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Virology (BIOL 612) > Exam 1 > Flashcards

Exam 1 Flashcards

1
Q

Which age groups are most susceptible to viral infection?

A

Elderly and toddlers (not newborns)

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2
Q

Why are toddlers more susceptible to viral infection than newborns?

A

Newborns gain passive immunity from their mothers through breast milk

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3
Q

Which vitamin is added to vaccines to enhance their effects?

A

Vitamin A

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4
Q

Vitamin A is known as an _______ because it enhances the effects of a vaccine.

A

Adjuvant

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5
Q

What are the 3 ways viruses can pass from a mother to a baby?

A
  1. Transplacental (in womb)
  2. Perinatal (during labor)
  3. Postnatal (after birth)
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6
Q

Mutations in ___ and ___ will make a person less susceptible to HIV

A

CCR4 and CCR5

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7
Q

Mutations in CCR4 make one less susceptible to HIV by __________.

A

Granting them large resistance to HIV infection

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8
Q

Mutations in CCR5 make one less susceptible to HIV by __________.

A

Making the disease progress much slower

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9
Q

Long-term usage of ________ will lead to an increased risk of infection

A

Glucocorticoids

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10
Q

What are restriction factors?

A

Proteins that block a particular infection

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11
Q

What molecule is implanted into the membranes of budded off visions to route them to endosomes for degradation?

A

Tetherin

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12
Q

What kinds of pathogens does innate immunity protect against?

A

All pathogens. Non-specific

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13
Q

(T/F) Innate immunity makes use of antibodies

A

False

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14
Q

Why does adaptive immunity take time?

A

It involves the production of antibodies

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15
Q

Phagocytes are a kind of _____ defense, and includes cells like ______, ______, and ______.

A

Mechanical

Macrophages, neutrophils, and monocytes

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16
Q

Phagocytes circulate through the _____ looking for foreign invaders

A

Blood

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17
Q

What is a PRR? What kind of molecule is it?

A

Pattern-recognition receptor. Recognize PAMPs. It is a receptor protein

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18
Q

What is a PAMP?

A

Pathogen-associated molecular pattern

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19
Q

How do PRRs inhibit viral replication?

A

Upon recognition of PAMPs, PRRs undergo a conformational change that induces a specific signaling pathway that inhibits viral replication

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20
Q

What kind of nucleic acid does TLR3 recognize?

A

Long dsRNA

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21
Q

What is a TLR?

A

Toll-like receptor. Division of PRRs.

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22
Q

What kind of nucleic acid do TLR7 and TLR8 recognize? Which regions does it look for?

A

ssRNA. Regions rich in AU and GU

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23
Q

What kind of nucleic acid does TLR9 recognize?

A

Unmethylated CpG motifs of DNA viruses

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24
Q

What kinds of nucleic acid do RIG-1 like receptors recognize?

A

Short dsRNA and ssRNA

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25
Q

TLRs 7, 8, & 9 as well as RIG-1 like receptors produce ____ and _____.

A

Type 1 interferons & inflammatory cytokines

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26
Q

What are interferons made of?

A

Small proteins

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27
Q

Interferons are small proteins secreted by _________.

A

Virally infected cells

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28
Q

Interferons respond at (early/late) stages of infection

A

Early

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29
Q

Explain how interferons work

A

Interferons bind to receptors on surrounding non-infected cells, activating gene expression of antiviral proteins that inhibit viral replication

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30
Q

Which 3 interferon-induced genes are most important? Explain each.

A

1) PKR. dsRNA-activated protein kinase. Phosphorylates eIF2 to shut down protein synthesis
2) OAS1b. Produces 2’-5’-oligo adenylate that binds to and activates RNaseL
3) RNaseL. Degrades viral RNAs

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31
Q

What are the 3 types of interferons?

A

Alpha, beta, and gamma

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32
Q

Defensins protect against (naked/enveloped/naked & enveloped) viruses

A

Naked & enveloped

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33
Q

What are defensins made of?

