Figure 1.
NS1 immunization in A129 ADE infection model. (A) A129 mice were immunized i.p. three times with 20 µg NS1(16681) or OVA with MPLA and Addavax as adjuvants. 8 wk after immunization, mice were passively transferred with DENV1-immune serum 1 d before i.v. challenge with 106 PFU DENV2 (D2Y98P). (B and C) Circulating sNS1 levels (B) and viremia titers (C) were measured (n = 5) at days 2 and 4 p.i. (D and E) Mice (n = 8) were monitored daily upon challenge. Kaplan–Meier survival curve and clinical scores are shown. (F) Vascular leakage was quantified by Evans blue dye extravasation assay in liver and small intestines at day 4 p.i. (n = 5). (G and H) Systemic aspartate aminotransferase levels were measured (n = 4–5; G) and histological analysis of liver was performed at day 4 p.i. (n = 4–5; H). Images were taken at 20× and 40× magnification. Representative sections are shown. Scale bar, 10 µm. Data are representative of at least two independent experiments. Data were analyzed by nonparametric Mann–Whitney U test. *, P < 0.05; **, P < 0.01; ns, not significant. Results were expressed as averages ± SD (B and F).