A nonviral peptide can replace the entire N terminus of zucchini yellow mosaic potyvirus coat protein and permits viral systemic infection.
Systematic deletion and peptide tagging of the amino-terminal domain (NT, ~43 amino acids) of an attenuated zucchini yellow mosaic potyvirus (ZYMV-AGII) coat protein (CP) were used to elucidate its role in viral systemic infection. Deletion mutants truncated by 8, 13, and 33 amino acid residues from the CP-NT 5' end were systemically infectious and produced symptoms similar to those of the AGII virus. Tagging these deletion mutants with either human c-Myc (Myc) or hexahistidine peptides maintained viral infectivity. Similarly, addition of these peptides to the intact AGII CP-NT did not affect viral life cycle. To determine which parts, if any, of the CP-NT are essential for viral systemic infection, a series of Myc-tagged mutants with 8 to 43 amino acids removed from the CP-NT were constructed. All Myc-tagged CP-NT deletion mutants, including those from which virtually all the viral CP-NT had been eliminated, were able to encapsidate and cause systemic infection. Furthermore, chimeric viruses with deletions of up to 33 amino acids from CP-NT produced symptoms indistinguishable from those caused by the parental AGII virus. In contrast to CP-NT Myc fusion, addition of the foot-and-mouth disease virus (FMDV) immunogenic epitope to AGII CP-NT did not permit systemic infection. However, fusion of the Myc peptide to the N terminus of the FMDV peptide restored the capability of the virus to spread systemically. We have demonstrated that all CP-NT fused peptides were exposed on the virion surface, masking natural CP immunogenic determinants. Our findings demonstrate that CP-NT is not essential for ZYMV spread and that it can be replaced by an appropriate foreign peptide while maintaining systemic infectivity.
Arazi
T
T
ViroGene Ltd., Har-Hotzvim, Jerusalem 91045, Israel.
Shiboleth
Y M
YM
Gal-On
A
A
D020121:5' Untranslated Regions / Q000235:genetics; D000595:Amino Acid Sequence; D002213:Capsid / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D036022:Capsid Proteins; D017353:Gene Deletion; D016259:Genes, myc; D005816:Genetic Complementation Test; D006639:Histidine / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D010446:Peptide Fragments / Q000235:genetics / Q000378:metabolism; D010455:Peptides / Q000737:chemistry; D010935:Plant Diseases / Q000821:virology*; D017800:Potyvirus / Q000737:chemistry / Q000502:physiology*; D014779:Virus Replication
D020121:5' Untranslated Regions; D036022:Capsid Proteins; D010446:Peptide Fragments; D010455:Peptides; C086081:coat protein, Zucchini yellow mosaic virus; D006639:Histidine