A

Small peptides

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34
Q

Alpha defensins block (naked/enveloped) viruses by what mechanism?

A

Naked viruses. Block them by aggregating virions on cell surface (blocking viral uncoating)

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35
Q

Beta defensins block (naked/enveloped) viruses by what mechanism?

A

Enveloped. Block them by binding to viral envelopes to disrupt the envelope, disrupting viral entry

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36
Q

What is the complement system composed of?

A

Over 30 different serum and membrane-bound glycoproteins

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37
Q

Complement proteins in blood are (active/inactive)

A

Inactive

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38
Q

How are complement proteins activated?

A

By 1 of 3 pathways. Activates membrane attack complex (MAC) causing osmotic lysis

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39
Q

Where are dendritic cells found?

A

Tissues in contact with the environment

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40
Q

What kinds of molecules are expressed on the surfaces of dendritic cells to identify foreign invaders?

A

MHC class I and II

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41
Q

Describe the process used by dendritic cells to stimulate an immune response

A
  1. Internalize the pathogen
  2. Digest the pathogen
  3. Display the foreign peptides on their surfaces using MHC class II molecules
  4. Foreign peptides are presented to TH cells
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42
Q

TH cells are only activated to recognize foreign antigens using the ____ _______.

A

B7 costimulator

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43
Q

Once TH cells are activated, they leave the _____ _____ and ________.

A

Lymph notes

Travel to the site of infection

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44
Q

What are the 3 types of antigen presenting cells?

A

Dendritic cells, macrophages, and B cells

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45
Q

Why is it said that TH cells act indirectly?

A

They recruit and activate other immune cells to eliminate pathogens

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46
Q

TC cells act (directly/indirectly) to destroy virally infected cells

A

Directly

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47
Q

Natural killer cells (NK cells) are activated by _____ and ______.

A

Interleukins and interferons

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48
Q

Once activated, what 3 molecules do NK cells release to kill virally infected cells?

A

Perforins, granzymes, and chemokines

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49
Q

What do perforins do?

A

Create pores in membranes

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50
Q

For a new infection, the (innate, adaptive) immune system plays an important role in the early stages of infection.

A

Innate

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51
Q

____ contains white blood cells that circulate through the lymphatic system.

A

Lymph

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52
Q

The main types of lymphocytes are __ lymphocytes and __ lymphocytes.

A

B lymphocytes and T lymphocytes

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53
Q

What are the 2 main subtypes of T lymphocytes?

A

TH and TC cells

54
Q

Mature B cells display about _____ membrane bound antibodies

A

150,000

55
Q

Viral antigens can act as _______.

A

Immunogens

56
Q

What is an immunogen?

A

Provokes immunity when introduced into the body

57
Q

(T/F) B cells patrol the lymphatic system

A

True

58
Q

Describe the process when a B cell encounters a virus

A

The B cell is activated and differentiates into a large population of clones of plasma cells and a population of memory cells that express the correct antibody

59
Q

Activated B cells differentiate into ______ cells and _______ B cells for 4-5 days

A

Plasma cells and memory B cells

60
Q

What is the role of a plasma cell?

A

Specialize in rapidly secreting large numbers of antibodies

61
Q

What is the average lifespan of a plasma cell?

A

1-2 weeks

62
Q

What is the average lifespan of a memory B cell?

A

A lifetime

63
Q

(T/F) Memory B cells take time to respond to future secondary infections

A

False.

64
Q

What is an epitope?

A

A certain sequence of amino acids that gives an immunological response. Site on the surface of an antigen

65
Q

Which antibody is most abundant (IgG, IgA, IgM)?

A

IgG

66
Q

Which antibody crosses the placenta (IgG, IgA, IgM)?

A

IgG

67
Q

Which antibody is a monomer (IgG, IgA, IgM)?

A

IgG

68
Q

Which antibody is a dimer (IgG, IgA, IgM)?

A

IgA

69
Q

Which antibody is a pentamer (IgG, IgA, IgM)?

