Omicron: The role of T cells

Kern.The Omicron variant of SARS-CoV-2 has many mutations, which scientists believe help it escape neutralizing antibodies.However, if Omicron cannot escape T cells, then they may still have a level of protection against the variant.To identify whether Omicron can escape the T cell response, the researchers analyzed 1,500 SARS-CoV-2 epitopes — a type of viral fragment.“The authors effectively downloaded a list of recognized SARS-CoV-2 peptides from a public repository and aligned them to the mutated protein amino acid sequence of the Omicron variant.”“This allowed them to identify exactly which of the peptides recognized in earlier viral variants no longer existed with exactly the same sequence in the Omicron variant,” said Prof. This phenomenon is also known to occur with other human respiratory viruses, and signals that T cell immunity to SARS-CoV-2, once established, is potentially more broadly protective and [may be more] important than antibodies.”“Although antibodies are effective at neutralizing SARS-CoV-2, mutations within the spike protein in new variants often result in reduced ability of the preexisting antibodies to do so.”“These data may indicate that T cell immunity is more protective than antibodies against severe disease caused by Omicron, supporting some of the recent clinical findings,” Prof. “Overall, it is less likely that variants escaping T cell immunity will appear, as the T cell epitopes are often under less pressure to change, unlike the antibody epitopes, which tend to cluster in surface areas of the spike that have a critical function allowing entry of the virus into cells.”“T cells operate by seeking out and destroying cells infected with virus, targeting different parts of the spike compared [with] antibodies, thereby tolerating mutations found in new variants.”Dr. Quadeer said that T cells would likely offer protection whether they were developed following vaccination or a natural infection — however, further research is needed to confirm this.“Both natural infection and COVID-19 vaccines have been demonstrated to generate a strong T cell response.