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Immunology > Introduction to viruses > Flashcards

Introduction to viruses Flashcards

1
Q

viruses are obligate

A

intracelluar parsite

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2
Q

are viruses living

A

no - inert particles

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3
Q

if virus needs enzyme to replicate its genome, the virus must do what

A

provide it itself - certain enzymes virus needs for replication and the virus has to carry those in itself

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4
Q

anything needed after stage of mRNA

A

virus doesn’t need to carry, ti will just happen

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5
Q

virus will self ______ within host cell

A

assemble

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6
Q

virus particle called

A

virion

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7
Q

virus has to have

A

genome

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8
Q

what kind of genome does virus have

A

DNA or RNA

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9
Q

if DNA genome can be

A

linear or circular

single or double stranded

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10
Q

RNA genome can be

A

linear or segmented

single or double stranded

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11
Q

if single stranded rna genome what is important

A

polarity

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12
Q

what are three possibilities for rna genome for virus

A

positive sense or negative sense or ambiesense (+ at one end - at one end)

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13
Q

negative sense RNA

A

opposite to mRNA cannot be directly translated
need enzyme to make RNA
RNA dependent RNA polymerase

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14
Q

all viral genoms have to be associated with what kind of proteins

A

capsid

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15
Q

what are possible structures for capsid

A

helical capsid

icosahedral capsid

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16
Q

capsid + nucleic acid is calld

A

nucleocapsid

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17
Q

what is actually introduced into cytoplasm of cell

A

nucleocapsid

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18
Q

minimal structure of virus

A

genome + capsid proteins

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19
Q

some viruses will have add’l structures

A

envelope
peplomers
packaged enzymes

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20
Q

envelope viruses will have

A

envelop

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21
Q

what is envelope

A

part of membrane of cell that the virus affected and assembled in
lipid bilayer that surrounds nucleocapsid

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22
Q

peplomers

A

viral glycoprotein spikes

targets for neutralizing antibodies

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23
Q

what is important about peplomer

A

targets for neutralizing antibodies

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24
Q

many viruses are designed to neutralize

A

peplomer

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25
Q

what does virus use to attach to specific receptor on host cell

A

peplomer (viruses block attachment!)

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26
Q

if virus needs enzyme the host cell can’t provide ie needs

A

pakcaged enzyme

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27
Q

what are examples of packaged enzymes

A

replicases, proteases

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28
Q

viral proteins that make up virion are called

A

structural proteins

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29
Q

oms proteins made during replication cycle of virus - they don’t become part of virus - they are called

A

non-structural proteins (not part of virion)

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30
Q

encoded enzymes a virus may need are not always packaged in

A

virion

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31
Q

ultimately virus needs to get to what stage on its own

A

mRNA

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32
Q

examples of helical enveloped virus

A

pox virus
rabies virus
HIV

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33
Q

how are viruses classified into order, family, etc (taxonomic classification)

A

how they replicate
*polarity/strand of genome
type of disease it will cause

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34
Q

most common route for infectious disease and true for virus

A

mucousal route (inhalation or ingestion)

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35
Q

once virus enters,once a virus enters,

A

limited replication then virus spreads

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36
Q

how can virus enter

A

repiratory, wounds, STD, fecal-oral

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37
Q

when virus enters there can be replication at

A

initial site it entered

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38
Q

incubation preriod

A

there can be asymptomatic period or prodrom period

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39
Q

dissemination may occur -

A

they may spread from primary to secondary site

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40
Q

some viruses spread to what site

A

tertiary

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41
Q

what is responsible for spreading HIV

A

dendritic cells

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42
Q

primary site replication can be spread to

A

secondary site

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43
Q

secondary site replication can be spread to

A

tertiary site

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44
Q

but not all viruses will spread correct?

A

yes

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45
Q

4 types of viral infection

A

abortive
productive - nonlytic
latent
productive - lytic

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46
Q

abortive

A

cell cannot survive replication of virus or virus itself is defective

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47
Q

productive (non-lytic)

A

the host cell is altered but not killed- permissive and productive

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48
Q

producive nonlytiic is often viruses that have

A

envelope

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49
Q

productive - lytic

A

host cell death and release of progeny viruses
- permissive and productive

cell is lysed during replication

50
Q

producitve - lytic characteristic of what virus

A

no envelope

51
Q

latent viral infection

A

viral genome persists inside host cell without production of virus particles
latent viruses can become reactivated

52
Q

when latent viruses are reactivated lead to production of

A

virus particles

53
Q

lytic infections mediated by

A

naked viruses (no evvelope)

54
Q

budding is mediated by

A

envloped virus (during budding iti will aquire envelope)

55
Q

regardless if relase is lytic or budding what are the steps

A 
Adherence
Penetration
Replication
Assembly
Release
56
Q

penetration

A

release nucleocapsid into cell

57
Q

replication

A

synthesis of viral proteins

58
Q

release

A

lysis or budding

59
Q

transofrming virus e cause

A

cancer

60
Q

do all transofrming viruses integrate

A

no

61
Q

first step due o highly speicif reaction of

A

peptomer

62
Q

specificity of peplomer receptor interaction determins

A

tropism (type of cell virus can affect)

