With an eye on developing countries, U of T researcher develops low-cost COVID-19 antibody test

A researcher at the University of Toronto Mississauga has received funding to develop an inexpensive, easy-to-use COVID-19 antibody detection test.

The field test kits could be used for long-term disease monitoring and provide information critical for creating effective public health strategies, says David McMillen, an associate professor with the department of chemical and physical sciences.

“As we move past the current acute phase of the pandemic, surveillance will become increasingly important to enable our health-care infrastructure to anticipate and prepare for new outbreaks,” he says.

McMillen says the test could be made cheaply using engineered yeast cells, and would be well suited to low- and middle-income countries where the cost of antibody testing is currently insurmountable.

McMillen’s team has already used engineered yeast cells to detect antibodies for Chagas disease and dengue fever in previous research projects. The team was in the process of collaborating with researchers from the University of the Philippines to create a similar antibody detection test for malaria when the lockdown closed the lab.

Then the opportunity for COVID-specific funding arose through the Canadian Institutes of Health Research. McMillen says he decided to use the same approach to detect antibodies for SARS-CoV-2, the virus responsible for COVID-19. Work on the malaria test continues, so this new project will run in parallel with existing research in partnership with the University of the Philippines.

“The COVID test could potentially be made very cheaply,” McMillen says, explaining that yeast is simple and inexpensive to cultivate. It can grow in big vats with just water and sugar. He estimates the raw materials for 5,000 kits would cost a dollar. A fully assembled kit would cost more, but there’s not a “whole lot extra to add, which is why it’s appealing,” McMillen says.

Unlike most available tests, the yeast-based test could be shipped dry and wouldn’t need to be continuously refrigerated, making it more accessible to areas with limited access to electricity, especially rural communities. The yeast cells do need to be put in a centrifuge, so McMillen has been testing non-electrical alternatives. Preliminary results suggest salad spinners might work.

Aside from centrifugal force, the test doesn’t require expensive lab equipment, technical expertise by the user or specialized materials. Everything needed could be sourced locally, says McMillen. Testing wouldn’t rely on the global supply chain, which could become strained as the crisis in testing continues.

To conduct a test, a blood sample would be mixed with the engineered yeast cells. If antibodies are present, McMillen says, the yeast would look like a flat, gray sheet, while a negative result would produce a dot or button-like shape. This would provide a visual yes or no result in about 90 minutes, he says.

McMillan notes the yeast-based kits would be a little less sensitive than existing tests but much cheaper to produce.

With the scaffolding for his research in place, McMillen anticipates having a new COVID-19 version of the test up and running within the first few months of this one-year funded project. He will then move to the testing phase and work toward developing a prototype of the kit, collaborating with the university in Manila to ensure he creates the best possible fit for where the tests will be used.

From there, McMillen will create a user-friendly kit with easy-to-follow instructions that is suited to the conditions, requirements and constraints of developing countries.