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89 Cards in this Set

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In what form is the genome of Picornaviruses?
linear (+)ssRNA
How big the the genome of Picornaviruses?
7-8.5kb
How many capsid proteins do Picornaviruses have?
4
How many proteinases are made in Picornaviruses?
1-3
How many proteins in Picornaviruses are responsible for replication?
6-8
What protein is linked to the 5' end of the genome?
VPg
How many proteins are originally transcribed?
a single polyprotein which will be cleaved co-translationally
What kind of genome do Picornaviruses have?
(+) ssRNA
Where does Picornavirus replication take place in the cell?
tethered to ER membrane
Name some genera of the Picornavirus family:
-Enterovirus (polio, coxsackie...)
-Rhinovirus
-Cardiovirus (ECMV)
-Apthovirum (FMDV)
-Hepatovirus (Hepatitus A)
-Parechoviruses
Which Picornaviruses are acute?
ECMV (cardiovirus)
FMDV (aphthovirus)
Which Picornaviruses are chronic?
rhinovirus
hepatovirus (hepatitis A)
What kind of receptors are used by Picornaviruses?
-immunoglobulins
-compliment proteins
-integrins
-GAGs
-carbohydrate
What is a receptor used by poliovirus?
Pvr/CD155
What is a receptor used by Coxsackie virus?
Car
many others
What is a receptor used by Rhinovirus?
Icam-I
FMDV
heparan sulfate
vitronectin receptor (alphaVbeta2)
Which proteins make up a face of the icosahedral capsid of picornaviruses?
VP1
VP2
VP3
VP4
What is required to make a virion particle active?
cleavage of VP0 to VP2 and VP4 by furin (cellular protease)
What are the 2 methods of entry of Picornaviruses?
1. endocytosis
2. uncoating
In endocytosis, which pH is required for uncoating?
pH = 2-3
Which capsid protein makes up a pore for uncoating?
VP1
Which protein acts as a primer and enters the VP1 pore first during uncoating?
VPg
Which element in the 5' portion of the genome is important for binding of the replicase complex?
IRES (600-1200NTs)
What are the structural proteins of the genome?
L
VP4
VP2
VP3
VP1
-------->initially = P1
What three proteases are there in the genome?
3C (conserved in all Picornaviruses)
2A
L (not in Polio)
Which protein is the RNA-dep.-RNA-pol.?
3D
Which NS protein serves as a replication primer?
VPg
Which part of the genome is required for export from the cellular nucleus?
poly(A) tail
At what time after infection do we see begining of viral protein synthesis?
3 hours
What are the two types of IRES's?
A - 6 loops
B - 12 loops
How were the structures of IRES's predicted?
RNase digestion
computer prediction
Where is polyC bound during replication? during transcription?
loop I - replication
loop IV - translation
Which region is highly conserved?
pyrimidine-rich region
initiator AUG
What is conserved between different IRES's?
structure
NOT sequence!!!
Which cellular protein binds to the cap?
eIF-4E
Which cellular protein is a scaffold (brings RNA and cap together)?
eIF-4G
Which cellular protein in RNA helicase?
eIF-4A
Which ribosome subunit is brought to the RNA by the pre-initiation complex?
40S (small subunit)
What is brought to the initiation complex when the 40S subunit when it find the AUG sequence?
60S (large subunit)
met-tRNA binds
Which proteases cleave eIF-4G to inhibit cellular protein synthesis?
2A/L
Which viruses cleave eIF-4G?
EMCV
FMDV
polio
----->acute infections
What is another method to inhibit cellular translation?
dephosphorylation of 4E-BP1 (binds 4E)
-polio
-EMCV
Which viruses have L?
cardio (ECMV)
aphtho (FMDV)
Which protease is self-cleaving?
2A
What is an advantage of replication from (+) ssRNA --> (-) ssRNA --> (+) ssRNA?
amplification during multistrand replicative intermediate
Which three genera make up the Flaviviridae?
Flaviviruses
Pestiviruses
Hepaciviruses
What treatment is currently available for Hepatitis C?
interferon + ribavirin
What are disadvantages or this therapy?
-expensive (40000$/year)
-limitted efficacy (20-40%)
-side-effects: flu-like symptoms!!
What are the structural viruses of HCV?
core
glycoproteins - E1, E2
What are the 2 proteases of HCV?
NS2 - cleaves cysteine (like 2A)
NS3 - cleaves serine (like 3C)
Which protein is the RNA-dep.-RNA-pol. in HCV?
NS5B
Which protein is also a helicase?
NS3
Which is the NS3 cofactor?
NS4
release and binds to NS3 to become part of the protease
Does the HCV genome need a primer?
No! (nothing like VPg...)
Does the HCV genome have a poly(A) tail?
No! (but the 3' region is conserved)
What are the receptors for HCV?
unknown (3 or 4)
Which cell culture can be used to culture HCV?
Huh-7 cells (hepatoma cell line)
What are three drug targets for HCV?
-protease (non-cellular)
-polymerase
-helicase
What was the first target explore for HCV?
NS3 serine protease
What is a non-random method of finding drugs to target specific enzymes called?
rational drug design
Why was Compound A rejected?
cardiovascular side effects
What are some potential drug targets for HCV?
receptors
p7 (ion channel)
NS3 helicase
NS5 polymerase
membrane-association
NS2, NS3 protease
What is the size of Flaviviruses?
50nm
What form is the capsid of Flaviviruses in?
icosahedral
What sort of symmetry does the envelope have?
icosahedral
What form is the genome of Flaviviruses?
(+) ssRNA
10 - 12.3Kb
Which genera of Flaviruses have a 5' cap?
Flavivirus genus (NOT pesti/HCV)
Where do these viruses replicate?
cytoplasm
need own capping enzymes
What are the envelope proteins of Flaviviruses?
M and E
prM hides E until it is cleaved by Furin (host protease)
How are most Flaviviruses transmitted?
by insect bites
Which genera have IRES's?
pesti
Hepaci
Is Flavivirus uncoating pH-dependent?
yes!!
What is the size of Coronaviruses?
120-160nm
What is the form of the Coronavirus nucleocapsid?
helical
What form can the core shell of the Coronavirus be in?:
icosahedral
What is the form of the Coronavirus genome?
(+) ssRNA
27-32kb (BIG)
5' cap
3' poly(A) tail
How many genes/proteins are coded for by the Coronavirus genome?
6-9 genes
> 20 proteins produced by cleavage
Describe the inital replicase genes transcribed:
2 ORFs connected by frameshift (polyprotein)
cleaved to 14-16 proteins
How are other Coronavirus genes transcribed?
multiple 3-coterminally
What kinds of diseases do Coronaviruses cause?
common cold (30%)
SARS (severe exception)
vet diseases
How are Coronaviruses spread?
direct contact
aerosol
fecal-oral
contact with contaminated surfaces
Where did SARS come from?
probably animal source; changed so it could infect humans via direct contact
What is the fatality rate of SARS?
10%
What groups of Coronaviruses exist?
I
II
IIb (SARS
III
Which protein binds to receptor?
S
How does the polymerase produce different mRNAs from one genome?
polymerase recognizes 70bp leader region, then jumps to get different lengths of 3' elements
Which mutation in SARS was associated with the jump to humans?
29bp deletion alters ORF encoding an NS protein (unknown function)
What is unique to Coronaviruses?
a cell infected with 2 types has a high frequency of recombination by copy-choice mechanism (used as a lab tool)