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Microbiology > Intro to Virology (EXAM III) > Flashcards

Intro to Virology (EXAM III) Flashcards

1
Q

Compare the organization of viruses vs. cellular organisms:

A

Virus: simple organization

Cellular organisms: complex organization

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2
Q

Compare the genome of viruses vs. cellular organisms:

A

Viruses: DNA or RNA

Cellular organisms: DNA genome and RNAs

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3
Q

Describe the reproduction or viruses vs. cellular organisms:

A

Viruses are unable to reproduce outside of living cells

Cellular organisms carry out cell division

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4
Q

All viruses are _____ while only some cellular organisms are ____

A

Obligate intracellular parasites (both)

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5
Q

According to the theory of ____ viruses evolved by degenerative evolution from intracellular parasitic cells

A

Theory of reductive origin

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6
Q

The theory of reductive origin states that viruses evolved by degenerative evolution from:

A

Intracellular parasitic cells

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7
Q

The theory of reductive origin results in a:

A

DNA virus

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8
Q

According to the theory of _______, viruses evolved from functional parts of cells that acquired an ability to reproduce themselves uncontrolled by the cell

A

Theory of intracellular origin

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9
Q

The theory of intracellular origin a states that viruses evolved from ______ and acquired an ability to _____ uncontrolled by the cell

A

Functional parts of cells; reproduce themselves

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10
Q

The theory intracellular origin results in an:

A

Retrovirus

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11
Q

The theory of _____ holds that viroid nucleic acids could have evolved outside of cells during the “RNA world” and acquired the ability to infect cells

A

Theory of independent origin

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12
Q

The theory of independent origin holds that ______ could have evolved outside of cells during the “RNA world” and acquired the ability to infect cells

A

Viroid nucleic acids

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13
Q

The theory of independent origin results in a:

A

RNA virus

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14
Q

_____ virus is bigger by far than any other known virus, and rivals bacteria

A

Pandoravirus (1000nnm)

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15
Q

_____ viruses genomes are segmented and the segments are distributed into separate viral particles

A

Multicomponent viruses

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16
Q

Cultivation of viruses requires:

A

Inoculation of living host cell

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17
Q

What four things are required in order for a virus to inoculate a living host cell:

A
  1. Suitable host
  2. Embryonated eggs
  3. Tissue (cell) cultures
  4. Cytopathic effects (CPEs)
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18
Q

Tissue cell cultures include:

A
  1. Monolayers of animal cells
  2. Plaques
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19
Q

Localized area of cellular destruction & lysis:

A

Plaque

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20
Q

Microscopic or macroscopic degenerative changes or abnormalities in host cells & tissues:

A

Cytopathic effects (CPEs)

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21
Q

A nucleocapsid is a:

A

Naked capsid virus

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22
Q

What components comprise a nucleocapsid (naked capsid virus)

A
  1. DNA or RNA
  2. Structural proteins
  3. Enzymes & nucleic acid-binding proteins
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23
Q

A nucleocapsid + glycoproteins & membrane result in:

A

Enveloped virus

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24
Q

Allows the virus to increase the number of structural units in each face to expand capsid size:

A

Icosahedral symmetry

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25
Q

What components comprise an icosahedral virus?

A
  1. Nucleocapsid
  2. Capsid
  3. Capsomers (proteins)
  4. Nucleic acid
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26
Q

What is an example of a virus that displays an icosahedral symmetry:

A

HSV-1

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27
Q

An icosahedral symmetric virus with the addition of a tail:

A

Bacteriophage T4 capsid

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28
Q

Virus in which the protein subunits & nucleic acid are arranged in a helix:

A

Helical symmetry

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29
Q

A helical virus includes:

A
  1. Nucleocapsid
  2. Nucleic acid
  3. Protein (monomeric units)
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30
Q

Give an example of a filamentous virus:

A

Ebola

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31
Q

Compared to a nonenveloped virus, an enveloped virus contains:

A
  1. Glycoprotein spikes
  2. Lipid bilayer
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32
Q

Both _____ & _____ viruses can be enveloped or non enveloped

A

Helical & icosahedral

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33
Q

Viruses that are referred to as complex because they posses a capsid that is neither purely helical nor purely icosahedral & may possess extra structures such as protein tails or complex outer walls

A

Asymmetrical virus

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34
Q

Give an example of an asymmetrical virus:

A

Vaccinia poxvirus

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35
Q

An asymmetrical virus has both:

A

An outer membrane & core envelope

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36
Q

Main groups of human viruses:

RNA viruses break down into:

A
  1. Nonenveloped
  2. Enveloped
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37
Q

Main groups of human viruses:

Nonenveloped RNA viruses break down into:

A
  1. Single stranded positive sense
  2. Double stranded
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38
Q

Main groups of human viruses:

Enveloped RNA viruses break down into:

