Clonotypic Tracing of Human T cells During Infection

Prof. Yamasaki describes his research on SARS-CoV-2-specific CD4⁺ T cells, particularly TFH cells that support protective antibody responses. His team identified public TCR clonotypes recognizing conserved epitopes in the spike protein (mainly in the S2 region), some of which may be primed by cross-reactivity with oral commensal bacteria. These clonotypes were associated with milder COVID-19 outcomes and sustained antibody responses after vaccination. He also described how, in immunodeficient patients lacking antibodies, flexible CD4⁺ T cells with cytotoxic-like features could help control infection—though viral escape mutations may still arise under such selective pressure.