Evaluation of immunogenicity elicited from two DNA vaccine candidates that expresses the prM and E genes of the dengue-3 virus

Abstract

In this work, we report the evaluation of two DNA vaccines against dengue-3 virus (DENV-3). The first construction, called pVAC3DEN3, was engineered inserting the pre-membrane (prM) and envelope (E) gene of DENV-3 truncated with a restriction site between them, as previously described. The second construction was de-veloped cloning the full gene sequence of prM and E from DENV-3 virus in pCI plasmid for mammalian expression and was denominated pVAC1WDEN3. The results showed that both constructions were capable of expressing the prM and E proteins, as demonstrated by ELISA and immunoblotting detection in cell culture transfected with the plasmids. After positive " in vitro " results, the vaccine candidates were used to immunize BALB/c mice and the elicited re-sponse was investigated. After immunization by intramuscular inoculation with three doses of each vaccinal clone the animals were sacrificed, the cytokine levels and T cell response were analyzed in the spleens, after three days of cul-ture with stimulus, our analysis showed that the two constructions elicited T cell responses mea-sured by BrdU incorporation assay and high levels of IFN-γ, detected in the supernatant of the cultures. Moreover, both constructions in-duced detectable titers of neutralizing antibod-ies in mice. And finally the survival rate of the immunized animals after intracerebral challenge was analyzed, showing a better result in the pVAC3DEN3 group with an 80% survival com-pared with a 50% survival of the pVAC1 WDEN3. Thus, these data showed that our two construc-tions were able to induce specific immune re-sponse and protects mice against a lethal chal-lenge with DENV-3, and these vaccine candi-dates can be employed to develop a viable den-gue vaccine.