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Journal of Virology, February 1999, p. 1546-1554, Vol. 73, No. 2
Department of Molecular Genetics and
Microbiology, State University of New York at Stony Brook, Stony
Brook, New York 11794-5222
Received 5 June 1998/Accepted 20 October 1998
H.-H. Lu and E. Wimmer (Proc. Natl. Acad. Sci. USA 93:1412-1417,
1996) have demonstrated that the internal ribosomal entry site (IRES)
of poliovirus (PV) can be functionally replaced by the related genetic
element from hepatitis C virus (HCV). One important finding of this
study was that open reading frame sequences 3' of the initiating AUG,
corresponding to the open reading frame of the HCV core polypeptide,
are required to create a viable chimeric virus. This made necessary the
inclusion of a PV 3C protease (3Cpro) cleavage site for
proper polyprotein processing to create the authentic N terminus of the
PV capsid precursor. Chimeric PV/HCV (P/H) viruses, however, grew
poorly relative to PV. The goal of this study was to determine the
molecular basis of impaired replication and enhance the growth
properties of this chimeric virus. Genetic modifications leading to a
different proteinase (PV 2Apro) cleavage site between the
HCV core sequence and the PV polyprotein (P/H701-2A) proved far
superior with respect to viral protein expression, core-PV fusion
polyprotein processing, plaque phenotype, and viral titer than the
original prototype PV/HCV chimera containing the PV
3Cpro-specific cleavage site (P/H701). We have used this
new virus model to answer two questions concerning the role of the HCV
core protein in P/H chimeric viral proliferation. First, a derivative of P/H701-2A with frameshifts in the core-encoding sequence was used to
demonstrate that production of the core protein was not necessary for
the translation and replication of the P/H chimera. Second, a viral
construct with a C-terminal truncation of 23 amino acids of the core
gene was used to show that a signal sequence for signal peptidase
processing, when present in the viral construct, is detrimental to P/H
virus growth. The novel P/H chimera described here are suitable models
for analyzing the function(s) of the HCV elements by genetic analyses
in vivo and for antiviral drug discovery.
0022-538X/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Poliovirus/Hepatitis C Virus (Internal Ribosomal
Entry Site-Core) Chimeric Viruses: Improved Growth Properties through
Modification of a Proteolytic Cleavage Site and Requirement for
Core RNA Sequences but Not for Core-Related Polypeptides
*
Corresponding author. Mailing address: Department of
Molecular Genetics and Microbiology, State University of New York at Stony Brook, Stony Brook, NY 11794-5222. Phone: (516) 632-8787. Fax:
(516) 632-8891. E-mail: wimmer{at}asterix.bio.sunysb.edu.
Present address: Department of Antiviral Therapeutics,
Schering-Plough Research Institute, Kenilworth, NJ 07033.
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