NEUTRALIZATION ANTIGENIC SITES ON TYPE ASIA-1 FOOT-AND-MOUTH-DISEASE VIRUS DEFINED BY MONOCLONAL ANTIBODY-RESISTANT VARIANTS

Seven neutralizing monoclonal antibodies (nMAbs) produced against sero type Asia-1 foot-and-mouth disease virus (FMDV) were used to select ne utralization-resistant variants. Seven single and six multiple antibod y-resistant variants were selected to identify neutralization antigeni c sites on FMDV Asia-1. The variants no longer reacted with nMAbs whic h were used to select them when tested by microneutralization test (MN T), radioimmunoassay (RIA) and agar gel immunodiffusion (AGID) assay. Based on the binding and neutralization patterns of the variants, the nMAbs could be divided into discrete groups indicating the presence of three independent antigenic sites with evidence for occurrence of pos sibly a fourth site on the virus surface. Site 1 was present on 140S, 12Sps and VPI and thus was conformation-independent. Sites 2 and 3 wer e restricted to the intact virion (140S) and thus were more conformati on-dependent. Site 4 present on 140S virions and 12S protein subunits was less conformation-dependent. The site 3 nMAbs neutralized the infe ctivity of all the ten different Asia-1 virus isolates tested indicati ng that this site is conserved in Asia-1 virus serotype. Both cross-ne utralization of different Asia-1 viruses with the nMAbs and cross-inhi bition assays between MAbs demonstrated that the nMAbs recognized at l east six different epitopes on Asia-1 virus. (C) 1997 Elsevier Science B.V.