Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

virology #1 > MST 1 (1-10) > Flashcards

MST 1 (1-10) Flashcards

1
Q

what family is Influenza? and what genome is it?

A

Orthomyxoviridae

-ssRNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

does influenza use splicing

A

-6 of its proteins code for 1 protein only

however 2 of them can use splicing to make non-structural proteins like NS1 (for immune evasion)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

are Paramyxoviridae enveloped?

A

Yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Does polio produce a long poly-protein? or individual proteins? How?

A

-polio will produce a large poly-protein
-this will then be cleaved by the viral protease
proteins are in Equimolar amounts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what capsid does influenza have?

A

Helical

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What genome does Coronaviridae have?

A

+ssRNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

where does reovirus replicate?

A

in its capsid - in the cytoplasm

as dsRNA is highly immunogenic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How does Togaviridae regulate translation of its proteins?

A
  • by using a sub genomic promoter

- structural proteins are made from the sub-genomic promoter which is not transcribed straight away

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What capsid does Poliovirus have

A

Icosahedral

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What capsid does Paramyxoviridae have?

A

helical

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

is reovirus enveloped?

A

no

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How does Polio control transcription?

A
  • it has a 5’ cloverleaf and a 3’ Pseudoknot that cell proteins bind to - they bring the ends together to form a loop
  • this activates the RdRp, which will use the 5’ Vpg to start transcription
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What virus is in Caliciviridae?

A

Norovirus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How does polio control translation?

A
  • it has an IRES on the 5’ end
  • ribosome and other translation factors will bind to IRES
  • translation will occur CAP independent
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

where does Paramyxoviridae replicate?

A

cytosol

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what capsid does Parvoviridae have?

A

icosahedral

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

is influenza enveloped

A

yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

where does Parvoviridae repliciate?

A

nucleus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How does Coronaviridae control transcription?

A
  • the common leader sequence is joined to one of several IG sequences
  • it causes the RdRp to skip/frameshift
  • this produces a nested set of discontinuous sub-genomic mRNA
  • similar to splicing
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How does adenovirus enter the cell?

A
  • penton spike binds to CAR receptor on host cell
  • enters via endocytosis
  • penton base’s release in the endosome which cause the endosome to lyse
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What viruses are in the Flaviviridae family?

A

Flavivirus and Hep. C

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Are Flaviviridae enveloped?

A

Yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the capsid structure for Flaviviridae?

A

Icosahedral

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Does influenza carry a RdRp in its capsid?

A

Yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

how does influenza enter the cell?

A
  • HA attaches to sialic acid
  • enters via endocytosis
  • the acidification of the endosome causes a change in the HA which exposes a fusion domain that embeds into the target membrane and causes fusion
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

what capsid does reovirus have

A

icosahedral

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

what genome does Rhabdoviridae have?

A

-ssRNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

does paramyxoviridae have a segmented genome?

A

no - it is unimolecular

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What capsid does Coronaviridae have?

A

Helical

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

How does LT protein drive DNA replication for SV40?

A
  • in late gene transcription LT will form a hexamer around the Ori
  • the hexamer will unwind the dsDNA and promote full dsDNA replication
  • the transcription complex will bind and make lots of copies of circular dsDNA
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

what is the transcription process for SV40?

A

-early mRNAs are transcribed using the cells RNA pol. counter clockwise
-early proteins produced include Large T protein (LT) and short t protein (sT)
-LT will bind to the early gene promoter and make transcription fore efficient
-so many mRNAs will be made that it dilutes the inhibatory binding proteins present on the late gene promoters
-LT will then bind to the late gene promoters to drive late gene transcription - they will transcribe late mRNA as they are not repressed anymore
(LT dilutes the inhibatory proteins of the late genes)
-full DNA replication will also then occur - it occurs via fork replication from the Ori with a hexamer of LT

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

is herpes linear or circular

A

linear - but becomes circular in replication

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

how does influenza control transcription?

A
  • the PB2 protein of the viral polymerase will bind to the 5’ cap on cellular mRNA, and the PA protein will cleave it off and add it to the viral mRNA to use as a primer
  • the RdRp will now use the viral -ssRNA to make + and - mRNA strands
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

Is Coronaviridae enveloped?

A

No

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

is adenovirus linear or circular

A

linear

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

what is significant about pox virus?

A

-it is the largest dsDNA virus, with a complex capsid

IT IS THE ONLY DNA virus to replicate in the cytoplasm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What virus is in the Togaviridae family

A

Ross river

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

how does transcription occur for reovirus?

