People exposed to members of the coronavirus family before meeting SARS-CoV-2 are less likely to become infected through home contact with covid patients, according to a study published in the journal Nature Communications. Such people develop cross-immunity – memory T cells, which are able to respond to protein motifs in SARS-CoV-2, similar to those of less dangerous coronaviruses.
Biologists knew about the existence of coronaviruses (viruses with a shell similar to a crown) long before the COVID-19 pandemic – this family was described in the journal Nature back in 1968. The viruses isolated then caused only the symptoms of a common cold. Studies show that memory T cells specific for infection with such human coronaviruses are able to exhibit an immune cross-reaction – to bind particles of the deadly SARS-CoV-2. However, until now it was not known exactly how the presence of such T cells affects the likelihood of infection with covid.
Researchers from Imperial College London, led by Rhia Kundu, analyzed the process of infection with covid during home contact with patients and its relationship with the presence of memory T cells to other coronaviruses. The study involved 52 people living with patients recently diagnosed with covid. After several days of contact with covid patients, blood samples were collected from the participants to determine the number of cross-reactive T cells. To do this, biologists identified similar regions of the proteins of SARS-CoV-2 and other coronaviruses – they turned out to be regions of adhesion proteins (it is it that is used for the production of many vaccines), nucleocapsid, membrane, envelope and ORF1 protein. Participants were also given PCR tests to track their contamination.
It turned out that in those 26 people who managed not to get sick after contact with patients, the level of memory T-cells was significantly higher than in those who became infected (p = 0.0139). Interestingly, these cells were targeted to recognize the internal proteins of the virus, but did not recognize adhesion proteins. Thus, the study not only showed that immunity to the common cold due to the harmless coronavirus can protect against SARS-CoV-2 infection, but also opens up a new way to produce effective vaccines – using the internal proteins of the virus instead of spike proteins.
A vaccine based on T-cell activation will be tested by Emergex in Switzerland. Its developers believe that their vaccination in the form of a patch with microneedles can create a more durable and resistant to mutations immunity. Read about how new mutations and variants of SARS-CoV-2 appear in the material “Heirs and troublemakers”.