Expression of CTB::fasG Gene against Piglet Bacterial Diarrhea Disease in Transgenic Rice and Its Callus

Antigen production in plant is a safe and effective strategy for vaccine development. In this study, rice transformants were developed for oral vaccine against pigs diarrhea disease. DNA cassette composed with the cholera toxin subunit B (CTB) connected to the 987P-fasG, for stimulating a strong oral immune response, was introduced to rice through Agrobacterium mediated genetic transformation. Copy number analysis by TaqMan real-time PCR for transgenes revealed that transgene of 1 to 8 copies have been introduced into T1 and T2 rice seeds. The expression level of mRNA in the transformants T1 and T2 generations were up to 35 times higher than the reference value in the result of analysis by Quantitative real time-PCR. In addition, the callus cultured from rice transformants was confirmed that the introduced gene has been maintained till 9-month subculture duration. The amount of mRNA expression value was also confirmed in callus, which was maintained above 2.6 times compared with that of the standard control for a long time. These results provide that the introduced antigen for plant-based vaccine against bacterial diarrhea disease can be maintained in the callus as well as in the transgenic plant and suggest that the callus culture of plant transformant will be an effective way to obtain a plant-derived edible vaccine.