New MHC technologies to identify and analyze SARS-CoV-2-specific CD8+ T cells

The ongoing COVID-19 pandemic has had a devastating impact on public health and the global economy. Development of effective COVID-19 vaccines and therapeutics is critically dependent on better understanding the human immune response to SARS-CoV-2, the causal agent of COVID-19. CD8+ T cells are critical for anti-viral defense, as they have a unique ability to recognize and kill virus-infected cells. However, the role of CD8+ T cells in COVID-19 protection and/or pathology is currently unknown. This is mainly due to lack on information CD8+ T cell specificity during COVID-19, and lack of reagents to identify and characterize SARS-CoV-2-specific CD8+ T cells.

We will use new MHC class I technologies to identify SARS-CoV-2 peptides presented on MHC (HLA in human) class I variants common in the Singaporean population, generating tetramers to identify and characterize the phenotype, signaling and function of SARS-CoV-2-specific CD8+ T cells from recovered patients, and to expand SARS-CoV-2-specific CD8+ T cells for potential use in immunotherapy. We will use UV-cleavable conditional MHC-I technology to test SARS-CoV-2-derived peptides for binding to HLA class I variants common in Singapore. We developed a new MHC technology using soluble single chain dimers of HLA heavy chain and 2-microglobulin, expressed in mammalian cells. This is simple to implement, offering a way to generate MHC molecules with intact glycosylation. We will use this technology to identify SARS-CoV-2-specific CD8+ T cells, and to analyze their phenotype, function and signaling. We will use HLA class I presenting SARS-CoV-2-derived peptides expressed as covalently linked single chain trimers, shown before to be more stable and immunogenic than conventional MHC, to expand SARS-CoV-2-specific CD8+ T cells. Our work will generate a critical set of reagents to identify, analyze and expand SARS-CoV-2-specific CD8+ T cells, with special relevance to the Singapore population.