Competitive ELISA for a serologic test to detect dengue serotype-specific anti-NS1 IgGs using high-affinity UB-DNA aptamers

Serologic tests to detect IgGs specific to antigens related to viral infections are urgently needed for diagnostics and therapeutics in endemic, epidemic, and pandemic situations. We present a diagnostic method for serotype-specific IgG identification of dengue infection by a competitive enzyme-linked immunosorbent assay (ELISA), using high-affinity unnatural-base-containing DNA (UB-DNA) aptamers. Dengue is a widespread mosquito-borne viral disease, with four categorized serotypes. Using UB-DNA aptamers that bind specifically to each serotype or sub-serotype dengue NS1 protein (DEN-NS1), we developed an ELISA format with an aptamer − antibody sandwich system for dengue diagnostics. We found that IgGs highly specific to DEN-NS1 inhibit the serotype-specific NS1 detection by the ELISA format, inspiring us to develop another competitive ELISA format for serotype-specific IgG detection of dengue infection. Analyses of clinical blood samples from Singaporean patients with primary or secondary infections confirmed the highly specific IgG detection of this format, and the IgG production initially reflected the serotype of the past infection, rather than that of the recent infection. The combination of the ELISA and competitive ELISA using the UB-DNA aptamers allows the diagnosis of both past and current viral infections and will facilitate prompt and specific medical care and vaccine development for infectious diseases.