The working principle of a vaccine is to provide a molecule to the body to help the immune system “learn” how to recognize certain pathogens. These molecules are called antigens, and the large antigen targeted by our first wave of COVID-19 vaccines is the infamous new coronavirus spike protein.
Looking forward to the next generation of COVID-19 vaccines, researchers are looking for things other than spike proteins and studying alternative SARS-CoV-2 antigens. The new study started by studying a group of medical workers in the UK. Although they were exposed to a large number of viruses, it is strange that their tests for SARS-CoV-2 seemed to be repeatedly negative.
This cohort has always been negative for ordinary antibody and PCR tests. However, the researchers did detect some blood markers suggesting SARS-CoV-2 infection. The detection of an increase in immune T cells that specifically target SARS-CoV-2 indicates that medical staff may have experienced a low-level infection, but managed to resist it in some way.
“We know that some people are not infected even though they may be exposed to the virus,” explains Leo Swadling, the lead author of the new study. “What we don’t know is whether these people actually managed to avoid the virus completely, or whether they cleared the virus naturally before routine testing could detect it. Through intensive monitoring of medical staff for signs of infection and immune response, we found a small number of people With this special SARS-CoV-2 specific T cell response.”
The T cells detected in the study were trained to target non-structural proteins that play a role in the early stages of the virus life cycle. These proteins are part of the viral replication transcription complex, more commonly called replication proteins.
The most interesting thing is that these specific replication proteins are common to all coronaviruses. Therefore, the researchers hypothesized that those who have a strong T-cell response to these proteins may have recently been exposed to a more harmless coronavirus that causes the common cold.
Swadling said: “The virus regions recognized by these T cells are highly conserved among other members of the coronavirus family, such as those viruses that cause the common cold every year. Previous exposure to the common cold may have given these people the first chance to fight the virus. Machine, so that their immune system will wipe out the virus before it starts to replicate.”
These findings are based on an increasing hypothesis that suggests that there is a cross-reactive immune response between SARS-CoV-2 and common coronaviruses. A recent Stanford University study speculated that previous exposure to the coronavirus that causes the common cold may explain why some people experience incredibly mild or even asymptomatic forms of COVID-19.
But the most promising implication of this research is to speculate that these replication proteins can be used as antigens to be included in future COVID-19 vaccines. The senior author of the new study, Mali Maini, said that vaccines that induce T cells to target these replication proteins may provide protection against all current coronaviruses, including those that cause the common cold.
Maini also pointed out that future vaccines will include these newer antigens, as well as those spike protein antigens. This will create a free system with antibodies trained to quickly recognize spike proteins and memory T cells that target these replicating proteins.
This new research is published in“nature”In the magazine.