C19 SARS-CoV-2-specific T cells in the infected nasel epithelium

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Summary The acquired, antigen-specific immune response to SARS-CoV-2-infection is likely central to determining the outcome of COVID-19 and the efficacy and durability of vaccination. CD4 T cell help is required for lasting, avid antibody responses. The leading vaccine candidates include some formats that can also induce CD8 T cells, such as viral vectors and nucleic acids, and other formats such as adjuvanted protein that cannot. Compelling evidence for an antiviral effects of virus-specific CD8 T cells could tilt the balance in favor of CD8-eliciting vaccine platforms. Aim 1 and Aim 2 of this exploratory R21 on the T cell response to SARS-CoV-2 concern CD8- and CD4 T cell responses, respectively. Upper and lower airway respiratory epithelium are the primary target tissues for SARS-CoV-2. The nasal epithelium is particularly rich in expression of ACE2 and TMPRSS2, host molecules required for viral entry. We leverage Co-Investigator Abuzeid’s experience in harvesting nasal cells and expanding primary nasal epithelial cells (HNEpC) and Collaborator Greninger’s expertise in BSL3 virology and quantitative RNA measurement to create systems to study T cell-infected epithelial cell interactions in vitro. We use our large COVID-19 biobank, in-lab experience, and other NIAID resources to generate functionally unlimited amounts of highly avid SARS-CoV-2-specific CD8 and CD4 T cells with precisely known HLA restriction and defined peptide targets. Infection of HNEpC will be carefully characterized and optimized. We will then measure T cell effector functions including the killing of infected cells, reduction of viral progeny output, and cytokine release. In follow-up studies, we hope to leverage SARS-CoV-2 genetic systems to make defined mutants in candidate immune evasion genes and extend our studies to lower respiratory tract cells and organoids. Overall, we strive to model important interactions between immune cells and the SARS-CoV-2 infected respiratory tract. Relevance Vaccines may need to elicit SARS-CoV-2 specific T cells that can quickly recognize SARS-CoV- 2-specific infected upper respiratory tract epithelial cells and shut down their production of progeny virus, to both limit the progression of infection and symptoms within patients, and reduce the shedding of infectious virus that may infect other persons. In this R21 grant application, we will use established, working methods to isolate large quantities of pure SARS- CoV-2-specific T cells from recovered persons and study their ability to exert anti-viral effects using cell cultures of the cells that line the nasal cavity that are normally infected during COVID- 19.