Numerous assays evaluating serological and cellular responses have been developed to characterize immune responses against SARS-CoV-2. Serological assays are both cost- and time-effective compared to cellular assays, but cellular immune responses may provide a diagnostic value to determine previous SARS-CoV-2 infection in seronegative individuals. However, potential cross-reactive T cell responses stemming from prior encounters with human coronaviruses (HCoVs) may affect assay specificity. In this study, we evaluated the specificity and sensitivity of a SARS-CoV-2 IFN-γ Release Assay (IGRA) based on the FluoroSpot method employing commercially available SARS-CoV-2-specific peptide pools, as well as an in-house designed SARS-CoV-2 peptide pool restricted to 5 amino acid stretches or less aligning with endemic HCoVs. Blood samples were obtained from healthcare workers (HCW) 5–6 months post SARS-CoV-2 spike (S) IgG and nucleocapsid (N) IgG dual seroconversion (n = 187) and HCW who had been S IgG and N IgG dual seronegative at repeated occasions, including the current sampling time point (n = 102). In addition, samples were obtained 4 to 5 months post infection from 55 polymerase chain reaction (PCR)-confirmed COVID-19 patients. Assay specificity and sensitivity were calculated with serology as a reference standard for HCW. The in-house generated peptide pool displayed a specificity of 96.1%, while the commercially available peptide pools displayed specificities of 80.4% and 85.3%, respectively. Sensitivity was higher in a cohort of previously hospitalized COVID-19 patients (96.4% and 84.0% for the commercially available peptide pools and 92.7% for the in-house generated peptide pool) compared to the HCW cohort (92.0% and 66.8% for the commercially available peptide pools and 76.0% for the in-house generated peptide pool). Based on these findings, the individual diagnostic value of T cell immune responses against SARS-CoV-2 currently appears to be limited but remain an important research tool ahead.
【초록키워드】 SARS-CoV-2, IgG, Release, immune response, Healthcare workers, serology, Cellular immune response, SARS-COV-2 infection, peptide, healthcare worker, polymerase chain reaction, sensitivity, specificity, Cohort, T cell, Seroconversion, nucleocapsid, serological assays, immune responses, Research, serological, T cell response, seronegative, reference standard, human coronaviruses, COVID-19 patients, IFN-γ, SARS-CoV-2 spike, cellular response, hospitalized COVID-19 patient, Amino acid, cellular, cross-reactive, HCW, dual, Chain Reaction, Blood samples, house, diagnostic value, blood sample, cellular immune responses, Specificities, HCoVs, peptide pools, post infection, endemic HCoVs, Affect, repeated, polymerase chain, human coronavirus, assays, addition, evaluated, calculated, appear, less, determine, individuals, Numerous, aligning, peptide pool, 【제목키워드】 SARS-CoV-2, diagnostic, T cell response, determine,