A
  • it occurs in the capsid as the dsRNA genome is highly immunogenic
  • the rdrp will transcribe mRNA
  • the mRNA will be pushed out of the capsid into the cytosol for translation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

is SV40 linear or circular

A

circular

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

how many segments does influenza have?

A

8

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

how does SV40 get over the end replication problem?

A

anti-repression

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

what genome does norovirus have?

A

+ssRNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

does reovirus have a rdrp?

A

yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

what dsDNA viruses use antirepression

A

adenovirus, herpes virus, SV40

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

How does Flaviviridae transcribe?

A
  • it has complimentary sequences on its 5’ and 5’ end which come together to form a circle via complementarity
  • the RdRp (NS5) recognises this and transcribes
  • the NS5 is also a methyltransferase which adds a 5’ CAP onto the new mRNA
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

What genome does poliovirus have

A

ss+RNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

where does influenza replicate?

A

nucleus! (rare for RNA virus)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

what genome is SV40?

A

dsDNA circular

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

What virus is in the Picornaviridae Family

A

Poliovirus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

what genome does Parvovirus have

A

ssDNA! (only ssDNA virus)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

What genome does Togaviridae have?

A

+ssRNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

what virus out of all the dsDNA viruses is ss?

A

Parvovirus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

what capsid does Togaviridae have

A

Icosahedral

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

what genome does reovirus have?

A

dsRNA! (the only dsRNA virus)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

What genome does Flaviviridae have?

A

+ssRNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

what virus is in the Rhabdoviridae family?

A

Rabies

57
Q

how does measles/mumps enter the cell?

A

it uses a fusion glycoprotein to enter via fusion at the plasma membrane!

58
Q

how can polio dominate host translation?

A
  • viral protein 2A will cleave cellular protein ELF4G which stops the cells ability to translate capped mRNA
  • virus dominates the cell and cell will die after 4 hours
59
Q

How does reovirus enter the cell

A
  • virus enters via receptor mediated endocytosis
  • the particle undergoes proteolysis by the cell proteosome and creates the ISVP
  • the ISVP penetrates the membrane
60
Q

how does poliovirus enter the cell

A
  • binds to CD155 on host cell
  • enters via receptor mediated endocytosis
  • receptor binding causes a loss of VP4
  • VP1 will now insert into the endosome membrane form a pore
61
Q

How does norovirus control transcription?

A

-uses a sub genomic promoter to encode its structural proteins

62
Q

What virus is in Paramyxoviridae family?

A

-measles and mumps

63
Q

how does transcription occur for Parvoviridae

A

-as Parvoviridae is ssDNA it uses the cell transcription machinary to produce a dsDNA copy
-it has complementary sequences (inverted terminal repeat sequences) on its ends that fold back on each other to form pan handle structures
the ITR’s act as a primer for transcription of a dsDNA strand

64
Q

how does nucleoprotein assist Paramyxoviridae

A

-nucleoprotein is the first gene on the genome
-it is produced first, lots of it is made in early gene transcription (most abundant protein in the infected cell)
nucleoprotein can form the RNP complex which binds to the ig regions on the RNA to stabilise them - this allows for full sequence readthrough of the genome
-the nucleoprotein also self assembles to become the nucleocapsid

65
Q

Does Flavivirus produce singular proteins, or a large polyprotein that is cleaved?

A
  • it produces a large poly-protein that is cleaved by the viral protease enzyme
  • all proteins are produced in equimolar amounts
66
Q

How does Hep. C control translation

A
  • it has IRES on the 5’ end
  • the host cell translation proteins will bind to this and start translation CAP independent
  • Hep. C has a IRES but DOES NOT destroy the host cell machinary as polio does
67
Q

how does norovirus control translation?

A
  • translation is mediated by the VpG on the 5’ end of the mRNA (called NS5 for norovirus)
  • the translation machinery recognises the VpG and translates
68
Q

how does HIV enter the cell

A
  • gp160 is cleaved into gp120 and gp41
  • gp120 and gp41 bind to CD4 which reveals a binding region on gp120 for CCR co-receptor
  • when CCR is bound gp140 will bind to PM and cause fusion at the PM
69
Q

how does Paramyxoviridae control transcription?

A
  • in early transcription lots of early mRNA will be produced first (structural genes)
  • the RdRp falls off at the ig regions on the genome hence lots of early genes made
  • when nucleoprotein is produced it will form the RNP complex and bind to the Ig regions to stablise them
  • full genome copies will then be produced
70
Q

where does SV40 replicate?

A

nucleus

71
Q

what family is Rotavirus in?

A

Reoviridae

72
Q

Is Poliovirus enveloped

A

No

73
Q

does Paramyxoviridae have a Rdrp in its capsid?

