Innovative antibody tests in pipeline

April 10, 2020

By Anna Lynn Sptizer and Lori Brandt

The human toll is far and away the most serious consequence of COVID-19, but the economy has suffered a blow as well. The key to getting people back to work could lie in determining who might be immune to the virus. Those people could return to school and work, helping to slowly restart the economy. Two Samueli School professors are working to develop antibody tests to help identify those with immunity.

Peter Burke, professor of electrical engineering, is proposing an inexpensive point-of-care method to detect COVID-19 immunity. (Burke and colleagues at the University of Illinois have recently filed for a patent.) Antibodies in blood serum presumably can be used to determine immune patients. Ordinarily, blood tests need expensive proteins to detect antibodies produced by the immune system in response to infection, but Burke is investigating the feasibility of using short DNA sequences as the capture agent instead. He says this could be less expensive to manufacture, and could even be implemented on a low-cost paper test, like those used for pregnancy. Those who test positive for the antibodies would presumably no longer be infectious and could be cleared to return to work. Low-cost tests such as Burke’s would enable clinicians to determine how long this immunity lasts and how robust the immunity is at a global population level.

Burke says the primary goal of his study is to find and exploit DNA- or RNA-aptamers (short strands of DNA) that bind with specific affinity to the binding site of antibodies for the virus. These are known to be specific to the virus’s spike protein. “If we are successful, then a point-of-care, in-home test of patients that are immune to COVID-19 could follow,” Burke said, adding that it could be paper-based and cost only a few cents to produce. “This would be like a pregnancy test for COVID-19 immune patients.”

Marc Madou also is working on antibody testing. He is collaborating with immunologist Phil Felgner, director of UCI’s Vaccine Research and Development Center and the Protein Microarray Laboratory and Training Facility, to develop a CD system that can provide low-cost, high-throughput semi-automated immunoassay processing.

Over the past 15 years, Felgner’s laboratory has developed a protein microarray analysis that can quantify antigen-specific antibody responses induced after infection from any microorganism. Felgner and colleagues recently developed a coronavirus antigen microarray that includes multiple antigens from each of the four common coronavirus strains, as well as from the SARS, MERS and SARS-CoV-2 emerging coronavirus strains. The protein microarray also includes antigens from other common respiratory viruses including influenza, which will generate additional data and serve as a control for coronavirus infection.

Madou’s team pioneered a CD fluidic platform that has now been commercialized by several companies for different applications.

Together, the two are working to integrate coronavirus antigen arrays onto CD-based fluidic platforms, which could lead to a quick, inexpensive microarray digital imaging test. The key innovation in the disposable immunoassay disc design is a fluidic structure that enables efficient micro-mixing. “Several arrays can be put on the CD at once and the spinning makes the binding of the proteins go 10 times faster,” Madou said. 

He added that the system is simpler than his previous fluidic CD systems for three reasons: blood samples need no sample preparation; the system uses fluorescence to indicate protein binding, a much quicker approach than absorption; and newly available digital fluorescence microscopes reduce assay quantification costs.

Data processing of results will be cloud-based, allowing for rapid analysis – Madou expects about 10 minutes.

“This platform is particularly relevant today with the coronavirus outbreak because of the urgent need to understand who in our environment has been exposed to the virus, to predict whether those people are susceptible to severe, mild or asymptomatic infection, or whether they have protective antibodies and are unknowingly spreading the infection to close contacts,” he said.