MST1 L2-10 Questions Flashcards
(156 cards)
1
Q
What is required for negative staining?
a. Compounds should be proton dense
b. The compounds should be able to crystallise
c. The compounds should be highly soluble
d. Calcium phosphotungstate
A
c. The compounds should be highly soluble
2
Q
What is false about cryo-electron microscopy?
a. The sample is not distorted and allows the structure to be analysed
b. A negative stain must be applied first
c. Different 2D views can be reconstructed to form a 3D structure
d. A computer can be used to reconstruct the image of the virus
A
b. A negative stain must be applied first
3
Q
What is the name for each component described?
Protective protein shell. Surrounds genome, forms core of particle. Clusters of subunits called capsomers
The proteins closely assembled with viral nucleic acid
Lipoprotein membrane. Surround capsid or nucleocapsid. Phospholipids from host PM, glycoproteins virus encoded
Protein layer under envelope. Connects capsid and envelope glycoproteins.
A
Capsid
Nucleocapsid
Envelope
Matrix
4
Q
The following does not have icosahedral capsid symmetry:
a. Herpesvirus
b. Papillomavirus
c. Adenovirus
d. Paramyxovirus
A
d. Paramyxovirus
5
Q
What is false about Poxvirus?
a. It can possess either icosahedral or helical capsid symmetry depending on the species
b. It is the largest and most complex virus
c. IT has over 100 proteins in the virion
d. It has a 130-280 kb dsDNA genome
A
a. It can possess either icosahedral or helical capsid symmetry depending on the species
6
Q
What is true about classifying viruses according to family and genus?
a. Family names end in virus and genus names end in viridae
b. The size of the genome and differences in sequence can distinguish a genus from other genera
c. The number and size of proteins is used to classify families
d. Viral replication strategies and morphology are used to distinguish between genera
A
b. The size of the genome and differences in sequence can distinguish a genus from other genera
7
Q
What is false about determining if a virus has ssRNA or dsRNA?
a. RNase only digests ssRNA
b. TCA precipitates radioactive RNA polymers and the presence of precipitate demonstrates undigested RNA (double stranded)
c. ssRNA forms a precipitate when exposed to TCA
d. ssRNA would produce free uracil nucleotides when exposed to RNase and these remain in solution after treatment with TCA
A
c. ssRNA forms a precipitate when exposed to TCA
8
Q
What is the order of modified Koch’s postulates?
• Virus reisolated from experimentally infected animal
• Clinical syndrome reproducible in volunteers/animals
• Virus characterised. Isolated via animal/cell0culture passage and distinguished from other viruses immunologically or genetically
• Virus associated with clinical disease
A
- Virus associated with clinical disease
- Virus characterised. Isolated via animal/cell0culture passage and distinguished from other viruses immunologically or genetically
- Clinical syndrome reproducible in volunteers/animals
- Virus reisolated from experimentally infected animal
9
Q
What is false about Hepatitis D?
a. It is a covalently closed circular RNA viroid element
b. It is dependent on hepatitis B for transmission and acts as a parasite of a virus
c. It can be considered an emerging infectious agent
d. It encodes RNA polymerase
A
d. It encodes RNA polymerase
10
Q
• X ray diffraction can only be used on non-enveloped viruses.
A
T
11
Q
• In a viral envelope, the phospholipids are virus-encoded whilst the glycoproteins and host encoded.
A
F
12
Q
• Icosahedral capsid symmetry is only found in enveloped viruses.
A
F
13
Q
• Enveloped viruses are less stable than naked viruses.
A
T
14
Q
• Purified virions containing H suggest that the virus has an RNA genome whilst purified virions containing C suggest that the virus has a DNA genome.
A
T
15
Q
• When extracting NA from viruses and cells, the upper aqueous phase contains protein and the lower phenol phase contains nucleic acids.
A
F
16
Q
What sample would be taken to identify a virus from the following infections?
a. A faecal sample for a systemic fever
b. CSF for encephalitis
c. Nasal secretions for a vesicular rash
d. Blood for an enteric infection
A
b. CSF for encephalitis
17
Q
What part of an embryonated chicken egg would be used to cultivate Poxvirus?
a. Chorioallantoic membrane
b. Yolk sac
c. Amniotic fluid
d. Allantoic fluid
A
a. Chorioallantoic membrane
18
Q
What is false about mammalian cell culture methods?
a. Primary cells can only survive up to 10 divisions
b. Continuous cell lines are aneuploid
c. Diploid cell lines can survive up to 100 divisions
d. All modern vaccines are cultivated using continuous cell lines
A
d. All modern vaccines are cultivated using continuous cell lines
19
Q
What is false about syncytia?
a. It can be a result of measles virus
b. It involves the loss of all nuclei in a cell
c. It occurs during virus replication when neighbouring cells may fuse
d. Viral fusion proteins expressed on host membranes aid syncytia
A
b. It involves the loss of all nuclei in a cell
20
Q
What is false about infectivity/serology assays?
