Expression of the protective antigen (SpaA) in transgenic hairy roots of tobacco

摘要

A surface protective antigen (SpaA) was fused to a cholera toxin B subunit (CTB) and expressed in tobacco hairy roots obtained usingAgrobacterium rhizogenes harboring theCTB-spaA fusion. A full-lengthspaA transcript was detected by reverse transcription-PCR but not by a Northern blot analysis. To investigate the reason for the low-level expression of SpaA, the number of copies of thespaA gene in transgenic hairy roots was confirmed by a genomic Southern blot analysis. The results suggested that the presence of multiple transfer DNA copies may be correlated with the low expression level of thespaA gene.