A

yes

74
Q

Norovirus, is it enveloped?

A

No

75
Q

How does Togaviridae control transcription?

A
  • the Togaviridae has a sub-genomic promoter
  • the subgenomic promoter can only be produced from the - strand of mRNA hence will not be produced straight away
  • the sub genomic promoter encodes for the structural proteins
76
Q

name the 6 DNA viruses

A 
Pox 
Herpes 
Hepadna 
Parvo 
Papovavirus - SV40 
Adenovirus
77
Q

what is the only ssDNA virus

A

Parvovirus

78
Q

what DNA virus replicates in the cytoplasm

A

Poxvirus

79
Q

what type of genome does Herpes virus have

A

dsDNA linear but it can become circular during replication

80
Q

what are the 3 structural proteins for SV40

A

VP1, VP2 and VP3

81
Q

is SV40 circular or linear?

A

circular

82
Q

how does SV40 replicate?

early and late phase

A
  • in the nucleus
  • host cell polymerase will bind to the Ori and transcribe the early proteins first, including the transcription of LT protein (made by splicing)
  • LT protein will bind to the early promoter and increase efficiency of early gene transcription
  • when there is lots of protein produced - the inhibitory protein on the late promoter will be diluted. (anti-repression)
  • LT will now bind to the late gene promoter and drive transcription of late genes
  • LT will then form a hexamer around Ori, and unwind the dsDNA which will drive dsDNA replication. lots of dsDNA copies will be made
83
Q

where does herpes virus replicate

A

nucleus

84
Q

how does herpes virus replicate?

A
  • it has terminal repeat sequences on its genome that ligate together to form a circle during replication
  • it introduces a nick in one of the strands
  • leading and lagging strand synthesis will begin, using the viruses own polymerase
  • genome length copies of dsDNA will be made (concatemers) that are cleaved and encapsidated
  • this is called ‘rolling circle’ and is a solution to the end replication problem
85
Q

is adenovirus circular or linear

A

linear

86
Q

what is adenovirus’s solution to the end replication problem

A
  • it uses its own protein primer - terminal protein
  • which binds to the 5’ end of the DNA strand to attract its own viral polymerase
  • (DNA synthesis will occur in a 5’ to 3’ direction)
87
Q

How does adenovirus regulate replication?

A
  • early proteins will be transcribed first, and alternatively spliced
  • early protein EIA will be translated, this will go back into the nucleus and increase transcription of early proteins
  • EIA will also bind to the promoter of early protein E2 which will make lots of viral mRNA
  • this will dilute the inhibitory proteins on the late gene promoter (anti-repression)
  • E2 will now bind to the late gene promoter and drive transcription of late genes (structural genes)
88
Q

what type of genome does parvovirus have?

how does it replicate

A
  • parvo has a ssDNA genome (rare)
  • it replicates in the nucleus
  • it has inverted terminal repeats that fold back on each other to form pan handles via complementarity
  • the ITR sequence is used as a primer to synthesise DNA on one strand, then a dsDNA strand is formed
89
Q

what type of genome does Hep. B have

is it linear, or circular

A

dsDNA

incomplete circular ‘relaxed circle’

90
Q

where does Hep. B replicate

A

in the nucleus

91
Q

what type of capsid does hep b have

A

icosahedral

92
Q

does hep b have a polymerase

A

-yes it is included in the capsid, bound to the genome

93
Q

how does Hep. B produce 4 different mRNAs from its genome?

what is the most important mRNA

A
  • it has 4 different promoters that encode for 4 different mRNAs
  • the most important mRNA is the pregenome mRNA which is more than one lap of the circle
  • the pre-genome is important for producing infectious particles
94
Q

what does the pre-genome mRNA of Hep. B make?

A
  • the pre-genome makes the capsid and polymerase proteins

- itself is also packaged into the capsid to make infectious particles

95
Q

explain the replication process for hep. b

A
  • enters hepatocyte cell
  • the incomplete circular dsDNA enters the nucleus where the cellular machinary repairs it - to make a full covalently closed loop of dsDNA (the episome)
  • the episome makes mRNA with the cell transcription machinery, and capsid and polymerase proteins are made
  • a copy of the pregenomic mRNA will now be encapsidated by a capsid with a polymerase
  • in the capsid (in the cytoplasm) reverse transcription of pregenome mRNA to dsDNA will occur
  • the virus particle will then be released
96
Q

explain the reverse transcription process for hep. b

where does it occur

A
  • it occurs in the capsid in the cytoplasm
  • cis-acting signals will allow pregenome to be packaged into the capsid with a polymerase
  • the Direct repeats on the mRNA are at the 5’ and the 3’ end
  • the polymerase will bind to the 5’ end and synthesise
  • it will then template switch to the 3’ end and finish the strand
  • the RNA is degraded by RNAseH
  • the dsDNA will then be made
97
Q

where does retrovirus replicate?

