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A new instrument can be attached to a smartphone to quickly test the Zika virus in blood

As seen with the COVID-19 pandemic, rapid, simple, accurate and sensitive detection methods are essential for detecting viral pathogens and controlling the spread of infectious diseases. Unfortunately, laboratory methods often require trained personnel and involve complex procedures. In a new study, researchers from the University of Illinois at Urbana-Champaign have combined efforts to develop an instrument that can be clipped onto a smartphone to quickly test for the Zika virus in a single droplet of blood.

The Zika virus is mainly transmitted by Aedes aegypti mosquitoes. Although the disease is largely asymptomatic or causes mild symptoms in adults, it causes developmental problems in newborns if their mothers are infected early in pregnancy. Currently, the virus is circulating in more than 87 countries, infecting thousands of people each year, requiring better testing and control measures.

Mosquito-borne viruses cause serious illnesses, but they show similar symptoms. If you have Zika, malaria, dengue, or chikungunya, you might come to the doctor with a fever and he won’t know why. But it is important to know if it is Zika, especially if the patient is a pregnant woman, because the consequences on the developing fetus are really serious.”


Brian Cunningham (CGD/MMG Director), Intel Alumni Chair in Electrical and Computer Engineering

Zika virus infections are currently detected by polymerase chain reaction tests performed in the laboratory, which can amplify the genetic material of the virus, allowing scientists to detect it. In the new study, the researchers used loop-mediated isothermal amplification to detect the virus in blood samples using an approach suitable for point-of-care clinics. While PCR requires 20 to 40 repeated temperature changes to amplify genetic material, LAMP only requires one temperature – 65°C – which makes monitoring easier. Additionally, PCR tests are very sensitive to the presence of contaminants, especially the other components of a blood sample. Accordingly, the sample is first purified before it can be used. On the other hand, LAMP does not require any such purification step.

A cartridge, which contains the reagents needed to detect the virus, is inserted into the instrument to perform the test while the instrument is clipped onto a smartphone. Once the patient adds a drop of blood, a set of chemicals breaks down viruses and blood cells in five minutes. A heater under the cartridge heats it up to 65°C. A second set of chemicals then amplifies the viral genetic material and the liquid inside the cartridge fluoresces bright green if the blood sample contains the Zika virus. The whole process takes 25 minutes.

“The other interesting aspect is that we’re doing the reading with a smartphone,” Cunningham said. “We designed a clip-on device for the rear camera of the smartphone to watch the cartridge while the amplification is happening. When there is a positive reaction, you see little green flowers of fluorescence that eventually fill the entire cartridge of green light.”

Researchers are now developing similar devices to simultaneously detect other mosquito-borne viruses and are working to make the devices even smaller. “Although our clip-on detector is quite small, much of the space is taken up by batteries. In the next version, it will be powered by the phone battery,” Cunningham said.

Source:

Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign

Journal reference:

Jankelow, AM, et al. (2022) Smartphone-clamp instrument and microfluidic processor for rapid sample detection of Zika virus response in whole blood using space-based RT-LAMP. Analyst. doi.org/10.1039/d2an00438k.