ASU researcher helps develop $1 paper test for Zika virus, other life-threatening diseases
In 2016, young women around the world were struck with fear by the emergence of the Zika virus. In populations across 45 countries in the Western Hemisphere, they feared the unrelenting virus would result in newborns with malformations and brain damage. The World Health Organization declared an international health emergency.
Concern peaked in March when Brazil reported an all-time high of nearly 8,000 suspected new infections. People across the Americas were being told to refrain from sexual relations. At Arizona State University’s Biodesign Institute, a young assistant professor wanted to help.
Fast-tracking a solution
Only a year into his professorship at the Center for Molecular Design and Biomimetics at ASU’s Biodesign Institute, Alexander Green received a call from his former mentor at Harvard, James Collins. With news of Zika spreading as fast as the virus itself, Collins and Green knew they had a technology that could make a difference.
In 2014, Green and Collins were part of a team at Harvard’s Wyss Institute for Biologically Inspired Engineering. Together, they had developed a concept for a simple virus sensor that could be embedded into a piece of paper.
The team had successfully used the technology during a similar crisis: the West African Ebola epidemic, but had not made the leap to testing it against the whole virus particles that would be present in patients, like those suspected of having the Zika virus.
“From our first study, we knew our sensors had a lot of potential in a rapid diagnostic test,” Green says. “I wanted to see if we could pull together what we’d learned since then and apply the technology to an urgent problem.”
A team of scientists from seven different institutions pooled their collective brainpower to create a low-cost, rapid diagnostic test for the Zika virus. Even while facing daunting technology hurdles, the team moved from idea to effective prototype within just six weeks.
“In the world of science, that is extremely fast,” Green says.
The need for amplification
When a person is infected with the Zika virus, it is typically found in very low concentrations. So, the test needed to be very sensitive, but also specific for Zika. The team designed a process that amplifies the virus in a sample before applying it to the paper test strip.
Green specializes in a field called molecular programming, and he spends much of his time carefully designing molecules that respond to cues in the cell. One class of these molecules are called toehold switches. These switches are necessary for reading critical RNA molecules that are a unique molecular signature, like a fingerprint, to rapidly identify a virus’s DNA.
“Viruses like Zika have a genetic barcode in their RNA sequence that we can detect using toehold switches,” Green explains. “A specific sensor on that piece of paper detects the RNA barcode and lets us know if the virus is present.”
After a blood sample is taken, the amplification makes many copies of the RNA. Then, once the sample is put onto the paper, the sensors can easily and accurately read it. On the paper, the amplified sample causes a color change from yellow to purple if Zika is present.
Refining the technology
Since the prototype was created, the team has worked to make the testing process simpler, faster and easier to use. The test also needed to work anywhere in the world at any time. Traditional RNA-based tests require freezing the test components and shipping them frozen to the labs and clinics where they will be used, which adds to testing costs and is problematic in remote locations where electricity is unreliable.
Green’s colleague, Keith Pardee, a professor at the University of Toronto and a collaborator with Green at the Wyss Institute, specializes in analyzing the biochemical circuitry inside living cells. He breaks these circuits down into their simplest elements to replicate them in a test tube. This process is critical to the tests being used anywhere in the world.
Pardee uses a unique freeze-drying method that allows the tests to be stored at room temperature, even up to a year. They can be shipped and used anywhere without temperature concerns.
“What we did was make an extract of these cells and freeze-dried it,” Pardee says. “Then we learned that if you add water — like you would with making Ramen noodles — the enzymes stored on the paper reactivate in just seconds. Now, a paper you can hold in your hand has the capability of a cell.”
The test is completely programmable. It uses a breakthrough gene-editing system called CRISPR to aid in the identification of the particular viral strain of Zika (be it American, Asian or other varieties). The technology can even parse out Zika from its viral cousin, the Dengue Fever virus. The test also can be quickly modified. Within a week, a new test can be created for a completely different disease.
This past fall, the team successfully used the test on human samples in Ecuador. In four to six months, the test will be used on additional human samples in Latin America to test for different strains of Zika and Dengue.
The test also is inexpensive, only costing a dollar to make. Because of its portability, low cost and immediate applicability to a current real-world problem, Popular Science magazine presented the team with its annual “Best of What’s New” award in 2016.
Now, Green’s team is still working to make the test even better. The amplification process, which requires some basic lab equipment, needs further refining, he says.
“It’s very simple, but those are the steps that currently need to be done by someone semiskilled. We’re aiming to make it so that anyone, anywhere can do it; so that it can be used out in the field or in take-home tests,” the professor adds.
Right now, the paper test takes roughly one hour to 90 minutes to produce a result. The goal is to get results within 30 minutes to an hour.
Once further testing in Latin America is complete, Green is hopeful that the test can then be applied to diagnosing other diseases, possibly HIV, SARS, hepatitis C and others.
“In principle, it can be used against any virus or pathogen. My dream is to see it being used around the world to combat the spread of infectious diseases, and to help ensure all patients, no matter their income, receive the right treatments,” Green says.
Green and his colleagues know from Zika that the next epidemic could be right around the corner, and they are determined to do all they can to help.
An important role
“Members of the community have an important role to play in the fight against devastating diseases,” Green says.
His team is looking for altruistic individuals who share their vision to bring advanced diagnostics to everyone, everywhere. They hope to raise $1 million to fund field tests for HIV and Zika detection in Africa and South America, and to further develop their technology.
More and more, private support from individuals and entities who believe in cultivating science for the common good is accelerating scientific advancement. Such partnerships drive Campaign ASU 2020, a universitywide fundraising initiative that seeks, in part, to fuel the discovery and innovation originating from ASU.
“The result,” Green says, “will be real progress in diagnosing more diseases at lower cost — and fewer people who fear the emergence of the next disease.”
Originally published at www.azcentral.com on March 9, 2017.