By Brooklyn Neustaeter, CTVNews.ca writer
TORONTO, Ontario (CTV network) – A new study has found that those who were granted immunity to the original strain of SARS-CoV-2, the virus that causes COVID-19, are likely to have some protection against the Omicron variant.
The study, conducted by an international team of researchers from Johns Hopkins Medicine, reports that people who have been vaccinated or exposed to infection have a certain level of protection against Omicron, as its mutations are not found in the parts of the virus that stimulate a cellular immune system. response.
However, researchers warn that their findings relate to only one type of cellular immune response. Because of this, they say, it may be the antibody-related immune response that fails when Omicron causes breakthrough infections.
The results were published earlier this month in mBio, a peer-reviewed scientific journal of the American Society for Microbiology. The research was conducted in collaboration with the US National Institute of Allergy and Infectious Diseases (NIAID) and ImmunoScape, a US-Singapore biotechnology company.
Researchers say the study reinforces other findings from the United States and South Africa that have shown similar results for people previously infected with or vaccinated against the original strain of COVID-19.
Scientist and study leader Andrew Redd said that in a January 2021 study, researchers found that specific epitopes or parts of a protein that elicit an immune response from the virus are recognized by immune system cells called CD8 + T lymphocytes, also known as killer T cells or cytotoxic T cells, in those previously infected with the original COVID-19 strain.
Redd explained in a press release that this recognition allows for a “cell-mediated attack on COVID” in an attempt to remove the virus from the body.
“In our recent work, we found that these epitopes remained virtually unaffected by the mutations found in the Omicron variant. Therefore, the CD8 + T cell response to Omicron should be practically as strong as it was on the original form of SARS. CoV-2, ”said Redd.
According to researchers, the T cells used in the most recent study were from convalescent blood samples collected in 2020 from 30 U.S. patients who had recovered from mild to moderate cases of COVID-19. These samples were taken between 26 and 62 days after the donors stopped having COVID-19 symptoms to ensure that their immune response to the virus was “fully mature,” according to the study.
They were then analyzed to identify which T cells had responded to the virus.
In the January 2021 analysis, the blood samples were tested with 408 different SARS-CoV-2 epitopes from peaks on the virus surface, the virus capsule, and non-structural proteins inside the virus, according to the study.
After analysis, the researchers found that T cells from the convalescent donors were able to recognize 52 of the 408 epitopes.
In the latest study, researchers re-examined these 52 previously identified epitopes to see if they had been altered by “escape mutations,” which are genetic changes that can allow a virus to avoid being susceptible to cell-mediated immunity.
Researchers noted that blood samples were stored correctly between each study period.
Redd said in the release that researchers found only “one low-prevalence epitope from the Omicron tip protein that had a minor change” compared to the original strain of the virus.
“Overall, the Omicron variant is known to have more than 50 mutation differences between it and the original SARS-CoV-2 strain, but it appears that the virus has not developed the ability to avoid T-cell recognition,” said Redd.
While the results suggest that immunity is maintained from the original COVID-19 strain through its subsequent variants, the study authors say more research is needed to fully define why people who have this protection can still get sick. by Omicron.
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