biostudies-literatureKar RDepartment of Biotechnology-Junior Research FellowshipDBT/Wellcome Trust India Alliance FellowshipDBT-NIIDBT/Wellcome Trust India AllianceWellcome Trust420-439https://www.ebi.ac.uk/biostudies/studies/S-EPMC7616077biostudies-literatureUnknown172(3)Latent human cytomegalovirus (hCMV) infection can pose a serious threat of reactivation and disease occurrence in immune-compromised individuals. Although T cells are at the core of the protective immune response to hCMV infection, a detailed characterization of different T cell subsets involved in hCMV immunity is lacking. Here, in an unbiased manner, we characterized over 8000 hCMV-reactive peripheral memory T cells isolated from seropositive human donors, at a single-cell resolution by analysing their single-cell transcriptomes paired with the T cell antigen receptor (TCR) repertoires. The hCMV-reactive T cells were highly heterogeneous and consisted of different developmental and functional memory T cell subsets such as, long-term memory precursors and effectors, T helper-17, T regulatory cells (T_REGs) and cytotoxic T lymphocytes (CTLs) of both CD4 and CD8 origin. The hCMV-specific T_REGs, in addition to being enriched for molecules known for their suppressive functions, showed enrichment for the interferon response signature gene sets. The hCMV-specific CTLs were of two types, the pre-effector- and effector-like. The co-clustering of hCMV-specific CD4-CTLs and CD8-CTLs in both pre-effector as well as effector clusters suggest shared transcriptomic signatures between them. The huge TCR clonal expansion of cytotoxic clusters suggests a dominant role in the protective immune response to CMV. The study uncovers the heterogeneity in the hCMV-specific memory T cells revealing many functional subsets with potential implications in better understanding of hCMV-specific T cell immunity. The data presented can serve as a knowledge base for designing vaccines and therapeutics.ImmunologySingle-cell transcriptomic and T cell antigen receptor analysis of human cytomegalovirus (hCMV)-specific memory T cells reveals effectors and pre-effectors of CD8<sup>+</sup>- and CD4<sup>+</sup>-cytotoxic T cells.PMC7616077DBT/JRF/BET-19/I/2019/AL/89IA/I/18/2/504012Kar RSharma APatil VSSinha SArimbasseri GAChattopadhyay SSharma KfalseSingle-cell transcriptomic and T cell antigen receptor analysis of human cytomegalovirus (hCMV)-specific memory T cells reveals effectors and pre-effectors of CD8<sup>+</sup>- and CD4<sup>+</sup>-cytotoxic T cells.Latent human cytomegalovirus (hCMV) infection can pose a serious threat of reactivation and disease occurrence in immune-compromised individuals. Although T cells are at the core of the protective immune response to hCMV infection, a detailed characterization of different T cell subsets involved in hCMV immunity is lacking. Here, in an unbiased manner, we characterized over 8000 hCMV-reactive peripheral memory T cells isolated from seropositive human donors, at a single-cell resolution by analysing their single-cell transcriptomes paired with the T cell antigen receptor (TCR) repertoires. The hCMV-reactive T cells were highly heterogeneous and consisted of different developmental and functional memory T cell subsets such as, long-term memory precursors and effectors, T helper-17, T regulatory cells (T_REGs) and cytotoxic T lymphocytes (CTLs) of both CD4 and CD8 origin. The hCMV-specific T_REGs, in addition to being enriched for molecules known for their suppressive functions, showed enrichment for the interferon response signature gene sets. The hCMV-specific CTLs were of two types, the pre-effector- and effector-like. The co-clustering of hCMV-specific CD4-CTLs and CD8-CTLs in both pre-effector as well as effector clusters suggest shared transcriptomic signatures between them. The huge TCR clonal expansion of cytotoxic clusters suggests a dominant role in the protective immune response to CMV. The study uncovers the heterogeneity in the hCMV-specific memory T cells revealing many functional subsets with potential implications in better understanding of hCMV-specific T cell immunity. The data presented can serve as a knowledge base for designing vaccines and therapeutics.2024-01-01T00:00:00Z2024 Jul2026-05-07T14:11:48.196Z2026-04-07T22:51:21.678ZS-EPMC76160773850130210.1111/imm.13783