Serotype-cross-reactive immunoglobulin M responses in dengue virus infections determined by enzyme-linked immunosorbent assay

We developed immunoglobulin M (IgM) antibody capture enzyme-linked immunosorbent assays (ELISAs) with four monovalent dengue virus antigens. We attempted to determine whether IgM responses in dengue virus infections are serotype specific or serotype cross-reactive. Serum samples from 14 confirmed dengue cases were examined. In these 14 cases, which consisted of 12 Japanese and 2 non-Japanese patients, infecting dengue virus serotypes were defined by reverse transcription-PCR. Thirteen of the 14 cases were IgM positive in ELISA. IgM responses were serotype cross-reactive in these 13 cases but were highest against infecting dengue virus serotype in 9 of the 13 cases. These results indicate that IgM responses are generally dengue serotype cross-reactive but that IgM levels are highest against the infecting serotype in most dengue cases.