People with higher levels of T cells from coronaviruses that cause common colds are less likely to be infected with SARS-CoV-2, according to a new study published in the scientific journal ‘Nature Communications’ and directed by researchers from Imperial College from London (UK).
While previous studies have shown that T cells induced by other coronaviruses can recognize SARS-CoV-2, this research examines for the first time how the presence of these T cells at the time of exposure to SARS-CoV-2 influences someone getting infected.
The researchers also claim that their findings provide a model for a universal second-generation vaccine that could prevent infection by current and future variants of SARS-CoV-2, including omicron.
The importance of the vaccine
“Exposure to the SARS-CoV-2 virus does not always lead to infection, and we wanted to understand why. We have discovered that high levels of pre-existing T cells, created by the body when infected with other human coronaviruses such as common cold, they can protect against infection with the covid virus. Although this is an important discovery, it is only a form of protection, and I would like to emphasize that the best way to protect against covid is to be completely vaccinated, including booster dose “, has commented the doctor Rhia Kundu, first author of the study, of the National Institute of the Heart and the Lungs of the Imperial College of London.
The study began in September 2020, when the majority of people in the UK had not been infected or vaccinated against SARS-CoV-2. It included 52 people who lived with someone with a PCR-confirmed SARS-CoV-2 infection and who had therefore been exposed to the virus. The participants underwent PCR tests at the beginning and 4 and 7 days later, to determine if they had developed an infection.
Blood samples were taken from the 52 participants 1 to 6 days after they were exposed to the virus. This allowed the researchers to analyze pre-existing T-cell levels induced by previous common cold coronavirus infections that also cross-recognize SARS-CoV-2 proteins.
The researchers found that there were significantly higher levels of these cross-reactive T cells in the 26 people who were not infected, compared to the 26 that did get infected. These T cells targeted the internal proteins of the SARS-CoV-2 virus, rather than the spike protein on the surface of the virus, to protect themselves from infection.
Immune response
Current vaccines do not induce an immune response to these internal proteins. The researchers say that, along with the effective spike protein vaccines that already exist, these internal proteins offer a new vaccine target which could provide long-lasting protection, as T-cell responses persist longer than antibody responses, which decline within a few months of vaccination.
Related news
“Our study provides the clearest evidence to date that T cells induced by common cold coronaviruses play a protective role against SARS-CoV-2 infection. These T cells provide protection by attacking proteins within the virus. , rather than the spike protein on its surface. spike protein it is under intense immune pressure from vaccine-induced antibodies, which drives the evolution of vaccine escape mutants.
In contrast, the internal proteins targeted by the protective T cells we have identified mutate much less. Consequently, they are highly conserved among the various SARS-CoV-2 variants, including omicron. Therefore, new vaccines that include these conserved internal proteins would induce broadly protective T cell responses that should protect against current and future variants of SARS-CoV-2“, emphasizes Professor Ajit Lalvani, lead author of the study.
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