Objective: To secreted express envelope glycoprotein (E) of dengue virus type 2 extracellularly.
Methods: The entire prM/E gene was amplified by RT-PCR. An optimized signal sequence gene from Japanese encephalits virus (JEV, SA14-14-2 strain) was introduced using fusion PCR. The impact of E protein transmembrane and cytoplasmatic domains was compared by amplifying prM and E with full length of E gene, with 20% truncation of the E gene at 3' terminus and one chimeric gene, which was generated by replacing the 3' terminal 20% region of E gene with the corresponding sequence of JEV (SA14-14-2 strain). The PCR segments were inserted into the NheI and NotI sites of pcDNA5/FRT vector or into the NheI and XhoI sites of pAcUW51-M. Then they were transfected into 293T cells or Sf9 cells respectively. The expression and secretion of E protein were detected by immunofluorescence assay (IFA) and Western Blot.
Results: After transected into 293T cells or Sf9 cells, all constructs expressed E protein intracellularly indentified by IFA while only two plasmids could secret detectable E protein into tissue culture using Western Blot analysis.
Conclusion: Signal peptide as well as the transmembrane and cytoplasmatic domains is crucial for the secretion of dengue E protein.