Important Epitopes Targeted by T Cells in Convalescent COVID-19 Patients Identified

NEW YORK (Reuters Health) – A meta-analysis of SARS-CoV-2 epitopes targeted by T cells in convalescent patients identified 20 that are prevalent in multiple cohorts, and potentially relevant to vaccine development and diagnostics, researchers say.

“Increasing evidence suggests T-cell immunity to be an important factor in protecting against severe COVID-19 disease,” Drs. Matthew McKay and Ahmed Abdul Quadeer of the Hong Kong University of Science and Technology told Reuters Health in a joint email. “This knowledge can yield clinically relevant insights by helping to identify possible correlates between specificity of T-cell responses and favorable disease outcomes.”

“It could also be used for the purpose of rationally designing novel vaccines that attempt to elicit robust T-cell responses against specific epitopes, and to design novel T-cell-based diagnostics,” they said.

Their meta-analysis pooled data from 18 immunological studies involving (852) COVID-19 survivors from four continents who are well-distributed in age, gender, disease severity and blood collection time.

“We developed a web platform to integrate this data, report relevant analytics, and make it collectively available to scientists for further research,” they said. (https://bit.ly/3fPO55S) “We also intend to keep the platform updated with the most recent data of global SARS-CoV-2 genetic sequences (which is increasing rapidly), and with information about emerging variants of concern as they arise.”

As reported in Cell Reports Medicine, half of the studies in the meta-analysis characterized T cell responses against the whole proteome; the others focused on responses mounted against subsets of SARS-CoV-2 proteins.

Overall, the analysis demonstrated the broad diversity of T-cell epitopes that have been recorded for SARS-CoV-2. A large majority are seemingly unaffected by the current variants of concern.

The team also identified a set of 20 immunoprevalent epitopes that induced T-cell responses in multiple cohorts and in a large fraction of tested patients.

The authors state, “Collectively, the observed heterogeneity of T-cell responses against SARS-CoV-2 provides little evidence to suggest that the observed genetic variation in the (spike) protein may significantly affect T-cell immunity, in line with a recent report.” (https://bit.ly/34LzDpi)

Drs. McKay and Quadeer added, “Our data would suggest that T-cell responses are likely to be robust, particularly if the T cell responses triggered upon vaccination are similar to those of natural infection.”

Dr. Jacob Elmer, Associate Professor of Chemical Engineering at Villanova University’s College of Engineering in Pennsylvania, commented in an email to Reuters Health, “The study summarizes findings from several other studies, so it does not have a high degree of novelty, but it is still intriguing to see an analysis at this scale.”

“It will be very interesting to see if the T-cell responses described in this study match the T-cell responses in vaccinated individuals…treated with mRNA that expressed the spike protein of COVID-19,” he said. “This type of comparison could help to confirm that mRNA vaccines are just as effective (or potentially more effective) as traditional infections at inducing an immune response.”

SOURCE: https://bit.ly/3pfyWOA Cell Reports Medicine, online May 21, 2021.

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