Longitudinal high-throughput TCR repertoire profiling reveals the dynamics of T-cell memory formation after mild COVID-19 infection

COVID-19 is a global pandemic caused by the SARS-CoV-2 coronavirus. T cells play a key role in the adaptive antiviral immune response by killing infected cells and facilitating the selection of virus-specific antibodies. However, neither the dynamics and cross-reactivity of the SARS-CoV-2-specific T-cell response nor the diversity of resulting immune memory is well understood. In this study, we use longitudinal high-throughput T-cell receptor (TCR) sequencing to track changes in the T-cell repertoire following two mild cases of COVID-19. In both donors, we identified CD4(+) and CD8(+) T-cell clones with transient clonal expansion after infection. We describe characteristic motifs in TCR sequences of COVID-19-reactive clones and show preferential occurrence of these motifs in publicly available large dataset of repertoires from COVID-19 patients. We show that in both donors, the majority of infection-reactive clonotypes acquire memory phenotypes. Certain T-cell clones were detected in the memory fraction at the preinfection time point, suggesting participation of pre-existing cross-reactive memory T cells in the immune response to SARS-CoV-2.

Automated summary

This study tracked changes in the T-cell repertoire of two mild COVID-19 cases and found transient clonal expansion of T-cell clones post-infection. The research revealed characteristic motifs in TCR sequences of COVID-19-reactive clones, with a preferential occurrence in publicly available datasets. Additionally, the study showed that the majority of infection-reactive clonotypes acquire memory phenotypes, indicating the potential involvement of pre-existing cross-reactive memory T cells in the immune response to SARS-CoV-2.