Abstract: PURPOSE:To detect the protein expression level of foreign fused gene in the first generation of genetically modified tomatoes transformed with fused gene of antigen epitope PacP in surface protein of Streptococcus mutans and cholera toxin B subunit. METHODS: The total DNA in tomatoes was extracted and PCR was applied to screen the first generation of transgenic tomatoes carrying Streptococcus mutans surface protein coding PAcP with cholera toxin B subunit fusion gene. Total proteins were extracted and quantitatively tested with BAC kit. Foreign fused protein expression level was analysed by Western blotting and ELISA. RESULTS: Ten DNA samples with the full length of 1.6 kb foreign fused DNA fragment was detected by PCR among all 18 samples. The crude protein in the transgenic tomato fruit tissue was 3.93 mg/mL. Compared with the normal tomatoes, Western blotting showed that the transgenic tomato protein contained a distinct protein band with a molecular weight about 60 kD. The results of ELISA suggested that fused foreign protein level was up to 0.18% of the total soluble protein in genetically modified tomato fruit. CONCLUSIONS: The target protein encoded by fused foreign gene of antigen epitope PacP in surface protein and cholera toxin B subunit was expressed in genetically modified tomatoes fruit.

Key words: Streptococcus mutans, Cholera toxin B Subunit, Transgenic tomatoes, Edible vaccine