Neutralizing and infection-enhancement activities against each of the 4 serotypes of dengue virus.

aSerum samples obtained from DENV patients. Infecting DENV serotype was determined by RT-PCR.bOthers consist of a total of 55 serum samples from 55 non acute dengue patients. Serum samples were derived from the following categories: DENV genome and NS1 antigen negative (n = 34), and chikungunya virus (CHIKV) genome positive (n = 21).cPositive infection-enhancement activity was defined as fold-enhancement values greater than cut-off plus a 2 times SD (or cut-off+2SD) in the mean plaque count in the presence of human serum samples.