a. Detecting viral antigens is highly sensitive and can yield false positives
b. Anti-viral antibodies in patient serum can be detected using western blot
c. Detecting host antibodies is highly specific and can yield false negatives
d. It is a quick method and the gold standard for diagnosing viral infection
A
d. It is a quick method and the gold standard for diagnosing viral infection
21
Q
How might viral nucleic acid be detected?
a. A southern blot for viral RNA
b. RT-PCR for viral RNA
c. A northern blot for viral DNA
d. Whole genome sequencing
A
b. RT-PCR for viral RNA
22
Q
What is not a feature of PCR?
a. It requires a single stranded DNA sample
b. It is very specific and sensitive
c. Contamination can easily occur
d. It is cheap and automated
A
a. It requires a single stranded DNA sample
23
Q
• Direct visualisation by EM is the gold standard required to study a virus.
A
F
24
Q
• Virus cultures are always handled in PC4 conditions.
A
F
25
• Nuclear inclusions are usually caused by DNA viruses whilst cytoplasmic inclusions are usually caused by RNA viruses.
T
26
• Antigen capture assays are highly sensitive whilst anti-viral antibody assays are highly specific.
T
27
What describes a structural unit?
a. The infectious viral particle
b. The nucleic acid-protein assembly within a virion
c. Unit which makes up the capsid or nucleocapsid
d. Single folded polypeptide chain
c. Unit which makes up the capsid or nucleocapsid
28
In what ways are virions metastable?
a. Virions do not have moving parts
b. Viral particles have reached the minimum free energy conformation
c. Virions are always stable so that they can protect the genome
d. Target cells act as a trigger for virions to disassemble
d. Target cells act as a trigger for virions to disassemble
29
Which best describes density gradient centrifugation?
a. Rate zonal density gradient centrifugation depends on the size and mass of a particle
b. Equilibrium density gradient centrifugation depends on the density, mass and sedimentation coefficient of a particle
c. Equilibrium density gradient centrifugation requires a pre-formed gradient and can be completed in a few hours
d. Rate zonal density gradient centrifugation uses a high density solution and takes many hours to complete
a. Rate zonal density gradient centrifugation depends on the size and mass of a particle
30
What is false about SDS gel electrophoresis?
a. SDS is anionic and binds to proteins after disrupting the virion
b. Smaller protein mass correlates to a higher intensity stained band
c. Proteins move to the cathode according to their molecular weight
d. Equimolar proteins contain the same number of molecules
b. Smaller protein mass correlates to a higher intensity stained band
31
What is not a feature of poliovirus?
a. It is part if the Picornaviridae family and has a +ssRNA genome
b. It has tiny viral particles with an icosahedral structure
c. The virus has 60 capsomers and each has one copy of four viral proteins
d. SDS gels show that the virus has four viral proteins not present in equimolar amounts
d. SDS gels show that the virus has four viral proteins not present in equimolar amounts
32
Which feature is not used to distinguish helical capsids?
a. Left, right or central helix
b. Number of nucleocapsids per turn
c. Axial rise per subunit
d. Pitch per turn
a. Left, right or central helix (no central)
33
What is not a feature of the Measles virus nucleoprotein?
a. It is 60kDa and has 525 amino acids
b. It is found exclusively in the nucleus
c. It is abundant in infected cells and self assembles to form the nucleocapsid
d. It can form a ribonucleoprotein complex
b. It is found exclusively in the nucleus
34
• The steps (in order) for chemical purification of a virus are cell disruption, centrifugation and density gradient centrifugation.
T
35
• Non-ionic detergents are best used to disrupt viruses found in the nucleus.
F
36
• Low speed centrifugation results in small organelles, ribosomes and viruses pelleting.
F
37
• High speed centrifugation results in virus particles being found in the pellet and the supernatant can be discarded.
T
38
• The virion structure is not permanently bonded together in order for the viral genome to be exposed or released.
T
39
• Adenovirus contains a similar amount of proteins to Poliovirus and these are present in equimolar amounts.
F
40
• Papillomavirus has 72 capsomers which are all hexons as expected.
F
41
• The genome is a viral structural component and present in purified virions.
T
42
• Non-structural viral proteins can be found in infected cells but not uninfected cells.
