While neutralizing antibodies are the basis for the development of future SARS-CoV-2 vaccines, we must nevertheless remain cautious, say researchers from the Research Center of the Center hospitalier de l’Université de Montréal (CRCHUM ).
“Our study shows that more than 6 in 10 infected people produced neutralizing antibodies just two weeks after the onset of symptoms of the disease. However, this neutralization capacity decreases after six weeks. In this case, a few booster shots of the vaccine may be necessary to protect the population in the long term, “says researcher Andrés Finzi, Canada Research Chair in retroviral entry and professor at the University of Montreal.
In a non-peer-reviewed study posted on the bioRxiv prepublishing server, the D teamr Finzi assessed the ability to neutralize plasma – the liquid component of the blood containing antibodies – one, two, three, and six weeks after symptoms of the disease began. To do this, it used viral pseudoparticles which express on their surface the glycoproteinS (or glycoproteinSpike) of SARS-CoV-2. This “key to entry” allows the virus to unblock the door of healthy cells, enter and infect them.
To conduct their experiments, the scientific team used plasma samples from 108 patients, healthy, infected or convalescent, supplied by their colleagues from Héma-Québec and the Laboratoire de santé publique du Québec.
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To recognize is not to neutralize
Professor Andrés Finzi
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The results of the study also confirm those of other recent studies: after three weeks, more than 90% of infected people have antibodies that recognize one of the signatures of SARS-CoV-2, the glycoprotein S. After six weeks , it’s 100%.
But for an antibody, recognizing a virus does not mean that it is able to neutralize it. The range of action is wide: some effectively defeat it, others block it timidly or not at all.
“Will people who have developed neutralizing antibodies be protected from reinfection? We don’t know yet, says Andrés Finzi. In the event of reinfection, we can assume that the so-called memory B cells will be rapidly activated to produce neutralizing antibodies to the virus. ”
More studies will be needed to determine, for example, how long a person exposed to the virus a second time is protected or whether protection requires the production of neutralizing antibodies. These are the next questions that the D teamr Finzi plans to tackle it, now that ELISA serology, flow cytometry, and viral neutralization tests have been developed in his laboratory.
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About CRCHUM
The Research Center of the Center hospitalier de l’Université de Montréal (CRCHUM) is one of the main hospital research centers in North America. Its mission is to improve health in adults through a research continuum spanning disciplines such as basic sciences, clinical research and public health. More than 1,850 people work at CRCHUM, including more than 550 researchers and more than 460 graduate students.
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