How Covid infection spurs antibodies against common colds

New York, May 5 Getting sick with a common cold doesn't make you immune to Covid-19, but a Covid infection might, at least temporarily, boost the number of antibodies you have against common cold-causing coronaviruses and the SARS-CoV-1 and MERS-CoV viruses, all of which are closely related, finds a study.

A Scientists at Scripps Research in California have characterised coronavirus antibodies isolated from 11 people to reveal how Covid impacts the immune system's ability to recognise other coronaviruses.

"Getting a better understanding of how immunity against this broad family of coronaviruses changes with Covid-19 infection is an important step toward developing better coronavirus vaccines, both for Covid-19 and for future, related pathogens," said Andrew Ward, Professor of Integrative Structural and Computational Biology at Scripps Research.

The findings, published in the journal Science Advances, showed that the immune system's antibodies against one coronavirus spike protein could, potentially, also recognise other similar spike proteins as disease-causing.

In the study, the team studied serum samples from 11 people - eight dated to before the Covid pandemic, while three samples were from donors who recently had Covid.

In each case, the researchers measured how strongly the samples reacted to isolated spike proteins from different coronaviruses - OC43 and HKU1, both associated with common colds, along with SARS-CoV-1, MERS-CoV and SARS-CoV-2.

Only the serum from recovered Covid patients reacted to the SARS-CoV-2 spike proteins. However, these Covid patient samples also reacted more strongly than the pre-pandemic samples to the other spike proteins as well.

Further tests revealed that most coronavirus antibodies from before the pandemic recognised a section of the OC43 and HKU1 spike proteins known as the S1 subunit, which tends to vary greatly between coronaviruses.

In Covid patient samples, however, the researchers identified a broader swatch of antibodies, including ones that recognised the S2 subunit - which varies less between different coronaviruses.

Indeed, some antibodies from the Covid patients are not only bound to the common cold coronaviruses, but to SARS-CoV- and MERS-CoV spike proteins as well.

However, since these studies were done directly on serum antibodies, the researchers don't know whether the presence of these antibodies, in any of the cases, is enough to provide full immunity to coronaviruses in the more complex setting of the human immune system. They assert the need for further studies.