Nonstructural protein 5A is incorporated into hepatitis C virus low-density particle through interaction with core protein and microtubules during intracellular transport

PLoS One. 2014 Jun 6;9(6):e99022. doi: 10.1371/journal.pone.0099022. eCollection 2014.

Abstract

Nonstructural protein 5A (NS5A) of hepatitis C virus (HCV) serves dual functions in viral RNA replication and virus assembly. Here, we demonstrate that HCV replication complex along with NS5A and Core protein was transported to the lipid droplet (LD) through microtubules, and NS5A-Core complexes were then transported from LD through early-to-late endosomes to the plasma membrane via microtubules. Further studies by cofractionation analysis and immunoelectron microscopy of the released particles showed that NS5A-Core complexes, but not NS4B, were present in the low-density fractions, but not in the high-density fractions, of the HCV RNA-containing virions and associated with the internal virion core. Furthermore, exosomal markers CD63 and CD81 were also detected in the low-density fractions, but not in the high-density fractions. Overall, our results suggest that HCV NS5A is associated with the core of the low-density virus particles which exit the cell through a preexisting endosome/exosome pathway and may contribute to HCV natural infection.

MeSH terms

  • Cell Line
  • Exosomes / metabolism
  • Exosomes / pathology
  • Exosomes / virology
  • Hepacivirus / physiology*
  • Hepatitis C / metabolism*
  • Hepatitis C / pathology
  • Host-Pathogen Interactions
  • Humans
  • Lipid Droplets / metabolism
  • Lipid Droplets / pathology
  • Lipid Droplets / virology*
  • Microtubules / metabolism
  • Microtubules / pathology
  • Microtubules / virology
  • Protein Transport
  • Viral Core Proteins / metabolism*
  • Viral Nonstructural Proteins / metabolism*

Substances

  • Viral Core Proteins
  • Viral Nonstructural Proteins
  • NS-5 protein, hepatitis C virus

Grants and funding

This work was supported by Academia Sinica Institutional Fund. No additional external funding received for this study. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.