Researchers at the Francis Crick Institute and University College London have found that some antibodies, created by the immune system during infection with common cold coronaviruses, can also target SARS-CoV-2 and may confer a degree of protection against the new viral strain.
In their article, published in Science, the scientists found that some people, notably children, have antibodies reactive to SARS-CoV-2 in their blood, despite not ever having been infected with the virus. These antibodies are likely the result of exposure to other coronaviruses.
The authors report that SARS-CoV-2 spike glycoprotein (S)-reactive antibodies were detectable by a flow cytometry-based method in SARS-CoV-2-uninfected individuals and were particularly prevalent in children and adolescents. They were predominantly of the immunoglobulin G (IgG) class and targeted the S2 subunit.
SARS-CoV-2 infection induced higher titers of SARS-CoV-2 S-reactive IgG antibodies, targeting both the S1 and S2 subunits, and concomitant immunoglobulin M and A antibodies, lasting throughout the observation period.
SARS-CoV-2-uninfected donor sera exhibited specific neutralising activity against SARS-CoV-2 and SARS-CoV-2 S pseudotypes.
George Kassiotis, senior author and group leader of the Retroviral Immunology Laboratory at the Crick says: "Our work shows that the S2 subunit is sufficiently similar between common cold coronaviruses and SARS-CoV-2 for some antibodies to work against both."
"It was previously thought that only antibodies to the S1 could block infection, but there is now good evidence that some antibodies to S2 can be just as effective. This is exciting as understanding the basis for this activity could lead to vaccines that work against a range of coronaviruses, including the common cold strains, as well as SARS-CoV-2 and any future pandemic strains."
"But it is important to stress that there are still many unknowns which require further research. For example, exactly how is immunity to one coronavirus modified by exposure to another? Or why does this activity decline with age? It is not the case that people who have recently had a cold should think they are immune to COVID-19."
A large study is now underway, in partnership with researchers at Imperial College London and University College London, to uncover the role that different antibodies and other immune defences play in protection against COVID-19 and how severely ill people become.