Receptor transporter protein 4 (RTP4)-mediated repression of hepatitis C virus replication in mouse cells

Area of Science:

• Virology
• Immunology
• Genetics

Background:

• Hepatitis C virus (HCV) has a limited host range, primarily infecting humans and chimpanzees.
• Developing small animal models for HCV research is challenging due to unknown host and restriction factors.
• Receptor transporter protein 4 (RTP4) is a known inhibitor of RNA virus replication.

Purpose of the Study:

• To investigate the role of mouse RTP4 (mmRTP4) in restricting HCV replication.
• To identify the specific domain of mmRTP4 responsible for HCV inhibition.
• To understand the mechanism by which mmRTP4 inhibits HCV infection.

Main Methods:

• Interspecies domain-mapping to identify inhibitory domains.
• Introduction of mmRTP4 into HCV-infected Huh7 cells.
• RNA sequencing (RNA-seq) to assess interferon-stimulated genes.
• In situ proximity ligation to detect protein interactions.
• Analysis of mice with humanized CD81 and occludin alleles.

Main Results:

• Murine RTP4 (mmRTP4) potently inhibits HCV infection and disrupts replication complexes.
• The zinc-finger domain (ZFD) of mmRTP4 is crucial for HCV inhibition.
• mmRTP4 directly associates with the HCV NS5A protein.
• HCV inhibition by mmRTP4 is independent of interferon-stimulated genes.
• Altering RTP4 expression in humanized mice did not enhance HCV permissiveness.

Conclusions:

• RTP4 is a significant host restriction factor contributing to HCV's narrow host tropism.
• mmRTP4 directly targets HCV replication, likely via interaction with NS5A.
• Further research into RTP4 and other restriction factors is essential for developing better HCV small animal models.