Active RNA replication of hepatitis C virus downregulates CD81 expression

PLoS One. 2013;8(1):e54866. doi: 10.1371/journal.pone.0054866. Epub 2013 Jan 22.

Abstract

So far how hepatitis C virus (HCV) replication modulates subsequent virus growth and propagation still remains largely unknown. Here we determine the impact of HCV replication status on the consequential virus growth by comparing normal and high levels of HCV RNA expression. We first engineered a full-length, HCV genotype 2a JFH1 genome containing a blasticidin-resistant cassette inserted at amino acid residue of 420 in nonstructural (NS) protein 5A, which allowed selection of human hepatoma Huh7 cells stably-expressing HCV. Short-term establishment of HCV stable cells attained a highly-replicating status, judged by higher expressions of viral RNA and protein as well as higher titer of viral infectivity as opposed to cells harboring the same genome without selection. Interestingly, maintenance of highly-replicating HCV stable cells led to decreased susceptibility to HCV pseudotyped particle (HCVpp) infection and downregulated cell surface level of CD81, a critical HCV entry (co)receptor. The decreased CD81 cell surface expression occurred through reduced total expression and cytoplasmic retention of CD81 within an endoplasmic reticulum -associated compartment. Moreover, productive viral RNA replication in cells harboring a JFH1 subgenomic replicon containing a similar blasticidin resistance gene cassette in NS5A and in cells robustly replicating full-length infectious genome also reduced permissiveness to HCVpp infection through decreasing the surface expression of CD81. The downregulation of CD81 surface level in HCV RNA highly-replicating cells thus interfered with reinfection and led to attenuated viral amplification. These findings together indicate that the HCV RNA replication status plays a crucial determinant in HCV growth by modulating the expression and intracellular localization of CD81.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Down-Regulation
  • Gene Expression Regulation, Viral
  • HEK293 Cells
  • Hepacivirus / genetics*
  • Hepacivirus / growth & development
  • Humans
  • Membrane Proteins / genetics
  • RNA, Viral / genetics*
  • Replicon / genetics
  • Tetraspanin 28* / genetics
  • Tetraspanin 28* / metabolism
  • Virus Replication / genetics*

Substances

  • CD81 protein, human
  • Membrane Proteins
  • RNA, Viral
  • SYTL1 protein, human
  • Tetraspanin 28

Grants and funding

This study was supported by research grants from the National Health of Research Institute (NHRI-EX100-10051SI and NHRI-EX101-10051SI), the National Science Council (NSC99-2320-B-001-003-MY3 and NSC101-2320-B-001-022-MY3), the Ministry of Education (EMRPD1B0161), Chang Gung University (NMRPD1B12 and CMRPD1B0461), and by Foresight Research Grants (AS97FP-L15-1, AS98FP-L15-1, and AS99FP-L15-1), Summit Project III from Academia Sinica, and the Liver Disease Prevention & Treatment Research Foundation. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.