Fig. 2.

Circulating levels of sialic acid and NS1 are associated with DENV infection outcome. Ifnar ^−/− mice were infected i.v. with different doses of DENV2 D220, and survival was monitored for 10 days. These are the same mice as those tested in Fig. 1. (a) A Kaplan–Meier survival curve is shown. (b) Sia and (c) NS1 levels in serum were evaluated by ELISA on day 3 post-infection and plotted in relation to DENV infection outcome (mean±sd), with significantly higher amounts being found in animals that succumbed to the infection, with P-values as indicated (two-sided Student t-test). Data were combined from two similar experiments. ADE, antibody-dependent enhancement; p.f.u., plaque-forming units.