Figure 3.

Kinetics of enhancing activity. Serum samples from children born to dengue virus serotype 3 (DENV-3)–immune mothers were heat inactivated, mixed with DENV-2 16681 (prototype), and cultured with K562 cells for 2 days. Shown is the n-fold increase in the percentage of DENV-2–infected cells in children's sera, compared with that in Flavivirus-naive control serum. Sera from 2-month-old infants provided significantly more enhancement than sera collected at any other time point (P < .05, by the Mann–Whitney test).