If antibodies fail, T cells in people who have recovered from COVID may protect against omicrons, says US study

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New Delhi: The body’s immune response – driven by T cells – may be able to counteract the new SARS-CoV-2 variant omicron in individuals recovered from COVID, even if it is able to evade antibodies, a new study Researchers in the US have said.

AT cells are a type of white blood cell that play a central role in the immune response that involves killing already infected cells and releasing proteins that act as signals to other cells to develop antibodies.

The study was conducted by the US National Institute of Allergy and Infectious Diseases and Johns Hopkins University. This was posted on the preprint portal biorxiv To be peer reviewed on December 9th and now.

With a large number of re-infections (people who have had covid before becoming infected with Omicron) Reported, as well as more than 30 mutations in the spike protein of Omicron (the stretched part of the coronavirus that allows the pathogen to enter the host cell), which most vaccines target, there is a concern that the variant may evade the immune response. May be caused by both prior infection or vaccination.

Now, study data suggest that nearly all individuals with existing anti-SARS-CoV-2 CD8+ T cell responses should recognize the omicron variant. CD8+ T cells are the ones that are known to initiate the death of infected cells.

The researchers note that SARS-CoV-2 has not developed widespread T-cell escape mutations at this time. However, the researchers acknowledged that the study had some limitations, such as a very small sample size.

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No change in viral epitopes

Researchers studied blood samples from 30 people who had recovered from a Covid infection in the US in April and May 2020.

They then identified viral epitopes — or parts of the virus that are targeted by CD8+ T-cells. The team found at least 52 separate episodes that are targeted by CD8+ T-cells in people who have recovered from COVID.

The team studied about 50 mutations in the oomicron, they found no changes in all but one epitope, meaning it is unlikely to escape action by CD8+ T cells. In one epitope, they found a single amino acid change in the spike protein.

Small sample size, only infected individuals

The team acknowledged several limitations to their study. The results, he said, are based on a relatively small sample size of individuals who were all from the US.

The team analyzed T-cell responses only in previously infected individuals, but not in those who had been vaccinated.

It is thus possible that T-cell responses in people who have received vaccines but have not been previously infected are limited.

However, the team said that in the past work examining T-cell responses from vaccinated people has demonstrated stronger T-cell responses, suggesting that similar trends should be observed in this population.

(Edited by Polomi Banerjee)

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