A
  1. Single stranded positive sense
  2. Single stranded negative sense
  3. Retrovirus
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39
Q

Viruses are classified using a combination of properties including:

A
  1. Type & structure of nucleic acid used for viral genome
  2. Presence or absence of an envelope
  3. Type of capsid symmetry
  4. Replication strategy
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40
Q

Main groups of human viruses:

DNA viruses break down into:

A
  1. Nonenveloped
  2. Enveloped
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41
Q

Main groups of human viruses:

DNA nonenveloped viruses break down into:

A
  1. Single-stranded linear
  2. Double-stranded linear
  3. Double-stranded circular
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42
Q

Main groups of human viruses:

DNA enveloped viruses break down into:

A
  1. Double-stranded linear
  2. Double-stranded circular
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43
Q

Discuss the steps of virus replication:

A
  1. Adsorption
  2. Penetration & uncoating
  3. Synthesis of viral proteins & nucleic acids
  4. Assembly of visions
  5. Release
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44
Q

Step of viral replication characterized by viral surface proteins and/or enzymes mediate attachment to specific host receptors:

A

Adsorption of virions

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45
Q

Step of viral replication characterized by three mechanisms, including:

-injection of nucleic acid
-fusion of envelope with host membrane
-endocytosis

A

Penetration & uncoating

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46
Q

Penetration & uncoating involves:

A
  1. injection of nucleic acid
  2. fusion of envelope with host membrane
  3. endocytosis
47
Q

Describe the genomic structure of Adenovirus:

A

-Linear, double-stranded DNA genome
-Nonenveloped
-Icosahedral capsid

48
Q

Discuss the location of viral replication characteristic of most DNA viruses, including adenovirus:

A

The nucleus is going to be involved

49
Q

Follow the rupture of the endosome containing the adenovirus particles, what occurs?

A

Viral nucleoprotein complex enter cell nucleus

50
Q

DNA viruses have larger genomes and more genes, resulting in a cascade of gene expression, this typically involves three waves. What are the waves of gene expression in the adenovirus & describe the regulation:

A

Temporal regulation; pre-early, early & late genes

51
Q

Adenovirus, along with most DNA viruses produces ______ during viral gene expression

A

Transcriptional regulators

52
Q

Transcriptional regulators produced during one phase of gene expression/viral replication act to:

A

Promote transcription of genes of subsequent phase

53
Q

Describe the priming of DNA synthesis in adenovirus:

A

By pTP serine residue (pre-terminal protein)

54
Q

Adenovirus DNA replication:

  1. Only ________ is copied at each replication fork
  2. No _______ replication
  3. Priming is by _______
A
  1. One of the two DNA strands
  2. Discontinuous
  3. Viral protein (pTP)
55
Q

Adenovirus infections can be described as extremely ________

Explain:

A

Widespread

5-10% of all viral infections

56
Q

Symptoms of adenovirus usually resemble:

A

Common cold

57
Q

Adenovirus is one of the common agents of:

A

Common cold

58
Q

Is there a vaccine for adenovirus?

If so describe:

A

Vaccine (live virus) given to new military recruits for serotypes 4 & 7

59
Q

What virus is responsible for causing ARD (acute respiratory disease):

A

Adenovirus serotypes 4 & 7

60
Q

ARD:

A

Acute respiratory disease

61
Q

Why are adenovirus serotypes 4 & 7 vaccinated against in some populations:

A

They can become life-threatening

62
Q

Discuss the mechanisms for evasion of host defenses used by adenovirus:

A
  1. Block MHC class I mRNA production
  2. Block transport of MHC class I proteins to cell surface
63
Q

How does adenovirus block transport of MHC class I proteins to cell surface in order to evade host defense:

A

Viral E3gp19K protein does this & results in block of killing by cytotoxic T cells

64
Q

One thing we will encounter with most DNA viruses, including adenovirus is their ability to drive host cell into:

A

Cell division, as this is necessary for DNA virus to replicate

65
Q

Adenovirus virus drives the host cell into cell division as this is necessary for:

A

Adenovirus replication

66
Q

What aspect of host cell division is necessary for adenovirus to replicate?

A

S phase factors

67
Q

What aspects of adenovirus interfere with cell division controlled?

A

E1a & E1b proteins

68
Q

What is the function adenovirus proteins E1b & E1a?

A

Both interfere with cell division controllers, but specifically E1b sequesters p53 & E1a sequesters Rb (retinoblastoma protein)

69
Q

Adenovirus protein E1b:

A

Sequesters p35

70
Q

Adenovirus protein E1a:

A

Sequesters Rb (retinoblastoma protein)

71
Q

Because of the interference with cell division controllers, adenovirus infection can potentially:

A

Drive a cell towards cancerous state

72
Q

In typical cell cycle _____ recognizes DNA damage & activates _____

A

p53; p21

73
Q

p53 recognizes DNA damage & activates p21 which will bind & inactivate the _____

A

Cyclin-cdk complex

74
Q

As DNA damage is repaired what happens to p53 & p21?

