Transient expression of a full-size antibody against Hepatitis B surface antigen in plant cell suspension cultures

When generating stably transformed transgenic plants, transient gene expression experiments are especially useful to confirm that the foreign molecule of interest is expressed with an adequate biological activity. In this paper we report the transient expression of a full-size mouse monoclonal antibody against Hepatitis B surface antigen in tobacco cell suspension cultures. Transient expression in tobacco cell cultures was fast, and protein expression could be detected in just a few days. We were able to verify that the gene construction was functional, and that 0.3-0.5 μg of a biologically active antibody was easily purified from 1 mL of cell culture by Protein A chromatography. Recovered recombinant antibodies were sufficient for a detailed characterization by SDS-PAGE, Western-blot, and ELISA. These results allowed us to move on to the large-scale production of the plantibody in stably transformed transgenic plants.