Cutting Edge: Circulating Exosomes with COVID Spike Protein Are Induced by BNT162b2 (Pfizer-BioNTech) Vaccination prior to Development of Antibodies: A Novel Mechanism for Immune Activation by mRNA Vaccines

J Immunol. 2021 Nov 15;207(10):2405-2410. doi: 10.4049/jimmunol.2100637. Epub 2021 Oct 15.

Abstract

Severe acute respiratory syndrome corona virus 2 (SARS-CoV-2) causes severe acute respiratory syndrome. mRNA vaccines directed at the SARS-CoV-2 spike protein resulted in development of Abs and protective immunity. To determine the mechanism, we analyzed the kinetics of induction of circulating exosomes with SARS-CoV-2 spike protein and Ab following vaccination of healthy individuals. Results demonstrated induction of circulating exosomes expressing spike protein on day 14 after vaccination followed by Abs 14 d after the second dose. Exosomes with spike protein, Abs to SARS-CoV-2 spike, and T cells secreting IFN-γ and TNF-α increased following the booster dose. Transmission electron microscopy of exosomes also demonstrated spike protein Ags on their surface. Exosomes with spike protein and Abs decreased in parallel after four months. These results demonstrate an important role of circulating exosomes with spike protein for effective immunization following mRNA-based vaccination. This is further documented by induction of humoral and cellular immune responses in mice immunized with exosomes carrying spike protein.

Publication types

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

MeSH terms

  • Animals
  • Antibodies, Viral / metabolism*
  • Blood Circulation
  • COVID-19 / immunology*
  • COVID-19 Vaccines / immunology*
  • Cells, Cultured
  • Exosomes / immunology
  • Exosomes / metabolism*
  • Healthy Volunteers
  • Humans
  • Immunization
  • Interferon-gamma / metabolism
  • Mice
  • Mice, Inbred C57BL
  • SARS-CoV-2 / physiology*
  • Spike Glycoprotein, Coronavirus / immunology
  • Spike Glycoprotein, Coronavirus / metabolism*
  • T-Lymphocytes / immunology
  • T-Lymphocytes / metabolism*
  • Tumor Necrosis Factor-alpha / metabolism
  • Vaccination

Substances

  • Antibodies, Viral
  • COVID-19 Vaccines
  • Spike Glycoprotein, Coronavirus
  • Tumor Necrosis Factor-alpha
  • spike protein, SARS-CoV-2
  • Interferon-gamma
  • BNT162 vaccine