A

p53 decreases; p21 no longer blocks cyclin-cdk; cell cycle progression

75
Q

Acts as a checkpoint controlled to stop cell cycle progression:

A

p52

76
Q

Inactivation of p53 by adenovirus protein E1b prevents:

A

Activation of p21 & Bax

77
Q

Adenovirus E1a protein binds to:

A

Rb complex

78
Q

When adenovirus E1a protein binds to Rb complex, this:

A

Prevents Rb fro negatively regulating E2F

79
Q

What is E2F responsible for in the cell cycle?

A

Transcribing a number of different genes for DNA synthesis

80
Q

Describe the genomic & viral structure of HPV:

A

-Double-stranded circular DNA
-Noneveloped viral particles

81
Q

How many types of HPV are there & what are their broad categories?

A

At least 100 different types; cutaneous or mucosal

82
Q

The infection process of HPV usually takes:

A

3-4 months

83
Q

HPV accesses _____ through breaks in skin

A

Basal layer

84
Q

In HPV infection:

Viral early genes stimulate _____ which facilitates ____

A

Cell growth; viral replication

85
Q

HPV reproduction is coordinated with:

A

Development of keratinocytes

86
Q

Nondividing, physical barrier; anuclear:

A

Keratinocytes

87
Q

In HPV infection:

As cells move through skin layers:

A

HPV gene expression & DNA replication begins

88
Q

For HPV replication & DNA replication _____ is used:

A

Cellular DNA polymerase

89
Q

In HPV infection:

______ are only made in differentiated layers

A

Late proteins (capsid proteins)

90
Q

In HPV infection:

Assembly occurs in ____ during _____ development

A

Nucleus; keratinocyte

91
Q

In HPV infection:

As the nucleus breaks down, you end up with nuclear remnants with ___ shed at ____

A

Viral particles; skin surface

92
Q

HPVs are not considered:

A

Lytic

93
Q

HPVs are not considered lytic, as they simply reply on ______ to create a viral release event

A

The natural production of keratinocytes

94
Q

Enlarged keratinocytes with clear halos around enlarged nuclei; characteristic of HPV infection:

A

Koilocytes

95
Q

HPV is spread by _____ contact, especially:

A

Skin-to-skin; breaks in skin, mucous membranes; during birth

96
Q

A dental concern of HPV is the causing:

A

Warts of the oropharynx

97
Q

HPV-6 & -11 are responsible for:

A

Largyneal papillomas

98
Q

Laryngeal papillomas caused by HPV-6 & -11 may lead to:

A

Respiratory papillomatosis

99
Q

Caused by HPV-6 & -11, occurs in young children leading to respiratory distress; hoarseness is a usual symptom which signifies obstructing HPV lesions; & secondary bacterial pneumonia may result:

A

Respiratory papillomatosis

100
Q

The most benign epithelial tumors of the oral cavity that are caused by HPV:

A

Single oral papillomas

101
Q

Condylomata acuminata is commonly referred to as:

A

Anogenital warts

102
Q

90% of ______ are caused by HPV-6 & -11

A

Anogenital warts (Condylomata acuminata)

103
Q

HPV is present in ______ of cervical cancers

A

99.7%

104
Q

Greater than 85% of cervical carcinomas contain:

A

Integrated HPV DNA

105
Q

What are the high risk strains of HPV that are associated with cervical papillomas:

A

16 & 18 (& 31 & 45)

106
Q

Cells are scraped from the cervix and examined under a microscope to check for disease and other problems:

A

PAP smear

107
Q

What cells determine if a PAP smear is abnormal?

A

Koilocytic cells

108
Q

Are there vaccines against HPV? If so explain:

A

Yes; vaccinations protect against 16 & 18 (high risk strains associated with cervical cancer)

109
Q

The HPV proteins ____ & ____ are important for cancer development

A

E6 & E7

110
Q

What are the only HPV proteins ALWAYS expressed in cervical cancer cells:

A

E6 & E7

111
Q

How does HPV protein E6 work to induce cancer?

A

Inactivation of p53

(E6 signals the binding of ubiquination factors to bind to p53 & target its destruction)

112
Q

How does HPV protein E7 work to induce cancer?

A

Prevents Rb from controlling cell division

(E7 binds to Rb complex & prevents Rb from negatively regulating E2F)

113
Q

HPV E7 protein acts like _____ protein which promotes disassembly of _____

A

SV40 virus LT protein; of Rb-E2F complex

114
Q

SV40 LT (similar to HPV E7 protein) promotes the disassembly of Rb-EF2 complex which allows EF2 to:

A

Be free & activate transcription of cellular DNA synthesis genes

Microbiology (22 decks)

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