Two-step affinity purification of the hepatitis C virus ribonucleoprotein complex

Area of Science:

• Virology
• Molecular Biology
• Hepatitis C Research

Background:

• Positive-strand RNA viruses, including hepatitis C virus (HCV), replicate their genetic material within intricate ribonucleoprotein (RNP) complexes.
• These viral RNPs are known to associate with cellular membranes, suggesting a crucial role in the replication process.

Purpose of the Study:

• To isolate and characterize the hepatitis C virus (HCV) ribonucleoprotein (RNP) complex.
• To identify the specific viral proteins associated with the HCV RNP complex during replication.

Main Methods:

• A two-step purification strategy was employed using a human hepatoma cell line (Huh7) stably expressing HCV replicons.
• The method involved oligonucleotide-mediated hybridization, sequential enrichment using avidin-agarose and anti-digoxigenin antibody, followed by Western blot analysis.
• Native polyacrylamide gel electrophoresis was used to determine the molecular mass of the purified HCV RNP complex.

Main Results:

• The purification successfully isolated HCV RNP complexes associated with cellular membranes.
• All nonstructural (NS) proteins encoded by the HCV subgenomic replicon (NS3, NS4a, NS4b, NS5a, and NS5b) were found to be associated within the RNP complex.
• The intact HCV RNP complex exhibited an approximate molecular mass of 450 kD.

Conclusions:

• The study confirms the integral association of all HCV nonstructural proteins within the viral RNP complex.
• These findings reinforce the model of viral RNA replication occurring within a membrane-associated RNP structure.