Geometric mean PRNT50 titers against DENV-1 at 14, 28, 60, and 90 days. The mice in group A received 5-ng vaccine doses on study days 0, 14, and 28. The mice in group B mice received 10-ng vaccine doses on study days 0, 14, and 28. The mice in group C received 10-ng vaccine doses on study days 0, 28, and 60.