Expression of ORF2 partial gene of hepatitis E virus in tomatoes and immunoactivity of expression products.
OBJECTIVE
To transfer hepatitis E virus (HEV) ORF2 partial gene to tomato plants, to investigate its expression in transformants and the immunoactivity of expression products, and to explore 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 (named HEV-E2), was constructed by linking the fragment to a constitutive CaMV35s promoter and nos terminator, then directly introduced into Agrobacterium tumefaciens EHA105. With leaf-disc method, tomato plants medicated by EHA105 were transformed and hygromycin-resistant plantlets were obtained in selective medium containing hygromycin. The presence and integration of foreign DNA in transgenic tomato genome were confirmed by Gus gene expression, PCR amplification and Southern dot blotting. The immunoactivity of recombinant protein extracted from transformed plants was examined by enzyme-linked immunosorbant assay (ELISA) using a monoclonal antibody specifically against 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 tomato plants confirmed by PCR and Southern blotting were obtained and the immunoactivity of recombinant protein could be detected in extracts of transformants. The expression levels of recombinant protein were 61.22 ng/g fresh weight in fruits and 6.37-47.9 ng/g fresh weight in leaves of the transformants.


CONCLUSIONS
HEV-E2 gene was correctly expressed in transgenic tomatoes and the recombinant antigen derived from 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.
Ma
Ying
Y
The Key Laboratory of the Ministry of Education for Cell Biology and Tumor Cell Engineering, Xiamen University, Xiamen 361005, Fujian Province, China.
Lin
Shun-Quan
SQ
Gao
Yi
Y
Li
Mei
M
Luo
Wen-Xin
WX
Zhang
Jun
J
Xia
Ning-Shao
NS
D000284:Administration, Oral; D000906:Antibodies; D018506:Gene Expression Regulation, Plant; D016751:Hepatitis E / Q000517:prevention & control*; D006801:Humans; D018551:Solanum lycopersicum / Q000235:genetics*; D030821:Plants, Genetically Modified; D014614:Vaccines, Synthetic / Q000008:administration & dosage / Q000235:genetics*; D014764:Viral Proteins / Q000235:genetics* / Q000276:immunology
D000906:Antibodies; C400971:ORF2 protein, Hepatitis E virus; D014614:Vaccines, Synthetic; D014764:Viral Proteins