Researchers from Washington University have developed a novel diagnostic test that uses nanotech to rapidly detect the presence of Zika virus in blood samples.
The team’s system, which was described in the journal Advanced Biosystems, could enable earlier diagnosis and treatment for people infected with Zika virus compared to traditional diagnostic methods.
Often people infected with Zika don’t know they’re sick, the researchers reported.
“Zika infection is often either asymptomatic or mildly symptomatic,” co-senior investigator Dr. Evan Kharasch said in prepared remarks. “The most effective way to diagnose the disease is not to wait for people to develop symptoms but to do population screening.”
Conventional testing for Zika requires a blood sample to be refrigerated and shipped to a medical center. This additional step delays diagnosis and treatment.
The test developed by Washington University researchers doesn’t require refrigeration, making it suitable for resource-poor environments.
“If an assay requires electricity and refrigeration, it defeats the purpose of developing something to use in a resource-limited setting, especially in tropical areas of the world,” co-senior investigator Srikanth Singamaneni said. “We wanted to make the test immune from variations in temperature and humidity.”
The team evaluated its system using blood samples taken from four people who had been infected with Zika virus and compared it to blood from five people without the virus. The test produced no false-positive results, according to the researchers.
The team’s device uses gold nanorods mounted to paper to detect Zika – which it can accomplish in a few minutes.
The researchers attached a protein, one produced by the Zika virus, to gold nanorods and then covered the paper with tiny nanocrystals. The nanocrystals protect the nanorods during shipping and storage.
When it’s time to use the test, a healthcare worker can rinse the paper with acidic water, exposing the protein. Then, the worker applies a drop of the patient’s blood to the paper. If the patient is infected with the virus, their blood will contain compounds that react with the virus-produced protein.
“We’re taking advantage of the fact that patients mount an immune attack against this viral protein,” co-senior investigator Jeremiah Morrissey said. “The immunoglobulins persist in the blood for a few months, and when they come into contact with the gold nanorods, the nanorods undergo a slight color change that can be detected with a hand-held spectrophotometer.
“With this test, results will be clear before the patient leaves the clinic, allowing immediate counseling and access to treatment.”
The team reported that they are working on changes to the diagnostic test, including making the color change visible to the naked eye and using saliva rather than blood samples.