Antigenic structure of the coat protein of potato mop-top furovirus
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L G Pereira1, L Torrance, I M Roberts
1Scottish Crop Research Institute, Dundee, Scotland, United Kingdom.
Abstract:
The antigenic structure of the coat protein (CP) of potato mop-top furovirus (PMTV) was studied by electron microscopy of virus particles labeled with gold-conjugated monoclonal antibodies (MAbs) and by the reactions of MAbs with overlapping octapeptides (Pepscan) representing the complete amino acid sequence of the CP. A total of seven epitopes were identified in the CP. MAb SCR 69 detected a continuous epitope, which was located at the extreme N-terminus of the CP, was exposed at the surface along the sides of PMTV particles, and was removed by treating them with trypsin. MAb SCR 68 detected a discontinuous epitope found at the concave end of PMTV particles. Five other epitopes, which were detected by Pepscan tests, were located internally in, and at intervals along, the CP amino acid sequence. A tentative model of the PMTV CP subunit was produced, based on computer-aided prediction of its secondary structure and apparent similarities with the CP of tobacco mosaic virus. In this model, four of the epitopes occur at high radius in each of the pairs of parallel and anti-parallel alpha-helices in the CP subunit. The fifth is at low radius in the putative left radial alpha-helix. The epitope detected by MAb SCR 77, although amenable to study by Pepscan, contains three reactive elements, separated by short runs of nonessential residues, in a sequence of 13 amino acids. In intact virus particles, the CPs of beet necrotic yellow vein furovirus and PMTV apparently differ in the accessibility of their N- and C-termini.
Insights
Researchers mapped seven key antigenic sites on the potato mop-top furovirus coat protein (CP). This antigenic structure analysis provides insights into virus-host interactions and potential control strategies.
Area of Science:
- Virology
- Structural Biology
- Immunology
Background:
- Potato mop-top furovirus (PMTV) poses a significant threat to potato crops worldwide.
- Understanding the antigenic structure of viral coat proteins is crucial for developing effective control measures.
Purpose of the Study:
- To delineate the antigenic structure of the PMTV coat protein (CP).
- To identify and characterize specific epitopes on the PMTV CP.
Main Methods:
- Electron microscopy with gold-conjugated monoclonal antibodies (MAbs).
- Pepscan analysis of overlapping octapeptides representing the CP sequence.
- Computer-aided prediction of secondary structure.
Main Results:
- Seven distinct epitopes were identified on the PMTV CP.
- One continuous epitope at the N-terminus was trypsin-sensitive and surface-exposed.
- One discontinuous epitope was located at the concave end of the virus particle.
- Five internal epitopes were mapped along the CP sequence.
- A model of the CP subunit revealed epitope locations relative to alpha-helices.
Conclusions:
- The study provides a detailed antigenic map of the PMTV CP.
- Differences in N- and C-termini accessibility exist between PMTV and beet necrotic yellow vein furovirus CPs.
- This antigenic information can inform the development of diagnostics and antiviral strategies.