Hepatitis B virus-specific T cell receptors with high functional redirect T cells to eliminate HBV

Adoptive T-cell therapy of chronic hepatitis B or hepatitis B virus (HBV)-induced hepatocellular carcinoma intends to restore antiviral T-cell immunity to clear the infection or control tumor growth. Question: to identify T-cell receptors (TCR) with high functional avidity to redirect T cells and to test their potential to cure HBV infection in vitro and in vivo. We isolated a series of HLA-A*02 restricted TCRs specific for HBV S or core protein derived peptides from patients with acute and resolved HBV infection. Primary human T cells were genetically modified by retroviral transduction to express these HBV-specific TCRs. One S20- and one C18-specific TCR each with high functional avidity were selected for further analysis. Upon TCR grafting, CD8 as well as CD4 T cells became polyfunctional HBV-specific effector T cells recognizing even picomolar concentrations of cognate peptide. TCR-grafted T cells secreted IFN gamma, TNF alpha and interleukin-2, controlled HBV replication and effectively killed hepatoma cells with an integrated HBV genome as well as HBV-infected cells. Notably, these HBV-specific TCRs recognized peptide of different HBV genotypes and presented on different HLA-A*02 subtypes common in areas with high HBV prevalence.When co-cultured with HBV-infected HepaRG or HepG2-NTCP cells, TCR-transduced T cells stopped viral replication, killed approximately 80% of plated cells and eliminated viral antigens as well as cccDNA from the cell culture. Importantly, TCRs also mediated elimination of HBV when expressed on CD4 T cells or on T cells from patients with chronic hepatitis B. In vivo, TCR-redirected T cells targeted the liver when transferred into HBV-infected uPA-SCID/beige/IL2rg-/- (USG) mice repopulated with HLA-A*02-matched primary human hepatocytes. After 5 days, alanine amino transferase levels were moderately increased. Subsequently, viremia decreased more than 4 – 5 log and HBsAg as well as HBeAg dropped to the level of detection. Intrahepatic analysis after three weeks revealed strong reduction of cccDNA loads (> 95%), and HBcAg staining in the liver had become negative. HBV rebound was not observed till the end of the experiment.

Our experiments indicate that T cells stably transduced with TCRs of high functional avidity allow adoptive T-cell therapy of chronic hepatitis B and HBV-induced hepatocellular carcinoma, because they have a remarkable cytotoxic potential and may mediate clearance of the virus.Moreover, HBV-specific TCRs represent an interesting tool for elucidating mechanisms of TCR-MHC interaction and dissecting specific anti-HBV mechanisms exerted by T cells.