The ESCRT system is required for hepatitis C virus production.
BACKGROUND
Recently, lipid droplets have been found to be involved in an important cytoplasmic organelle for hepatitis C virus (HCV) production. However, the mechanisms of HCV assembly, budding, and release remain poorly understood. Retroviruses and some other enveloped viruses require an endosomal sorting complex required for transport (ESCRT) components and their associated proteins for their budding process.


RESULTS
To determine whether or not the ESCRT system is needed for HCV production, we examined the infectivity of HCV or the Core levels in culture supernatants as well as HCV RNA levels in HuH-7-derived RSc cells, in which HCV-JFH1 can infect and efficiently replicate, expressing short hairpin RNA or siRNA targeted to tumor susceptibility gene 101 (TSG101), apoptosis-linked gene 2 interacting protein X (Alix), Vps4B, charged multivesicular body protein 4b (CHMP4b), or Brox, all of which are components of the ESCRT system. We found that the infectivity of HCV in the supernatants was significantly suppressed in these knockdown cells. Consequently, the release of the HCV Core into the culture supernatants was significantly suppressed in these knockdown cells after HCV-JFH1 infection, while the intracellular infectivity and the RNA replication of HCV-JFH1 were not significantly affected. Furthermore, the HCV Core mostly colocalized with CHMP4b, a component of ESCRT-III. In this context, HCV Core could bind to CHMP4b. Nevertheless, we failed to find the conserved viral late domain motif, which is required for interaction with the ESCRT component, in the HCV-JFH1 Core, suggesting that HCV Core has a novel motif required for HCV production.


CONCLUSIONS
These results suggest that the ESCRT system is required for infectious HCV production.
Department of Tumor Virology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama, Japan. ariumi@md.okayama-u.ac.jp
Yasuo
Y
Ariumi
Misao
M
Kuroki
Masatoshi
M
Maki
Masanori
M
Ikeda
Hiromichi
H
Dansako
Takaji
T
Wakita
Nobuyuki
N
Kato
D002460:Cell Line; D056827:Endosomal Sorting Complexes Required for Transport / Q000378:metabolism / Q000502:physiology*; D016174:Hepacivirus / Q000502:physiology*; D006526:Hepatitis C / Q000378:metabolism / Q000821:virology*; D006801:Humans; D014779:Virus Replication
C478397:CHMP4B protein, human; D056827:Endosomal Sorting Complexes Required for Transport
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