Monoclonal antibodies to equine arteritis virus proteins identify the GL protein as a target for virus neutralization.

This study produced and characterized Monoclonal antibodies (MAbs) to equine arteritis virus (EAV) proteins, specifically identifying the GL protein as a prime target for virus neutralization.

Antibody Production and Determination of Specificities

• The research team produced Monoclonal antibodies, which are antibodies derived from a single parental cell, to substances present in the equine arteritis virus (EAV). This virus is responsible for causing equine viral arteritis, a condition that can lead to respiratory illness and abortion in horses.
• These antibodies were then characterized, and the protein specificities of eight Monoclonal antibodies were definitively determined through a process known as immunoprecipitation. In this process, immune materials such as antibodies are added to a solution to trigger a reaction that causes specific antigens (foreign substances in the body) to form visible clumps.
• The proteins were expressed from vaccinia virus recombinants (VVRs), which are engineered viruses that contain genes or proteins from EAV. Two new VVRs were created for this study to express the M and GL proteins.

Identification of N-Specific and GL-Specific Antibodies

• Three of the Monoclonal antibodies were found to be N-specific, meaning they target the N protein of the EAV. Five Monoclonal antibodies were determined to be GL-specific, targeting the GL protein.
• One GL-specific Monoclonal antibody, named 17F5, and classified under the IgA class, was found to effectively neutralize the infectivity of EAV. Neutralizing antibodies inhibit or abolish the biological effect of the virus.

Understanding Antigenic Domains Through Competitive Binding Assays

• In competitive binding assays, a technique used to evaluate binding affinities and interactions between molecules, it was discovered that the N-specific Monoclonal antibodies identified a single antigenic domain, or region that can interact with an antibody, on the N protein.
• The four GL-specific Monoclonal antibodies exhibited strong reciprocal competition in binding to the GL proteins. This suggests that their respective areas of interest, or epitopes, are closely adjacent or overlapping on the antigenic domain of the GL protein.
• Despite demonstrating competition in binding, these antibodies displayed varying levels of virus-neutralizing abilities.
• The fifth GL-specific MAb, proposed to be a non-neutralizing antibody, potentially identifies an epitope close to the antigenic domain of the GL protein since it demonstrated lower competition in the binding assays.