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