A

IgM

70
Q

Which antibody is most present in serum (IgG, IgA, IgM)?

A

IgG

71
Q

Which antibody is present in body secretions and breast milk (IgG, IgA, IgM)?

A

IgA

72
Q

Which antibody is the first responder after immunization (IgG, IgA, IgM)?

A

IgM

73
Q

Which antibody provides years of protection (IgG, IgA, IgM)?

A

IgG

74
Q

Which antibody lasts just a few weeks or months (IgG, IgA, IgM)?

A

IgM

75
Q

In a primary antibody response, (IgM/IgG) antibodies are released in abundance whereas (IgM/IgG) antibodies take longer to produce

A

IgM, IgG

76
Q

In a primary antibody response, (IgM/IgG) antibodies are released in abundance whereas (IgM/IgG) antibodies are produced in lesser abundance.

A

IgG, IgM

77
Q

Where are T cells produced? Where do they migrate to mature?

A

Bone marrow. Migrate to the thymus

78
Q

(T/F) T cells recognize antigens directly.

A

False. T cells recognize presented antigens via MHC molecules present on the outside of antigen presenting cells.

79
Q

TH cells express (CD4/CD8) on their surface. They recognize antigens bound to (MHC I/MHC II)

A

CD4

MHC II

80
Q

TC cells express (CD4/CD8) on their surface. They recognize antigens bound to (MHC I/MHC II)

A

CD8

MHC I

81
Q

What are the viral evasion strategies (there are 7)?

A
  1. Mutate rapidly
  2. Hide
  3. Molecular mimicry
  4. Synthesize excessive amounts of soluble viral antigens
  5. Inactivate cytokine signals
  6. Inactivate immune cells
  7. Block apoptosis, complement, and interferon pathways
82
Q

What is passive immunization?

A

Transfer of active premade antibodies.

83
Q

How long does passive immunization last?

A

2-3 weeks, helps immunized person overcome infection

84
Q

What is the rationale for vaccines?

A

Prevent infections (prophylactic)

85
Q

What is the difference between a live and attenuated virus?

A

Live: Attenuated, avirulent. Live virus that is unable to produce a disease. Produces a good infection of the body, but will not produce a disease

Inactivated: Killed. Noninfectious virus particles

86
Q

What factors led to the successful elimination of smallpox?

A

Severe disease with high mortality, no animal reservoir, no recurrence, only 1 serotype, effective diagnosis, available vaccine, non-infectious until rash appears

87
Q

What is variolation?

A

Inoculating an individual through deliberate exposure to generate a mild disease and immunity against further severe infection

88
Q

Which nations were the first to use variolation?

A

China and Turkey

89
Q

Who was Edward Jenner?

A

First to approach inoculation in a scientific manner. Inoculated small child with cowpox and later smallpox. Prevented development of disease.

90
Q

What are the different types of vaccines?

A

Live attenuated, inactivated, virion subunit, live recombinant, virus-like particles, and DNA

91
Q

What is the family that poliovirus is a part of?

A

Picornaviridae

92
Q

How large is poliovirus?

A

Small. 30nm

93
Q

What kind of nucleic acid is poliovirus made of?

A

RNA. +RNA

94
Q

Poliovirus is a (naked/enveloped) virus

A

Naked

95
Q

What is the most notable feature of the poliovirus capsid?

A

It is acid stable

96
Q

How is poliovirus transmitted?

A

Oral-fecal

97
Q

What are the primary and secondary sites of infection for poliovirus?

A

Primary: Gastrointestinal tract
Secondary: CNS

98
Q

What is the role of CD155 with relation to poliovirus?

A

CD155 is a receptor of poliovirus that belongs to the immunoglobulin superfamily

99
Q

What mechanism does poliovirus use to evade the immune system?

A

Hides

100
Q

After attachment of picornavirus to the cell surface receptors, the virion undergoes major conformational changes and ___ is lost.

A

VP4

101
Q

Why is VPg uridylated by the RNA polymerase?