63
Q

tropism:

A

(type of cell virus can affect)

64
Q

permissiveness

A

allows virus to enter and replciate

65
Q

two main strains of HIV

A

T tropic

M tropic

66
Q

T tropic HIV straing primarlily affects

A

t lymphocyte

67
Q

m tropic strain primarlily affects

A

macrophage

68
Q

both strains HIV the receptor primarily binds to

A

CD4

69
Q

once virus binds to CD4 what happens

A

it undergoes conformational change that allows it to bind to a coreceptor

70
Q

coreceptor for m tropic strain of HIV

A

CCR5 (chemokine receptor)

71
Q

coreceptor for t trophic strain

A

CXCR4 (chemokine receptor)

72
Q

m tropic strain of hiv will not affect

A

t lymphocytes

73
Q

t trophic strain of hiv will not affect

A

macrophage

74
Q

influenza virus peplomer called

A

Haemagglutinin

75
Q

HA stands for

A

Haemagglutinin

76
Q

where does human flu replicate

A

airway epithelia

77
Q

once it binds has to deliver

A

nucleocapsid into cell

78
Q

can enevloped viruses fuse

A

yes - they can fuse with bilayer of host cell

79
Q

where does fusion occur

A

often cell membrane but can be membrane inside cell like endosome

80
Q

can naked viruses fuse

A

no b/c they just have coating of protein and own’t fuse with lipid

81
Q

adenovirus enduses induces

A

lysis of endosome once its taken up

82
Q

main mechanisms virus can enter cell - draw out

A

pg 20

83
Q

influenza virus will only fuse at

A

acidic pH

84
Q

HIV virus will fuse at

A

neutral pH

85
Q

neutral pH fusion takes place where

A

at surface of cell

86
Q

acidic pH fuses wehre

A

endosome

87
Q

fusion at acidic pH is also called

A

pH dependent fusion

88
Q

poliovirus will form what in endosome

A

pore - it allows genome to be available for replication

89
Q

adenovirus lead to what of endosome

A

lysis - then the nucleocapsid is delivered to where it replicates

90
Q

what is function of spike glycoproteins

A

bind to receptor on surface of cell allowing the cell to become infected (they remain in membrane!)
they define where they are going to bud from cell by the spike glycoproteins

91
Q

multinucleated giant cells are called

A

syncytia

92
Q

influenza viruses taken up into endoxomes and then

A

it fuses - it needs the pH to drop

93
Q

will syncytia formation happen during influenza

A

no

94
Q

will ther be fusion at neutral pH for influenza virus

A

no - they cannot force fusion at the neutral pH it needs pH to drop

95
Q

entry does not necesarilly require

A

fusion (naked virus!)

96
Q

naked virus will not fuse with

A

lipid membrane

97
Q

once nucleocapsid is delivered and uncoated what needs to happen

A

need to replicate

98
Q

enzymes that carry ou replication are

A

host or viral enzymes (or both)

99
Q

enzymes always made on host

A

ribosomes

100
Q

once repplication happens there will be

A

assembly & release

101
Q

naked virus released by

A

lysis

102
Q

not naked virus released by

A

budding

103
Q

large DNA viruses life cycle

A

wave of transcription
immediate early genes expressed followed by early genes, they encode proteins that regulate the transcription and replication of virus. they are made early on. many RNA virsuses don’t have wave of transcription, most you just straigt away mke structural/nonstructural proteins

104
Q

in macromolecule once genome made then

A

make what is needed to package enome

105
Q

what are stages of macromolecular syntehssis and replciation

A

Transcription of Immediate Early and Early mRNA  synthesis of nonstructural regulatory proteins
Replication of genome
Transcription of Late mRNA  structural protein synthesis

106
Q

when viruses are assembling they can give rise to

A

inclusion bodies

107
Q

inclusion bodies

A

proteins falling out of solution - so many proteins being made

108
Q

where will inclusion bodies be

A

wherever replication is taking places

109
Q

what is period b/w addition of virus where amount of virus seems to decrease

A

eclipse period

110
Q

why does amoutn of virus decrease once injected

A

b/c it is being taken up into cell

111
Q

eclipse period

A

b/w infection and when more virus can be detected than what was added (length depends on virus)

112
Q

RNA viruses encode

A

RNA-dependent RNA polymerase

113
Q

permissivness =?

A

entry + replication

114
Q

what are syncytia

A

multinucleated cells

115
Q

pH independent fusion leads to the formation of what

A

syncytia (multinucleated cells)

116
Q

what are chemokines

A

chemoattracts that a cells in our body make to tell immune system there is infection going on

117
Q

HIV fuses with what membrane

A

plasma

118
Q

enveloped viruses fuse with what

A

host cell membrane - often plasma membrane but isn’t always

119
Q

fusion at neutral ph is also called

A

ph independent fusion

120
Q

what is the result of fusion at neutral pH

A

once nucleocapsid is released into cell, spike glycoproteins remain in the plasma membrane
the spike glycoproteins allows them to fuse with other cells with spike glycoproteins resulting in multinucleated cells

Immunology (12 decks)

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