Figure 5. DENV2 E85-VRP-immune T cells from WT mice can reduce viral RNA levels in mice whereas DENV2 E85-VRP-immune serum from WT mice can enhance infection when transferred into AG129 mice.

(A) WT129 mice were immunized on d-14 and d-5 with 1×10⁶ IU DENV2 E85-VRP i.p. Splenic T cells were isolated on day 0 and adoptively transferred into naïve AG129 recipients one day prior to challenge with 5×10⁸ GE DENV. Control groups include the “baseline” and “ADE” groups, as well as groups receiving naïve T cells. Viral RNA was quantified in the liver 3 days after challenge. (B, C) 2×10⁸, 4×10⁷ or 5×10⁶ B cells from WT mice immunized with DENV2 E85-VRP (d-14 and -5) as described above were transferred into naïve AG129 mice one day prior to challenge with DENV (as above). The “baseline” and “ADE” groups received no B cells. Viral RNA was quantified in the liver 3 days after challenge (B) and serum levels of DENV-IgG was measured by ELISA 3 days after challenge (C). (D) Serum (200 µl) from WT mice immunized with DENV2 E85-VRP (d-14 and -5) as described above was passively transferred into naïve AG129 mice one day prior to challenge with DENV (as above). Viral RNA was quantified in the liver 3 days after challenge. (E) Serum (200 µl) from WT mice immunized with DENV2 E85-VRP (d-14 and -5) was transferred into naïve AG129 mice with or without 4×10⁷ T cells from WT mice immunized with DENV2 E85-VRP (d-14 and -5) one day prior to challenge with DENV2. Viral RNA was quantified in the liver 3 days after challenge. Each symbol depicts one mouse, except for C where n = 4 for the groups receiving B cells and 2 for the groups receiving no B cells (base and ADE), P-values from two-tailed unpaired t-test with Welch's correction, confidence interval 95%, * P≤0.05, ** P≤0.01, *** P≤0.001. The dotted line represents the limit of detection of the assay.