Classification, Structure, and Replication of Viruses - AuCoin Flashcards
1
Q
T/F: viruses can pass through a filter
A
true
2
Q
Viruses are obligate (blank)
A
intracellular parasties
3
Q
T/F: viruses can make energy and proteins independent of a host cell
A
false
4
Q
What are the limitations of the viral genome?
A
it can be DNA or RNA BUT NOT BOTH
5
Q
What are the two general viral morphologies?
A
naked capsid or enveloped
6
Q
What two processes have optimized viruses to infect humans and other hosts?
A
mutation and selection
7
Q
What is a important characteristic of the genes a virus encodes to ensure its survival?
A
it must code for any process not provided by the host cell and its components MUST SELF ASSEMBLE
8
Q
What types of cellular components do viruses hijack?
A
polymerases and transcription factors
9
Q
structural proteins and enzymes and nucleic acid binding proteins all together form the (blank)
A
nucleocapsid
10
Q
A nucleocapside and a glycoprotein and a membrane make a (blank)
A
enveloped virus
11
Q
Papilloma virus, adenovirus, and polio viruses are all (blank) viruses
A
naked capsid viruses
12
Q
herpesvirus and retrovirus are both (blank) viruses
A
enveloped viruses
13
Q
Hepatitis A virus is a (blank) virus, while all other hepatitis viruses are RNA viruses
A
DNA
14
Q
What are the means of classifying viruses?
A
- structure: size, morph, and nucleic acid
- BCH characteristics like structure and mode of rep
- disease (encephalitis)
- means of transmission
- tissue or organ affected
15
Q
what is viral tropism?
A
when a virus preferentially targets a specific tissue type
16
Q
Picornavirus is a example of (blank) naming
A
structural
17
Q
Retroviruses is an example of (blank) naming
A
BCH
18
Q
adenoviruses and reoviruses are examples of (blank) naming
A
tropism
19
Q
Pox, herpes, and hepadna viruses are all (blank) DNA viruses
A
enveloped
20
Q
Polyoma, papilloma, adeno, and parvo viruses are all (blank) DNA viruses
A
enveloped
21
Q
Parvovirus is special because it is (ds/ss) DNA
A
ssDNA
22
Q
+ RNA is equal to (blank)RNA
A
mRNA
23
Q
What is the unit of measurement for viruses? How do they compare to the size of staph?
A
nanometers, 1/4 the size
24
Q
T/F: larger virions hold larger genomes and are therefore more complex
A
true
25
What is a virion?
infectious particle made of nucleic acid genome packaged into a protein coat or membrane
26
Where are viral proteins packaged within the virion?
in the tegument layer, between the capsid and envelope
27
What is the size of poxvirus? E. coli? Human cell?
Poxvirus: 0.3um
E. Coli: 6.0um
Human cell: 30-100 um
28
What is the shape of the nucleocapsid in nake viruses?
icosahedral
29
What are the two shapes of the nucleocapsid in enveloped viruses?
icosahedral or helcial ribonucelocapsid
30
What makes up a ribonucleocapsid?
Protein and RNA together
31
The (blank) on the surface of the capsid envelope mediates the interaction of the virus and target cell
viral attachment protein
32
Neutralizing Abs bind to (blank) and block infection
viral attachment proteins
33
T/F: the capsid is a fluid structure
false
34
Viruses with (capsid/membrane) are resistant to drying, acid, and detergents
capsids
35
(Naked/enveloped) viruses can be transmitted via fecal oral or via sewage
naked
36
The viral envelope contains lipids, proteins, and glyco(proteins/lipids)
glycoproteins
37
Since the envelope is only maintained in aqueous solution, enveloped viruses are only transmitted via (blank)
body fluids
38
gp120 protein on HIV binding CD4 on Tcells is an example of the (blank) protein
viral attachment protein
39
An (icosahedral/ribonucelocapsid) is found in most negative strand RNA viruses
helical ribonucleocapsid
40
T/F: the helical ribonucleocapsid can self assemble
true
41
Vesicular stomatitis virus nucleocapsid is a good example of the (blank) structure
helical ribonucleocapsid
42
What two protein subunits make of the ribonucleocapsid?
