SARS-CoV-2-specific T cell immunity in cases of COVID-19 and SARS, and uninfected controls

The memory T cell responses against SARS-CoV-2 in patients infected with SARS-CoV-1 or SARS-CoV-2 was examined. Peripheral blood mononuclear cells (PBMC) collected from the COVID-19 convalescents could show the T cell reactivity against nucleoprotein of SARS-CoV-2. The memory T cell reactivity of SARS-CoV-1-infected patients against SARS-CoV-1 infection still remains 17 years after the 2003 outbreak, which also showed a cross-reactivity to SARS-CoV-2. Surprisingly, the T cell response against SARS-CoV-2 was observed in PBMC collected from SARS-CoV-1/2 uninfected individuals. Although the T cell response was dominantly in nucleoprotein in the case of SARS-CoV-1/2 infected individuals, that of uninfected individuals showed a unique pattern of responses against nucleoprotein and ORF-1-coded NSP7 and 13. The history of infection with other non-pathogenic coronavirus may have possibility to explain why such responses was observed.