T
43
How is the growth curve different between enveloped and non-enveloped viruses?
a. Non-enveloped viruses do not demonstrate a latent period
b. Enveloped viruses have a higher yield when they are intracellular
c. Intracellular viruses have a higher yield when non-enveloped and extracellular viruses have a higher yield when enveloped
d. The uncoating phase is only seen in enveloped viruses and has a low gradient on the curve
c. Intracellular viruses have a higher yield when non-enveloped and extracellular viruses have a higher yield when enveloped
44
What does it mean if P(0) = 0.02?
a. The multiplicity of infection is at 2%
b. 2% of cells are not infected
c. There is a 2% chance that any cell will become infected
d. There are 2 plaque forming units/cell
b. 2% of cells are not infected
45
What is not a method used by viruses to invade host cells?
a. Fusion and direct uncoating at the plasma membrane
b. Pinocytosis or phagocytosis
c. Endocytosis followed by uncoating within the endosome
d. Endocytosis followed by uncoating at the nuclear membrane
b. Pinocytosis or phagocytosis
46
What is not involved in the entry and uncoating of adenovirus?
a. The virus directly fuses with the host cell using CAR receptors and uncoats at the cell surface
b. When the endosome acidifies, the penton base is released and bursts the endosome so the capsid can be released
c. The adenovirus penton fibre interacts with intergrins recpetors called CAR to initiate RME
d. Once the capsid is released from the endosome, it travels to the nuclear pore using the host cell microtubule network
a. The virus directly fuses with the host cell using CAR receptors and uncoats at the cell surface
47
What is not involved in the entry and uncoating of Reovirus?
a. The capsid undergoes proteolysis in the endosome to produce the infectious subviral particle (ISVP)
b. ISVP proteins prevent endosome maturation and the virus can persist in the host
c. The outer capsid proteins bind cell receptors to mediate RME
d. ISVP proteins mediate membrane penetration
b. ISVP proteins prevent endosome maturation and the virus can persist in the host
48
What does not occur during entry of Influenza?
a. Envelope haemagglutinin molecules bind sialic acid on cell glycoproteins
b. Neuraminidase releases sialic acid and is part of the viral envelope
c. Endosome acidification is required so that the fusion domain of haemagluttinin can be exposed
d. The virus enters host cells by interacting with glycoprotein sialic acid and directly fusing with the plasma membrane
d. The virus enters host cells by interacting with glycoprotein sialic acid and directly fusing with the plasma membrane
49
What is CD46/SLAM?
a. A paramyxovirus ligand that reacts initiates fusion of the measles virus
b. A HIV-1 ligand that interacts with CD4 co-receptors during cell entry
c. The product of VP4 in Rotavirus following cleavage by trypsin
d. The flavivirus peptide that initiates membrane fusion following conformational change
a. A paramyxovirus ligand that reacts initiates fusion of the measles virus
50
What is the correct description for HIV-1 glycoproteins?
a. Gp120, gp41 and gp160 all exist as a trimer
b. Only gp160 can bind CD4
c. Gp160 is the precursor for gp41 and gp120
d. Gp41 is a surface protein and gp120 is a transmembrane protein
c. Gp160 is the precursor for gp41 and gp120
51
What happens during HIV entry? (put in order)
• Binding of gp120 to CCR causes conformational change in gp41 (transmembrane) and fusion peptide is inserted into membrane
• Gp120 (surface) binding to CD4 causes conformational change in gp120. Exposes binding site for chemokine coreceptor (CCR)
• HIV-1 envelope glycoproteins gp120-41 bind CD4
1. HIV-1 envelope glycoproteins gp120-41 bind CD4
2. Gp120 (surface) binding to CD4 causes conformational change in gp120. Exposes binding site for chemokine coreceptor (CCR)
3. Binding of gp120 to CCR causes conformational change in gp41 (transmembrane) and fusion peptide is inserted into membrane
52
What is used to determine is a virus infects a cell via endocytosis or direct fusion?
a. Genome sequencing and analysis
b. Exposing cells to a weak base to prevent endosome acidification
c. Electron microscopy
d. PCR for well-known fusion proteins such as SLAM, Gp120 and Gp41
b. Exposing cells to a weak base to prevent endosome acidification
53
• Initial binding of a virus is specific and the strongest form of attachment due to covalent protein-protein interactions.
F
54
• Virions may enter a cell by fusion, receptor mediated endocytosis or passive pinocystosis.
F (not pino)
55
• Measles virus unocats by fusing their envelope with the cell plasma membrane.
T
56
• Poliovirus enters a cell after interaction between the CD155 receptor and capsid leads to a conformational change of the VP1 capsid protein.
T
57
• All reoviruses have a double shelled capsid except for rotavirus.
F
58
• It is common for enveloped viruses to enter in the endosome and rely on endosome acidification initiating a conformational change.
