Prokaryotic expression of partial E gene of DENV strain and its effect on HUVEC permeability

Dengue virus (DENV) has become the one of the major public health problems worldwide, especially in Tropical and subtropical regions. E protein is the biggest structural proteins and the major envelope protein of the virion, which can induce protective immune response and subsequently immune pathological damage. The pathology of DENV infection is characterized as increased vascular permeability. However, the effect of Protein E on the vascular permeability is not well understood. We isolated DENV2 (M strain) from Aedes albopictus in 2002 and sequenced 1-476 bp of its E gene (GenBank No. AY278226). Here we prepared fusion protein of E gene 1-476 sequence of DENV-2 M strain and NGC strain, named M476 and N476 respectively, and their respective polyclonal antibody. In co-culture system of human umbilical vein endothelial cell (HUVEC) and recombinant protein, indirect immunofluorescence staining showed that the recombinant protein of M and NGC can bind to HUVEC. Through detecting FITC fluorescence change, it was found that M476 protein had significant effect on the permeability of HUVEC during the period of 0.5 similar to 24 h and 32 similar to 48 h, 12 h at the peak. As for N476 protein, it functioned at 0.5 similar to 48 h, 3 h at the peak. Compared with untreated cells, the morphology of HUVEC cells treated with M476 or N476 protein showed shrinking cell, wider width between cells and disrupted cell connection. Taken together, our work strongly confirmed the effect of protein E of DENV-2 on vascular permeability, which might help understanding the pathogenesis of DENV in depth.