Protection of mice against challenge with foot and mouth disease virus (FMDV) by immunization with foliar extracts from plants infected with recombinant tobacco mosaic virus expressing the FMDV structural protein VP1

A tobacco mosaic virus (TMV)-based vector has been used to express in plant s the complete open reading frame coding for VP1, the major immunogenic pro tein of foot and mouth disease virus (FMDV). In vitro RNA transcripts were inoculated into Nicotiana benthamiana plants and detectable amounts of reco mbinant VPI were identified by Western blot as soon as 4 days postinfection . Foliar extracts prepared from infected leaves were injected intraperitone ally into mice and all of the immunized animals developed a specific antibo dy response to both the complete virus particle and the major immunogenic r egion as determined by ELISA and Western blot analysis. Most importantly, a ll immunized mice developed a protective immune response against experiment al challenge with virulent FMDV To our knowledge, this is the first report showing the expression of a complete open reading frame of an antigenic for eign protein in plants, using a recombinant plant virus, in sufficient: qua ntity to permit use of the crude plant extract as an experimental immunogen to protect animals against virus challenge, (C) 1999 Academic Press.