Molecular analysis of peptides from the GH loop of foot-and-mouth disease virus C-S30 using surface plasmon resonance: a role for kinetic rate constants

A foot-and-mouth disease virus (FMDV) field variant, isolate C-S30 (also na med C-1-Barcelona), is known to contain four changes within the main antige nic site A (GH loop of capsid protein VP1, residues 136-150), at least one of which (Leu147 --> Val) involves a highly conserved position, critical fo r antibody recognition in the reference strain C-S8c1. However, immunoenzym atic analysis of FMDV C-S30 showed it was recognised by 4C4, a monoclonal a ntibody that specifically targets site A. This remarkable behaviour has led us to analyse the individual and combined contributions of the four mutati ons to the antigenicity of C-S30, by surface plasmon resonance (SPR) and en zyme-linked immunosorbent assay (ELISA) studies of pentadecapeptides displa ying all possible combinations of the four replacements. Analysis of this f amily of C-S30-derived analogues shows a certain level of antibody recognit ion by SPR. In addition, SPR data suggest that kinetic rate constants provi de an indirect measure, on the one hand, of paratope accessibility (associa tion rate constant) and, on the other hand, of peptide fitness to the same paratope (dissociation rate constant). (C) 2001 Elsevier Science Ltd. All r ights reserved.