Immune Memory in Mild COVID-19 Patients and Unexposed Donors Reveals Persistent T Cell Responses After SARS-CoV-2 Infection

• Published in: Frontiers in immunology Vol. 12; p. 636768
• Main Authors: Ansari, Asgar, Arya, Rakesh, Sachan, Shilpa, Jha, Someshwar Nath, Kalia, Anurag, Lall, Anupam, Sette, Alessandro, Grifoni, Alba, Weiskopf, Daniela, Coshic, Poonam, Sharma, Ashok, Gupta, Nimesh
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Media S.A 11.03.2021
• Subjects: Adult; Antibodies, Neutralizing - blood; Antibodies, Viral - blood; B cells; B-Lymphocytes - immunology; B-Lymphocytes - virology; Case-Control Studies; CD4+ T cells; CD4-Positive T-Lymphocytes - immunology; CD4-Positive T-Lymphocytes - virology; CD8-Positive T-Lymphocytes - immunology; CD8-Positive T-Lymphocytes - virology; COVID-19 - blood; COVID-19 - diagnosis; COVID-19 - immunology; COVID-19 - virology; Female; human coronavirus; Humans; Immunity, Cellular; Immunologic Memory; Immunology; Male; Middle Aged; neutralizing antibody; pre-existing immunity; SARS-CoV-2 - immunology; Spike Glycoprotein, Coronavirus - immunology; Time Factors; Young Adult; neutralizing antibody; human coronavirus; B cells; CD4+ T cells; pre-existing immunity
• ISSN: 1664-3224; 1664-3224
• DOI: 10.3389/fimmu.2021.636768

Understanding the causes of the diverse outcome of COVID-19 pandemic in different geographical locations is important for the worldwide vaccine implementation and pandemic control responses. We analyzed 42 unexposed healthy donors and 28 mild COVID-19 subjects up to 5 months from the recovery for SARS-CoV-2 specific immunological memory. Using HLA class II predicted peptide megapools, we identified SARS-CoV-2 cross-reactive CD4 + T cells in around 66% of the unexposed individuals. Moreover, we found detectable immune memory in mild COVID-19 patients several months after recovery in the crucial arms of protective adaptive immunity; CD4 + T cells and B cells, with a minimal contribution from CD8 + T cells. Interestingly, the persistent immune memory in COVID-19 patients is predominantly targeted towards the Spike glycoprotein of the SARS-CoV-2. This study provides the evidence of both high magnitude pre-existing and persistent immune memory in Indian population. By providing the knowledge on cellular immune responses to SARS-CoV-2, our work has implication for the development and implementation of vaccines against COVID-19.