A

nucleus

98
Q

what is a simple retrovirus, what is a complex retrovirus

A

koala retrovirus

HIV and HTLV

99
Q

what genome does HIV have?

A

+ssRNA diploid

100
Q

does HIV have an envelope?

what is its capsid

A

yes

icosahedral

101
Q

what genes does the pro-viral HIV genome encode?

A

Gag Env and Pol proteins
gag - matrix, capsid and nucleocapsid
pol - reverse transcriptase
env - TM and SU glycoproteins

102
Q

what genes have high sequence variability in retroviruses?

why

A

gag and env genes

the RT is highly error prone

103
Q

retrovirus is diploid, how is it joined?

A

-joined loosely on the 5’ end
-cellular tRNA binds to the primer binding site on each strand
the TRNA acts as a primer!

104
Q

in koala retrovirus the gag-pol proteins are produced via frameshifting - how does this work

A
  • -the provirus can express gag and pol via frame-shifting
  • gag will be translated, the polymerase will hit a stem loop structure called a slippery sequence this will cause the polymerase to skip - the gag-pol polyprotein is produced this way
  • gag-pol encodes a bunch of viral proteins
105
Q

explain simple retrovirus replication process (koala retrovirus)

A
  • the genome will not translate upon entry into the cytoplasm - first the pro-virus is made
  • the virus enters via binding to CCR and CD4
  • the capsid is released and will let DNTPs in (in cytoplasm)
  • it will now make a dsDNA strand using its reverse transcriptase (dsDNA=provirus)
  • the intergrase will bind to the dsDNA will translocate it to the nucleus -it becomes randomly integrated into the host DNA
  • mRNA will be produced from the pro-virus to make proteins, others will become packaged into new virus particles
106
Q

can simple retroviruses incorporate their DNA into terminally differentiated cells?

A

no (koala retrovirus)

however complex retroviruses can - HIV

107
Q

the intergrated provirus of retrovirus has a structure that is on either side of it - what is this called?

A

-the LTR sequences are on either side of the integrated viral DNA
-they are formed via the integration process
it will look like U3-R-U5-(viral DNA)-U3-R-U5

108
Q

what are the differences between HTLV and HIV?

what are the similarities

A

Differences:
HIV- spread by infectious particles, kills cells, makes more pro-virus to spread
HTLV - spread by infected cells, drives cell poliferation, uses cell mitosis to spread

both infect CD4 cells and have lifelong infection

109
Q

where does HIV assemble?

A

at the PM in the cytosol

110
Q

why is HIV a complex retrovirus?

A

it is complex because it can produce additional proteins via splicing

111
Q

name the genes encoded on the provirus of HIV

A

Env- GP160 which is cleaved into gp120 SU and gp41 TM

Gag- matrix, capsid, nucleocapsid

pol - reverse transcriptase, integrase, protease

112
Q

what genes encode for the structural genes of HIV?

A

gag and gag-pol

113
Q

explain the replication cycle of HIV

A
  • enters the cell via CD4 and CCR
  • genome is released into cytoplasm
  • here it will use its RT to make a dsDNA strand
  • the integrase will recognise the LTR’s on the ends of the dsDNA strand and translocate it to the nucleus where it will randomly integrate it into the host DNA
  • the incorporated provirus can now produce mRNAs
  • splicing of the mRNA can occur to produce around 40 different proteins - most of these will assemble on the PM
  • after virus exit the gag-pol proteins will cleave all the proteins into their active form
114
Q

when is HIV most suceptible to host recognition

A

when its assembling on the PM

115
Q

what are the resevoirs for HIV infection?

A

resting memory t-cells

116
Q

how do LTR sequences form on the HIV dsDNA

A

-it occurs when the RT duplicates the sequences at the ends of the viral RNA - this forms the LTRs on the DNA copies

117
Q

what does the LTR sequence in the integrated HIV pro-virus do?

A

it acts as a promoter
the LTR has a binding site for TAT protein which increases transcription. it also has binding sites for cellular factor NFkB which increases transcription also

118
Q

what are the two HIV regulatory proteins?
when are they made?
what do they do?

