The three-dimensional structures of the Fab fragment of a neutralizing antibody raised against a foot-and-mouth disease virus (FMDV) of serotype C1, alone and complexed to an antigenic peptide representing the major antigenic site A (G-H loop of VP1), have been determined. As previously seen in a complex of the same antigen with another antibody which recognizes a different epitope within antigenic site A, the receptor recognition motif Arg-Gly-Asp and some residues from an adjacent helix participate directly in the interaction with the complementarity-determining regions of the antibody. Remarkably, the structures of the two antibodies become more similar upon binding the peptide, and both undergo considerable induced fit to accommodate the peptide with a similar array of interactions. Furthermore, the pattern of reactivities of five additional antibodies with versions of the antigenic peptide bearing amino acid replacements suggests a similar pattern of interaction of antibodies raised against widely different antigens of serotype C. The results reinforce the occurrence of a defined antigenic structure at this mobile, exposed antigenic site and imply that intratypic antigenic variation of FMDV of serotype C is due to subtle structural differences that affect antibody recognition while preserving a functional structure for the receptor binding site.

Type

Journal article

Journal

Journal of virology

Publication Date

01/1998

Volume

72

Pages

739 - 748

Addresses

Centre de Investigació i Desenvolupament (CSIC), Barcelona, Spain.

Keywords

Animals, Cattle, Aphthovirus, Antibodies, Monoclonal, Antibodies, Viral, Antigen-Antibody Complex, Antigens, Viral, Neutralization Tests, Crystallography, X-Ray, Serotyping, Antigenic Variation, Binding Sites, Amino Acid Sequence, Protein Conformation, Models, Molecular, Molecular Sequence Data, Immunoglobulin Fab Fragments