- 作者: Hsiao-Fen Li; Chia-Hsuan Huang; Li-Shuang Ai; Chin-Kai Chuang; Steve S.-L. Chen
- 作者服務機構: Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan, R.O.C.
- 中文摘要: --
- 英文摘要:
Background :
Envelope (E) glycoprotein E2 of the hepatitis C virus (HCV) mediates binding of the virus to
target cell receptors. Nevertheless, the precise role of E1 in viral entry remains elusive.
Methods :
To understand the involvement of the fusion peptide-like domain positioned at residues 264
to 290 within envelope glycoprotein E1 in HCV infection, mutants with Ala and Asn
substitutions for residues conserved between HCV and E proteins of flaviviruses or the fusion
proteins of paramyxoviruses were constructed by site-directed mutagenesis and their effects
on membrane fusion and viral infectivity were examined.
Results :
None of these mutations affected the synthesis or cell surface expression of envelope proteins,
nor did they alter the formation of a non-covalent E1-E2 heterodimer or E2 binding to the
large extracellular loop of CD81. The Cys residues located at positions 272 and 281 were
unlikely involved in intra- or intermolecular disulfide bond formation. With the exception of
the G267A mutant, which showed increased cell fusion, other mutants displayed reduced or
marginally inhibited cell fusion capacities compared to the wild-type (WT) E1E2. The
G267A mutant was also an exception in human immunodeficiency virus type 1 (HIV-1)/HCV
E1E2 pseudotyping analyses, in that it showed higher one-cycle infectivity; all other mutants
exhibited greatly or partially reduced viral entry versus the WT pseudotype. All but the
G278A and D279N mutants showed a WT-like profile of E1E2 incorporation into HIV-1
particles. Since C272A, C281A, G282A, and G288A pseudotypes bound to Huh7 cells as effectively as did the WT pseudotype, the reduced infectivity of these pseudotypes was due to
their ability to inhibit cell fusion.
Conclusion :
Our results indicate that specific residues, but not the structure, of this fusion peptide-like
domain are required for mediating cell fusion and viral entry. - 中文關鍵字: --
- 英文關鍵字: --