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

Front Immunol. 2021 Mar 11:12:636768. doi: 10.3389/fimmu.2021.636768. eCollection 2021.

Abstract

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.

Keywords: B cells; CD4+ T cells; human coronavirus; neutralizing antibody; pre-existing immunity.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Antibodies, Neutralizing / blood
  • Antibodies, Viral / blood
  • B-Lymphocytes / immunology*
  • B-Lymphocytes / virology
  • 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
  • Case-Control Studies
  • Female
  • Humans
  • Immunity, Cellular
  • Immunologic Memory*
  • Male
  • Middle Aged
  • SARS-CoV-2 / immunology*
  • Spike Glycoprotein, Coronavirus / immunology*
  • Time Factors
  • Young Adult

Substances

  • Antibodies, Neutralizing
  • Antibodies, Viral
  • Spike Glycoprotein, Coronavirus
  • spike protein, SARS-CoV-2