Abstract
Objectives: To evaluate cellular immune responses induced by
severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines
immunization in population based on HLA-E-restricted
CD8+ T cell epitopes identification.
Methods: HLA-E-restricted SARS-CoV-2 CD8+ T
cell nonamer peptides were predicted with software. HLA-E-transfected
K562 cells binding assay was used to screen for high-affinity peptides.
IFN-γ enzyme-linked immunospot assay were used to identify
HLA-E-restricted epitopes. HLA-E/epitope tetramer was employed to detect
the frequencies of epitope-specific CD8+ T cells.
Results: Four CD8+ T cell epitopes on spike
protein of SARS-CoV-2 restricted by both HLA-E*0101 and E*0103 were
identified. HLA-E-restricted epitope specific IFN-γ-secreting
CD8+ T cell responses could be detected in individuals
vaccinated with SARS-CoV-2 vaccines. Importantly, the frequencies of
epitope-specific CD8+ T cell in Ad5-nCoV vaccinated
individual were higher than that in individuals vaccinated with
recombinant protein or inactivated vaccines. Moreover, frequencies of
epitope-specific CD8+ T cells could maintain for at
least 120 days after only one dose Ad5-nCoV vaccination. While
frequencies of epitope-specific CD8+ T cells decreased
in individuals after two doses of Ad5-nCoV vaccination.
Conclusions: These findings may contribute to more
comprehensive evaluating protective effects of vaccines for SARS-CoV-2,
meanwhile may provide information to characterize HLA-E-restricted
CD8+ T cell immunity against SARS-CoV-2 infection.