Molecular biology of Hep C Flashcards
What did infectious clones allow researchers to do ?
Study individual viral components with confidence
What key RNA sequences were identified using infectious clones?
Critical sequences in the 5’ and 3’ untranslated regions
What viral enzymatic activities are required for HCV replication?
Protease, helicase and polymerase.
Why was RNA from infectiouus clones problematic for research?
It did not replicate in cultured cells.
What did subgenomic replicons demonstrate bout HCV replication?
The five non structural proteins are necessary and sufficient for RNA replication.
What role does NS3-%B play in HCV replication?
Forms a multiprotein replication complex.
What sequences must be present for HCV RNA replication?
The 5’ and 3’ UTRs.
Where does HCV RNA replication occur?
In a cytoplasmic membrane bound complement.
Why is the study of subgenomic replicons limited ?
Only works in Huh7 cells .
Full length genome replicons do not produce virus particles
Virus adapts mutation for more efficient replication
only allows sturdy of part of the viruses life cycle.
Requires selection of a cell population.
What were the key breakthroughs in HCV research?
2001: HCV genotype 2a clonned from a patient with fulminant hepititis.
2003:JFH-1 subgenommic replicons replicate without culture adaptation
2005:JJFH-1 replicons replicate Hela and 293 cells.
2005: full length JFH RNA transfection produces infectious virus particles
/What is the function of Ns4b in HCV
Multiple membrane spanning proteins
Induces membraneous web formation
Essential for RNA replication complex
Involved inn virus assembly
Binds viral RNA and cellular factors
A target for antiviral drugs
What is NS5B?
A 70 kDa RNA dependent RNA polymerase
How is NS5B anchored in the cell?
Tail anchored with a c-terminal membrane spanning helix
What is the function of NS5B
Catalyses the function of both negative and positive RNA strands
What is the role of the 5’ and 3’ UTRs in HCV?
Initiation of strand replication
Binds NS5A and NS5B for replication
contains an internal ribosomal entry site
Highly ordered RNA structure enables cap independent translation
Binds directly to the ribosome
What is the membraneous web ?
A structure of double membrane vesicles that concentrates replication components
Why is the membraneous web important for HCV replication?
Facilitates efficient viral replication
Protects against innate immune response
Contains 1000 replication complexes per cell
