Hepatitis C virus translation preferentially depends on active RNA replication

Area of Science:

• Virology
• Molecular Biology
• Cell Biology

Background:

• Hepatitis C virus (HCV) replication initiates on endoplasmic reticulum (ER)-derived membranes.
• HCV RNA moves from the ER during its lifecycle, but its relationship with translation is unclear.

Purpose of the Study:

• To investigate the regulation of HCV RNA translation by its trafficking.
• To determine if HCV RNA replication and protein translation occur at the same site.

Main Methods:

• Pulse-chase studies with BrU-labeled HCV RNA.
• Inhibition of ER-Golgi transport with nocodazole.
• Inhibition of viral RNA synthesis using an NS5B inhibitor.
• Analysis of replication-defective HCV replicons and NS5B mutants.
• Live cell labeling of newly synthesized HCV RNA and proteins.

Main Results:

• Blocking HCV RNA transport to the Golgi enhanced protein translation, suggesting translation occurs near RNA synthesis.
• HCV protein translation decreased upon inhibition of RNA synthesis, even with stable RNA levels.
• Replication-defective or mutated HCV RNA showed significantly reduced translation.
• Newly synthesized HCV proteins colocalized with newly synthesized viral RNA.

Conclusions:

• HCV RNA translation is coupled to RNA replication.
• Replication and translation likely occur together in the same subcellular membrane compartments, termed the "replicasome".