AsianScientist (Feb. 15, 2022) – Immune cells called T cells are effective in defending the body against the Omicron variant of SARS-CoV-2, the viral agent causing COVID-19. The Hong Kong-Australia research team published the finding in Viruses.
As viruses spread from person to person, they inevitably accumulate mutations in their genetic material, leading to the emergence of new variants. SARS-CoV-2 is no exception. The communities have already felt the brunt of new waves of infections as the Delta and Omicron variants swept through populations.
Vaccines help teach the body to recognize SARS-CoV-2 and mount an immune response, recruiting an arsenal of cells and molecules to protect against the disease. For example, antibodies produced by B cells bind with the viral spike protein, neutralizing its ability to invade human host cells.
However, Omicron harbors a whopping 30 mutations in its spike protein, much more than the mutations found in previous variants. Studies show that these mutations may help the virus escape the antibodies produced by vaccination or prior COVID-19 infection, indicating a higher chance of reinfection and breakthrough cases.
Amid these growing concerns, researchers from the Hong Kong University of Science and Technology and the University of Melbourne in Australia turned to another class of immune cells– T cells. Similarly elicited by vaccination or prior infection, T cells can help prevent severe illness by eliminating virus-infected cells.
The team analyzed over 1,500 viral epitopes, which are fragments of SARS-CoV-2 proteins that are recognized by T cells in fully vaccinated individuals or recovered COVID-19 patients. Only 20 percent of the viral epitopes showed mutations associated with Omicron, while over half are predicted to still be visible to T cells. Moreover, a broader analysis of non-spike proteins revealed that over 97 percent of these epitopes do not contain Omicron-specific mutations. Taken together, the results diminish the chances that Omicron can escape T cell immunity.
Despite being a preliminary study, the researchers believe that the findings suggest that broad escape from T cells is highly unlikely and that such immune responses produced by vaccines and boosters will continue to help protect against Omicron.
“While the number of infections may rise considerably as a consequence of Omicron’s ability to evade antibodies, robust T cell immunity provides hope that, similar to other variants, the level of protection against severe disease would remain high,” the authors concluded.
Source: Hong Kong University of Science and Technology; Photo: Shutterstock.
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