disease virus of a different subtype

An epitope involved in neutralization of foot-and-mouth disease virus (FMDV) of subtype Ca was generated by a single amino acid replacement in VP1 of FMDV of subtype C~. The replacement [Ser (139)-~ lie, in the immunodominant site A] was consistently found in those FMDV C1 Santa Pau-Sp/70 mutants resistant to neutralization by monoclonal antibody (MAb) SD6 (specific for most C ~ viruses) that acquired the capacity to be neutralized by MAb 7AB5 (specific for Ca viruses). Foot-and-mouth disease virus (FMDV) is a member of the Picornaviridae family and the causative agent of an economically important disease of cattle and other cloven-hoofed animals (reviewed in Bachrach, 1968; Domingo et al., 1990). A major difficulty in the control of the disease is the extreme antigenic diversity of FMDV that can be traced to variable regions of capsid protein VP1, and possibly also of VP2 and VP3 (Kitson et al., 1990; reviewed in Domingo et al., 1990). A major antigenic site involved in neutralization of infectivity (termed site A, first defined by Strohmaier et al., 1982) is located around amino acids 140 to 160 of VP1. For viruses of serotype O1 this VP1 segment is an exposed, disordered loop on the virion surface (Acharya et al., 1989). In FMDV of serotype C the equivalent residues 138 to 150 delineate a cluster of overlapping, continuous epitopes (Mateu et al., 1989, 1990). Maximum parsimony procedures have been applied to establish phylogenetic relationships among VP1 genes of type C viruses which have circulated in Europe an