AIM:To transfer hepatitis E virus(HEV)ORF2 partial geneto tomato plants,to investigate its expression in transformantsand the immunoactivity of expression products,and toexplore the feasibility of developing a new type of plant-derived HEV oral vaccine.METHODS:Plant binary expression vector p1301E2,carrying a fragment of HEV open reading frame-2(namedHEV-E2),was constructed by linking the fragment to aconstitutive CaMV35s promoter and nos terminator,thendirectly introduced into Agrobacterium tumefaciensEHA105.With leaf-disc method,tomato plants medicatedby EHA105 were transformed and hygromycin-resistantplantlets were obtained in selective medium containinghygromycin.The presence and integration of foreign DNAin transgenic tomato genome were confirmed by Gus geneexpression,PCR amplification and Southern dot blotting.The immunoactivity of recombinant protein extracted fromtransformed plants was examined by enzyme-linkedimmunosorbant assay(ELISA)using a monoclonal antibodyspecifically against HEV.ELISA was also used to estimatethe recombinant protein content in leaves and fruits of thetransformants.RESULTS:Seven positive lines of HEV-E2-transgenic tomatoplants confirmed by PCR and Southern blotting were obtainedand the immunoactivity of recombinant protein could bedetected in extracts of transformants.The expression levelsof recombinant protein were 61.22 ng/g fresh weight infruits and 6.37-47.9 ng/g fresh weight in leaves of thetransformants.CONCLUSION:HEV-E2 gene was correctly expressed intransgenic tomatoes and the recombinant antigen derivedfrom them has normal immunoactivity.Transgenic tomatoes may hold a good promise for producing a new type of low-cost oral vaccine for hepatitis E virus. AIM: To transfer hepatitis E virus (HEV) ORF2 partial geneto tomato plants, to investigate its expression in transformants and the immunoactivity of expression products, and to exploit the feasibility of developing a new type of plant-derived HEV oral vaccine. METHODS: Plant binary expression vector p1301E2, carrying a fragment of HEV open reading frame-2 (namedHEV-E2), was constructed by linking the fragment to aconititutive CaMV35s promoter and nos terminator, the directly introduced into Agrobacterium tumefaciens EHA105.With leaf-disc method, tomato plants medicatedby EHA105 were transformed and hygromycin-resistant plantlets were obtained in a selective medium containinghygromycin.The presence and integration of foreign DNA in transgenic tomato genome were confirmed by Gus geneexpression, PCR amplification and Southern dot blotting. The immunoactivity of recombinant protein extracted from formed plants was examined by enzyme-linked immunosorbant assay (ELISA) using a monoclonal antibodyspecifically ag ainst HEV. ELISA was also used to estimate the recombinant protein content in leaves and fruits of the transformants .RESULTS: Seven positive lines of HEV-E2-transgenic tomatoplasts were obtained by the immunoactivity of recombinant protein could bedetected in extracts of transformants The expression levels of recombinant protein were 61.22 ng / g fresh weight infruits and 6.37-47.9 ng / g fresh weight in leaves of the transformants. CONCLUSION: HEV-E2 gene was correctly expressed intransgenic tomatoes and the recombinant antigen derivedfrom them has normal immunoactivity. Transgenic tomatoes may hold a good promise for producing a new type of low-cost oral vaccine for hepatitis E virus.