The Immunogenicity of a YncE Antigen from E. coli Enterotoxigenic (ETEC) by Edible Delivery of Transgenic Hairy Roots Tobacco

One of the most causes of diarrhea disease is Escherichia coli enterotoxigenic (ETEC). The first stage of the disease is the binding of ETEC to small intestinal epithelial cells by colonization factors. ETEC then produces Heat-labile enterotoxin (LT) and heat-stable (ST) enterotoxins. The yncE gene potentially encodes a protein with sequence similarity to a pyrroloquinoline quinone containing periplasmic oxidase. The YncE gene is conserved in various strains of E. coli. The protein encoded by the YncE gene is present in the membrane structure of the ETEC. The YncE gene can be considered as a novel protective vaccine candidate. The aim of the present study was to investigate herbal vaccines as a solution to health problems, especially in developing countries.

In the present study, the expression of the YncE protein in tobacco hairy roots and its immunogenicity in mice were investigated. The YncE gene was cloned downstream of the CaMV-35S promoter in the binary expression vector, pBI121-YncE, by using different strains of the Agrobacterium rhizogenes (A4, MSU, 15834) and LBA4404. Three groups of mice including edible, edible-injection, and control were examined. ELISA method was used to determination of IgG and IgA in Feces and Serum.

The amount of the YncE protein was estimated approximately 0.9% of the Total Soluble Protein (TSP) in the transgenic hairy roots. The results indicate that the recombinant YncE protein produced in the transgenic hairy roots tobacco was able to stimulate the immune response in BALB/c mice. Also, it can be stated that recombinant YncE protein is an effective immunogen. The results implied the potential of transgenic tobacco hairy roots–based expression for oral-injection and oral delivery of YncE protein. The antibody titer showed that the immune system was well stimulated.

The plant-based vaccine recombinant YncE protein could both humoral and mucosal the immune response, effectively. Therefore, the YncE antigen was able to stimulate the immune system of mice and produce antibodies. Actually, it appears to be a suitable vaccine candidate for ETEC-induced diarrhea.