Broad T Cell Targeting of Structural Proteins After SARS-CoV-2 Infection: High Throughput Assessment of T Cell Reactivity Using an Automated Interferon Gamma Release Assay

• Published in: Frontiers in immunology Vol. 12; p. 688436
• Main Authors: Brand, Isabel, Gilberg, Leonard, Bruger, Jan, Garí, Mercè, Wieser, Andreas, Eser, Tabea M., Frese, Jonathan, Ahmed, Mohamed I. M., Rubio-Acero, Raquel, Guggenbuehl Noller, Jessica M., Castelletti, Noemi, Diekmannshemke, Jana, Thiesbrummel, Sophie, Huynh, Duc, Winter, Simon, Kroidl, Inge, Fuchs, Christiane, Hoelscher, Michael, Roider, Julia, Kobold, Sebastian, Pritsch, Michael, Geldmacher, Christof
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Media S.A 20.05.2021
• Subjects: Adolescent; Adult; Aged; Aged, 80 and over; Antibodies, Viral - blood; COVID-19; COVID-19 - blood; COVID-19 - immunology; Female; high through put; Humans; Immunology; interferon gamma release assay (IGRA); Interferon-gamma - immunology; Interferon-gamma Release Tests; Male; Middle Aged; SARS-CoV-2; SARS-CoV-2 - immunology; T cell response; T-Lymphocytes - immunology; Viral Structural Proteins - immunology; Young Adult; COVID-19; SARS-CoV-2; high through put; interferon gamma release assay (IGRA); T cell response
• ISSN: 1664-3224; 1664-3224
• DOI: 10.3389/fimmu.2021.688436

Adaptive immune responses to structural proteins of the virion play a crucial role in protection against coronavirus disease 2019 (COVID-19). We therefore studied T cell responses against multiple SARS-CoV-2 structural proteins in a large cohort using a simple, fast, and high-throughput approach. An automated interferon gamma release assay (IGRA) for the Nucleocapsid (NC)-, Membrane (M)-, Spike-C-terminus (SCT)-, and N-terminus-protein (SNT)-specific T cell responses was performed using fresh whole blood from study subjects with convalescent, confirmed COVID-19 (n = 177, more than 200 days post infection), exposed household members (n = 145), and unexposed controls (n = 85). SARS-CoV-2-specific antibodies were assessed using Elecsys  Anti-SARS-CoV-2 (Ro-N-Ig) and Anti-SARS-CoV-2-ELISA (IgG) (EI-S1-IgG). 156 of 177 (88%) previously PCR confirmed cases were still positive by Ro-N-Ig more than 200 days after infection. In T cells, most frequently the M-protein was targeted by 88% seropositive, PCR confirmed cases, followed by SCT (85%), NC (82%), and SNT (73%), whereas each of these antigens was recognized by less than 14% of non-exposed control subjects. Broad targeting of these structural virion proteins was characteristic of convalescent SARS-CoV-2 infection; 68% of all seropositive individuals targeted all four tested antigens. Indeed, anti-NC antibody titer correlated loosely, but significantly with the magnitude and breadth of the SARS-CoV-2-specific T cell response. Age, sex, and body mass index were comparable between the different groups. SARS-CoV-2 seropositivity correlates with broad T cell reactivity of the structural virus proteins at 200 days after infection and beyond. The SARS-CoV-2-IGRA can facilitate large scale determination of SARS-CoV-2-specific T cell responses with high accuracy against multiple targets.