N and M
43
The icosahedron of picornavirus, which is simple, is made of 12 (blanks) with five fold symmetry (i.e. a pentamer)
capsomers
44
Five protomers come together to form one (blank)
capsomer
45
How does something like herpesvirus create a more complex capsid?
by inserting structurally distinct proteins between the pentamers (capsomers)
46
what material is hijacked to make the building blocks of the viral envelope
cellular membrane
47
most (blanks) act as viral attachment proteins that bind to target cells to initiate entry
glycoproteins
48
VAPs that bind to RBCs are called (blank)
hemagglutinins
49
What are the spikes on viruses?
glycoproteins
50
T/F: cellular proteins are often found in viral membranes
false
51
T/F: the glycoprotein spikes on viruses are usually immunodominant
true
52
T/F: all negative strand RNA viruses are enveloped
treu
53
What is interesting about the influenza A genome?
it is segmented -RNA
54
The (blank) layer is betweent he envelope and nucleocapsid and contains enzymes and other proteins that facilitate viral infection
tegument
55
what are the processes involved in viral replication?
```
recognition
attachment
penetration
uncoating
delivery of genome to nucleus
```
56
Genome replication and macromolecular synth is followed by viral (blank) and release
assembly
57
(blank) is when extracellular infectious virus is not detected but viral genomes can be detected
latency
58
latency is a hallmark of what type of infection?
herpesvirus
59
T/F: viral protein synth and genome replication happen at the same time
true
60
what determines what cells can be infected by a virus?
binding of the VAP to the cell receptors
61
T/F: VAPs can be proteins, CHOs, glyocproteins, or glycolipids
true
62
what is a viral host range?
viruses can enter only the cells that express the right receptor type
63
What macromolecule are VAPs normally?
glycoproteins
64
The HA VAP of influenza A binds to the (blank) receptor of a broad range of cell types
sialic acid receptor
65
What type of macromolecule is HA?
glycoprotein
66
Most nonenveloped viruses enter the cell via (blank)
receptor mediated endocytosis
67
T/F: enveloped viruses fuse their membrane with the cell membrane to inject the nucleocapsid into the cytosol
true
68
at what pH are fusion proteins active?
neutral OR acidic conditions of the endosome following receptor mediated endocytosis
69
Where are DNA genomes delivered?
nucleus
70
Where are RNA genomes delivered?
cytoplasm
71
T/F: both the envelope and the capsid must be removed to begin replication
true
72
Which DNA virus does not have its DNA moved to the nucleus?
Pox virus
73
What RNA pol does the virus use to make mRNA?
RNA Pol II
74
what mods does viral mRNA get?
3' poly A tail and 5' methylated cap
75
T/F: viruses encode the enzymes for transcription RNA dependent RNA Pol
true
76
What is the function of the poly A tail?
nuclear export and mRNA stability
77
What is the function of the 5' 7-methyl-guanosine cap?
binds to the ribosomes
78
RNA retroviruses and orthomyxovirus like influenza replicate where
in the nucleus!
79
T/F: replication of viral DNA is semiconservative
true
80
T/F: replication of viral DNA can be rolling circle or linear
true
81
Describe dsDNA viral rep?
dsDNA to mRNA to protein
82
Describe ssDNA viral rep?
ssDNA to dsDNA to mNRA to protein
83
Describe segmented dsRNA viral rep?
segmented dsRNA makes mRNA from each segment
84
What is the difference between the requisites at the time of infection between + and -RNA viruses?
-RNA needs to have a synthesized protein RNA dep. RNA pol to initiate its own transcription while +RNA can code for it and the cell's ribosomes will make it for it
85
What happens during +RNA viral translation?
one large polyprotein is made and is cleaved by either viral or host enzymes
86
How are +RNA viruses replicated?
Host ribosome makes all the proteins from +RNA genome. RNA dep. RNA Pol from RNA genome makes -RNA template, from which it makes multiple +RNA genome copies for packaging
87
T/F: retroviruses are integrated into the host genome
true
88
T/F: DNA viruses are larger than RNA viruses
true
89
some complex DNA viruses can encode their own (blank) to regulate expression of viral genes
transcription factors
90
Viral DNA replication begins at the (blank), where viral replication factors bind, such as DNA dep DNA Pol
Ori
91
Large DNA viruses encode their own DNA Pol which will make more (blanks) creating mutations
errors
92
Antiviral nucleotide analogs target what?
viral polymerases
93
immediate early genes code for:
transcription factors
94
early genes code for:
protein synthesis and genome replication
95
late genes code for:
structural proteins; glycoproteins, capsid proteins, and tegument proteins
96
What two types of genes produce products that go back into the nucleus?
immediate early and early genes
97
the signal sequence in viral mRNA will signal it to attach to ribosomes located on the (blank0
rER
98
what types of modifications will the protein made in the rER undergo?
glycosylation and acetylation
99
What is the fate of the cytoplasmically created structural proteins?
