Active RNA replication of hepatitis C virus downregulates CD81 expression

Area of Science:

• Virology
• Cell Biology

Background:

• Hepatitis C virus (HCV) replication's impact on viral propagation is not fully understood.
• HCV entry relies on host factors like CD81.

Purpose of the Study:

• To investigate how HCV replication levels affect subsequent viral growth.
• To determine the role of HCV RNA replication status in modulating viral infectivity.

Main Methods:

• Engineered a full-length HCV genotype 2a JFH1 genome with a blasticidin resistance cassette in NS5A.
• Selected and maintained stable HCV-expressing human hepatoma Huh7 cells with varying replication levels.
• Assessed viral RNA/protein expression, infectivity titers, and CD81 surface levels using HCV pseudotyped particles (HCVpp).

Main Results:

• Highly-replicating HCV stable cells showed increased viral RNA, protein, and infectivity compared to non-selected cells.
• High HCV replication decreased susceptibility to HCVpp infection and downregulated cell surface CD81.
• Reduced CD81 expression resulted from decreased total expression and endoplasmic reticulum-associated cytoplasmic retention.
• Viral RNA replication in both subgenomic replicons and full-length genomes reduced HCVpp permissiveness by decreasing CD81 surface levels.

Conclusions:

• HCV RNA replication status is a critical determinant of HCV growth.
• Modulation of CD81 expression and localization by HCV replication impacts viral reinfection and amplification.
• Downregulation of CD81 interferes with viral spread and propagation.