RNA Viruses (8,9) Flashcards
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
What is not a +ssRNA virus?
a. Coronavirus
b. Reovirus
c. Calicivirus
d. Flavivirus
b. Reovirus
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
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
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
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
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
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
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
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
c. It stops translation of cellular capped RNA by the action of 2A protease
d. A single viral RNA can dominate translation due to having an extensive 3’ polyA structure
b. The mRNA has an IRES which interacts with the ribosome to initiate translation
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
• +ssRNA viruses manipulate host RdRp.
F
• Translation moves 5’ to 3’ and transcription moves 3’ to 5’ so viruses must evolve around the potential clash of Ribosome and RdRp.
T
• Ns5 is a RdRp and methyltransferase encoded for by Flavivirus and adds a 5’ cap to newly made +RNA.
T
• Structural/capsid genes are found at the 5’ end of the Togavirus genome and 3’ end of the picornavirus genome.
F
• The subgenomic promoter utilised by Togavirus transcribes only from positive strand RNA to produce large amounts of +RNA for structural proteins.
F
• 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
• Poliovirus polyproteins are cleaved by viral and host proteases and Flavivirus polyproteins are only cleaved by viral protease.
F
Which virus is not Baltimore class V?
a. Orthomyxoviridae
b. Flaviviridae
c. Paramyxoviridae
d. Filoviridae
b. Flaviviridae
Which virus is Baltimore class III?
a. Filoviridae
b. Picornaviridae
c. Bunyaviridae
d. Reoviridae
d. Reoviridae
What kind of viruses all carry their own virion polymerase?
a. dsDNA
b. dsRNA
c. +ssRNA
d. –ssRNA
d. –ssRNA
Which virus has a segmented RNA genome?
a. Orthomyxoviridae
b. Paramyxoviridae
c. Rhabdoviridae
d. Filoviridae
a. Orthomyxoviridae
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
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
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
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
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
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
• -ssRNA and +ssRNA virus genomes can be translated immediately upon infection.
F
• Paramyxoviridae have a non-segmented genome.
T
• 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
• 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
• In influenza virus, all 8 genome segments code for proteins in virion and all of the resulting mRNAs are spliced.
F
• Influenza virus (orthomyxoviruses) and paramyxoviruses are unique RNA viruses because they utilise the host nucleus during replication.
F
• 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
