The ongoing COVID-19 pandemic calls for more effective diagnostic tools. T cell response assessment serves as an independent indicator of prior COVID-19 exposure while also contributing to a more comprehensive characterization of SARS-CoV-2 immunity. In this study, we systematically assessed the immunogenicity of 118 epitopes with immune cells collected from multiple cohorts of vaccinated, convalescent, healthy unexposed, and SARS-CoV-2–exposed donors. We identified 75 immunogenic epitopes, 24 of which were immunodominant. We further confirmed HLA restriction for 49 epitopes and described association with more than 1 HLA allele for 14 of these. Exclusion of 2 cross-reactive epitopes that generated a response in prepandemic samples left us with a 73-epitope set that offered excellent diagnostic specificity without losing sensitivity compared with full-length antigens, and this evoked a robust cross-reactive response. We subsequently incorporated this set of epitopes into an in vitro diagnostic Corona-T-test, which achieved a diagnostic accuracy of 95% in a clinical trial. In a cohort of asymptomatic seronegative individuals with a history of prolonged SARS-CoV-2 exposure, we observed a complete absence of T cell response to our epitope panel. In combination with strong reactivity to full-length antigens, this suggests that a cross-reactive response might protect these individuals.
Aleksei Titov, Regina Shaykhutdinova, Olga V. Shcherbakova, Yana V. Serdyuk, Savely A. Sheetikov, Ksenia V. Zornikova, Alexandra V. Maleeva, Alexandra Khmelevskaya, Dmitry V. Dianov, Naina T. Shakirova, Dmitry B. Malko, Maxim Shkurnikov, Stepan Nersisyan, Alexander Tonevitsky, Ekaterina Khamaganova, Anton V. Ershov, Elena Y. Osipova, Ruslan V. Nikolaev, Dmitry E. Pershin, Viktoria A. Vedmedskia, Michael Maschan, Victoria R. Ginanova, Grigory A. Efimov