When a virus infects a person, their immune system creates antibodies to help fight it. Researchers have now found that some antibodies which are caused after infection with common cold coronaviruses, and which remain in the blood for some time, can also target SARS-CoV-2. The study, by researchers at the Francis Crick Institute and University College London, is published in the journal Science.
The researchers made their discovery while developing highly sensitive antibody tests for Covid-19. They compared the blood of Covid-19 patients with that of patients who had not had the disease. They found that some people have antibodies reactive to SARS-CoV-2 in their blood, despite not ever having being infected with this virus. These antibodies are likely the result of exposure to other coronaviruses, which cause a common cold and which have structural similarities with SARS-CoV-2.
To reconfirm, the scientists analysed over 300 blood samples collected before the pandemic, between 2011 and 2018. Nearly all samples had antibodies that reacted with common cold coronaviruses, which was expected. In addition, about 1 in 20 adults also had antibodies that cross-reacted with SARS-CoV-2, and this was not dependent on recent infection with a common cold coronavirus. Among children aged 6 to 16, such cross-reactive antibodies were found much more frequently.
“Our results show that children are much more likely to have these cross-reactive antibodies than adults. More research is needed to understand why this is, but it could be down to children being more regularly exposed to other coronaviruses. These higher levels we observed in children could also help explain why they are less likely to become severely ill with Covid-19. There is no evidence yet, however, that these antibodies prevent SARS-CoV-2 infection or spread,” lead author Kevin Ng said in a statement. 📣 Express Explained is now on Telegram
The spike protein of SARS-CoV-2 is made of two parts or subunits, S1 and S2. The S1 subunit allows the virus to latch onto cells, whereas S2 lets the virus into cells. The researchers found that the S2 subunit in common cold coronaviruses and SARS-CoV-2 is similar enough for some antibodies to work against both.
The researchers stressed that there are still many unknowns which require further research. A large study is now underway, in partnership with researchers at Imperial College London and University College London.