T
59
What kind of viruses can directly fit into the flow of cell genetic information and can use cell enzymes?
a. dsDNA virsues and ss +RNA genome viruses
b. ss-RNA viruses
c. ss-RNA viruses and ss+ RNA viruses
d. ssDNA viruses and ds linear DNA viruses
a. dsDNA virsues and ss +RNA genome viruses
60
What is involved in cellular transcription?
a. RNA pol II binds downstream of the promoter
b. Transcription initiation factors bind the core promoter or enhancer sequences
c. RNA pol II is recruited directly by the enhancer
d. mRNA is synthesised from a DNA template using dNTPs
b. Transcription initiation factors bind the core promoter or enhancer sequences
61
Which DNA viruses carry their own polymerase?
a. Adenovirus and Papovavirus
b. Poxvirus and Herpesvirus
c. Adenovirus and Herpesvirus
d. Hepadnavirus and Poxvirus
d. Hepadnavirus and Poxvirus
62
What is false about transcriptional regulation in Papovavirus SV40?
a. VP2 and VP3 genes overlap and share some AAs due to being in the same reading frame
b. Early genes are transcribed in a counter clockwise direction and late genes are transcribed in a clockwise direction
c. Early promoters are recognised by host cell RNA transcription factors
d. The large T protein is produced following transcription of late genes
d. The large T protein is produced following transcription of late genes
63
What is not a function of the large T protein in Papovavirus SV40?
a. It initiates clockwise transcription and the activation of late viral genes
b. It suppresses DNA replication
c. It removes cellular proteins from DNA that repress transcription from the late promoter (antirepression)
d. It binds near the ori and unwinds Sv40 DNA
b. It suppresses DNA replication
64
What is false about DNA replication in Papovavirus SV40?
a. Large T protein hexamers bind near the ori and unwind DNA
b. Replication protein A binds after single strdned DNA binding proteins and leads to further unwinding of the DNA
c. RNA primers are extended by DNA Pol δ with replication factors RfC, Pcna
d. SV40 DNA replication is less efficient than cellular DNA replication, but there are fewer errors
d. SV40 DNA replication is less efficient than cellular DNA replication, but there are fewer errors
65
What is true about the mechanisms of viral dsDNA replication?
a. Papovaviruses and herpesviruses follow the fork method
b. The displacement mechanism always requires a RNA primer
c. There is no lagging strand when the Fork mechanism is used
d. Adenovirus replicates using a RNA primer and the Fork mechanism
a. Papovaviruses and herpesviruses follow the fork method
66
What are the roles of HSV-1 proteins VP16, ICP4 and ICP0?
a. VP16 stabilises the tegument layer
b. ICP4 and ICP0 initiate the transcription of early genes
c. ICP0 initiates immediate early gene transcription
d. VP16 activates late promoters to encourage DNA replication
b. ICP4 and ICP0 initiate the transcription of early genes
67
What is false about Adenovirus protein E1A?
a. It turns on the E2 early protein which relieves the promoter for structural gene transcription
b. It is extensively phosphorylated before entering the nucleus
c. It is a late protein and critical for the production of pTP
d. It is one of the first genes transcribed during Adenovirus infection
c. It is a late protein and critical for the production of pTP
68
• Viruses modulate abnormal cellular control mechanism to favour virus replication.
F
69
• The production of RNA requires a supply of dNTPS.
F (NTPs)
70
• All DNA viruses replicate in the nucleus except poxvirus.
T
71
• A Papovavirus SV40 viral particle has the DNA organised with histones in a minichromosome.
T
72
• When the transcription initiation complex is stabilised on DNA, the rate of transcription of viral proteins decreases.
F
73
• High levels of SV40 DNA dilute the concentration of cellular inhibitory binding proteins (IBP) from the late DNA promoter to allow activation of late genes.
T
74
• HSV-1 has a 126kb dsDNA genome with many ORFs, Terminal Repeats and Inverted Repeats.
T
75
• Circular DNA is primed by RNA which leaves a gap on the template following replication.
F (linear)
76
• In adenovirus, E1A an early protein and the enzymes it helps transcribe are late proteins.
F (immediate early)
77
What do Rep78/68 do?
a. Allow for adenovirus to colonise the respiratory tract
b. Nick ds Parvovirus DNA to define the end of the genome
c. Bind to Parvovirus ITR to prime the ssDNA for replication
d. Prevent splicing of Poxvirus RNA
b. Nick ds Parvovirus DNA to define the end of the genome
78
What allows Poxvirus to replicate its genome in the cytoplasm?
a. The genome encodes extensive RNA splicing machinery that produces many different sized transcripts in the cytoplasm
b. It manipulates host RNA pol and DNA pol before entering the nucleus
c. Replication produces an immediate early T-protein which binds viral DNA and allows cytoplasmic replication
d. The virus encodes viral RNA pol, capping enzyme, polyA pol and DNA pol
d. The virus encodes viral RNA pol, capping enzyme, polyA pol and DNA pol
79
Which is a Baltimore class II virus? What does this mean?
a. Parvovirus. ssDNA is converted to +mRNA via a dsDNA intermediate
b. Adenovirus. Circular DNA can directly integrate into host DNA
c. Poxvirus. DNA is replicated in the cytoplasm
d. Herpesvirus. +ssRNA is duplicated to form dsDNA that can integrate into a host genome
a. Parvovirus. ssDNA is converted to +mRNA via a dsDNA intermediate
80
Which is correct?
