title: Display of epitopes on the surface of tobacco mosaic virus: impact of charge and isoelectric point of the epitope on virus-host interactions.
abstract: The biophysical properties of the tobacco mosaic tobamovirus (TMV) coat protein (CP) make it possible to display foreign peptides on the surface of TMV. The immunogenic epitopes G5-24 from the rabies virus (RV) glycoprotein, and 5B19 from murine hepatitis virus (MHV) S-glycoprotein were successfully displayed on the surface of TMV, and viruses accumulated to high levels in infected leaves of Nicotiana tabacum Xanthi-nn. The peptide RB19, which contains an arginine residue plus the 5B19 epitope fused to the CP (TMV-RB19), resulted in the induction of necrotic local lesions on inoculated leaves of N. tabacum Xanthi-nn and cell death of infected BY2 protoplasts. RNA dot blot assays confirmed that expression of the acidic and basic pathogenesis-related PR2 genes were induced in infected Xanthi-nn leaf tissue. TMV that carried epitope 31D from the RV nucleoprotein did not accumulate in inoculated tobacco leaves. Analysis of hybrid CPs predicted that the isoelectric points (pI):charge value was 5.31:-2 for wild-type CP, 5.64:-1 for CP-RB19, and 9.14:+2 for CP-31D. When acidic amino acids were inserted in CP-RB19 and CP-31D to bring their pI:charge to near that of wild-type CP, the resulting viruses TMV-RB19E and TMV-4D:31D infected N. tabacum Xanthi-nn plants and BY2 protoplasts without causing cell death. These data show the importance of the pI of the epitope and its effects on the hybrid CP pI:charge value for successful epitope display as well as the lack of tolerance to positively charged epitopes on the surface of TMV.
authors.affiliation: Department of Cell Biology Division of Plant Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, la Jolla, CA, 92037, USA.
authors.forename: M
authors.initials: M
authors.lastname: Bendahmane
authors.forename: M
authors.initials: M
authors.lastname: Koo
authors.forename: E
authors.initials: E
authors.lastname: Karrer
authors.forename: R N
authors.initials: RN
authors.lastname: Beachy
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D016923:Cell Death; D017931:DNA Primers; D000939:Epitopes / Q000737:chemistry*; D006824:Hybridization, Genetic; D007526:Isoelectric Point; D008954:Models, Biological; D008969:Molecular Sequence Data; D006517:Murine hepatitis virus / Q000235:genetics; D010947:Plants, Toxic; D011820:Rabies virus / Q000235:genetics; D014026:Nicotiana / Q000821:virology; D014027:Tobacco Mosaic Virus / Q000235:genetics / Q000276:immunology* / Q000502:physiology
chemical_list: D017931:DNA Primers; D000939:Epitopes