Generating protein reagents to evaluate the antibody and CD8+ T cell responses to SARS-CoV-2

DATE: October 21, 2021

TIME:  8:00am PDT

Coronavirus disease 2019 (COVID-19) is a global health crisis caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and there is a critical need to produce large quantities of high-quality SARS-CoV-2 antigens for characterization and evaluation of antibody responses to SARS-CoV-2. To address this, we optimized expression and purification of two previously reported SARS-CoV-2 Spike (S) protein constructs and show that ExpiCHO-S™ cells produce enhanced yields of both S proteins compared to other expression systems. Our expression and purification strategy yielded high quality material to allow biochemical, biophysical, and structural (cryo-EM) characterization of the SARS-CoV-2 S protein. We also generated protein microarrays using S protein along with other SARS-CoV-2 antigens (i.e., nucleocapsid) to detect SARS-CoV-2 antibodies in COVID-19 convalescent individuals. Our current efforts are focused on evaluating and activating CD8+ T cells that are specific for SARS-CoV-2. To this end we have developed protein biologics that behave similarly to antigen presenting cells and allow us to activate T cells in an antigen specific (i.e., peptide from an antigen is linked to an MHC molecule) manner. These peptide:MHC molecules are then linked to co-stimulatory molecules to generate proteins we refer to as synTac (artificial immunological synapse for T cell activation). We will develop SARS-CoV-2 synTac protein biologics to activate SARS-CoV-2 CD8+ T cells to determine if this will provide long-term immunity against SARS-CoV-2.

Learning objectives:

• Discuss and lean about glycosylated proteins and discuss different expression platforms for glycoproteins. This can be applied to the SARS-CoV-2 S protein and how glycosylated (or hyperglycosylated) S protein can be utilized for downstream clinical and basic science applications.
• Describe how SARS-CoV-2 antigens have been used to study antibody responses to COVID-19.
• Demonstrate how synTac protein biologics activate T cells in an antigen specific manner and compare synTac proteins with current immunotherapies.

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