a. Splicing occurs in Poxviridae and Hepadnaviridae
b. Only hepadnaviridae possess their own transciptase
c. Parvoviridae use cellular transcriptase and RNA is spliced
d. A viral reverse trancriptase is present in Papovaviridae
c. Parvoviridae use cellular transcriptase and RNA is spliced
81
What doesn’t constitute the Hepatitis B virus genome?
a. 3kb dsDNA
b. Viral polymerase
c. Four 12bp direct repeats
d. Capped RNA primer
c. Four 12bp direct repeats
82
What is Baltimore Class VI?
a. ssDNA is converted to mRNA via dsDNA. As shown by Parvovirus
b. +RNA is converted to –DNA before forming dsDNA and being transcribed. As shown by Retrovirus
c. –RNA is converted to –DNA before forming dsDNA and being transcribed. As shown by Hepadnavirus
d. dsRNA is converted to dsDNA before being transcribed. As shown by Reovirus
b. +RNA is converted to –DNA before forming dsDNA and being transcribed. As shown by Retrovirus
83
What is false about translation of retroviral proteins?
a. A highly stable RNA structure stalls ribosomes at the U-rich slippery sequence in pol
b. The reading frame of Pol shifts back -1 and gag can be translated
c. Envelope glycoproteins and viral enzymes are expressed from spliced mRNA
d. Structural proteins and viral enzymes are expressed from a Gag-pol polyprotein before autocleavage
c. Envelope glycoproteins and viral enzymes are expressed from spliced mRNA
84
What is false about the reverse transcription of viral genome RNA to proviral DNA?
a. Duplication of sequences in the middle of genome +ssRNA creates a LTR
b. The process is error prone (1 in every 10,000 nt)
c. Reverse transcriptase can switch between genomes to generate recombination and diversity
d. dsDNA LTRs are generated due to the duplication of +ssRNA end sequences
a. Duplication of sequences in the middle of genome +ssRNA creates a LTR
85
• The Inverted Terminal Repeat on Parvovirus DNA is the primer and template for dsDNA synthesis.
T
86
• Poxvirus RNA can be spliced in the cytoplasm.
F (no machinery)
87
• Adenovirus, Parvovirus and Poxvirus all use DNA hairpin primers to replicate their DNA via strand displacement.
F (not pox)
88
• As well as double walled virus particles, Hepatitis B virus has incomplete particles consisting of envelope proteins.
T
89
• There are four termination sequences in Hepatitis B mRNA.
F (one for four transcripts)
90
• In retroviruses, pol encodes MA, NC and CA whilst gag encodes RT.
F
91
• In retroviruses, the diploid RNA genome is capped and polyadenylated and the RNAs are loosely joined at the 5’ end with each binding a cell tRNA.
T
92
How does Retrovirus differ from other +ssRNa viruses?
a. It is non enveloped and icosahedral
b. It is Baltimore class V and has no virion polymerase
c. It’s genome is significantly larger
d. It carries virion polymerase and is Baltimore class VI
d. It carries virion polymerase and is Baltimore class VI
93
What is not a +ssRNA virus?
a. Coronavirus
b. Reovirus
c. Calicivirus
d. Flavivirus
b. Reovirus (dsRNA)
94
What are Baltimore class IV and VI?
a. Class VI is used by retroviruses to produce mRNA via a dsDNA intermediate
b. Most +ssRNA viruses are class VI and their genome can be translated immediately
c. Class IV is used by retroviruses to produce mRNA via a dsRNA intermediate
d. Most +ssRNA viruses are class IV and mRNA is produced via a dsDNA intermediate
a. Class VI is used by retroviruses to produce mRNA via a dsDNA intermediate
95
Which statement accurately describes the structure of a +ssRNA viruses genome?
a. Picornaviruses lack a 5’ cap and 3’ polyA tail
b. Flaviviruses have a 5’ cap but no 3’ polyA tail
c. Togaviruses have a 5’ Vpg and 3’ polyA tail
d. Corona viruses do not have a 5’ cap or 3’ polyA tail
b. Flaviviruses have a 5’ cap but no 3’ polyA tail
96
Which viruses make subgenomic mRNA during replication?
a. Picorna and Hepadna
b. Flavi and Calici
c. Calici and Toga
d. Toga and Picorna
c. Calici and Toga
97
What is not part of the poliovirus genome?
a. 5’ end cloverleaf
b. 3’ Ns5
c. CRE element within genome
d. 3’ end pseudoknot
b. 3’ Ns5
98
Which virus is correctly matched to a feature of its transcription mechanism?
a. Coronavirus utilises viral and host proteins to circularise its genome and release RdRp
b. Flavivirus demonstrates RdRp skipping to produce 8 discontinuous subgenomic RNAs
c. Togavirus utilises a subgenomic promoter which transcribes only –RNA to produce +RNA for structural proteins
d. Poliovirus has complimentary 5’ and 3’ ends which allow the genome to circularise and be recognised by the RdRp and methyltransferase NS5
c. Togavirus utilises a subgenomic promoter which transcribes only –RNA to produce +RNA for structural proteins
a. Circularise: Flavi
b. RdRp skipping: Corona
d. Complimetary 5'3': Flavi
99
What is false about Coronavirus replication?
