Updated May 8, 2020
A team of OIST scientists, led by Professor Matthias Wolf from the Molecular Cryo-Electron Microscopy Unit, have set up a blood test that can detect the presence or absence of specific antibodies against SARS-CoV-2, the coronavirus that causes COVID-19.
Unlike PCR tests that detect RNA from the virus in currently infected patients, the blood test is used to determine who has previously contracted COVID-19. The specific immune response against the disease can be detected for a longer time after the virus is gone, but it is not yet known if this results in lasting immunity.
The antibody test being used at OIST is an enzyme-linked immunosorbent assay (ELISA), which was originally developed and validated by the Krammer Lab at the Icahn School of Medicine at Mount Sinai, New York.
“The test works by using parts from the SARS-CoV-2 virus surface called spike proteins, which act as antigens,” said Prof. Wolf. “When an individual is infected with the novel coronavirus, the immune system reacts to these antigens and produces specific antibodies which can bind to them.
“In the test, we expose blood serum to bound antigens. The serum of infected individuals, containing these specific antibodies, then bind to the antigens. In a series of stages, we can detect the quantity of antibodies that bind and therefore determine whether an individual had COVID-19.”
To establish the test, staff scientist, Dr. Tae Gyun Kim, with help from staff scientist Dr. Jaekyung Hyun and PhD student, Keon Young Kim, produced and purified components of spike proteins from genetic constructs supplied by the Krammer Lab. Spike proteins, which form the characteristic “crown” shape of coronaviruses, are key to allowing the virus to enter host cells.
Postdoctoral researcher, Dr. Melissa Matthews, is in charge of setting up the test. Currently, the team are awaiting positive control samples in order to validate the test.
Other units at OIST are now collaborating to further improve the antibody test. Dr. Saacnicteh Toledo-Patino, a postdoctoral researcher from the Protein Engineering and Evolution Unit, led by Professor Paola Laurino, is aiming to optimize the production of antigens, by using E. coli bacterial cells.
Meanwhile, Christian Butcher, a technician from the Fluid Mechanics Unit, led by Professor Pinaki Chakraborty, is working on automating the testing process to expand the daily testing capacity. Presently, the scientists are able to manually test around 1,000 samples each day.
“Ultimately, we hope that the test will be used to screen communities in Okinawa to fully understand the spread of COVID-19, helping officials make more informed decisions,” said Prof. Wolf.
A dialogue with the medical community on Okinawa has been established and the Prefectural Government has requested a pilot screen of 6,000 residents.