Attenuated effector T cells are linked to control of chronic HBV infection

Hepatitis B virus (HBV)-specific CD8+ T cells play a dominant role during acute-resolving HBV infection but are functionally impaired during chronic HBV infection in humans. These functional deficits have been linked with metabolic and phenotypic heterogeneity, but it has remained unclear to what extent different subsets of HBV-specific CD8+ T cells still suppress viral replication. We addressed this issue by deep profiling, functional testing and perturbation of HBV-specific CD8+ T cells during different phases of chronic HBV infection. Our data revealed a mechanism of effector CD8+ T cell attenuation that emerges alongside classical CD8+ T cell exhaustion. Attenuated HBV-specific CD8+ T cells were characterized by cytotoxic properties and a dampened effector differentiation program, determined by antigen recognition and TGFβ signaling, and were associated with viral control during chronic HBV infection. These observations identify a distinct subset of CD8+ T cells linked with immune efficacy in the context of a chronic human viral infection with immunotherapeutic potential. Live HBV epitope-specific CD8+ T cells were sorted in 1,5mL microcentrifuge tubes (Eppendorf, Germany) containing 20µl PBS using BD Aria Fusion (BD, Germany). Naive, CD45RA+CCR7+, T cells were excluded. Sorted cells were processed through the 10x Genomics single-cell workflow with feature barcoding technology to multiplex cells from different donors so that they could be loaded on one well to reduce costs and minimize technical variability. Hashtag oligos were obtained as purified and already oligo-conjugated in TotalSeq-C (5’ chemistry) format from BioLegend. **Raw data are not provided due to privacy concerns**