ANTIGENIC ANALYSIS OF SAT-2 SEROTYPE FOOT-AND-MOUTH-DISEASE VIRUS ISOLATES FROM ZIMBABWE USING MONOCLONAL-ANTIBODIES

This paper compares strains of foot-and-mouth disease (FMD) serotype S AT (South African Territories) 2 viruses isolated from Zimbabwe and ot her African countries using monoclonal antibodies (MAb). A sandwich-EL ISA was used to examine the relative binding of anti-SAT 2 MAb to the various viruses. The MAb-binding profiles of viruses isolated from fie ld samples were compared using hierarchical cluster analysis. Viruses were obtained from game animals, mainly African buffalo (Syncerus caff er) which is the natural host and reservoir for SAT serotypes in Afric a, and from cattle showing clinical signs of FMD, as well as from anim als suspected of carrying the virus subclinically. Some isolates have been adapted for use as vaccine strains. The results showed that most of the Zimbabwe isolates collected between 1989 and 1992 were an antig enically closely-related group. Although differences were observed bet ween Zimbabwe isolates collected between 1989 and 1992 and those colle cted in 1987, there was no correlation with the different MAb binding patterns within the 1987 group and the epidemiological information rec eived from the field. Similar profiles were observed for many SAT 2 vi ruses, including viruses isolated over a 50-year period and from geogr aphically distant areas. This indicates an inherent stability in antig enic profiles of SAT 2 viruses. The MAb panel was capable of assessing antigenic variation, since very different profiles were obtained for some isolates. The work also allowed comparison and characterization o f anti-type SAT 2 MAb from different laboratories. The findings are di scussed with reference to selection of vaccine strains.