Ad5-nCoV vaccination could induce HLA-E restricted CD8 + T cell
responses specific for epitopes on severe acute respiratory syndrome
coronavirus 2 spike protein
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.