Antigenic variation among foot-and-mouth disease virus type A field isolates of 1997-1999 from Iran

The sequences of the antigenically relevant capsid proteins VP1-3 of 10 iso lates obtained during an epizootic of serotype A foot-and-mouth disease vir us in Iran, and collected within two and a half years, were found to he hig hly similar. However, each isolate differed by at least one amino acid from all others. This prompted us to analyze the immunological reactivity of th e isolates. To this end, monoclonal antibodies (mAbs) against one isolate w ere generated and characterized with regard to neutralizing activity and re activity with trypsinized virus. These mAbs as well as others raised agains t A22 virus were used for antigen profiling. This distinguished four antige nic conditions among the isolates and 16 reactivities among the mAbs. These findings: together with the observed sequence differences indicated the lo cation of several epitopes. Many mAbs recognized the minor antigenic sites on VP2 and 3 and some the major site, the GH-loop of VP1. One epitope was c omposed of residues of the capsid proteins VP1 and 2. (C) 2000 Elsevier Sci ence B.V. All rights reserved.