title: CD81 engineered with endocytotic signals mediates HCV cell entry: implications for receptor usage by HCV in vivo.
abstract: Although CD81 has been shown to bind HCV E2 protein, its role as a receptor for HCV remains controversial. In this study, we constructed two CD81 chimeras by linking the cytoplasmic domains of recycling surface receptors, low-density lipoprotein receptor (LDLR), and transferrin receptor (TfR), respectively, to CD81 and compared their internalization properties to wild-type CD81. Binding experiments with anti-hCD81 antibody showed that cell-surface CD81 chimeric receptors were internalized much more efficiently than wild-type CD81. In addition, CD81 chimeras, but not wild-type CD81, could internalize recombinant E2 protein and E2-enveloped viral particles from the serum of HCV-infected patients into Huh7 liver cells. The latter resulted in persistent positive-strand viral RNA and accumulation of replication intermediates, negative-strand viral RNA, in the infected cells, suggesting that the internalized viruses have undergone replication. Therefore, it appeared that CD81, possibly in association with a liver-specific endocytotic protein(s), represents one of the pathways by which HCV can infect hepatocytes.
authors.affiliation: Collaborative Anti-Viral Research Group, Institute of Molecular and Cell Biology, 30 Medical Drive, Singapore 117609. mcbtanyj@imcb.nus.edu.sg
authors.forename: Yee-Joo
authors.initials: YJ
authors.lastname: Tan
authors.forename: Siew-Pheng
authors.initials: SP
authors.lastname: Lim
authors.forename: Patrick
authors.initials: P
authors.lastname: Ng
authors.forename: Phuay-Yee
authors.initials: PY
authors.lastname: Goh
authors.forename: Seng Gee
authors.initials: SG
authors.lastname: Lim
authors.forename: Y H
authors.initials: YH
authors.lastname: Tan
authors.forename: Wanjin
authors.initials: W
authors.lastname: Hong
mesh_terms: D015703:Antigens, CD / Q000378:metabolism*; D001483:Base Sequence; D002460:Cell Line; D004705:Endocytosis; D016174:Hepacivirus / Q000502:physiology*; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D011990:Receptors, Transferrin / Q000378:metabolism; D011991:Receptors, Virus / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D060225:Tetraspanin 28; D014759:Viral Envelope Proteins / Q000378:metabolism*; D014771:Virion / Q000502:physiology; D014779:Virus Replication
chemical_list: D015703:Antigens, CD; C554798:CD81 protein, human; C087035:E1 protein, Hepatitis C virus; D008565:Membrane Proteins; D011990:Receptors, Transferrin; D011991:Receptors, Virus; D011993:Recombinant Fusion Proteins; D060225:Tetraspanin 28; D014759:Viral Envelope Proteins; C091015:glycoprotein E2, Hepatitis C virus