We have constructed transgenic tobacco plants (M1x2-FCP2IFN plants) ex
pressing viral RNA replication genes of brome mosaic virus (BMV) and B
MV RNA3 derivative (FCP2IFN) carrying the human gamma interferon (IFN-
gamma) gene. In M1x2-FCP2IFN plants the RNA3 derivative expressed from
the integrated cDNA was replicated and subgenomic RNA (i.e. mRNA of I
FN-gamma) was produced by BMV replicase. The accumulation level of the
mRNA of IFN-gamma was approximately 5-fold higher than that by the ca
uliflower mosaic virus (CaMV) 35S RNA promoter. In addition IFN-gamma
accumulated in M1x2-FCP2IFN plants.