ABSTRACT
Twelve subjects with positive SARS-CoV-2 neutralization test (NT) titers (>1:10) identified in a seroprevalence study with 1655 working adults were followed up for one year. Here we report that 7 of these 12 individuals (58%) still had NT titers [≥]1:50, S1-specific IgG concentrations [≥]50 BAU/ml and [≥]26% ACE2 receptor binding inhibition, measured with surrogate virus NT one year after mild COVID infection. Furthermore, NT_50 titers >1:10 and S1-specific IgG levels >60 BAU/ml present at three months post-infection persisted at detectable levels for 1 year and correlated with circulating S1-specific memory B-cells. Vaccine-induced SARS-CoV2 immune responses decline at similar rates as those after infection; thus the describes threshold of 60 BAU/ml at three months post infection might also be relevant for assessment of Ab persistence after vaccination.
ABSTRACT
CD8+ T cell immunity to SARS-CoV-2 has been implicated in COVID-19 severity and virus control, though direct evidence has been lacking so far. Here, we identified non-synonymous mutations in MHC-I restricted CD8+ T cell epitopes after deep sequencing of 747 SARS-CoV- 2 virus isolates. Mutant peptides exhibited diminished or abrogated MHC-I binding, which was associated with a loss of recognition and functional responses by CD8+ T cells isolated from HLA-matched COVID-19 patients. Our findings highlight the capacity of SARS-CoV-2 to subvert CD8+ T cell surveillance through escape mutations in MHCI-restricted viral epitopes. This provides evolutionary evidence for CD8+ T cell immunity controlling SARS-CoV-2 with consequences for COVID-19 vaccine design.
