PT  - JOURNAL ARTICLE
AU  - Swapnil Mahajan
AU  - Vasumathi Kode
AU  - Keshav Bhojak
AU  - Coral M. Magdalene
AU  - Kayla Lee
AU  - Malini Manoharan
AU  - Athulya Ramesh
AU  - HV Sudheendra
AU  - Ankita Srivastava
AU  - Rekha Sathian
AU  - Tahira Khan
AU  - Prasanna Kumar
AU  - Papia Chakraborty
AU  - Amitabha Chaudhuri
TI  - Immunodominant T-cell epitopes from the SARS-CoV-2 spike antigen reveal robust pre-existing T-cell immunity in unexposed individuals
AID  - 10.1101/2020.11.03.367375
DP  - 2020 Jan 01
TA  - bioRxiv
PG  - 2020.11.03.367375
4099  - http://biorxiv.org/content/early/2020/11/05/2020.11.03.367375.short
4100  - http://biorxiv.org/content/early/2020/11/05/2020.11.03.367375.full
AB  - The COVID-19 pandemic has revealed a range of disease phenotypes in infected patients with asymptomatic, mild or severe clinical outcomes, but the mechanisms that determine such variable outcomes remain unresolved. In this study, we identified immunodominant CD8 T-cell epitopes in the RBD and the non-RBD domain of the spike antigen using a novel TCR-binding algorithm. A selected pool of 11 predicted epitopes induced robust T-cell activation in unexposed donors demonstrating pre-existing CD4 and CD8 T-cell immunity to SARS-CoV-2 antigen. The T-cell reactivity to the predicted epitopes was higher than the Spike-S1 and S2 peptide pools containing 157 and 158 peptides both in unexposed donors and in convalescent patients suggesting that strong T-cell epitopes are likely to be missed when larger peptide pools are used in assays. A key finding of our study is that pre-existing T-cell immunity to SARS-CoV-2 is contributed by TCRs that recognize common viral antigens such as Influenza and CMV, even though the viral epitopes lack sequence identity to the SARS-CoV-2 epitopes. This finding is in contrast to multiple published studies in which pre-existing T-cell immunity is suggested to arise from shared epitopes between SARS-CoV-2 and other common cold-causing coronaviruses. Whether the presence of pre-existing T-cell immunity provides protection against COVID-19 or contributes to severe disease phenotype remains to be determined in a larger cohort. However, our findings raise the expectation that a significant majority of the global population is likely to have SARS-CoV-2 reactive T-cells because of prior exposure to flu and CMV viruses, in addition to common cold-causing coronaviruses.Competing Interest StatementAll authors are employees of MedGenome.