A

-Tat and Rev - they are produced via splicing
-TAT is made during early transcription
-initially lots of tat will be made which binds to TAR protein. it will bind to the start of the genome, make the RNA polymerase more effective and drive the transcription of lots of viral mRNA, including spliced mRNA
-Rev is produced a bit after, it will bind to the unspliced RNAs and stabilise them - to stop them being spliced. these mRNs will become structural proteins
(this is a timing mechanism - early lots of mRNAs, late - structural proteins produced)

119
Q

what are the accessory proteins produced from HIV provirus? what do they do?

A
  • Vif - blocks cell defence against ssRNA
  • Vpr - allows the virus to infect a resting t-cell
  • Nef -downregulates MHC
  • Vpu - downregulates MHC
120
Q

what gene has the most variability in HIV? why

A

the envelope gene
the RT is highly error prone
this allows the virus to escape immunity

121
Q

how do viruses distinguish themselves from cellular rna?

A

packaging signals

they are called psi sequences in the genome

122
Q

how does the packaging signal for HIV work?

A
  • the packaging signal is only retained in the RNAs that are not spliced
  • there is a sequence loop (kissing loop) in the packaging signal that will hybridise to another kissing loop. this will form a dimer of -ssRNA
  • the binding of the loops reveals a packaging signal that allows them to become encapsidated
123
Q

what viruses form their virion structural units from individual proteins that come together during assembly?

A
  • SV40 Vp1, Vp2 and Vp3 are formed seperately and come together during assembly
  • so do adenovirus hexamers and penton spikes
124
Q

what 2 viruses form large polyprotein units that are cleaved during assembly?

A

poliovirus - uses its own ribonuclease

retrovirus

125
Q

what is a virus that uses a viral chaperone to assemble? what is the chaperone called

A

Adenovirus uses L4 chaperone to assemble monomers into hexon trimers

126
Q

what is a DNA virus that assembles in the cytoplasm?

A

Hep. B - it is a DNA virus, but it has a RNA pre-genome hence it assembles in the cytoplasm?

127
Q

what are the two RNA viruses that replicate in the nucleus?

A

Retrovirus and influenza virus

128
Q

SV40 is a dsDNA virus that assembles in the nucleus. How does its structural proteins enter the nucleus?

A

-Vp1 Vp2 and Vp3 have nuclear localisation signals that cell proteins bind to and take them into the nucleus

129
Q

what is a NLS?

A

nuclear localisation signal
they are a string of basic amino acids flanked by hydrophobic amino acids
cell transport proteins bind to them to transport them into nucleus

130
Q

How does herpes virus encapsidate its concatemers?

A
  • viral DNA replication occurs in a rolling circle motion in the nucleus
  • the capsid will form in the nucleus
  • a bunch of proteins will bind to the ‘portal’ on the capsid
  • the portal proteins will recognise the packaging signal on the concatemer (in the ‘a’ sequence at the start and end of the concatemer, has a PAC1 and PAC2 sequence)
  • the proteins will begin stuffing the concatemer into the capsid and will cleave it off at the end
  • now the viral genome is fully encapsidated
131
Q

how does herpes exit the cell? what path does it take

A

it leaves the cell via the exocytosis route
it collects envelope and viral proteins along the way
exits via an exosome

132
Q

how are mRNAs directed to the ER to be translated?

A
  • these mRNAs have a string of 20 hydrophobic amino acids at their beginning that direct them to the ER
  • the proteins will be translated into the RER
  • they can undergo a range of modifications there
133
Q

how to MOST enveloped viruses leave the cell?

what are the exceptions?

A
  • enveloped viruses leave via the golgi network

- influenza and HIV are an exception. they assemble at the PM

134
Q

what is the process of influenza assembly and exit

A
  • influenza assembles in the nucleus
  • the viral proteins that are expressed in the cytoplasm (M1, nucleoprotein and NEP) will translocate to the nucleus and attach to the influenza RNA
  • they will transport influenza to the PM where it will assemble with the glycoproteins and bud off
135
Q

how does Flavivirus exit the cell?

A

-it will assemble in the RER and use the golgi network to leave the cell via exocytosis
-in the process the cell enzyme furin will cleave the viral PrM to M
-this allows E to fuse with the plasma membrane and leave the cell
the pH also helps the virus to mature

136
Q

how do the proteins for HIV assemble on the plasma membrane?

A

-they all have a code at their N terminus that sends them to the PM

137
Q

what does host enzyme furin cleave on HIV?

A

it cleaves the Env. protein to produce active subunits on virus exit

138
Q

how will non-enveloped viruses exit the cell?

A

most will lyse the cell upon exit!

139
Q

how could a non-enveloped virus leave the cell without lysing it?

A
  • enrobe themselves in lipid bilayer that is not an envelope
  • this protects them from detection from Ab’s and the in the blood stream

virology #1 (2 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions