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I And I Final > Viral Structure And Replication > Flashcards

Viral Structure And Replication Flashcards

1
Q

Virus size is

A

Small

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2
Q

Viruses are _____ _____cellular

A

Obligate intracellular

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3
Q

Viruses don’t have ____

A

Sub cellular organelles

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4
Q

Viruses can only ____ in living cells because they ___

A

Replicate

Rely on host cell protein synthesis machinery

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5
Q

Does a virus divide and proliferate

A

No, new virions are assembled

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6
Q

What is a virus made of

A

Nucleic acid
Protein shell
Envelope

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7
Q

What does the nuceleic acid provide

A

Genome
Either DNA or RNA

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8
Q

The genome and enzymes make

A

Core

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9
Q

What does the protein shell makeup

A

Capsid

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10
Q

A capsid can be ____ or ____

A

Helical

Icosahedral

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11
Q

Core + capsid =

A

Nucleocapsid

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12
Q

Nucleocapsid math

A

Genome + enzyme = core

Core + capsid = Nucleocapsid

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13
Q

What is the envelope of a virus

A

Lipid bilayer derived from the host membrane WITH viral encoded glycoproteins

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14
Q

Nucleocapsid aka

A

Naked capsid virus

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15
Q

Envelope math

A

Nucleocapsid + glycoproteins and membrane

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16
Q

We use the ___ classification system

A

Baltimore

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17
Q

Baltimore classification system is based off of

A

Genome and replication strategy

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18
Q

The ______ dictates replication strategy

A

Type of Nucleic acid

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19
Q

ssDNA viruses =

A

Noneveloped —> icosahedral —> PARVOVIRIDAE

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20
Q

How do viruses infect cells

A

Attachment
Entry/uncoating
Macromolecular synthesis
Assembly and release

MAAE

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21
Q

How does attachment work

A

Viruses bind and infect
If it can’t bind it is USELESS

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22
Q

How does entry/uncoating work

A

The genome needs to be released into the cell

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23
Q

What two steps are crucial for the virus to infect

A

Attachment and entry

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24
Q

How does macro molecular synthesis work

A

Viral proteins get transcribed/translated
Genome gets replicated!

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25
Q

How does assembly and release work

A

New viral particles assemble
Released thru lysis or budding

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26
Q

Review the picture as to how viruses infect

A

9 steps
Week 8

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27
Q

DNA genome can _____ like eukaryotic cells

A

Persist over time

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28
Q

Where does the DNA virus genome live

A

In the nucleus

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29
Q

The DNA viruses nucleus can utilize

A

The hosts cell chromosome
Or
Exist as a separate plasmid thing

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30
Q

DNA viruses can utilize ____ to copy Nucleic acid

A

Host polymerases

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31
Q

RNA virus has to make its own

A

Polymerases
RNA dependent RNA polymerase

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32
Q

Which mutates more, why

A

RNA viruses
Because RNA polymerases make more mistakes, it picks up more point mutations

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33
Q

DNA viruses and retroviruses are more _____ which can cause ___

A

Stable

Latent infections

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34
Q

Which turns into a cancer cell

A

DNA viruses and retroviruses

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35
Q

RNA Virus genome key characteristic

A

Labile/not long lasting/can’t just hang out

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36
Q

RNA virus genome lives where

A

Cytoplasm

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37
Q

Why do RNA have immune escape variants

A

They’re not as stable
The variability is changing the antigenicity

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38
Q

Quasi-species

A

Variability of RNA virus
Think of Quasimodo, he had lots of variable features

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39
Q

Helical vs iscosehedron shape

A

H= spiral

I = 20 sided shape

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40
Q

No human viruses that are ____ and _____

A

Naked and helical

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41
Q

Function of a capsid

A

Protect the genome
Help attachment - proteins on capsid bind to receptors on cell
Help entry/uncoating - capsid needs to fall apart to release genome
Help assembly

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42
Q

Assembly w/o capsid

A

Not infectious bc there is no genome incorporated

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43
Q

Naked icosahedral virus wet or dry, which means?

