IMMUNOGENICITY OF FOOT-AND-MOUTH-DISEASE VIRUS GROWN IN BHK-21 SUSPENSION CELLS - CORRELATION WITH CELL PLOIDY ALTERATIONS AND ABNORMAL EXPRESSION OF THE ALPHA-5-BETA-1 INTEGRIN

BHK-21 suspension cells were characterized with regard to genetic and phenotypic features which might adversely affect the immunogenic prope rties of foot-and-mouth disease virus (FMDV) grown therein. A positive correlation was found between number of passages in suspension cultur e and both prevalence of polyploid cells and reduced cell growth on su rfaces. Suspension cells also revealed differences in the expression o f RGD-specific integrins and, in particular, of alpha 5 beta 1, which was shown to work as an FMDV receptor structure. These features, along with the notable instability of a few non-structural FMDV A(5) protei ns in infected cells, outline a new scenario, in which the reduced imm unogenicity of FMDV might be accounted for by defined negative influen ces of the cell environment on viral replication.