Demonstration of antigenic site 3 in foot-and-mouth disease virus serotype A using neutralizing monoclonal antibody resistant mutants.

Foot-and-mouth disease (FMD) is a major viral infection in cloven-hoofed animals, causing significant economic losses worldwide. The etiological agent, Foot-and-Mouth Disease Virus (FMDV), exists in seven distinct serotypes (O, A, C, Asia 1, SAT 1-3), each with multiple subtypes. High mutation rate in FMDV often leads to the emergence of new antigenic variants, complicating vaccine development and control efforts. In this study, we focused on mapping antigenic determinants in the vaccine strain of FMDV serotype A. Using escape mutants generated with neutralizing monoclonal antibodies, we successfully mapped antigenic site 3. Furthermore, critical residues within antigenic site 1, (VP1 positions, 193/194 and 148) were identified in this serotype. Collectively, structural analyses reveal that antigenic sites across all FMDV serotypes are highly conserved, underscoring their potential as targets for broad-spectrum vaccine strategies.