Previous Article | Next Article ![]()
Journal of Virology, March 2003, p. 3247-3256, Vol. 77, No. 5
0022-538X/03/$08.00+0 DOI: 10.1128/JVI.77.5.3247-3256.2003
Copyright © 2003, American Society for Microbiology. All Rights Reserved.
S. Pfeffer,2 M. Erdinger,1 K. E. Richards,2 and V. Ziegler-Graff2*
UR-BIVV, INRA, Colmar 68021 Cedex,1 Institut de Biologie Moléculaire des Plantes du CNRS et de l'Université Louis Pasteur, Strasbourg 67084 Cedex, France2
Received 15 October 2002/ Accepted 5 December 2002
Point mutations were introduced into the major capsid protein (P3) of cloned infectious cDNA of the polerovirus beet western yellows virus (BWYV) by manipulation of cloned infectious cDNA. Seven mutations targeted sites on the S domain predicted to lie on the capsid surface. An eighth mutation eliminated two arginine residues in the R domain, which is thought to extend into the capsid interior. The effects of the mutations on virus capsid formation, virus accumulation in protoplasts and plants, and aphid transmission were tested. All of the mutants replicated in protoplasts. The S-domain mutant W166R failed to protect viral RNA from RNase attack, suggesting that this particular mutation interfered with stable capsid formation. The R-domain mutant R7A/R8A protected
90% of the viral RNA strand from RNase, suggesting that lower positive-charge density in the mutant capsid interior interfered with stable packaging of the complete strand into virions. Neither of these mutants systemically infected plants. The six remaining mutants properly packaged viral RNA and could invade Nicotiana clevelandii systemically following agroinfection. Mutant Q121E/N122D was poorly transmitted by aphids, implicating one or both targeted residues in virus-vector interactions. Successful transmission of mutant D172N was accompanied either by reversion to the wild type or by appearance of a second-site mutation, N137D. This finding indicates that D172 is also important for transmission but that the D172N transmission defect can be compensated for by a "reverse" substitution at another site. The results have been used to evaluate possible structural models for the BWYV capsid.
Present address: Unit of Phytovirology, Department of Botany, Lucknow University, Lucknow, India.
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»