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A Protocol for Analyzing Hepatitis C Virus Replication
13:04

A Protocol for Analyzing Hepatitis C Virus Replication

Published on: June 26, 2014

Hepatitis C virus suppresses C9 complement synthesis and impairs membrane attack complex function

Hangeun Kim1, Keith Meyer, Adrian M Di Bisceglie

  • 1Department of Internal Medicine, Saint Louis University, St Louis, Missouri, USA.

Journal of Virology
|March 15, 2013
PubMed

Insights

Hepatitis C virus (HCV) inhibits complement component C9, weakening the immune system's membrane attack complex (MAC). This impairs the body's defense against pathogens during chronic HCV infection.

Area of Science:

  • Virology
  • Immunology
  • Molecular Biology

Background:

  • Hepatitis C virus (HCV) infection can compromise the host immune response.
  • The complement system, particularly the membrane attack complex (MAC), is crucial for pathogen defense.
  • HCV's impact on complement component expression, specifically C9, was previously unclear.

Purpose of the Study:

  • To investigate how Hepatitis C virus (HCV) regulates the membrane attack complex (MAC) through complement component C9.
  • To determine the effect of HCV infection on C9 expression and MAC function in patients and cell models.

Main Methods:

  • Analysis of C9 mRNA levels in liver biopsy specimens from HCV-infected patients and controls.
  • Assessment of C9 mRNA and protein expression in HCV-infected hepatocytes and those expressing HCV core protein.
  • Promoter analysis to identify transcription factors involved in HCV core-mediated C9 regulation.
  • Measurement of C5b-9 levels and antimicrobial activity in sera from HCV-infected patients.

Main Results:

  • Lower C9 mRNA expression was observed in liver tissues of chronically HCV-infected patients compared to controls.
  • HCV infection and HCV core protein expression significantly repressed C9 mRNA and protein levels in hepatocytes.
  • T cell factor-4 (TCF-4E) was identified as a key transcription factor in HCV core-mediated C9 promoter regulation.
  • Sera from HCV-infected patients showed reduced C5b-9 levels and diminished antimicrobial efficacy.

Conclusions:

  • Hepatitis C virus core protein downregulates complement component C9 expression.
  • HCV-mediated C9 repression leads to functional impairment of the membrane attack complex (MAC).
  • These findings highlight a mechanism of immune evasion by HCV through attenuation of the innate immune system.

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