A rapid diagnostic test that can distinguish between Zika and Dengue viruses
25 Oct 2017
By Dr Guruprasad Medigeshi, Intermediate Fellow
India alone contributes to around 35% of global dengue cases. Four dengue virus (DENV) serotypes elicit poor cross-protective responses in humans. Antibody-dependent enhancement has been recognized to play a major role in secondary dengue infections leading to severe disease. Recent reports indicate that prior exposure to DENV may also be a risk factor for enhanced zika virus (ZIKV) infection due to cross-reactive antibodies. With the emergence of ZIKV, which is closely related to DENV, there is an increasing need to ramp up diagnostic capabilities to differentiate between different serotypes of DENV and also between DENV and ZIKV. Point-of-care (POC) diagnostic tests based on immunochromatographic techniques utilizing antibodies conjugated to gold nanoparticles are both economical and do not require sophisticated laboratory equipment. Currently POC tests are not available that differentiate between DENV serotypes or between DENV and ZIKV.
The non-structural protein, NS1, of DENV and ZIKV is a secretory protein which has been used as a target antigen in rapid diagnostic tests. As part of a multi-institutional collaborative team led by Dr. Lee Gehrke, we used the NS1 protein of both DENV (all four serotypes) and ZIKV to raise a panel of monoclonal antibodies, which recognized the conserved and unique epitopes on NS1 protein of DENV and ZIKV. Antibody pairs recognizing serotype-specific epitopes or conserved epitopes across all four serotypes in DENV were used to develop a POC test that was serotype specific or pan-dengue specific respectively. In addition, NS1 antibody pairs recognizing unique epitopes on DENV or ZIKV were also used to differentiate between these two viruses in the rapid POC test. The rapid diagnostic test showed a sensitivities of 76, 89, 100 and 100% for the four DENV serotypes respectively and a specificities of 89, 98, 100 and 96%. The pan-dengue test had a sensitivity and a specificity of 88 and 100% respectively and 81% and 86% respectively for ZIKV. Thus, we have developed the first rapid diagnostic test that can be implemented as a POC test to diagnose dengue infection, differentiate between the four DENV serotypes and also between DENV and ZIKV. We believe this test could impact current epidemiologic surveillance and patient care strategies for both DENV and ZIKV infection worldwide.
Figure description: Applying the rapid test to analyze human patient sera. (A) Map showing the endemic virus regions where the rapid tests were deployed to analyze patient serum samples. The areas of the circles correlate with the numbers of samples analyzed. The blue colors, faint to dark, represent DENV1–4. ZIKV is indicated in orange color. (B) ELISA results showing the amounts of DENV NS1 (left) and ZIKV NS1 (right) found in patient serum and supernatants from infected cell cultures. Lanes 1 and 6 are supernatants from Vero cells infected with DENV; lanes 2 and 7 are supernatants from Vero cells infected with ZIKV. Lanes 3 and 8 are PCR-negative sera; lanes 4 and 9 are sera from PCR-positive DENV patients. Lanes 5 and 10 are sera from PCR-positive ZIKV patients. (C) Images of rapid test analysis of DENV NS1 serotypes 1 to 4 and ZIKV NS1 on serotype-specific strips 1 to 4, as well as pan-DENV (P) and ZIKV (Z); the upward arrows mark positive tests, and q is serum from an uninfected patient.
Rapid antigen tests for dengue virus serotypes and Zika virus in patient serum. Bosch et al. Science Translational Medicine. October 2017