T cell immunity to SARS-CoV-2 following natural infection and vaccination

Abstract

SARS-CoV-2 first emerged in the human population in late 2019 in Wuhan, China, and in a matter of months, spread across the globe resulting in the Coronavirus Disease 19 (COVID-19) pandemic and substantial economic fallout. SARS-CoV-2 is transmitted between humans via respiratory particles, with infection presenting a spectrum of clinical manifestations ranging from asymptomatic to respiratory failure with multiorgan dysfunction and death in severe cases. Prior experiences with human pathogenic coronaviruses and respiratory virus diseases in general have revealed an important role for cellular immunity in limiting disease severity. Here, we review some of the key mechanisms underlying cell-mediated immunity to respiratory viruses and summarize our current understanding of the functional capacity and role of SARS-CoV-2-specific T cells following natural infection and vaccination.

SARS-CoV-2 human T cell epitopes: Adaptive immune response against COVID-19

“…Ten of the 25 epitope identification studies (Ferretti et Nelde et al, 2021;Saini et al, 2020Saini et al, , 2021Schulien et al, 2021;Snyder et al, 2020;Tarke et al, 2021a;, Prakash et al, 2020) screened peptides derived from the entire SARS-CoV-2 proteome (seventh column of Table 1). The main antigenic targets of CD4 and CD8 SARS-CoV-2 T cell responses have been defined by several studies by utilizing overlapping peptides, rather than by resolving the actual epitopes (Grifoni et al, 2020;Tarke et al, 2021a), and are reviewed elsewhere (Altmann and Boyton, 2020;DiPiazza et al, 2020). These studies determined that structural proteins (S, M and N) are dominant targets of T cell responses, with ORF3, ORF8, and nsp3, 4, 6, 7, 12, and 13 (ORF1ab) also being frequently targeted.…”

Expansion of tissue-resident CD8+ T cells and CD4+ Th17 cells in the nasal mucosa following mRNA COVID-19 vaccination

“…Studies that assess the quality and quantity of immune responses induced by vaccination in humans are beginning to emerge [11][12][13][14][15][16] , adding depth to what was generated in early phase clinical trials. While these studies suggest a high magnitude of humoral and cell-mediated immunity to SARS-CoV-2 17,18 , less is known regarding tissue and mucosal immunity induced by these vaccines, particularly in the URT, the primary site of viral entry.…”

Adaptive immune responses to SARS-CoV-2 in recovered severe COVID-19 patients

“…If confirmed in further studies, this phenomenon may be associated with COVID-19 severity. In this sense it has been postulated that exuberant or aberrant activation of the innate immune system upon encounter with SARS-CoV-2, resulting in suboptimal expansion of functional T cells, may be a hallmark in patients developing the severest forms of COVID-19 [1,25]. In support of this assumption, around 60% of individuals who had experienced mild forms of the disease were shown to display S1 and M-reactive T-cell responses by 6 months after COVID-19 diagnosis [26].…”