Antigenic relationships of foot-and-mouth disease virus serotype Asia-1 isolates demonstrated by monoclonal antibodies.

A panel (26) of monoclonal antibodies (MAbs) was elicited against three distinct isolates of foot-and-mouth disease virus (FMDV) serotype Asia-1. Each MAb was characterized according to the location of its epitope: Class I, restricted to the intact virion (140S); Class II, restricted to 140S and the virion protein subunit (12Sps); Class III, available on 140S, 12Sps and virus protein 1; Class IV, restricted to 12Sps. In addition, the MAbs were further categorized by isotype, neutralization of viral infectivity, capacity to bind in radioimmunoassay and precipitation in the Ouchterlony reaction. Neutralization of FMDV infectivity by a MAb of the IgA isotype is reported for the first time. A minimum of seven distinct neutralization epitopes were described on FMDV Asia-1. Some of the neutralizing MAbs bound FMDVs in addition to those that they neutralized. The MAbs defined epitopes common to FMDV serotypes Asia-1, A, O1 and C but neutralizing capacity was restricted to serotype Asia-1. Class IV MAbs defined epitopes highly conserved throughout the FMDV serotypes. Identification of FMDV neutralization epitopes makes possible the direct selection of optimal FMDV strains for vaccine fabrication. In addition, these data are crucial to the design of future synthetic vaccines.