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 properties of foot-and-mouth disease virus (FMDV) grown therein. A positive correlation was found between number of passages in suspension culture and both prevalence of polyploid cells and reduced cell growth on surfaces. Suspension cells also revealed differences in the expression of 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) proteins in infected cells, outline a new scenario, in which the reduced immunogenicity of FMDV might be accounted for by defined negative influences of the cell environment on viral replication.