A

Dry = retain infectivity

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44
Q

Naked, icosahedral virus acidic virus or not

A

Survive acidic conditions of GI bc

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45
Q

A viral particle that is not infectious has ____

A

No genome in it

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46
Q

Naked, icosahedral viruses in response to temp and detergents

A

They are resistant to
extreme temps
detergents
poor sewage treatments

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47
Q

How are naked, icosahedral viruses released

A

Usually by cell lysis

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48
Q

Bc N, Ico are dry that means

A

Transmits through fomites
And
Really hard to disinfect surfaces

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49
Q

Bc N, Ico survive in acid

A

This means they can transmit vis fecal/oral route

They are responsible for most cases of viral gastroenteritis

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50
Q

Bc N, Ico released through lysed cells that means they are

A

Cytopathic

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51
Q

Viral envelope is from

A

Host cell

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52
Q

The viral envelope includes

A

Viral encoded glycoproteins

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53
Q

Glycoproteins in the envelope

A

Matrix proteins
Surface glycoproteins

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54
Q

Matrix proteins helps virus infect through

A

Assembly
It’s a bridge btw capsid and bilayer

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55
Q

Surface helps virus infect through

A

Viral attachment
Virus-cell fusion - fusing the bilayers
Antibody????

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56
Q

Envelope virus properties

A

Must stay wet
Acid and heat labile
Detergents destroy it - respond to disinfecting
Released by budding

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57
Q

The budding of enveloped viruses means

A

Virus release over extended periods of time
More persistent

Slowly it will kill host off

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58
Q

When N, Ico lyse out of the cell what does it do to the cell

A

Kills it

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59
Q

Because enveloped viruses must stay wet that means

A

Transmitted through droplets, secretion, resp, blood, organ transplants

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60
Q

Because enveloped viruses are acid/heat labile

A

They can live in GI and cant be passed fecal/oral

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61
Q

How do enveloped viruses attach

A

Surface glycoproteins

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62
Q

How do naked viruses attach

A

Capsid proteins

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63
Q

____ is key for tropism

A

Attachment style and viral receptors

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64
Q

What are the different types of viral receptors

A

Enzymes
Hormone
Cytokine
Complement receptor
Molecules involved in cell-cell interactions

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65
Q

Virus has evolved to take advantage of ____

A

Host receptors

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66
Q

How do enveloped viruses enter a cell

A

Fusion event

67
Q

Describe fusion event
What viruses does it happen to

A

A hydrophobic domain/fusion peptide on the attachment protein of the virus is EXPOSED after it binds to a receptor on the host cell

Fuses to host cell and releases capsid

ENVELOPED

68
Q

Describe how N, Ico enters cell

A

Hydrophobic interactions create a channel through the membrane and the RNA is let into the cytoplasm

69
Q

pH dependent endocytosis

A

Involves clathrin proteins
And dynamin

1.Virus enters and turns into endosome
2.Endosome becomes acidic and fuses with lysosome
3.The acidic pH or lysosomal proteases activate fusion activity

70
Q

pH independent endocytosis

A

Involves caveolin protein
a lipid raft

1.virus internalized at an invagination with a lipid raft that has caveolin
2.caveolin vesicles fuse with caveosome
3.no lysosomes or acidification involved
4.viral fusion protein active a neutral pH can fuse without acidic environment

71
Q

What pH do you need to utilize for pH dependent entry?

A

Depends on the virus. Can utilize high or low pH

72
Q

Describe endocytosis of N, Ico viruses

A
  1. Capsid proteins form a pore through endosomal membrane
  2. Viral capsid proteins lyse membrane
  3. Confo Chang in capsid protein
    to either
    uncoat
    or
    create a pore
73
Q

