title: Virion stability and aphid vector transmissibility of Cucumber mosaic virus mutants.
abstract: The physical stability of virions of Cucumber mosaic virus (CMV) mutants was investigated to determine if relative stability correlated with efficiency of aphid transmission. Virion stability was evaluated by a urea disruption assay and by testing the infectivity of virus following purifications. All viruses were infectious when purified using a low salt buffer without organic solvent, whereas two of seven viruses were less stable and inactivated following purification with a high salt buffer and chloroform. These two viruses were both reassortants derived from the spontaneous transmission-defective mutant CMV-M (F1F2M3 and F1F2M3-L129P). F1F2M3 was relatively unstable, being disrupted between 0 and 1 M urea versus the wild-type CMV-Fny (F1F2M3) that was destabilized at 3-4 M urea. Modifications of F1F2M3 at three amino acid positions (129, 162, 168), singly or in combination, increased the relative stability of virions. A second class of transmission-defective CMVs with engineered mutations in the betaH-betaI surface loop of the CMV-Fny capsid protein (CP) exhibited near wild-type levels of stability. Lastly, a single Pro to Leu substitution at CP position 129 of CMV-Fny (F1F2M3-P129L) conferred the induction of necrosis in tobacco plants and reduced aphid transmissibility, but did not markedly alter the physical stability of virions. Thus, only among CMV-M derivatives harboring the CP mutation of Thr to Ala at position 162 were increases in stability correlated with restoration of transmissibility by the aphid Aphis gossypii.
authors.affiliation: Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907, USA.
authors.forename: James C K
authors.initials: JC
authors.lastname: Ng
authors.forename: Caroline
authors.initials: C
authors.lastname: Josefsson
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Clark
authors.forename: Alexander W E
authors.initials: AW
authors.lastname: Franz
authors.forename: Keith L
authors.initials: KL
authors.lastname: Perry
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D001042:Aphids / Q000821:virology*; D017799:Cucumovirus / Q000472:pathogenicity / Q000502:physiology*; D007303:Insect Vectors; D016865:Reassortant Viruses; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D014508:Urea / Q000494:pharmacology; D014771:Virion / Q000187:drug effects / Q000502:physiology*
chemical_list: D011993:Recombinant Fusion Proteins; D014508:Urea