Intro to Virology (EXAM III) Flashcards
1
Q
Compare the organization of viruses vs. cellular organisms:
A
Virus: simple organization
Cellular organisms: complex organization
2
Q
Compare the genome of viruses vs. cellular organisms:
A
Viruses: DNA or RNA
Cellular organisms: DNA genome and RNAs
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
4
Q
All viruses are _____ while only some cellular organisms are ____
A
Obligate intracellular parasites (both)
5
Q
According to the theory of ____ viruses evolved by degenerative evolution from intracellular parasitic cells
A
Theory of reductive origin
6
Q
The theory of reductive origin states that viruses evolved by degenerative evolution from:
A
Intracellular parasitic cells
7
Q
The theory of reductive origin results in a:
A
DNA virus
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
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
10
Q
The theory intracellular origin results in an:
A
Retrovirus
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
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
13
Q
The theory of independent origin results in a:
A
RNA virus
14
Q
_____ virus is bigger by far than any other known virus, and rivals bacteria
A
Pandoravirus (1000nnm)
15
Q
_____ viruses genomes are segmented and the segments are distributed into separate viral particles
A
Multicomponent viruses
16
Q
Cultivation of viruses requires:
A
Inoculation of living host cell
17
Q
What four things are required in order for a virus to inoculate a living host cell:
A
- Suitable host
- Embryonated eggs
- Tissue (cell) cultures
- Cytopathic effects (CPEs)
18
Q
Tissue cell cultures include:
A
- Monolayers of animal cells
- Plaques
19
Q
Localized area of cellular destruction & lysis:
A
Plaque
20
Q
Microscopic or macroscopic degenerative changes or abnormalities in host cells & tissues:
A
Cytopathic effects (CPEs)
21
Q
A nucleocapsid is a:
A
Naked capsid virus
22
Q
What components comprise a nucleocapsid (naked capsid virus)
A
- DNA or RNA
- Structural proteins
- Enzymes & nucleic acid-binding proteins
23
Q
A nucleocapsid + glycoproteins & membrane result in:
A
Enveloped virus
24
Q
Allows the virus to increase the number of structural units in each face to expand capsid size:
A
Icosahedral symmetry
25
What components comprise an icosahedral virus?
1. Nucleocapsid
2. Capsid
3. Capsomers (proteins)
4. Nucleic acid
26
What is an example of a virus that displays an icosahedral symmetry:
HSV-1
27
An icosahedral symmetric virus with the addition of a tail:
Bacteriophage T4 capsid
28
Virus in which the protein subunits & nucleic acid are arranged in a helix:
Helical symmetry
29
A helical virus includes:
1. Nucleocapsid
2. Nucleic acid
3. Protein (monomeric units)
30
Give an example of a filamentous virus:
Ebola
31
Compared to a nonenveloped virus, an enveloped virus contains:
1. Glycoprotein spikes
2. Lipid bilayer
32
Both _____ & _____ viruses can be enveloped or non enveloped
Helical & icosahedral
33
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
Asymmetrical virus
34
Give an example of an asymmetrical virus:
Vaccinia poxvirus
35
An asymmetrical virus has both:
An outer membrane & core envelope
36
Main groups of human viruses:
RNA viruses break down into:
1. Nonenveloped
2. Enveloped
37
Main groups of human viruses:
Nonenveloped RNA viruses break down into:
1. Single stranded positive sense
2. Double stranded
38
Main groups of human viruses:
Enveloped RNA viruses break down into:
1. Single stranded positive sense
2. Single stranded negative sense
3. Retrovirus
39
Viruses are classified using a combination of properties including:
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
40
Main groups of human viruses:
DNA viruses break down into:
1. Nonenveloped
2. Enveloped
41
Main groups of human viruses:
DNA nonenveloped viruses break down into:
1. Single-stranded linear
2. Double-stranded linear
3. Double-stranded circular
42
Main groups of human viruses:
DNA enveloped viruses break down into:
1. Double-stranded linear
2. Double-stranded circular
43
Discuss the steps of virus replication:
1. Adsorption
2. Penetration & uncoating
3. Synthesis of viral proteins & nucleic acids
4. Assembly of visions
5. Release
44
Step of viral replication characterized by viral surface proteins and/or enzymes mediate attachment to specific host receptors:
Adsorption of virions
45
Step of viral replication characterized by three mechanisms, including:
-injection of nucleic acid
-fusion of envelope with host membrane
-endocytosis
Penetration & uncoating
46
Penetration & uncoating involves:
1. injection of nucleic acid
2. fusion of envelope with host membrane
3. endocytosis
47
Describe the genomic structure of Adenovirus:
-Linear, double-stranded DNA genome
-Nonenveloped
-Icosahedral capsid
48
Discuss the location of viral replication characteristic of most DNA viruses, including adenovirus:
The nucleus is going to be involved
49
Follow the rupture of the endosome containing the adenovirus particles, what occurs?
Viral nucleoprotein complex enter cell nucleus
50
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:
Temporal regulation; pre-early, early & late genes
51
Adenovirus, along with most DNA viruses produces ______ during viral gene expression
Transcriptional regulators
52
Transcriptional regulators produced during one phase of gene expression/viral replication act to:
Promote transcription of genes of subsequent phase
53
Describe the priming of DNA synthesis in adenovirus:
By pTP serine residue (pre-terminal protein)
54
Adenovirus DNA replication:
1. Only ________ is copied at each replication fork
2. No _______ replication
3. Priming is by _______
1. One of the two DNA strands
2. Discontinuous
3. Viral protein (pTP)
55
Adenovirus infections can be described as extremely ________
Explain:
Widespread
5-10% of all viral infections
56
Symptoms of adenovirus usually resemble:
Common cold
57
Adenovirus is one of the common agents of:
Common cold
58
Is there a vaccine for adenovirus?
