| Title | Pre-existing T cell-mediated cross-reactivity to SARS-CoV-2 cannot solely be explained by prior exposure to endemic human coronaviruses. | ||
| Author | Tan, Cedric C S; Owen, Christopher J; Tham, Christine Y L; Bertoletti, Antonio; van Dorp, Lucy; Balloux, Francois | ||
| Journal | Infect Genet Evol | Publication Year/Month | 2021-Nov |
| PMID | 34509646 | PMCID | PMC8428999 |
| Affiliation + expend | 1.UCL Genetics Institute, University College London, Gower Street, London WC1E 6BT, United Kingdom. Electronic address: cedric.tan.18@ucl.ac.uk. | ||
T-cell-mediated immunity to SARS-CoV-2-derived peptides in individuals unexposed to SARS-CoV-2 has been previously reported. This pre-existing immunity was suggested to largely derive from prior exposure to \'common cold\' endemic human coronaviruses (HCoVs). To test this, we characterised the sequence homology of SARS-CoV-2-derived T-cell epitopes reported in the literature across the full proteome of the Coronaviridae family. 54.8% of these epitopes had no homology to any of the HCoVs. Further, the proportion of SARS-CoV-2-derived epitopes with any level of sequence homology to the proteins encoded by any of the coronaviruses tested is well-predicted by their alignment-free phylogenetic distance to SARS-CoV-2 (Pearson\'s r = -0.958). No coronavirus in our dataset showed a significant excess of T-cell epitope homology relative to the proportion of expected random matches, given their genetic similarity to SARS-CoV-2. Our findings suggest that prior exposure to human or animal-associated coronaviruses cannot completely explain the T-cell repertoire in unexposed individuals that recognise SARS-CoV-2 cross-reactive epitopes.