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Journal of Virology, November 2001, p. 10643-10650, Vol. 75, No. 22
Department of Exotic Disease, National
Institute of Animal Health, Kodaira, Tokyo 187-0022, Japan,1 and BBSRC Institute for
Animal Health, Pirbright, Woking, Surrey GU24 ONF, United
Kingdom2
Received 30 April 2001/Accepted 13 August 2001
Virulent and avirulent strains of swine vesicular disease virus
(SVDV), a picornavirus, have been characterized previously. The major
determinants for attenuation have been mapped to specific residues in
the 1D-2A-coding region. The properties of the 2A proteases from the
virulent and avirulent strains of SVDV have now been examined. Both
proteases efficiently cleaved the 1D/2A junction in vitro and in vivo.
However, the 2A protease of the avirulent strain of SVDV was much less
effective than the virulent-virus 2A protease at inducing cleavage of
translation initiation factor eIF4GI within transfected cells. Hence
the virulent-virus 2A protease is much more effective at inhibiting
cap-dependent protein synthesis. Furthermore, the virulent-virus 2A
protease strongly stimulated the internal ribosome entry sites (IRESs)
from coxsackievirus B4 and from SVDV, while the avirulent-virus 2A
protease was significantly less active in these assays. Thus, the
different properties of the 2A proteases from the virulent and
avirulent strains of SVDV in regulating protein synthesis initiation
reflect the distinct pathogenic properties of the viruses from which
they are derived. A single amino acid substitution, adjacent to His21
of the catalytic triad, is sufficient to confer the characteristics of
the virulent-strain 2A protease on the avirulent-strain protease. It is
concluded that the efficiency of picornavirus protein synthesis,
controlled directly by the IRES or indirectly by the 2A protease, can
determine virus virulence.
0022-538X/01/$04.00+0 DOI: 10.1128/JVI.75.22.10643-10650.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
An Attenuating Mutation in the 2A Protease of Swine
Vesicular Disease Virus, a Picornavirus, Regulates Cap- and Internal
Ribosome Entry Site-Dependent Protein Synthesis
*
Corresponding author. Mailing address: BBSRC Institute
for Animal Health, Pirbright, Woking, Surrey GU24 ONF, United Kingdom. Phone: 44 (0)1483 232441. Fax: 44 (0)1483 232448. E-mail:
graham.belsham{at}bbsrc.ac.uk.
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