Antibody-selected variation and reversion in Sindbis virus neutralization epitopes.

Area of Science:

• Virology
• Immunology
• Molecular Biology

Background:

• Sindbis virus is known for its genetic variability.
• Understanding viral antigenic change is crucial for vaccine development and disease control.

Purpose of the Study:

• To isolate and characterize Sindbis virus variants with altered antigenicity.
• To investigate the mechanisms of spontaneous antigenic change in Sindbis virus.
• To map neutralization epitopes on Sindbis virus envelope glycoproteins.

Main Methods:

• Selection of Sindbis virus variants resistant to neutralization by monoclonal antibodies against E1 and E2 glycoproteins.
• Generation of multisite variants through sequential selection with different monoclonal antibodies.
• Back-selection of phenotypic revertants exhibiting restored prototype antigenicity.
• Confirmation of true progeny using oligonucleotide markers.
• Comparative analysis of prototype and variant reactivities with a panel of monoclonal antibodies.

Main Results:

• Isolation of Sindbis virus variants demonstrating bidirectional antigenic change.
• Identification of variants with mutations in multiple neutralization sites, including one altered in three sites.
• Characterization of phenotypic revertants that regained original antigenicity.
• Confirmation of revertants as true progeny of antigenic variants via oligonucleotide markers.
• Determination of at least five independently mutable neutralization epitopes, organized into three antigenic sites (two on E2, one on E1).

Conclusions:

• Sindbis virus possesses a complex antigenic structure with multiple mutable neutralization sites.
• Spontaneous antigenic variation in Sindbis virus is a significant factor in viral evolution and immune evasion.
• The identified epitopes provide targets for further research into viral antigenicity and vaccine design.