Lecture 21 RNA virus replication

Question 1

RdRp source ssRNA

Answer 1

capsid or synthesise in host

Question 2

RdRp function

Answer 2

replicate RNA from RNA template

Question 3

positive sense ssRNA

Answer 3

act as mRNA=translate
1 or 2 polyprotein
sequential processing
self/host protease (1st cleave)
viral protease (2nd cleave)
RdRp is one product

Question 4

negative sense ssRNA

Answer 4

capsid RdRp
RdRp transcribe - into mRNA
mRNA translate=viral protein

Question 5

+ vs - sense dogma

Answer 5

goes through reciprocal intermediate during RdRp replication

Question 6

dsRNA gene expression (release)

Answer 6

RdRp in capsid
entry, RdRp transcribe + from - inside capsid

+ release from capsid translate into viral protein (RdRp etc)

Question 7

dsRNA genome replication (packing)

Answer 7

+ and RdRp packaged into capsid

in capsid RdRp replicate + into - (double strand genome)

virion mature and release

Question 8

retrovirus

Answer 8

+ ssRNA genome
reverse transcriptase viral enz into dsDNA cytoplasm

dsDNA viral enz integrase

Question 9

reverse transcription***

Answer 9

reverse transcriptase recruit tRNA near direct repeat

RdDp synth primer segment bind to self or opp DR 3’ as primer = hybrid made

RNAaseH, resistant primer

DdDp synth segment bind opposite DR, full genome

Question 10

retrovirus packaged genome

Answer 10

2 x +ssRNA

Question 11

reverse transcribing DNA virus

Answer 11

relaxed circular genome (RT, -) & (1/2 +, RNA segment)

repaired in nucleus into covalently closed circular dsDNA

dsDNA dogma to protein (reverse transcriptase),

pack pregenomic ssRNA with RT into capsid

self priming otherwise analogous to HIV

Question 12

reverse transcribing DNA virus incomplete because

Answer 12

replication in capsid, released from host before completion