Analysis of neutralizing antigenic sites on the surface of type A12 foot-and-mouth disease virus
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B Baxt1, V Vakharia, D M Moore
1Department of Molecular Biology, Plum Island Animal Disease Center, Greenport, New York 11944-0848.
Abstract:
A series of seven neutralizing monoclonal antibodies (nMAbs) directed against type A12 foot-and-mouth disease virus was used to generate neutralization-resistant variants. Both plaque reduction neutralization and microneutralization assays showed that the variants were no longer neutralized by the nMAbs used to generate them, although some of the variants still reacted with the nMAbs at high antibody concentrations. Results of cross-neutralization studies by both plaque reduction neutralization and microneutralization assays suggested the presence of at least one immunodominant antigenic site on the surface of type A12 foot-and-mouth disease virus, along with evidence of a second antigenic site on the viral surface. Two of the variants had reduced virulence in tissue culture as evidenced by their inability to inhibit cellular protein synthesis and a marked reduction in virus-induced cellular morphological alterations. Nucleotide sequencing of the variant genomes placed three epitopes of the major antigenic site on VP1 and the fourth epitope on VP3 and VP1. The one epitope of the minor site appears to reside only on VP1.
Insights
Researchers generated foot-and-mouth disease virus variants resistant to neutralizing monoclonal antibodies (nMAbs). These variants revealed at least two distinct antigenic sites on the virus, with implications for vaccine development.
Area of Science:
- Virology
- Immunology
- Molecular Biology
Background:
- Foot-and-mouth disease virus (FMDV) poses a significant threat to livestock globally.
- Neutralizing monoclonal antibodies (nMAbs) are crucial tools for FMDV research and potential therapeutic strategies.
- Understanding FMDV antigenic sites is key to developing effective vaccines and diagnostics.
Purpose of the Study:
- To generate neutralization-resistant variants of type A12 FMDV using a panel of nMAbs.
- To characterize the antigenic properties of these variants and identify key antigenic sites on the FMDV surface.
- To investigate the genetic basis of neutralization resistance and altered virulence.
Main Methods:
- Generation of FMDV variants by sequential passage in the presence of nMAbs.
- Plaque reduction neutralization and microneutralization assays to assess antibody resistance.
- Cross-neutralization studies to map antigenic sites.
- Tissue culture assays to evaluate viral virulence.
- Nucleotide sequencing of variant genomes to identify mutations in viral proteins.
Main Results:
- Generated FMDV variants that were resistant to the specific nMAbs used for selection.
- Identified at least two distinct antigenic sites on the FMDV surface through cross-neutralization experiments.
- Determined that three epitopes of the major antigenic site are located on VP1, with a fourth on VP3 and VP1. The minor site's epitope resides on VP1.
- Observed reduced virulence in two variants, indicated by impaired inhibition of cellular protein synthesis and altered cellular morphology.
Conclusions:
- The study successfully generated neutralization-resistant FMDV variants, providing insights into viral immune evasion.
- Evidence suggests the presence of at least two immunodominant antigenic sites on type A12 FMDV, crucial for antibody binding.
- Genetic analysis localized key antigenic epitopes to specific viral proteins (VP1 and VP3), informing future vaccine design.