PhD Candidate OHSU Oregon National Primate Research Center Beaverton, Oregon, United States
Disclosure(s):
Sofiya Yusova, MS: No financial relationships to disclose
Introduction/Rationale: Even though T cells are known to be essential for Hepatitis B virus (HBV) clearance, there is currently no FDA-approved immunotherapy against chronic HBV infection, one of the major global causes of liver cancer, hepatocellular carcinoma (HCC). We aimed to characterize and test HBV-specific T cell receptors (TCRs) in a rhesus macaque (RMs) model of acute HBV clearance.
Methods: We analyzed HBV-specific T cell responses using non-parenchymal liver cells from RMs that cleared HBV by enzyme-linked immunospot and intracellular cytokine staining (ICS). We live-sorted activated HBV-specific CD8+ T cells from an animal with the strongest response using the TNF-α processing inhibitor (TAPI-0) and analyzed their transcriptional profile as well as T cell receptors (TCRs) via single-cell RNAseq. We used the retroviral method of expressing the α and β TCR chains from the top 8 most enriched TCRs in naive CD8+ T cells to confirm their specificity, map the minimal epitope, and identify MHC restriction.
Results: We identified three animals with strong CD8+ T cell responses against the same HBV surface 15-mer. The transcriptional profile showed that the responding CD8+ T cells primarily expressed αβ TCR chains and were highly activated. Using ICS, we confirmed the anti-viral activity of 3 TCRs. Peptide dilution experiments using T cells transduced with these TCRs showed that the immunogenic peptide is FLLTRILTI, which is known to be presented by HLA-A*02 in humans. We also determined that in RMs the restricting allele for this peptide is Mamu-B*031:01:01.
Conclusion: One of the main challenges in developing immunotherapy against chronic HBV infection is a lack of pre-clinical animal models. We show that RMs can be used to identify HBV-specific CD8+ T cell responses. Future directions include developing MHC-peptide tetramers to detect and elucidate HBV-specific T cell responses, identifying HBV-specific TCRs against other HBV proteins, and testing T-cell-based immunotherapy efficiency and safety.
