Researchers at the Francis Creek Institute and University College London have discovered that the common cold can also target some antibodies produced by the immune system during coronavirus infection. SARS-CoV-2 And may provide a slight degree of protection against new viral strains.
In response to a virus infection, the immune system makes antibodies to help fight. These antibodies remain in the blood for the post-infection period, and in case of re-infection, they are able to fight the virus again.
Published in his paper, in Science Today (Friday, November 6, 2020), scientists discovered that some people, especially children, are reactive to antibodies to SARS-Cavi-2 in their blood, even though they are not infected with the virus. These antibodies are probably the result of exposure to other coronaviruses, which cause the common cold and which have structural similarities with SARS-CoV-2.
The researchers made the discovery while developing highly sensitive antibody tests COVID-19. To see how well their ASSO tests were doing, they compared the blood of Covid-19 patients with patients who did not have the disease. Surprisingly, they found that some people who had not been exposed to SARS-CoV-2 had antibodies in their blood that could detect the virus. To confirm their findings, they analyzed more than 300 blood samples collected before the epidemic, between 2011 and 2018.
Almost all samples contained antibodies that reacted to the common cold coronavirus, which was expected to show how everyone was exposed to the virus at some point in their lives. However, a small proportion of adult donors, up to 1 in 20, also had antibodies that cross-reacted with SARS-CoV-2, and this is not based on recent infections with the common cold coronavirus.*
Significantly, such cross-reactive antibodies have been found more frequently in blood samples taken from children aged 6 to 16 years.
Kevin Eng, a lead author and postgraduate student at Creek’s Retroviral Immunology Laboratory, says: “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 children may be exposed to other coronaviruses more regularly.
“We have observed these high levels in children, which can also help explain why they are less likely to become seriously ill with COVID-19. There is no evidence yet, however, that these antibodies prevent SARS-CoV-2 infection or spread. “
In the laboratory, researchers tested antibodies found in the blood from inadvertent people to make sure they were able to neutralize SARS-CoV-2. They found that cross-reactive antibodies target the S2 subunit of spike protein on the surface of the virus.
George Cassiotis, senior author and group leader at the Retroviral Immunology Laboratory at Creek, says: “This coronavirus is made up of two parts or subunits, doing different jobs. The S1 subunit allows the virus to spread to cells and is relatively diverse in coronaviruses, while the S2 subunit allows the virus to enter cells and is more similar to this virus. Our work shows that the S2 subunit is sufficiently similar between normal cold coronavirus and SARS-CoV-2 to work for both antibodies.
“Previously it was thought that only antibodies to S1 could block infection, but now there is good evidence that some antibodies to S2 can be so effective. It is exciting to understand the basis of this activity, as it leads to vaccines working against a range of coronaviruses, including common cold strains, as well as SARS-CoV-2 and future epidemics.
“But it is important to emphasize that there are still many unknowns that need further research. For example, how is immunity to one coronavirus modified by exposure to another? Or why is this activity declining with age? It is not that people who have had a cold recently should think that they are immune to COVID-19. “
A major study is now underway in partnership with researchers at Imperial College London And University College Lodge London, to protect against COVID-19 and highlight the role of various immune defenses and how to become seriously ill.
Notes
* Researchers have found that:
- Of the samples taken from 50 pregnant women in May 2018, 10% had cross-reactive antibodies.
- Between 2011 and 2018, 21 of the 48 blood samples taken from children aged 1 to 16 contained these cross-reactive antibodies.
- An additional set of 13 adult donors recently infected with another coronavirus, only one test positive for these cross-reactive antibodies.
Reference: “Pre-existing SARS-COV-2 in humans and de novo moral immunity in humans” by NG, K Et al., 6 November 2020, Science.
DOI: 10.1126 / Science.Bay 11107
