FIG. 4.

Range and dynamic plot of NS1 serotype-specific IgG ELISA from serum samples of patients with primary or secondary dengue virus infection. A total of 244 sera collected from 194 confirmed dengue patients (50 patients had paired serum samples) between days 4 and 45 after the onset of symptoms were analyzed. Among these, 123 sera were designated as showing primary infection, whereas the other 121 sera showed secondary infection, based on the dual analyses of capture IgM/IgG ratio and NS1 serotype-specific IgG ELISA. NS1 serotyping was done by calculating the ratio of the highest OD value to the second highest OD value read from the four dengue virus serotypes. For further details, see Materials and Methods.