Poliovirus neutralization epitopes: analysis and localization with neutralizing monoclonal antibodies

Area of Science:

• Virology
• Immunology
• Structural Biology

Background:

• Poliovirus neutralization is crucial for disease prevention.
• Understanding antibody binding sites on poliovirus is essential for vaccine development.

Purpose of the Study:

• To establish monoclonal antibodies neutralizing poliovirus type 1 (Mahoney strain).
• To characterize the distinct binding sites of these antibodies on poliovirus particles.
• To identify the specific viral structural protein involved in antibody binding and neutralization.

Main Methods:

• Hybridoma technology was used to generate monoclonal neutralizing antibodies (H3 and D3).
• Antibody binding sites were analyzed on intact virions, empty capsids, and precursor subunits.
• Viral variants resistant to neutralization were generated and analyzed.
• A heterobifunctional covalent cross-linking reagent (toluene-2,4-diisocyanate) was used to identify the target protein.

Main Results:

• Two distinct neutralizing antibody binding sites were identified on poliovirus type 1.
• The H3 antibody recognized sites on virions, empty capsids, and precursor subunits, while D3 recognized sites on virions and empty capsids.
• Neither site was present on heat-treated virions or free viral proteins.
• Viral variants resistant to individual antibodies emerged spontaneously during cell culture.
• VP1 was identified as the structural protein containing both antibody binding sites.

Conclusions:

• Monoclonal antibodies H3 and D3 bind to distinct sites on poliovirus type 1.
• VP1 is a critical structural protein involved in poliovirus neutralization by these antibodies.
• The identification of these sites and the VP1 protein advances our understanding of poliovirus-antibody interactions.