If so describe:
Vaccine (live virus) given to new military recruits for serotypes 4 & 7
59
What virus is responsible for causing ARD (acute respiratory disease):
Adenovirus serotypes 4 & 7
60
ARD:
Acute respiratory disease
61
Why are adenovirus serotypes 4 & 7 vaccinated against in some populations:
They can become life-threatening
62
Discuss the mechanisms for evasion of host defenses used by adenovirus:
1. Block MHC class I mRNA production
2. Block transport of MHC class I proteins to cell surface
63
How does adenovirus block transport of MHC class I proteins to cell surface in order to evade host defense:
Viral E3gp19K protein does this & results in block of killing by cytotoxic T cells
64
One thing we will encounter with most DNA viruses, including adenovirus is their ability to drive host cell into:
Cell division, as this is necessary for DNA virus to replicate
65
Adenovirus virus drives the host cell into cell division as this is necessary for:
Adenovirus replication
66
What aspect of host cell division is necessary for adenovirus to replicate?
S phase factors
67
What aspects of adenovirus interfere with cell division controlled?
E1a & E1b proteins
68
What is the function adenovirus proteins E1b & E1a?
Both interfere with cell division controllers, but specifically E1b sequesters p53 & E1a sequesters Rb (retinoblastoma protein)
69
Adenovirus protein E1b:
Sequesters p35
70
Adenovirus protein E1a:
Sequesters Rb (retinoblastoma protein)
71
Because of the interference with cell division controllers, adenovirus infection can potentially:
Drive a cell towards cancerous state
72
In typical cell cycle _____ recognizes DNA damage & activates _____
p53; p21
73
p53 recognizes DNA damage & activates p21 which will bind & inactivate the _____
Cyclin-cdk complex
74
As DNA damage is repaired what happens to p53 & p21?
p53 decreases; p21 no longer blocks cyclin-cdk; cell cycle progression
75
Acts as a checkpoint controlled to stop cell cycle progression:
p52
76
Inactivation of p53 by adenovirus protein E1b prevents:
Activation of p21 & Bax
77
Adenovirus E1a protein binds to:
Rb complex
78
When adenovirus E1a protein binds to Rb complex, this:
Prevents Rb fro negatively regulating E2F
79
What is E2F responsible for in the cell cycle?
Transcribing a number of different genes for DNA synthesis
80
Describe the genomic & viral structure of HPV:
-Double-stranded circular DNA
-Noneveloped viral particles
81
How many types of HPV are there & what are their broad categories?
At least 100 different types; cutaneous or mucosal
82
The infection process of HPV usually takes:
3-4 months
83
HPV accesses _____ through breaks in skin
Basal layer
84
In HPV infection:
Viral early genes stimulate _____ which facilitates ____
Cell growth; viral replication
85
HPV reproduction is coordinated with:
Development of keratinocytes
86
Nondividing, physical barrier; anuclear:
Keratinocytes
87
In HPV infection:
As cells move through skin layers:
HPV gene expression & DNA replication begins
88
For HPV replication & DNA replication _____ is used:
Cellular DNA polymerase
89
In HPV infection:
______ are only made in differentiated layers
Late proteins (capsid proteins)
90
In HPV infection:
Assembly occurs in ____ during _____ development
Nucleus; keratinocyte
91
In HPV infection:
As the nucleus breaks down, you end up with nuclear remnants with ___ shed at ____
Viral particles; skin surface
92
HPVs are not considered:
Lytic
93
HPVs are not considered lytic, as they simply reply on ______ to create a viral release event
The natural production of keratinocytes
94
Enlarged keratinocytes with clear halos around enlarged nuclei; characteristic of HPV infection:
Koilocytes
95
HPV is spread by _____ contact, especially:
Skin-to-skin; breaks in skin, mucous membranes; during birth
96
A dental concern of HPV is the causing:
Warts of the oropharynx
97
HPV-6 & -11 are responsible for:
Largyneal papillomas
98
Laryngeal papillomas caused by HPV-6 & -11 may lead to:
Respiratory papillomatosis
99
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:
Respiratory papillomatosis
100
The most benign epithelial tumors of the oral cavity that are caused by HPV:
Single oral papillomas
101
Condylomata acuminata is commonly referred to as:
Anogenital warts
102
90% of ______ are caused by HPV-6 & -11
Anogenital warts (Condylomata acuminata)
103
HPV is present in ______ of cervical cancers
99.7%
104
Greater than 85% of cervical carcinomas contain:
Integrated HPV DNA
105
What are the high risk strains of HPV that are associated with cervical papillomas:
16 & 18 (& 31 & 45)
106
Cells are scraped from the cervix and examined under a microscope to check for disease and other problems:
PAP smear
107
What cells determine if a PAP smear is abnormal?
Koilocytic cells
108
Are there vaccines against HPV? If so explain:
Yes; vaccinations protect against 16 & 18 (high risk strains associated with cervical cancer)
109
The HPV proteins ____ & ____ are important for cancer development
E6 & E7
110
What are the only HPV proteins ALWAYS expressed in cervical cancer cells:
E6 & E7
111
How does HPV protein E6 work to induce cancer?
Inactivation of p53
(E6 signals the binding of ubiquination factors to bind to p53 & target its destruction)
112
How does HPV protein E7 work to induce cancer?
Prevents Rb from controlling cell division
(E7 binds to Rb complex & prevents Rb from negatively regulating E2F)
113
HPV E7 protein acts like _____ protein which promotes disassembly of _____
SV40 virus LT protein; of Rb-E2F complex
114
SV40 LT (similar to HPV E7 protein) promotes the disassembly of Rb-EF2 complex which allows EF2 to:
Be free & activate transcription of cellular DNA synthesis genes
