S1

subunit 1

Here, we assessed the SARS-CoV-2 spike subunit 1 (S1)-specific T cell responses, anti-SARS-CoV-2 receptor-binding domain (RBD) IgG serum concentrations, and the neutralizing activity of serum antibodies before and one, four, and seven months after the BNT162b2 or mRNA-1273 booster vaccination in a cohort of previously infected and infection-naïve healthcare workers (HCWs).

Antibodies to C19 nucleocapsid (N), receptor-binding domain (RBD), spike 1 (S1), and spike 2 (S2) were measured.

We used electrochemiluminescence assays to quantify antibodies to SARS-CoV-2 spike subunit 1 (S1), subunit 2 (S2) and receptor-binding domain (RBD) in plasma (reported in WHO IU/mL).

The SARS-CoV-2 spike 1 (S1) protein specific IgA, IgG and the ACE2 binding inhibition to the ancestral SARS-CoV-2 and omicron (BA.1) variant receptor binding domain were measured in their nasal epithelial lining fluid and plasma.ResultIn the recovered group, the booster expanded the nasal IgA dominancy inherited from natural infection to IgA and IgG.

The SARS-CoV-2 spike 1 (S1) protein specific IgA, IgG and the ACE2 binding inhibition to the ancestral SARS-CoV-2 and omicron (BA.1) variant receptor binding domain were measured in their nasal epithelial lining fluid and plasma.ResultIn the recovered group, the booster expanded the nasal IgA dominancy inherited from natural infection to IgA and IgG.

ELISA detected IgM nucleocapsid (N) antibodies in 18 samples, and IgG (N) and IgG spike 1 (S1) antibodies in 31 and 29 samples, respectively.

IgG antibody levels against six recombinant HCoV spike subunit 1 (S1) proteins were measured by enzyme immunoassay.