IgG antibody response of mice immunized with aqueous and adjuvanted NS1. Four-week-old C3H mice were immunized with 1 μg of purified NS1. Two weeks after a second immunization was given at two months of age, mouse sera were sampled and the IgG titers were tested by indirect ELISA. The data for immunization with recombinant NS1 are derived from two independent experiments. Antibodies of 18 mice sera were titrated for each group and analyzed by Student’s t- test.