Coronavirus: strong T cell response against Omicron, study finds

A new study by researchers in Hong Kong and Australia suggests that T cells – a less discussed aspect of the body’s immune response – are equipped to fight Omicron, despite the variant’s many mutations.

When we talk about the immune response, we often focus on neutralizing antibodies, but there are other facets of the immune system as well. One of them is that of T cells, which can be generated by both vaccination and a previous infection with COVID-19.

Previous studies have suggested that Omicron has a greater ability to escape antibodies, potentially increasing its ability to transmit.

But this new research, published in the journal Virus on Sunday, found that Omicron might not be able to escape T cells as easily, potentially allowing T cells to help limit serious illness in people infected with the virus.

“Although this is a preliminary study, we believe this is positive news,” said Matthew Mckay, University of Melbourne professor and co-head of research, in A press release. “Even though Omicron, or another variant for that matter, can potentially evade antibodies, a robust T cell response can still be expected to provide protection and help prevent serious disease.”

One of the most concerning aspects of Omicron is its increased number of mutations, especially in the spike protein, which is how SARS-CoV-2 attaches to our cells to attack the human body.

The importance of the spike protein is why our existing vaccines target it so strongly in order to produce antibodies.

The response of T cells to infection with COVID-19 has not been studied as closely as antibodies, but T cells contribute to the immune response in large part by killing cells infected with viruses.

In order to study this T cell response, the researchers examined more than 1,500 T cell epitopes of SARS-CoV-2. Epitopes are part of an antigen that antibodies, T cells, or B cells can recognize and bind to in order to trigger the processes necessary to destroy the virus. By focusing on the epitopes that T cells have been observed to recognize in COVID-19 patients or those vaccinated, the researchers were looking to see if the Omicron mutations interfered with the ability of T cells to bind to these epitopes. .

They found that only 20 percent of T cell epitopes in vaccinated or previously infected individuals had mutations similar to Omicron, which could open a door for the virus. But that doesn’t mean that the 20% with these mutations will be able to escape T cells at all times, the researchers said.

“Of those T cell epitopes that have Omicron mutations, our further analysis revealed that more than half are still expected to be visible by T cells,” Ahmed Abdul Quadeer, assistant research professor in the Department of Electronics and computer science from Hong Kong University of Science and Technology. Engineering and co-lead of the study, said in the statement. “This further decreases the chances that Omicron will be able to evade T cell defenses.”

Apart from mutations on the spike protein, the researchers found that over 97% of the spike-free T cell epitopes lacked mutations similar to Omicron.

“Overall, these results suggest that a large T cell breakout is very unlikely,” McKay said. “Based on our data, we predict that T-cell responses elicited by vaccines and boosters, for example, will continue to help protect against Omicron, as seen for other variants. “

The researchers noted in the study that they had studied the epitopes of SARS-CoV-2 that were determined in previous experiments, which means that there may be other epitopes that they are not at. running.

“Further targeted experiments are needed to confirm the robustness of T cell responses against Omicron, and also to test the ability of specific epitope mutations to confer T cell escape,” the study said.

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