Protection, IFN-γ responses and antibody titers in tetravalent dengue vaccine-immunized mice after DENV-4 challenge.

<p>Groups of 6- to 8-week-old BALB/c female mice (n = 6, except n = 4 for pVax-1) were immunized three times at 2-week intervals with pVax-1, pTDV-ED3, rTED3 or prime-boost as the same schedule in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0145717#pone.0145717.g002" target="_blank">Fig 2</a>. Four weeks after the last immunization, mice were challenged with the intraperitoneal injection of 5 x 10⁷ DENV-4 infected K562 cells. (A) Plasma viremia titers from individual mice were determined by viremia assay and are represented as the mean and SD. The significance shown in the graph was determined in comparison to the pVax-1 group, if nothing else is indicated. (B) Spleen cells were harvested for the detection of the ED3-specific IFN-γ production by ELISPOT at 1 month post-challenge. (C and D) The sera collected at 1 month post-challenge were used for the detection of neutralizing titers in an FRNT assay (C) or ED3-specific IgG titers by ELISA (D).