Differentiation-induced reduction in functional diversity restricts the ability of cytomegalovirus-specific CD8 T cells to eliminate virus-infected cells

Lea Fritz; Ahmed Hassan; Lennart Riemann; Berislav Čuvalo; Bibiana Costa; Britta Wieland; Britta Eiz-Vesper; Christine Falk; Lennart M Roesner; Thomas Werfel; Ulrich Kalinke; Hristo Georgiev; Reinhold Förster; Berislav Bošnjak

doi:10.1016/j.ebiom.2025.106107

Differentiation-induced reduction in functional diversity restricts the ability of cytomegalovirus-specific CD8 T cells to eliminate virus-infected cells

EBioMedicine. 2026 Jan 5:123:106107. doi: 10.1016/j.ebiom.2025.106107. Online ahead of print.

Authors

Affiliations

¹ Institute of Immunology, Hannover Medical School, Hannover, Germany.
² Institute of Immunology, Hannover Medical School, Hannover, Germany; Department for Paediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany.
³ Institute for Experimental Infection Research, TWINCORE, Centre for Experimental and Clinical Infection Research, A Joint Venture Between the Helmholtz Centre for Infection Research and the Hannover Medical School, Hannover, Germany.
⁴ University Women's Hospital, Hannover Medical School, Hannover, Germany.
⁵ Institute of Transfusion Medicine and Transplant Engineering, Hannover Medical School, Hannover, Germany; German Centre for Infection Research (DZIF), Partner Site Hannover-Braunschweig, Hannover, Germany.
⁶ Institute of Transplantation Immunology, Hannover Medical School, Hannover, Germany; German Centre for Lung Research (DZL), BREATH Site, Hannover, Germany.
⁷ Department of Dermatology and Allergy, Hannover Medical School (MHH), Hannover, Germany; Cluster of Excellence RESIST (EXC 2155), Hannover Medical School, Hannover, Germany.
⁸ Institute for Experimental Infection Research, TWINCORE, Centre for Experimental and Clinical Infection Research, A Joint Venture Between the Helmholtz Centre for Infection Research and the Hannover Medical School, Hannover, Germany; Cluster of Excellence RESIST (EXC 2155), Hannover Medical School, Hannover, Germany.
⁹ Institute of Immunology, Hannover Medical School, Hannover, Germany; German Centre for Infection Research (DZIF), Partner Site Hannover-Braunschweig, Hannover, Germany; Cluster of Excellence RESIST (EXC 2155), Hannover Medical School, Hannover, Germany.
¹⁰ Institute of Immunology, Hannover Medical School, Hannover, Germany; Cluster of Excellence RESIST (EXC 2155), Hannover Medical School, Hannover, Germany. Electronic address: bosnjak.berislav@mh-hannover.de.

PMID: 41494240
DOI: 10.1016/j.ebiom.2025.106107

Abstract

Background: Human cytomegalovirus (HCMV) is one of the pathogens with the most significant impact on the immune system's composition, including the expansion of virus-specific CD8 T cells. Nevertheless, it remains unclear why individuals with expanded CD8 T cells recognising the pp65-HLA-A^∗02:01-restricted viral epitope NLVPMVATV (NLV-T cells) exhibit weakened immune control of HCMV reactivation.

Methods: Here, we characterised NLV-T cells from 116 healthy HCMV-positive donors, dividing them into two groups: those with low and those with high NLV-T cell frequencies (LF and HF, respectively). We phenotyped the cells using multi-colour spectral flow cytometry and single-cell RNA sequencing coupled with TCR profiling and examined their killing properties against peptide-loaded and virus-infected target cells.

Findings: Our comprehensive multimodal analysis revealed that NLV-T cells from HF donors exhibited a phenotype of advanced differentiation, marked by high levels of granzyme B and perforin expression, and efficiently eliminated peptide-loaded targets and HCMV-infected cells as long as cell surface HLA expression was unaffected. However, NLV-T cells from LF donors, possessing a less differentiated granzyme K-intermediate phenotype, demonstrated enhanced cytokine secretion and the ability to eliminate HCMV-infected cells, even in the presence of virus-induced HLA class-I downregulation.

Interpretation: Overall, these findings suggest that HCMV exploits CD8 T cell differentiation to evade immune protection. These data are crucial for understanding the previously observed decline in HCMV reactivation control in individuals with NLV-T cell accumulation. Moreover, our findings have clinical implications and could guide future research on adoptive T-cell therapy, and the potential use of HCMV as a vaccine vector.

Funding: Deutsche Forschungsgemeinschaft (DFG, German Research Foundation)-Projects number 390874280 and FO334/7-2.

Keywords: CD8 T cells; Differentiation; Functional diversity; Human cytomegalovirus; Infected cell killing; pp65.