Expression of hepatitis B surface antigen (HBsAg) gene in transgenic cherry tomato
The plasmid carrying the gene (adr subtype) encoding the hepatitis B surface antigen (HBsAg) was constructed. Cotyledonary leaves of cherry tomato (Lycopersicon esculentum Mill.) were transformed using Agrobacterium tumefaciens strain LBA4404 harboring pCAMBIA-1301/HB constructs to express HBsAg. The transformed nature of the plants was confirmed by polymerase chain reaction (PCR) analysis and Southern blot hybridization. Expression of HBsAg was confirmed by western blotting and levels of expression were assayed by enzyme-linked immunosorbent assay (ELISA). Southern blot hybridization confirmed the stable integration of the target genes into the genomes of cherry tomato, while western blotting showed high levels of biologically active HBsAg in transgenic plants. ELISA assay showed that HBsAg in transgenic cherry tomato was 100.36 ng/g fresh weight (FW) in leaves and 127.54 ng/g FW in fruits, implying that recombinant HBsAg had natural epitope. This study indicates the feasibility of the expression of foreign antigens in cherry tomato plant for possible use as a raw and edible vaccine.
Key words: Lycopersicum esculentum var. cerasiforme, cherry tomato, HBsAg gene, transgenic, expression.