They go back into the nucleus to make the capsid.
100
Where does the DNA containing naked capsid immediately go after exiting the necleus?
rER
101
Where does the capsid gain its envelope?
trans golgi
102
(blank) proteins will bind to the intracellular portion of the glycoprotein coat to link it to the capsid
tegument
103
Proteins involved in cell take over are expressed in what genes?
IE
104
DNA dep DNA pol is expressedin what type of genes?
early
105
T/F: the genome is replicated during the transcription of the late genes
false; BEFORE
106
What are the two methods that the virus is released from the cell?
exocytosis or cell lysis
107
RNA viruses must code for what type of Pol?
RNA dep RNA pol
108
What is unique about RNA dep RNA pol regarding virulence?
they are fast and have a high mutation rate
109
T/F: viral +RNA ALONE can initiate infection
true
110
T/F: viral -RNA ALONE can initiate infection
false
111
except for influenza, RNA viral transcription and replication occurs in the (blank)
cytoplasm
112
describe the fidelity of RNA dep RNA pol?
LOW FIDELITY
113
T/F: RNA dep RNA pol has the ability to proofread
false, that's why its low fidelity
114
RNA dep RNA pol have a mutation rate of (blank) while DNA dep DNA pol has a mutation rate of (blank)
1:3000 vs 1: billion
115
rhabdovirus is shaped like a (blank)
bullet
116
L and NS proteins come together to form (blank)
RNA dep RNA pol
117
What is the G protein, where is it modified, and how is it modified?
the surface glycoprotein, GLYCOSYLATED (for G) in the rER
118
Where does the G protein go?
embeds in the plasma membrane to await viral nucelocapsid
119
Discuss the formation of the envelope-nucleocapsid
matrix protein associates with the intracellular portion of G protein; nucleocapsid assembles and N protein also associates with the M protein intermediate.
120
what three proteins make up the nucleocapsid?
N, L, and NS
121
Does host or viral mRNA have translational priority?
viral mRNA
122
T/F: viral mRNA can block host mRNA egress from nucleus
true, they can also degrade host mRNA
123
What two amino acid sequence determined actions are necessary fro viral glycoproteins?
insertion into the rER and N-linked glycosylatoin
124
Addition of sugar molecules to the nitrogen atom of asparagine (N) linked is an example of what type of mod?
N-linked glycosylation
125
How are protease inhibitors used as antivirals?
they block the cleavage of polyproteins into individual functioning proteins
126
Are protease inhibitors effective against segmented genomes?
NO, they make one-gene-one-protein style translation, so no polyprotein
127
T/F: viral membranes contain host proteins since they got their membrane from the plasma membrane
false!
128
When the concentration of viral proteins is sufficiently high, what three types of protein-(blank) interactions occur>?
protein-nucleic acid
protein-protein
protein-membrane
129
(blank) only occurs after the association of the nucleocapsid with the intracellular portion of G protein
budding
130
Where do most RNA viruses bud?
from the plasma membrane
131
besides the PM, where else can viruses bud from?
ER or the golgi
132
what are the three methods that a virus can be released from a cell?
cell lysis, exocytosis, or budding from the plasma membrane
133
Naked capsid viruses take what route of cell exit?
lysis--the membrane is broken so you can't use it to form an envelope
134
What is the only step in viral capsid assembly that requires ATP?
insertion of the genome into the capsid
135
What two proteins can the G protein bind to?
the M protein or directly to the riboproteins on the RNA
136
T/F: mutated viruses by definition change the phenotype, are more detrimental, and enhance pathogenicity and drug resistance
false; just means that they're different that wild type
137
what happens if you have a mutation in an essential gene?
it is lethal to the virus
138
attenuated mutants cause (more/less) disease
less
139
New virus STRAINS can be produced by intermolecular exchange (aka blank) between viruses OR VIRUS AND THE HOST
recombination
140
What is viral reassortment?
when a segmented viral genome shuffles its segments if more than one viral strain is present in the host cell
141
the ideal host is a (blank) host
naive
142
100nm is how many angstroms?
10A
