Preparing for exotic foot-and-mouth disease virus outbreaks in the European neighbourhood: cross-neutralisation of internationally available vaccines against South American serotype O and serotype A field isolates.

Foot-and-mouth disease (FMD) is a highly contagious transboundary viral disease that affects domestic and wild cloven-hoofed animals. The disease is economically devastating due to severe production losses and restrictions on international trade. The emergence of novel FMD viruses in new locations can require different or new vaccines to control outbreaks. This report focuses on incursions of exotic viruses of serotypes A (A/EURO-SA topotype) and O (O/EURO-SA topotype) into Egypt in 2022. These viruses originate from South America and their introduction into North Africa poses an onward risk for circulation into Africa, the Middle east, and Europe. These cases have raised questions as to whether the vaccines held in antigen banks and those deployed during ongoing control programmes in Asia and Africa could be used to control the spread of these South American viruses. In the absence of representative serotype O and A viruses from Egypt, this study used virus neutralisation tests (VNT) to evaluate the antigenic relationship between the vaccines and representative viruses from South America, to predict the ability of current FMD vaccines to provide protection against these exotic lineages.