Blood single cell immune profiling reveals the interferon-MAPK pathway mediated adaptive immune response for COVID-19

Lulin Huang; Yi Shi; Bo Gong; Li Jiang; Xiaoqi Liu; Jialiang Yang; Juan Tang; Chunfang You; Qi Jiang; Bo Long; Tao Zeng; Mei Luo; Fanwei Zeng; Fanxin Zeng; Shuqiang Wang; Xingxiang Yang; Zhenglin Yang

Type I interferon (IFN-I) is crucial for promoting antiviral defenses through the induction of antiviral effectors (29) . In this study, our single cell transcriptome results showed that IRF27 was up-regulated 8.1 times more in critical patients, 51.7 times in severe patients, 39.9 times in moderate patients, 38.6 times in mild patients, and 29.5 times in cured patients compared to the normal controls (Fig. 4A) . These results suggest that IRF27 is a candidate marker gene for SARS-CoV-2 infection. BST2, which was previously shown to play a role in pre-B-cell growth (31) , also showed upexpression in COVID-19 patients. Consistent with our single cell transcription data, the expression profile of FOS, which is a transcription factor mediating MAPK pathway signaling, showed up-regulation in COVID-19 patients but down-regulation in cured patients. This result suggests that FOS is a candidate marker gene for cured COVID-19 patients. We further performed PBMC immunofluorescence testing to compare the protein expressions of IFI27 between patients with COVID-19 and controls. Immunofluorescence staining showed that IFI27 was highly expressed in the whole lymphocyte of patients with COVID-19, but only partially expressed on the lymphocyte of the controls (Fig. 4B) .