Although the issue had already been considered in previous studies, this is the first time that it has examined how memory T cells on previous coronaviruses influence the time of exposure to SARS-CoV-2.
Madrid, January 10 (Europa Press) .- People with higher levels of T cells from the coronaviruses that cause common colds have 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 London (United Kingdom).
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 the someone to get 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.
“Exposure to the SARS-CoV-2 virus does not always lead to infection, and we wanted to understand why. We have found that high levels of pre-existing T cells, created by the body when it becomes infected with other human coronaviruses such as the common cold, can protect against infection with the COVID-19 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-19 is to be fully vaccinated, including the booster dose, ”commented Dr. Rhia Kundu, first study author, from the National Heart and Lung Institute at Imperial College London.
Cross-reactive memory T cells associate with protection against SARS-CoV-2 infection in COVID-19 contacts
There is crossreactivity in some of us that helps. Vaccination is the best protection.https://t.co/W2b3Buf4iV
— Marc Veldhoen (@Marc_Veld) January 10, 2022
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 four and seven days later, to determine if they had developed an infection.
Blood samples were taken from the 52 participants between one and six 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 did not get infected, compared to the 26 who did. 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.
Current vaccines do not induce an immune response to these internal proteins. The researchers say that alongside effective spike protein vaccines that already exist, these internal proteins offer a new vaccine target that could provide long-lasting protection, as T-cell responses persist longer than responses. of antibodies, which decrease a few months after vaccination.
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The researchers found that there were significantly higher levels of these cross-reactive T cells in the 26 people who did not get infected, compared to the 26 who did. Photo: Paco Torrente, EFE
“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 inside the virus, rather than the spike protein on its surface. The spike protein 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.