Problems with BHK 21 cells.

The properties of baby hamster kidney (BHK 21) cells are modified by passage in suspension culture. The suspended cells differ from monolayer cells in the surface expression of some integrin chains involved in attachment of foot-and-mouth disease virus (FMDV), in particular the progressive down-regulation of both alpha5 and alphaV integrin chains. This down-regulation is correlated with the loss of actin stress fibres. FMDV particles from these cells are unstable towards the aziridine used in inactivating the virus for vaccine production. Moreover, growth of virus in suspended cells can lead to the selection of antigenic variants which differ from those produced in monolayer cells.