A

To be used as a primer to produce -mRNA, which is used as a template to make +mRNA

102
Q

What mechanism is used by poliovirus to take advantage of cellular machinery?

A

IRES

103
Q

A _____ is made and then processed into individual proteins in poliovirus.

A

Polyprotein

104
Q

Where does the entire process of poliovirus replication occur?

A

In the cytoplasm

105
Q

What is a procapsid?

A

Precursor to capsid.

106
Q

Picornavirus assembly and exit. A certain ______ residue is uridylated in VPg

A

Tyrosine

107
Q

Virions are released by (budding/cell lysis) in picornavirus

A

Cell lysis

108
Q

What are the types of vaccines for poliovirus?

A

Salk (inactivated)

Sabin (attenuated)

109
Q

Where are mutations present in attenuated strains of picornavirus vaccinations?

A

The IRES sequence

110
Q

Where is oral polio vaccine used and why?

A

Rural communities. Doesn’t require a trained professional to administer injection

111
Q

Where are polio cases found currently?

A

Nigeria, Pakistan, and Afghanistan

112
Q

How does poliovirus inhibit host cell transcription?

A

Some virus proteins enter the nucleus to inhibit host cell transcription

113
Q

Why can influenza epidemics be difficult to manage?

A

Incubation period is only 1-4 days
Large number of infectious particles shed in droplets (sneezing, coughing)
Many symptomatic individuals do not stay home

114
Q

Which family is influenza part of?

A

Orthomyxoviridae

115
Q

How many types of influenza exist?

A
  1. A, B, & C
116
Q

Describe the genome and capsid (naked vs. enveloped) of the influenza virus

A

ve ssRNA, segmented genome, enveloped

117
Q

Why does death occur when infection with influenza?

A

Cytokine storm. Systemic inflammatory response syndrome occurs when immune system is overreacting

118
Q

The antibody response against influenza is against _____ and _____.

A

Hemagglutinin and neuraminidase.

119
Q

What is the primary site or replication with influenza?

A

Ciliated epithelium

120
Q

_____ (N/H) outnumbers ______(N/H) 4:1 to 5:1 in influenza.

A

H outnumbers N

121
Q

What triggers fusion between the influenza viral membrane and the host endosomal membrane?

A

Low pH in endosomes

122
Q

H PROTEIN MEDIATES THE LOW PH DEPENDENT FUSION EVENT

A

A LOW PH-DEPENDENT IRREVERSIBLE CONFORMATIONAL CHANGE OF H PROTEIN IS NECESSARY

123
Q

THERE’S A FUSION PEPTIDE THAT CAUSES FUSION BETWEEN THE VIRAL AND ENDOSOMAL MEMBRANE THAT IS HIDDEN WITHIN THE VIRUS

A

PH CHANGE INDUCES CONFORMATIONAL CHANGE THAT EXPOSES THE FUSION PEPTIDE. 2 CELLULAR PROTEINS CLIP THE PEPTIDE, ALLOWING THE MEMBRANES TO FUSE

124
Q

Where does uncoating take place for influenza?

A

The endosome

125
Q

The viral transmembrane M2 protein forms a ___ ion channel in the viral envelope for influenza.

A

H+. H+ ions penetrate and weaken the interaction of viral M1 matrix protein from viral genomic RNAs. Viral RNA, NP, and RNA-dependent RNA polymerase is released into cytoplasm, exported to nucleus

126
Q

What is unique to influenza

A

Cap snatching. Uses cap as a primer to start viral mRNA synthesis

127
Q

What is the function of viral protein NS1 in influenza?

A

Prevents the export of cellular mRNA into the cytoplasm

128
Q

Influenza virus suppresses the ________ response.

A

Interferon

129
Q

NS1 protein binds to viral dsRNA intermediates and blocks activation of ____.

A

PKR

130
Q

Influenza is released via (lysis/budding)

A

Budding

Virology (BIOL 612) (3 decks)

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