Cross-reactive immune responses to SARS-CoV-2 have been observed in pre-pandemic cohorts and proposed to contribute to host protection. Here we assess 52 COVID-19 household contacts to capture immune responses at the earliest timepoints after SARS-CoV-2 exposure. Using a dual cytokine FLISpot assay on peripheral blood mononuclear cells, we enumerate the frequency of T cells specific for spike, nucleocapsid, membrane, envelope and ORF1 SARS-CoV-2 epitopes that cross-react with human endemic coronaviruses. We observe higher frequencies of cross-reactive (p = 0.0139), and nucleocapsid-specific (p = 0.0355) IL-2-secreting memory T cells in contacts who remained PCR-negative despite exposure (n = 26), when compared with those who convert to PCR-positive (n = 26); no significant difference in the frequency of responses to spike is observed, hinting at a limited protective function of spike-cross-reactive T cells. Our results are thus consistent with pre-existing non-spike cross-reactive memory T cells protecting SARS-CoV-2-naïve contacts from infection, thereby supporting the inclusion of non-spike antigens in second-generation vaccines. While cross-reactive immunity between human coronavirus and SARS-CoV-2 may contribute to host protection, validating evidences are still scarce. Here the authors assess a cohort of 52 donors with immediate-early contact with SARS-CoV-2 to correlate higher frequency of cross-reactive T cells with lower infection rate.
【저자키워드】 SARS-CoV-2, viral infection, Immunological memory, Antimicrobial responses, 【초록키워드】 COVID-19, Coronaviruses, coronavirus, immune response, Immunity, Vaccines, T cells, Infection, cytokine, Antigen, Peripheral blood, Epitopes, Cohort, T cell, nucleocapsid, immune responses, response, memory T cells, Peripheral blood mononuclear cells, membrane, infection rate, household contact, memory T cell, Protective, Donor, Evidence, Endemic, Frequency, Contact, cross-reactive, mononuclear cells, dual, contact with, significant difference, no significant difference, PCR-positive, PCR-negative, ORF1, while, Cross-reactive immune responses, Host, Inclusion, observé, human coronavirus, remained, contribute, cross-react, SARS-CoV-2 epitope, timepoint, 【제목키워드】 COVID-19, SARS-COV-2 infection, memory T cell, Contact,