LAUSR

BACKGROUND AND AIMS T-cell based therapy is a novel approach developed for cancer treatment, and recently in chronic infectious diseases. Potential target populations are immunosuppressed patients with chronic hepatitis E virus infection (cHEV) who are ineligible or failed current treatment options with off-label ribavirin. T cell responses are important for viral control. We here aimed to identify HLA-A2 restricted HEV-specific CD8+ T cell epitopes and T cell receptors (TCR) targeting these epitopes, as the basis for redirected TCR treatment approach for patients with cHEV. METHODS HEV genotype 3 overlapping peptide pools were used to screen HEV-specific CD8+ T cell immune responses in HLA-A2+ patients with acute HEV infection and healthy donors, by intracellular cytokine staining. CD8+ T cells targeting the identified epitopes were sorted for sequencing of the TCR repertoires by Next Generation Sequencing. Messenger RNA encoding these TCRs were introduced into lymphocytes of healthy donors and cHEV patients through TCR redirection. TCR-engineered lymphocytes were evaluated for Dextramer-binding capacity, target sensitivity and cytotoxicity against peptide-loaded T2 cells. RESULTS HEV-specific responses were observed across ORF1 and ORF2 of the HEV genome in patients with acute resolving HEV infection. HLA-A2-restricted HEV-specific CD8+ T cell epitopes targeting the HEV RNA helicase and RNA-dependent RNA polymerase were selected for functional studies. Introduction of HEV-specific TCRs into lymphocytes of immunocompetent donors and also patients with chronic hepatitis E enabled the lymphocytes to bind HEV Dextramers, secrete multiple cytokines and exert cytotoxicity in a target-specific manner. CONCLUSION We identified TCRs targeting HEV-specific CD8+ T cell epitopes, and characterized their immune properties, which may have clinical potential in future T-cell based therapy. LAY SUMMARY Patients who are immunosuppressed are vulnerable to develop chronic liver disease following infection with Hepatitis E virus (HEV). To-date, there is no approved therapy for chronic hepatitis E. Interferon-α and ribavirin are off-label treatment options, but their applications are limited by side effects. Immunotherapy, more specifically T cell-based therapy, may hence be an alternative approach. We designed T cell receptor-engineered T cells that effectively conferred immune cells from patients with chronic hepatitis E with the ability to recognize virus-specific epitopes and mediate killing of target cells in-vitro.