QIMR Berghofer researchers have developed a way of testing whether or not COVID-19 patients’ immune systems are gearing
up to fight the virus that causes the deadly disease.
They hope the discovery could be used to identify early on which patients’ immune systems are not responding
appropriately, and who might therefore be at higher risk of becoming seriously unwell.
The prototype test detects high levels of two key chemical signals that are produced by T cells when they recognise
SARS-CoV-2-infected cells and start to fight the infection. SARS-CoV-2 is the virus that causes COVID-19.
T cells are the immune cells that recognise and destroy cells infected with SARS-CoV-2. They typically mount an early
response, even before the body starts to produce antibodies. Most importantly, T cells develop a lasting memory of viral
infections, which enables the immune system to respond rapidly in the event of reinfection.
Study leader and the head of QIMR Berghofer’s Translational and Human Immunology Group, Associate Professor Corey Smith,
said the researchers examined blood donated by 44 Queenslanders who had recovered from COVID-19. He said their goal was
to find out which combination of viral peptides could be used to stimulate T cells in the laboratory and allow
researchers to measure their response to SARS-CoV-2.
“T cells produce a range of signalling molecules when they fight viruses,” Associate Professor Smith said.
“These signalling molecules are basically indicators of whether T cells are responding to the SARS-CoV-2 virus and are
mobilising the immune army to launch an attack.
“If we can find a way to detect whether or not they are present, then we can find out whether or not a patient’s immune
system is responding as it should.
“We isolated the T cells from the donated blood, exposed them to viral peptides, and measured the production of a number
of different signalling molecules. We then compared the levels produced by T cells from the recovered COVID-19 patients
with levels released by T cells from 20 healthy donors who had never been infected with SARS-CoV-2.
“We found that T cells from people who had recovered from COVID-19 produced larger amounts of the signalling molecules
interferon gamma and interleukin-2, which are involved in killing virus-infected cells and encouraging other T cells to
come to the infected area.
“We screened a range of SARS-CoV-2 peptides to work out which combination could be used to detect a successful T cell
immune response, which we can then measure by detecting these two key signalling molecules.
More than 67 million cases of COVID-19 have been reported worldwide and the disease has caused more than 1.5 million
deaths, according to Johns Hopkins University data. In Australia 908 people have died from the disease, and there have
been more than 27,970 reported infections.
QIMR Berghofer researcher Dr Katie Lineburg said while Australia had been largely successful in controlling infection
rates, a blood test for early immune response to the virus could particularly help other countries experiencing second
and third waves.
“Now that we’ve refined a way to detect whether or not T cells are reacting to SARS-CoV-2, we believe this information
could be used to develop a blood test,” Dr Lineburg said.
“A blood test could help doctors identify patients whose T cells have not started mounting an immune response and who
are therefore not fighting the virus and are at higher risk of becoming seriously unwell. Those patients could then be
monitored more closely to ensure they receive treatment early, rather than waiting until they experience severe
symptoms.
“While the world waits for a vaccine to be rolled out, it’s clear the virus will continue to spread and people will
continue to get sick, placing more pressure on health systems. A blood test that could detect whether a patient is
developing an effective immune response would be another important tool in managing how countries deal with the
pandemic.
“This prototype test and our enhanced understanding of COVID-19 was only made possible by the generous actions of
Queenslanders who donated blood samples for this study.
“These are the first results from this COVID-19 study, and we will follow up with as many participants as possible in
future, to improve our understanding of long-term immunity to the virus.”
More than 60 Queenslanders who tested positive for COVID-19 donated blood for the project. Forty-four samples were used
for the analysis, which included 17 men and 27 women aged between 20 and 75. The remaining samples are still being
analysed.
Details of the study have been published today in the journal Clinical & Translational Immunology.
The research was funded by philanthropic donations, including from Mr Clive Berghofer AM and the Brazil Family
Foundation.
The researchers have recently been awarded a Medical Research Future Fund grant from the Australian Government to
continue their study and explore immunotherapeutic options for the virus, in collaboration with scientists at The
University of Queensland, Monash University and Mater Research.