San Francisco, May 20 : An antibody first identified in a blood sample from a patient who recovered from Severe Acute Respiratory Syndrome (SARS) in 2003 has demonstrated ability to prevent SARS-CoV-2 live virus infection of cells in laboratory, says a study, raising new hope in the fight against COVID-19.
The antibody, called S309, is now on a fast-track development and testing path at San Francisco-headquartered Vir Biotechnology in the next step toward possible clinical trials.
The initial results, published in the journal Nature, could ultimately pave the way for using the S309 antibody, alone or in a mixture, as a preventive measure for people at high-risk of exposure to the COVID-19 coronavirus or as post-exposure therapy to limit or treat severe illness, according to the scientists.
“We still need to show that this antibody is protective in living systems, which has not yet been done,” said study co-author David Veesler, Assistant Professor of Biochemistry at the University of Washington School of Medicine.
“Right now there are no approved tools or licensed therapeutics proven to fight against the coronavirus that causes COVID-19,” he added.
Vir Biotechnology in a separate statement said it is advancing two clinical development candidates based on the S309 antibody as potential therapeutics for COVID-19 — VIR-7831 and VIR-7832 — in collaboration with GlaxoSmithKline plc.
The research showed that the S309 antibody is particularly potent at targeting and disabling the spike protein that promotes the coronavirus entry into cells.
It was able to neutralise SARS CoV-2 by engaging with a section of the spike protein near the attachment site to the host cell.
Through their cryo-electronmicroscopy studies and binding assays, the researchers learned that the S309 antibody recognises a binding site on the coronavirus that is conserved across many sarbocoviruses, not just the SARS and COVID-19 viruses.
That is probably why this antibody, instead of being single-minded, is able to act against related coronaviruses.
Combining the S309 antibody with other, though weaker, antibodies identified in the recovered SARS patient enhanced the neutralisation of the COVID-19 coronavirus, said the study.
This multiple antibody cocktail approach might help limit the coronavirus’ ability to form mutants capable of escaping a single-ingredient antibody treatment, according to the researchers.
“Remarkably, we believe S309 likely covers the entire family of related coronaviruses, which suggests that, even as SARS-CoV-2 continues to evolve, it may be quite challenging for it to become resistant to the neutralizing activity of S309,” Herbert “Skip” Virgin, Chief Scientific Officer, Vir, said in a statement.
“In addition, S309 exhibits potent effector function in vitro, potentially allowing the antibody to engage and recruit the rest of the immune system to kill off already infected cells.”