Diagnosing Zika virus from a device attached to your smartphone
A small apparatus that attaches to a smartphone and tests a blood sample for Zika virus has been developed by researchers, welcoming another wave of diagnostic innovations.
In light of the COVID-19 pandemic, researchers and companies are pushing to create more efficient diagnostic tests for viruses. Researchers from the University of Illinois Urbana-Champaign (IL, USA) are no exception and are focusing on Zika virus. The team has built a device that can be fitted onto a smartphone and screen a single drop of blood for the virus.
Thousands of people every year are infected by Zika virus, which is transmitted by Aedes aegypti mosquitoes and causes a viral infection that is often asymptomatic or shows mild symptoms. However, the virus poses a greater threat if pregnant women are infected as the virus can cause neurodevelopmental disorders in newborns.
“Mosquito-borne viruses cause serious diseases, but they have similar symptoms. If you have Zika, malaria, dengue, or chikungunya, you just might show up to the doctor with a fever and they won’t know why,” commented senior author, Brian Cunningham. “But it’s important to know whether it’s Zika, especially if the patient is a pregnant woman, because the consequences to a developing fetus are really severe.”
Currently, polymerase chain reaction (PCR) tests are used to diagnose Zika virus; however, this method needs to cycle through 20–40 temperature shifts and the sample needs to be purified due to its sensitivity to contaminants. Instead, the research team utilized loop-mediated isothermal amplification (LAMP) in their device. Unlike PCR, LAMP works at one temperature and does not require a purification step, making it a more attractive option for rapid virus detection and point-of-care clinics. Additionally, the LAMP device can process a blood sample in 25 minutes.
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The device holds a cartridge that contains virus-detecting reagents and a heater. Once a drop of blood is added to the device, one set of chemicals breaks open the viral particles and blood cells. The sample is then heated to 65 degrees Celsius. Following heating, another set of chemicals amplifies the virus’ genetic material, causing the material within the cartridge to fluoresce green if the virus is present.
“The other cool aspect is that we’re doing the readout with a smartphone,” reported Cunningham. “We’ve designed a clip-on device so that the smartphone’s rear camera is looking at the cartridge while the amplification occurs. When there’s a positive reaction, you see little green blooms of fluorescence that eventually fill up the entire cartridge with green light.”
The team is continuing to develop the device to simultaneously detect multiple mosquito-borne viruses, as well as make it even smaller. They plan to remove the batteries from the device and use the smartphone battery to power the device instead. Such an efficient screening technique could provide diagnostic support that became evidently needed during the COVID-19 pandemic.