a. RdRp skipping occurs at the splciesome
b. The RNA has a 5’ cap and 3’ polyA tail which is added by viral enzymes
c. The –ssRNA replicative intermediate is transcribed in the cytoplasm
d. RdRp skipping produces a nested set of 8 discontinuous subgenomic RNAs
a. RdRp skipping occurs at the splciesome (cytoplasm)
100
What is false about the effects +RNA viruses have on host cell membrane architecture?
a. Effects are due to the replicative intermediate which is partly dsRNA which is foreign to human cells
b. Viruses replicate in vesicles from intracellular membranes to hide from the host interferon induction system
c. The induction of interferons and cytokines is caused by the +ssRNA genome
d. Poliovirus and Flavivirus use ER derived vesicles
c. The induction of interferons and cytokines is caused by the +ssRNA genome
101
What is unique about translation of poliovirus proteins?
a. The mRNA has an IRES that directly proteolyses the 5’ caps on cellular RNA
b. The mRNA has an IRES which interacts with the ribosome to initiate translation
d. A single viral RNA can dominate translation due to having an extensive 3’ polyA structure
c. It stops translation of cellular capped RNA by the action of 2A protease
102
What is involved in the translation of hepacivirus proteins?
a. An IRES that is identical to that of poliovirus
b. The destruction of cell protein translation machinery
c. Extensive pathology and the death of hepatocytes
d. A 5’ IRES and highly structure 5’ and 3’ UTRs
d. A 5’ IRES and highly structure 5’ and 3’ UTRs
103
• +ssRNA viruses manipulate host RdRp.
F
104
• Translation moves 5’ to 3’ and transcription moves 3’ to 5’ so viruses must evolve around the potential clash of Ribosome and RdRp.
T
105
• Ns5 is a RdRp and methyltransferase encoded for by Flavivirus and adds a 5’ cap to newly made +RNA.
T
106
• Structural/capsid genes are found at the 5’ end of the Togavirus genome and 3’ end of the picornavirus genome.
F
107
• The subgenomic promoter utilised by Togavirus transcribes only from positive strand RNA to produce large amounts of +RNA for structural proteins.
F
108
• The simplest method to control +ssRNA virus translation is to produce one polyprotein from a long ORF and then cleave it using host and/or viral proteases.
T
109
• Poliovirus polyproteins are cleaved by viral and host proteases and Flavivirus polyproteins are only cleaved by viral protease.
F
110
Which virus is not Baltimore class V?
a. Orthomyxoviridae
b. Flaviviridae
c. Paramyxoviridae
d. Filoviridae
b. Flaviviridae (IV)
111
Which virus is Baltimore class III?
a. Filoviridae
b. Picornaviridae
c. Bunyaviridae
d. Reoviridae
d. Reoviridae
112
What kind of viruses all carry their own virion polymerase?
a. dsDNA
b. dsRNA
c. +ssRNA
d. –ssRNA
d. –ssRNA
113
Which virus has a segmented RNA genome?
a. Orthomyxoviridae
b. Paramyxoviridae
c. Rhabdoviridae
d. Filoviridae
a. Orthomyxoviridae
114
What is the first critical step in the transcription and translation of –RNA viral genomes?
a. The –RNA is translated to produce replicative proteins
b. RdRp synthesises +RNA from the –RNA genome
c. Structural proteins are translated
d. There is exponential growth of –RNA transcripts
b. RdRp synthesises +RNA from the –RNA genome
115
What is false about the transcriptional regulation of non-segmented –ssRNA viruses?
a. Genes further away from the transcription start site are copied less frequently
b. mRNAs have polyA tails and are capped
c. genes are separated by polyA signals and start signals for the next gene
d. Genes at the 5’ end of the genome are produced to the highest level
d. Genes at the 5’ end of the genome are produced to the highest level
116
Which henipavirus protein is matched with its correct description?
a. V protein: from RNA editing. Inhibits immune response, block IFNa/b production
b. P protein: from leaking scanning of P mRNA. Prevent antiviral state, block IFNa/b signalling
c. C protein: makes RNA polymerase
d. W protein: makes DNA polymerase
a. V protein: from RNA editing. Inhibits immune response, block IFNa/b production
117
How does influenza interact with the host nucleus?
a. It prevents the transcription of new host cellular mRNAs
b. Its RNP adds a cap to viral mRNAs that has been “snatched” from cellular mRNAs
c. The PB2 protein is an endonuclease that cleaves host cellular mRNA caps
d. The PB1 protein induces cyclisaiton of the viral RNA and directly binds he m7ppg Cap
b. Its RNP adds a cap to viral mRNAs that has been “snatched” from cellular mRNAs
118
What is false about ambisense viruses?
a. Both genomic Nucleic Acid strands encode proteins
b. All are segmented and negative stranded
c. Examples include Arenavirus, phlevirus, tospovirs, tenuvirus
d. Bunyavirus is an example with a non-segmented genome
d. Bunyavirus is an example with a non-segmented genome
119
Which virus transcribes and replicates it’s RNA whilst concealed in the inner core to avoid triggering an IFN response?
a. Bunyavirus
b. Picornavirus
c. Reovirus
d. Parvovirus
c. Reovirus
120
• -ssRNA and +ssRNA virus genomes can be translated immediately upon infection.