Uncoating means

A

Release of genome

74
Q

RNA uncoating is in

A

Cytoplasm

75
Q

DNA uncoating is in

A

Nucleus

76
Q

Uncoating coincides with entry refers to what kind of virus

A

RNA

77
Q

Triggers for uncoating

A

Binding to a receptor
Change in pH
Proteolytic degration

78
Q

DNA viruses travel on what to get to the nucleus

A

MICROTUBLES
dynein

79
Q

Steps in taking over the host cell

A

1: control transcription
2: replicate genome
3: control protein synthesis

80
Q

Early transcripts vs late transcripts

A

Early: this is allll the stuff you need to shut down the host

late: now you’ve shut down the host, you can encode viral structural proteins

81
Q

Where does transcription and translation occur in DNA viruses

A

Nucleus

82
Q

DNA genome is ____ for mRNA

A

Template

83
Q

Most DNA viruses use ______ encoded polymerases to replicate genome

A

Virally

84
Q

Most DNA viruses use ______ polymerases to transcribe viral mRNA

A

Cellular

85
Q

Positive strand RNA virus genome can function as

A

MRNA

86
Q

Positive strand is the equivalent of the ____ strand

A

Coding

87
Q

+ strand RNA aka

A

+ssRNA

88
Q

What happens after the +ssRNA is dumping into the cell

A

1: translated to polyprotein
2: cleaved into viral proteins
3: on specific viral protein made is the RNA dependent RNA polymerase (RDRP)
4: the RDRP copies + strand to - strand
5: the - is a template to make more + ssRNA
6: those +ssRNA made turn into viral proteins
or Nucleocapsid
the viral proteins also eventually go to Nucleocapsid

89
Q

What is located inside the polyprotein

A

A protease

90
Q

-ssRNA is the ____ strand

A

Complement

91
Q

The - strand is the _____ for mRNA

A

Template

92
Q

When the -ssRNA enters a cell what does it need to bring with it

A

RDRP

93
Q

What is a core protein and who encodes it

A

RDRP

Negative strand RNA

94
Q

When - enters with RDRP what happens next

A

1: can either make (a)mRNAs or (b)+ssRNA
(A) then they make viral proteins
which then go to nucleoplasmids

(b)they then make more copies of viral 		genome
	which then go to nucleoplasmid
95
Q

A ___ strand copy of the genome is the template for genomic RNA

A

+

96
Q

Reoviruses aka

A

dsRNA

97
Q

Genome is segmented for

A

dsRNA

98
Q

Segmented genome means

A

Diff proteins on diff pieces of RNA

99
Q

RDRP is incorporated in

A

dsRNA and +/- ssRNA

100
Q

____ strand RNA is transcribed into DNA =

A

+

Retrovirus

101
Q

What is the core enzyme in retrovirus

A

RNA dependent DNA polymerase (RDDP)

102
Q

____ travels to the nucleus where it integrates into the host cell

A

Provirus

103
Q

The DNA provirus of retrovirus goes on to do what

A

It’s transcribed to make mRNA and genomic RNA

104
Q

See retrovirus pic

A

Yub yub

105
Q

Capsids ____ assemble

A

Self

106
Q

____ determine site of budding for _____

A

Matrix proteins

Enveloped viruses

107
Q

Viral budding can happen at the ___ or the _____

A

Plasma membrane or at the ER membrane

108
Q

Antiviral therapy targets 3 things

A

Disrupt viral structure
Block virus specific activity
Avoids interfering with host

109
Q

How does an antiviral disrupt viral structure

A

Detergents inactivate enveloped virus

110
Q

How does an antiviral block virus specific activity

A

Target polymerases(this one is common), proteases, and attachment proteins

Targets steps in replication that only viruses use

111
Q

Productive vs nonproductive

A

P: actively making virus particles
permissive

NP: not making viral particles
non permissive

112
Q

Types of productive infection

A

Lytic

Persistent/chronic

Persistent with Lytic virus

113
Q

What kind of infection produces changes to a cell and what is that called

A

Lytic

Cytopathic effect (CPE)

114
Q

Virus buds with no lysing

Continual shedding

A

Chronic/persistent

115
Q

At tissue or organ
Some cells lysed but not all

A

Persistent infection with Lytic virus

116
Q

What are the types of CPE

A

Syncytial formation
Cell rounding or vacuolization
Inclusion bodies

117
Q

MEGA cell is what

A

Syncytia formation = fusion of cytoplasm of adjacent cells making mega cells

118
Q

Areas within a cell with lots of replication going on. Can be seen on a stain

A

Inclusion bodies

119
Q

____ can help clinical virologists identify virus

A

CPE

120
Q

Non reproductive infection

A

Abortive
Latent

121
Q

Virus is dormant within host cell

A

Latent infection

122
Q

_____ occurs in retroviruses or DNA viruses ____ RNA viruses

A

Latent

NOT

123
Q

Why can’t our immune system detect latent infection

A

Bc the cell is not making any viral protein, so there is nothing for us to act on

