Researchers respond to urgent call for COVID-19 testing
Clemson University researchers are volunteering their time and resources as part of a statewide effort to develop serologic tests that could play a key role in reigniting South Carolina’s economy and protecting healthcare professionals on the frontlines of the COVID-19 pandemic.
A test on track to be ready this week would be aimed at detecting antibodies that form in the bloodstream when someone has been exposed to the novel coronavirus and is therefore thought to have a lowered chance of re-infection.
Commercial labs are also developing the tests, but some South Carolinians are concerned that the tests will be in short supply and that the lion’s share will go to larger states with more purchasing power and more cases of COVID-19.
Clemson researchers are developing the South Carolina tests with colleagues from the University of South Carolina, Prisma Health and the Medical University of South Carolina.
Delphine Dean is overseeing the Clemson portion of the work as the Clemson lead for the state’s Serological Testing and Diagnostic Working Group.
“We’re all working on it together,” said Dean, who is the Ron and Jane Lindsay Family Innovation Professor of bioengineering. “Many of the barriers between institutions that sometimes slow down collaboration have been removed. Everyone has been working around the clock to make these things go much faster than typically happens.”
Before any test is deployed, it would need to be validated for effectiveness to meet Food and Drug Administration regulations.
The test that will be available this week is aimed at checking healthcare professionals for antibodies. The idea is that those who test positive for the antibodies could be cleared to re-enter public life, allowing them to work with minimal concern they could come down with COVID-19 or infect others.
About 500-1,000 tests could be ready as early as this week, less than a month since the project started, researchers said.
The two Clemson researchers working on the test are Mark Blenner, the McQueen Quattlebaum Associate Professor of chemical and biomolecular engineering, and Sarah Harcum, professor of bioengineering.
Blood samples would need to be tested in a lab, which limits how many can be done. In a parallel effort, Clemson researchers are working to create tests that could take saliva, urine or blood and show results with a color change in as little as 15 minutes, similar to a home pregnancy test.
Researchers involved in developing those tests are: Blenner, Terri Bruce, research assistant professor of bioengineering and director of the Clemson Light Imaging Facility; Dean; Harcum; and R. Kenneth Marcus, University Professor of chemistry.
The tests would be an improvement on current methods. Antibody tests that check for immunity require a blood draw and are inaccurate and scarce, Blenner said. Testing directly for the virus itself requires an uncomfortable nasal swab and puts healthcare workers at a heightened risk of catching the virus, he said.
Martine LaBerge, the chair of Clemson’s bioengineering department, said all the researchers are volunteering their time, efforts and resources to help the state, as it faces the unprecedented challenges posed by the COVID-19 pandemic.
“They are working tirelessly to protect the health and safety of South Carolina’s healthcare professionals and the general public,” said LaBerge, who is playing a central role in coordinating Clemson’s research response to the pandemic. “Institutional barriers are coming down so that we can work together as one South Carolina. I offer all those sacrificing sleep and time with family my deepest gratitude.”
The process to develop the tests starts with Blenner, who is making spike proteins, which give the novel coronavirus its distinguishing feature and is believed to be how the viral infection is mediated.
In his lab, Blenner puts the DNA for the spike proteins inside of human or hamster cells. When the cells grow, they produce the spike proteins, which will ultimately serve as the key reagent in the antibody tests.
“Our group is going to make a stable cell line that we can scale up,” Blenner said. “Right now the procedure is not meant to make a lot of protein. It’s meant for quick protein production. I’m going to make a productive cell line and work with Sarah Harcum to get that in larger bioreactors.”
Harcum said she will put the cells in computer-controlled bioreactors that can sense oxygen and pH levels. Pumps carefully control the nutrients that feed the cells.
“I grow cells to make them happier so they make more protein,” Harcum said. “Normally, I look at how to make pharmaceuticals, but the pharmaceuticals I make are proteins, which makes this COVID-19 work a good fit for what I do.”
Once she has the protein grown, Harcum will then purify it so that it can be used in the diagnostic tests.
Meanwhile, Bruce, Marcus and Dean are starting to lay the groundwork for simple tests that could reach large numbers of people.
“What we really need is something simple that’s a colorimetric test that can be done in under 15 minutes at the point of care,” Bruce said.
The team is working to improve upon a commercially-developed enzyme-linked immunoabsorbent assay, or ELISA, that checks blood samples for antibodies.
Antibodies are plentiful in blood but less so in saliva. One of the challenges in developing a saliva-based test is isolating the antibodies.
To do so, Marcus and Bruce are turning to capillary-channeled polymer fiber-based films, a technology they have been researching for years.
“Antibodies exist in this tremendously complex soup, and what you would like to be able to do is pull them out of the soup selectively in a fairly high-throughput fashion,” Marcus said. “We can modify our fibers so that the only things that stick are the antibodies.”
Clemson researchers are working to make a prototype, but a manufacturer would be needed to produce large quantities of the test, Bruce said.
Dean, who is helping develop the optical portion of the test, said it could also be possible to use the fibers to capture the virus itself from urine. There is evidence that the virus comes out in urine after it is no longer detectable in blood, she said.
“Patients could maybe test themselves at home,” Dean said. “The same principle could be used to test waste streams. If you wanted to do population monitoring, you might be able to get a sense for what percent of the population has the virus.”
Researchers said they are finding ways to pay for the development of the tests with existing funds but that eventually they will need financial support, particularly when the semester ends next month.
“We are going to need lab supplies and graduate student salaries, and we could accelerate development by outsourcing some of the work,” Dean said. “Typically, when we launch big projects, we apply for federal funding, a process that normally takes months, if not a year or more. But time is of the essence, and we are finding ways to quickly ramp up work. What we need most now is the funds to help keep the work going.”