Selvin Lab on the Hunt for a Better COVID-19 Test

Photo: Professor of Physics Paul Selvin (L) discussing next steps in COVID-19 detection with students Chaoyi Jin (center) and Duncan Nall (right). Photo taken prior to the pandemic.

Does a physicist have a role in containing the novel coronavirus that is the cause of the latest pandemic?

“We need to be able to rapidly and sensitively detect the virus,” says Paul Selvin, a physics professor at the University of Illinois at Urbana-Champaign. “That way we can identify people who have been exposed, get them help, and prevent the rapid spread of the virus.” Selvin and his students are using their exquisitely sensitive single-molecule imaging techniques to develop a new method for detecting the novel coronavirus.

Current COVID-19 tests rely on breaking open the virus and extracting its genetic component, called RNA. “While very successful,” says Selvin, “it’s difficult and time-consuming.” An alternative is to detect proteins on the surface of the virus. “There are more proteins on the surface, and they’re easier to access,” he says. Selvin explains, “The ‘spike’  proteins,” so called because they protrude from the surface of the virus, “bind the virus to a host cell during an infection, allowing the viral RNA to enter the  host cell, replicate, and finally kill the cell.”

Instead of cracking open the virus, extracting the RNA, and amplifying it via a polymerase chain reaction to get enough material to test, Selvin’s group is looking directly at the spikes. Each virus cell has only one RNA strand but about 50 spikes—giving the scientists more material to examine and considerably simplifying and shortening the process.

Another reason to focus on spike proteins is that many different coronaviruses exist in nature, but each one may have a slightly different mutation in its spike proteins. “If we could develop a technique that binds to the novel coronavirus spike proteins, we could distinguish them, and all the other coronaviruses would not give a positive signal,” said Selvin. “In humans, variations of the spike proteins may be related to the wide clinical variations in the severity of the disease.”

Working with Yi Lu, a chemistry professor at Illinois who is busy developing new antibody-like molecules for detecting spike proteins, Selvin is developing new methods for watching these molecules bind to viruses. In the past, Li and Selvin have collaborated to detect other biomolecules, but now to succeed with the novel coronavirus, said Selvin, "will require all of our experience, and then some."