Sensitivity of Enhanced Immunoassays Evaluated for Dengue

A newly developed blood test for Dengue Fever, that combines an assay for the virus' nonstructural protein 1 (NS1) with a commercial immunoassay test, has been evaluated.

The use of dengue NS1 antigen detection in combination with antiglycoprotein E immunoglobulins IgM and IgG serology can significantly increase the sensitivity of acute dengue diagnosis and enhances the clinical utility of rapid immunochromatographic testing for dengue.

In a retrospective study, led by scientists at the Research and Development Unit at Alere (Brisbane, Australia), the Dengue Early Rapid test was tested using stored acute plasma samples from 100 clinically suspected dengue patients, but with no laboratory evidence of acute or recent dengue virus infection and 198 samples from patients with laboratory-confirmed dengue. The performance of the Dengue Early Rapid test in combination with the IgM/IgG Rapid test was evaluated in Malaysia with 263 laboratory-confirmed positive and 30 negative samples.

In Vietnam the sensitivity and specificity of the test was 69.2% and 96% respectively, while in Malaysia the performance was similar with 68.9% sensitivity and 96.7% specificity compared to a real-time polymerase chain reaction test (RT-PCR). Importantly, when the PanBio Dengue Early Rapid test (PanBio Diagnostics; Sinnamon Park, QLD, Australia) was used in combination with their Dengue Duo cassette IgM/IgG test, sensitivity increased to 93.0%. When the two tests were compared at each day post-onset of illness, there was clear differentiation between the antigen and antibody markers.

The authors concluded that that a combined testing approach for both circulating NS1 antigen and antibody responses to the glycoprotein E of the virus can significantly improve diagnostic sensitivity compared to the detection of NS1 alone. Importantly, the combined antigen and antibody testing approach also provides an expanded window of detection from as early as the first day after the onset of illness. The study was published online in June 2011, in the journal Public Library of Science Neglected Tropical Diseases.

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