Abstract: Methods and compositions for increasing the production of large amounts of empty capsids of the foot-and-mouth disease virus (FMDV) in a stable manner in mammalian cells by regulating the expression of FMDV 3C protease. The instant methods and compositions are based on the fact that a decreased expression of 3C protease results in a reduced cell toxicity and an increased synthesis of viral capsid proteins, as well as production of recombinant empty capsids. The invention provides recombinant plasmids that direct the expression of P1, 3C, and the use of the plasmids for producing new stable cell lines capable of generating high titers of FMDV empty capsids. The invention provides methods for regulating the expression of the FMDV 3C protease gene at a transcriptional and translational level in order to achieve the required process level of 3C protease for the selection process, as well as the production process.