F
121
• Paramyxoviridae have a non-segmented genome.
T
122
• In terms of the transcription of non-segmented –ssRNA genomes, the ability for RNA pol to reinitiate lessens along the length of genomic RNA.
T
123
• High levels of N binding to intergenic junctions promotes RNA pol read-through of full length +ssRNA template and encourages the switch from mRNA synthesis to genome replication.
T
124
• In influenza virus, all 8 genome segments code for proteins in virion and all of the resulting mRNAs are spliced.
F (only 2 spliced)
125
• Influenza virus (orthomyxoviruses) and paramyxoviruses are unique RNA viruses because they utilise the host nucleus during replication.
F (only ortho)
126
• In influenza, PB2 is responsible for generating capped mRNAs and PA is responsible for RNA replication. The mRNA synthesis to RNA replication switch is mediated by increased NP which binds viral RNA.
T
127
What is not a step in virus assembly shared by all viruses?
a. Form individual structural units of protein shell from one/several viral proteins
b. Selective nucleic acid packaging and other essential virion components
c. Envelope acquiring
d. Protein shell assembly, interactions between structural units
c. Envelope acquiring
128
What is not an issue to consider during virus assembly?
a. Some viruses require access to viral-encoded non-structural morphogenetic factors, such as chaperones
b. Proteins and nucleic acids must reach their correct location
c. Intracellular trafficking is essential
d. Virion components can be hard to locate when mixed up in the cytoplasm of non-compartmentalised eukaryotic cells
d. Virion components can be hard to locate when mixed up in the cytoplasm of non-compartmentalised eukaryotic cells
129
What is ψ?
a. Viral nucleic acid that has been distinguished from host cell DNA/RNA
b. Packaging signals in the viral genome
c. A morphogenetic chaperon required for virus assembly
d. The inverted repeat present in the HIV genome that aids in genome packaging
b. Packaging signals in the viral genome
130
What is involved in the genome packaging of adenovirus?
a. The RNA genome is spliced and each mRNA is tagged with a specific packaging signal
b. A complex, repeating and overlapping packaging signal at the left IR and origin has enhancers to stimulate late transcription
c. The packaging signal at the right IR interacts with viral IV2A to stimulate early transcription
d. Because it has a dsDNA genome, it manipulates host cell machinery to selectively target viral proteins
b. A complex, repeating and overlapping packaging signal at the left IR and origin has enhancers to stimulate late transcription
131
What is not involved in the packaging of the HIV genome?
a. Stem Loop 3 is only exposed in monomeric RNA which signals for packaging to occur
b. Gag NC mediates selective encapsidation of genome RNA during assembly
c. Ψ signals are in spliced regions so that only genomic RNA, and not mRNA, is packaged
d. The NC only binds to dimeric RNA that represents genomic HIV nucleic acid
a. Stem Loop 3 is only exposed in monomeric RNA which signals for packaging to occur
132
What is not a way that virions can be assembled?
a. Association of individual monomeric proteins translated as separate components
b. From large polyprotein subunits refolded after proteolytic processing
c. With assistance of viral or cellular chaperon proteins for folding
d. Using scaffold proteins that bring components together and are incorporated into the mature particle
d. Using scaffold proteins that bring components together and are incorporated into the mature particle
(not incorporated)
133
How does the virion assembly of SV40 and Adenovirus compare?
a. Both viruses require the chaperon protein L4
b. Adenovirus has spliced mRNAs that translate monomeric proteins
c. In adenovirus monomeric proteins assemble to penton units first as homo-multimers
d. Sv40 has Hexon units made from trimers of papovaviral protein II
c. In adenovirus monomeric proteins assemble to penton units first as homo-multimers
134
What is not involved in the encapsidation of Herpes Virus?
a. Genome replication makes concatomers
b. Packaging signals, pac1 pac2 are recognised so viral DNA can be cleaved within DR1
c. One end of the genome is recognised by the pac proteins before cleavage and encapsidation
d. Scaffold proteins are involved and a protease is required to finalise the viral structure
c. One end of the genome is recognised by the pac proteins before cleavage and encapsidation
135
What happens during the assembly and encapsidation of poliovirus?