124
Q

In latent infection there are _____ for antiviral drugs to act on

A

No targets

125
Q

Viral genomes usually integrate into the chromosome in _____ infections

A

Transforming

126
Q

Transformed cells are ____

A

Immortalized

127
Q

Immortalized cells may or may not become ____

A

Tumor cells

128
Q

Mechanism for transforming cells

A

1: inactivate growth-regulatory proteins
2: provide or up-regulate genes involved in cell progression through the cell cycle

129
Q

What growth reg proteins does transformation effect

A

P53
Retinoblastoma gene product

130
Q

What are some consequences of transformation

A

Uncontrolled cell growth
Increased growth rate
Alteration of morphology and metabolism
Loss of contact inhibition of growth
just continual divisions

131
Q

See nice map of viral replication

A

Yub yub

132
Q

Acute infection remains ___

A

Localized

133
Q

What type of infection is cleared by immune response

A

Acute

134
Q

Acute disease leads to

A

Symptomatic illness

135
Q

Where do acute infections enter host

A

Mucosal surfaces

136
Q

When a host has a subacute / sub clinical infection what does that mean

A

They are asymptomatic BUT they are still shedding active virus

137
Q

___ provides protection against actue infection

A

IgA response

138
Q

Localized infection starts acute then ____ through _____

A

Disseminates

Blood

139
Q

Where do you see symptoms of a localized infection

A

Replication at the secondary site

140
Q

A disseminated infection means people are _____ before _____ is recognized

A

Infectious

Illness

141
Q

Time period between exposure and symptoms show up

A

Incubation period

142
Q

Prodrome

A

Nonspecific or flu-like symptoms during dissemination

143
Q

___ is important for immunity of disseminated infections

A

IgG

144
Q

Chronic infections could be _____ or ______

A

Productive or nonproductive

145
Q

Cellular level vs tissue level productive chronic infections

A

C = host cell is not destroyed by infection

T = only a few cells in the population are infected at any one time

146
Q

Non reproductive chronic infection latency vs transformation

A

L = reactivating of latent virus results in productive infection

T = cells are altered

147
Q

a person is ___ during ______ but not during ______ or a nonproductive chronic infection

A

Infectious

Reactivating

Latency

148
Q

When the cells are altered during nonproductive chronic infection that means they are ____ and not _____

A

Transforming

Infectious

149
Q

Latency to deactivation steps

A

1: primary infection - local or disseminated, symptomatic or asymptomatic
2: latent infection -asymptomatic
3: reactivating - secondary infections cleared more rapidly than primary

150
Q

Why are reactivated infections cleared more rapidly than priamary

A

Cuz or our memory in our immune system

151
Q

Course of infection pic

A

Yub yub

152
Q

Getting a disease depends on

A

Whether or not the pathogen can overwhelm the immune response

153
Q

Balance between pathogenicity and immune response =

A

Whether or not you’ll get a disease

154
Q

Symptoms of a disease are from

A

Our immune response
Or
Results of virus infecting and killing a cell

155
Q

Disease pic

A

Yub yub

156
Q

Transmission determines

A

Site of entry

157
Q

Inoculum size influences

A

Severity

158
Q

Tissue tropism determines

A

Site of pathology

159
Q

Viral virulence factors =

A

Mech to control host cell protein synthesis
Mech to evade immune response
Mech to directly damage cells

160
Q

If you have an acute viral infection you are treating the

A

Symptoms

161
Q

Current antivirals do what

A

Inhibit actively replicating virus, not latent infections

162
Q

The ____ the better with antivirals because __

A

Earlier

The viral replication may precede symptoms

163
Q

Define chemoprophylaxis

A

Using antiviral to prevent disease from even starting

I And I Final (5 decks)

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