Novel rapid test diagnoses Zika, dengue subtypes

A novel, low-cost test was sensitive and specific for identifying Zika virus infection, as well as all four subtypes of dengue virus, without cross-reactivity, study data showed.

“Cost-effective diagnostics are urgently needed to detect and distinguish DENV (dengue virus) and ZIKV (Zika virus), as well as other pathogenic viruses,” Irene Bosch, PhD, of the Institute for Medical Engineering and Science at Massachusetts Institute of Technology, and colleagues wrote.

The researchers noted that flavivirus nonstructural 1 protein (NS1) is a useful marker of infection, and that rapid tests that used the protein to confirm dengue virus infection had already been studied.

“However, these studies were performed before the ZIKV epidemic, and a recent publication confirms DENV-ZIKV NS1 cross-reactivity using a commercial rapid test,” the researchers wrote. “In addition, none of the commercial rapid tests distinguishes the DENV serotypes.”

Bosch and colleagues developed an immunochromatography assay that “sandwiched” flavivirus nonstructural 1 protein between membrane dipsticks that were coated with one flavivirus nonstructural 1 protein antibody and gold nanoparticles connected to another antibody. The researchers identified antibody pairs by evaluating 300 combinations of antibodies for Zika virus and 726 combinations for dengue viruses. They validated the test using serum samples from patients with confirmed infections.

When Bosch and colleagues used a 30-µL serum sample, sensitivity and specificity of tests for all four dengue subtypes as well as a pan-dengue test ranged from 0.76 to 1.0, the researchers reported. With a 150-µL serum input, sensitivity for a Zika virus rapid test was 0.81, with a specificity of 0.86, Bosch and colleagues wrote.

“Together, we demonstrate that we have developed and characterized NS1 antigen tests capable of distinguishing the DENV serotypes and detecting ZIKV and DENV infections without cross-reactivity, in anticipation of broader clinical applications,” the researchers wrote. – by Andy Polhamus

Disclosures: Bosch is listed as an inventor on patents covering NS1 diagnostic tests for dengue and Zika virus. Please see the study for a complete list of all other authors’ relevant financial disclosures.