a. The process relies on the action of the L4 chaperone
b. Proteolytic cleavage and correct protein folding is essential
c. VP2 and VP4 are cleaved to form VP0
d. The 5s structural unit is made up of 3CDpro subunits
b. Proteolytic cleavage and correct protein folding is essential
136
Put the sequence of poliovirus maturation and exit in order
1. Particles assemble in cytoplasm (incompletely cleaved, retain VP0)
2. Cell dies, virus released
3. RNA genome replication in cytoplasm in smooth ER
4. Package viral RNA and form non-infectious virion
5. Final cleavage of VP0 to VP4 and 2 leads to infectious virus
1. RNA genome replication in cytoplasm in smooth ER
2. Particles assemble in cytoplasm (incompletely cleaved, retain VP0)
3. Package viral RNA and form non-infectious virion
4. Final cleavage of VP0 to VP4 and 2 leads to infectious virus
5. Cell dies, virus released
137
Which virus is huge and capable of inducing cell lysis to release viral particles?
a. Adenovirus
b. Poxvirus
c. Poliovirus
d. Mimivirus
d. Mimivirus
138
What best describes a strategy used in the assembly of an enveloped virus?
a. Alphavirus depends on envelope glycoproteins and capsid
b. Coronavirus requires the internal matrix and capsid proteins to drive budding
c. Retrovirus budding is driven by envelope proteins
d. Picornavirus budding is driven by matrix proteins and RNP for efficiency
a. Alphavirus depends on envelope glycoproteins and capsid
139
What is false about the targeting of virus glycoproteins and enveloped virus assembly?
a. BFA can block viral infection by blocking ER to Golgi transport
b. Glycoproteins with retention motifs are destined for the ER or Golgi
c. Glycoproteins can only target the plasma membrane due to the thickness of their transmembrane domain
d. Glycoproteins require specific processing in the ER and Golgi
c. Glycoproteins can only target the plasma membrane due to the thickness of their transmembrane domain
140
What is not involved in the assembly of influenza virus?
a. Mature HA, NA and M2 are made in the nucleus
b. M1 binds RNP and prevents further transcription and NEP binds the complex via M1
c. When the membrane pinches off, NA cleaves sialic acid and the virion is released
d. Glycoproteins concentrate in the PM and are bound by M1 which initiates budding
a. Mature HA, NA and M2 are made in the nucleus (ER)
141
What would happen if furin was not functional in a cell infected with Flavivirus?
a. The virus would fail to exit the recycling endosome
b. prM would not be cleaved to M and the virus would not mature
c. The viral envelope would fuse with cell envelopes during its transport
d. pH would not have a role in maturation of the virion
b. prM would not be cleaved to M and the virus would not mature
142
What is false about the assembly and maturation of HIV?
a. The virus assembles at the plasma membrane due to the accumulation of TM-SU, myr-MA-GAG into lipid rafts
b. HIV Gag-MA is modified by myristoylation and phosphorylation
c. TM-SU has RNA binding sites (basic) and two zinc-finger motifs
d. Furin cleavage releases Tm and SU from env precursor
c. TM-SU has RNA binding sites (basic) and two zinc-finger motifs
(Gag-NC does)
143
How does vaccina exit the cell?
a. It travels to the edge of the cell via actin
b. It exits the cell by hijacking microtubules and using them as propeller like tails
c. It uses the secretory network to exit via exocytosis
d. It utilises microtubules and actin
d. It utilises microtubules and actin
144
The adenovirus packaging signals is in spliced regions so only genomic RNA is packaged as opposed to mRNAs.
F (HIV)
145
• New DNA virus particles are often released after a cell breaks down due to the toxic effects of viral proteins.
T
146
• Most DNA viruses assemble in the nucleus.
T
147
• SV40 Vp1,2,3 can enter the nucleus due to the action of the L4 chaperone.
F (adenovirus. Vps have NLS)
148
• Adenovirus hexon proteins lack a NLS but still enter the nucleus due to the action of a chaperon.
T
149
• Nuclear localisation signals have a high amount of basic charged AAs which can bind nucleic acid.
T
150
• Membrane bound glycoproteins are translated on free ribosomes.
F
151
• Ribosomes dock to the ER if the translated protein has a N terminal 20 AA hydrophilic sequence.
F (hydrophobic)
152
• Enveloped viruses bud from the cell membrane so that the cell membrane forms the coat with viral proteins and the nucleocapsid is inside.
T
153
• The movement of viral proteins and particles with the cell is independent of host cell processes.
F
154
• Flavivirus exits the cell by exocytosis after passing through the ER, Golgi and Recycling Endosome.
T
155
• During HIV maturation, Gag myristoylation promotes binding to phosphatidylinositol-(4,5)-bisphosphate which is only found in the PM.
T
156
• When exiting polarised cells, viruses that exit apically come into contact with blood, lymph and nerves and can spread systemically.
F
