Shane Crotty, PhD, the La Jolla Institute for Immunology, “Targets of T cell responses to SARS-CoV-2 coronavirus in humans with COVID-19 disease and unexposed individuals”
Dr. Crotty presented on his recent work that aimed to address major knowledge gaps in our understanding of immunity to SARS-CoV-2: (1) How much of an adaptive immune response is there to COVID-19? The answer to this question is important for vaccine design as well as predicting of herd immunity and future social distancing policies; (2) How long does the immunological memory to COVID-19 last?; and (3) What kind of immunity is important against COVID-19? His group looked at aspects of the immune system—antibodies (important in almost all currently licensed human vaccines), CD4 T cells (critical for antibody responses), and CD8 T cells (important in many viral infections)—to determine what type of immunity is important against the average symptomatic COVID-19 case. Using cytokine-agnostic T cell assays, they found that circulating SARS-CoV-2−specific CD8+ and CD4+ T cells were identified in ~70% and 100% of COVID-19 convalescent patients, respectively. They also found that CD4+ T cells respond to not just the spike protein but multiple SARS-CoV-2 antigens that can be mapped to the viral M, N, and ORFs. Importantly, they detected SARS-CoV-2−reactive CD4+ T cells in ~40-60% of unexposed individuals, suggesting cross-reactive T cell recognition between circulating ‘common cold’ coronaviruses and SARS-CoV-2. This work was recently published in Cell (Grifoni et al. 2020).
