The ESCRT system is required for hepatitis C virus production

Area of Science:

• Virology
• Cell Biology
• Molecular Biology

Background:

• Lipid droplets are implicated in hepatitis C virus (HCV) production.
• Mechanisms of HCV assembly, budding, and release are not fully understood.
• Enveloped viruses often utilize the endosomal sorting complex required for transport (ESCRT) machinery for budding.

Purpose of the Study:

• To investigate the role of the ESCRT system in HCV production.
• To determine if ESCRT components are necessary for HCV assembly, budding, and release.

Main Methods:

• Utilized short hairpin RNA (shRNA) and siRNA to knockdown ESCRT components (TSG101, Alix, Vps4B, CHMP4b, Brox) in HCV-permissive HuH-7-derived RSc cells.
• Assessed HCV infectivity, Core protein levels, and viral RNA levels in culture supernatants.
• Examined colocalization and binding of HCV Core protein with ESCRT-III component CHMP4b.

Main Results:

• Knockdown of ESCRT components significantly suppressed infectious HCV release into supernatants.
• HCV Core protein release was significantly reduced in knockdown cells.
• Intracellular HCV infectivity and RNA replication remained largely unaffected.
• HCV Core protein colocalized and bound with CHMP4b, but lacked a conserved viral late domain motif.

Conclusions:

• The ESCRT system is required for efficient infectious HCV production.
• HCV appears to utilize a novel motif for interaction with the ESCRT machinery.