U of T Develops Rapid Low Cost Method to Measure COVID-19 Immunity

The pinprick test can accurately measure in under one hour concentrations of coronavirus antibodies in blood and is cheaper than the market gold standard.

Investigators from the University of Toronto have developed a novel method that can measure COVID-19 immunity in those who have recovered from the disease. The results from the recent study were published in the journal Nature Communications.

Prior to the pandemic, the team was building a molecular tool to combat cancer, but turned their efforts towards COVID-19 when the virus began to spread widely last spring.

"It's really useful to have that quantitative ability to know what someone's antibody status is, whether it's from a past infection or a vaccination,” Igor Stagljar, a professor of biochemistry and molecular genetics in the Donnelly Centre for Cellular and Biomolecular Research at U of T's Temerty Faculty of Medicine said. “This will be of crucial importance for the next stage of the pandemic, especially now when governments of all countries started with mass vaccinations with recently approved anti-COVID-19 vaccines.”

The new method of testing, called Serological Assay based on split Tripart Nanoluciferase (SATIN), is the first serology test for COVID-19 that uses a highly sensitive protein complementation chemistry in which a light-emitting luciferase protein is reconstituted from separate fragments as a test readout. 

The luciferase, a type of oxidative enzyme that produces bioluminescence, is first supplied in fragments that do not glow on their own. A piece of the luciferase is attached to the viral spike protein and another is hooked onto a bacterial protein which interacts with antibodies. The simultaneous binding allows the luciferase pieces to bind together as a whole molecule which causes a light to shine and be converted into an antibody concentration by a plate reader instrument.

The team behind the development is now looking to find industry partners that will be able to help make the method widely available.

"Our assay is as sensitive, if not better than any other currently available assay in detecting low levels of IgG antibodies, and its specificity, also known as false-positive rate, is as good as the best antibody test on the market," said Stagljar.