title: Nonstructural protein 5A is incorporated into hepatitis C virus low-density particle through interaction with core protein and microtubules during intracellular transport.
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.
authors.affiliation: Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan; Graduate Institute of Toxicology, National Taiwan University, Taipei, Taiwan.
authors.forename: Chao-Kuen
authors.initials: CK
authors.lastname: Lai
authors.affiliation: Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan.
authors.forename: Vikas
authors.initials: V
authors.lastname: Saxena
authors.affiliation: Department of Microbiology and Immunology, and Center of Infectious Disease and Signaling Research, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Chung-Hsin
authors.initials: CH
authors.lastname: Tseng
authors.affiliation: Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan.
authors.forename: King-Song
authors.initials: KS
authors.lastname: Jeng
authors.affiliation: Department of Microbiology and Cell Biology, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan.
authors.forename: Michinori
authors.initials: M
authors.lastname: Kohara
authors.affiliation: Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan; Department of Molecular Microbiology and Immunology, University of Southern California, Los Angeles, California, United States of America; Department of Microbiology and Immunology, and Center of Infectious Disease and Signaling Research, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Michael M C
authors.initials: MM
authors.lastname: Lai
mesh_terms: D002460:Cell Line; D055354:Exosomes / Q000378:metabolism / Q000473:pathology / Q000821:virology; D016174:Hepacivirus / Q000502:physiology*; D006526:Hepatitis C / Q000378:metabolism* / Q000473:pathology; D054884:Host-Pathogen Interactions; D006801:Humans; D066292:Lipid Droplets / Q000378:metabolism / Q000473:pathology / Q000821:virology*; D008870:Microtubules / Q000378:metabolism / Q000473:pathology / Q000821:virology; D021381:Protein Transport; D014758:Viral Core Proteins / Q000378:metabolism*; D017361:Viral Nonstructural Proteins / Q000378:metabolism*; D012324:RNA-Dependent RNA Polymerase
chemical_list: D014758:Viral Core Proteins; D017361:Viral Nonstructural Proteins; C087036:NS-5 protein, hepatitis C virus; D012324:RNA-Dependent RNA Polymerase