses only _______, before they enter host cells

A

at the extracellular stage of infection

30
Q

What is the Ig class that is most effective in neutralizing the virus?

A

IgG

31
Q

Immunity against re-infection is mediated by circulating virus-neutralizing antibodies which prevent _______ into host cells

A

virus attachment and entry

32
Q

Antibodies can promote clearance of ______ from the circulation by clumping viruses and facilitating their ______ by phagocytic cells

A

promote clearance of virus particles
facilitating their removal

33
Q

Antibodies are only effective when the virus is [inside/outside] the cell

A

OUTSIDE

34
Q

Antibodies ____ viruses by covering surface and sticking viral particles together

A

agglutinate

35
Q

______ are also readily engulfed and phagocytosed

A

Opsonized viruses

36
Q

Lysis of some enveloped viruses by the _____ can occur when IgG or IgM bind to surface and activate complement

A

membrane attack complex

37
Q

What is the exception to the rule of viruses outside of the cell with antibody-mediated immunity?

A

virus-infected cells when coated with antibody and with C3b bound to their surfaces
may be engulfed and destroyed by phagocytes

38
Q

During viral infection, CD8+T cells recognize viral antigen displayed in association with MHC class [I/II] molecules on nucleated cells and undergo rapid proliferation

A

MHC I

39
Q

Differentiation into effector cytotoxic CD8+ T cells results in release of _____, _______, and _____ which promote recruitment of inflammatory cells to the site of infection and interfere with viral replication

A

cytokines
IFN-gamma
TNF

40
Q

CTLs also kill infected cells through the release of _____ and _____, or through the induction of apoptosis by ______ interactions (death receptors)

A

perforin
granzymes
Fas/FasL

41
Q

A small portion of CTLs persist as ______ and have distinct survival receptors

A

memory cells

42
Q

Granzymes are a family of ______, such as caspase-3

A

serine proteases

43
Q

_______ system up-regulates T-cell survival

A

CD95L-CD95 (meaning T cells are eliminated)

44
Q

When ____ cells detect foreign nucleic acids through their toll-like receptors and others, they are triggered to secrete ______

A

type I interferons

45
Q

_______ are effective against extracellular viruses and can prevent them binding and infecting cells and thus neutralizing them

A

Antibodies

46
Q

[Humoral/cell-mediated] responses are primarily responsible for antiviral immunity

A

Cell-mediated

47
Q

The major mechanism involved is the killing of virus-infected cells by _______

A

cytotoxic T cells

Immunology (36 decks)

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