Preparation of vaccine master cell lines using recombinant plant suspension cultures

Disclosed is a plant cell culture for producing proteinaceous vaccine antigen comprising: a) a NT-l cell stably transformed to express a transgene encoding a proteinaceous vaccine antigen comprising SEQ ID NO:2; and b) a growth medium which supports the growth of said NT-1 cell in culture but which does not support the growth of Mycoplasmataceae and contains no materials of animal origin, said growth medium comprising no materials of animal origin and NT-1 liquid medium, wherein said NT-1 cell is capable of being continuously passaged such that consistent transgene expression is maintained during passaging and wherein said NT-1 cell is capable of being cryopreserved such that consistent transgene expression is recovered upon recovery from cryopreservation.