Previous Article | Next Article ![]()
Journal of Virology, July 2000, p. 6339-6347, Vol. 74, No. 14
Department of Antiviral Therapy, Schering-Plough Research
Institute, Kenilworth, New Jersey 07033-0539,1
and Department of Veterinary and Biomedical Sciences,
University of Nebraska, Lincoln, Nebraska
68583-09052
Received 4 February 2000/Accepted 17 April 2000
Unique to pestiviruses, the N-terminal protein encoded by the
bovine viral diarrhea virus (BVDV) genome is a cysteine protease (Npro)
responsible for a self-cleavage that releases the N terminus of the
core protein (C). This unique protease is dispensable for viral
replication, and its coding region can be replaced by a ubiquitin gene
directly fused in frame to the core. To develop an antiviral assay that
allows the assessment of anti-hepatitis C virus (HCV) NS3 protease
inhibitors, a chimeric BVDV in which the coding region of Npro was
replaced by that of an NS4A cofactor-tethered HCV NS3 protease domain
was generated. This cofactor-tethered HCV protease domain was linked in
frame to the core protein of BVDV through an HCV NS5A-NS5B junction
site and mimicked the proteolytic function of Npro in the release of
BVDV core for capsid assembly. A similar chimeric construct was built
with an inactive HCV NS3 protease to serve as a control. Genomic RNA
transcripts derived from both chimeric clones, PH/B
(wild-type HCV NS3 protease) and PH/B(S139A) (mutant HCV
NS3 protease) were then transfected into bovine cells (MDBK). Only the
RNA transcripts from the PH/B clone yielded viable viruses,
whereas the mutant clone, PH/B(S139A), failed to produce
any signs of infection, suggesting that the unprocessed fusion protein
rendered the BVDV core protein defective in capsid assembly. Like the
wild-type BVDV (NADL), the chimeric virus was cytopathic and formed
plaques on the cell monolayer. Sequence and biochemical analyses
confirmed the identity of the chimeric virus and further revealed
variant viruses due to growth adaptation. Growth analysis revealed
comparable replication kinetics between the wild-type and the chimeric
BVDVs. Finally, to assess the genetic stability of the chimeric virus,
an Npro-null BVDV (BVDV
0022-538X/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Generation and Characterization of a Hepatitis C
Virus NS3 Protease-Dependent Bovine Viral Diarrhea Virus
Npro in which the entire Npro coding region
was deleted) was produced. Although cytopathic, BVDV
Npro was highly
defective in viral replication and growth, a finding consistent with
the observed stability of the chimeric virus after serial passages.
*
Corresponding author. Mailing address: Department of
Antiviral Therapy, K-15-4945, Schering-Plough Research Institute, 2015 Galloping Hill Rd., Kenilworth, NJ 07033-0539. Phone: (908) 740-3152. Fax: (908) 740-3918. E-mail: zhi.hong{at}spcorp.com.
This article has been cited by other articles:
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»