Identification of HCMV-derived T cell epitopes in seropositive individuals through viral deletion models

M Lübke, S Spalt, DJ Kowalewski… - Journal of Experimental …, 2019 - rupress.org
M Lübke, S Spalt, DJ Kowalewski, C Zimmermann, L Bauersfeld, A Nelde, L Bichmann
Journal of Experimental Medicine, 2019rupress.org
In healthy individuals, immune control of persistent human cytomegalovirus (HCMV)
infection is effectively mediated by virus-specific CD4+ and CD8+ T cells. However,
identifying the repertoire of T cell specificities for HCMV is hampered by the immense protein
coding capacity of this betaherpesvirus. Here, we present a novel approach that employs
HCMV deletion mutant viruses lacking HLA class I immunoevasins and allows direct
identification of naturally presented HCMV-derived HLA ligands by mass spectrometry. We …
In healthy individuals, immune control of persistent human cytomegalovirus (HCMV) infection is effectively mediated by virus-specific CD4+ and CD8+ T cells. However, identifying the repertoire of T cell specificities for HCMV is hampered by the immense protein coding capacity of this betaherpesvirus. Here, we present a novel approach that employs HCMV deletion mutant viruses lacking HLA class I immunoevasins and allows direct identification of naturally presented HCMV-derived HLA ligands by mass spectrometry. We identified 368 unique HCMV-derived HLA class I ligands representing an unexpectedly broad panel of 123 HCMV antigens. Functional characterization revealed memory T cell responses in seropositive individuals for a substantial proportion (28%) of these novel peptides. Multiple HCMV-directed specificities in the memory T cell pool of single individuals indicate that physiologic anti-HCMV T cell responses are directed against a broad range of antigens. Thus, the unbiased identification of naturally presented viral epitopes enabled a comprehensive and systematic assessment of the physiological repertoire of anti-HCMV T cell specificities in seropositive individuals.
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