Characterization of anti-viral immunity in recovered individuals infected by SARS-CoV-2

Chen Dong; Ling Ni; Fang Ye; Meng-Li Chen; Yu Feng; Yong-Qiang Deng; Hui Zhao; Peng Wei; Jiwan Ge; Xiaoli Li; Lin Sun; Pengzhi Wang; Peng Liang; Han Guo; Xinquan Wang; Cheng-Feng Qin; Fang Chen

To assess virus-specific cellular immunity, we then treated PBMCs with recombinant NP, main protease and S-RBD, followed by IFN-g ELISpot analysis. The results were considered positive if there were at least 1-fold increase in the numbers of IFN-g-secreting T cells in the subject than in the healthy donors. As shown in Figure 2B , compared with healthy donors, the numbers of IFN-g-secreting NP-specific T cells in patients #1, 2, 4 and 5 were much higher than other patients, suggesting that they had developed SARS-CoV-2-specific T cell responses. Of note, patients #1, 2, 4 and 5 developed both strong humoral and cellular immune responses. Main protease-specific T cells were detected in patient #1, 2 and 5, while patients # 1, 2, 4, 5 and 6 showed S-RBD-specific T cells. Although the numbers of IFN-gsecreting S-RBD specific T cells were much lower than those of NP-specific T cells, they could be detected in more patients than those for other viral proteins. S-RBD thus not only elicited humoral immunity that may result in blockade of receptor binding during viral entry in host cells, but also induced T cell immune responses, suggesting S-RBD is a promising target for SARS-CoV-2 vaccines. In the follow-up patients, only patient #8 who showed lymphopenia before treatment still had a high number of IFN-g-secreting T cells in response to NP, main protease and S-RBD ( Figure 2B ), which suggests that anti-viral T cells may not be maintained at high numbers in the PBMCs in the recovered patients. More interestingly, when combining all 12 patients in our analysis, there was a significant correlation between the neutralizing All rights reserved. No reuse allowed without permission. the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.