HBV X Protein-Based Therapeutic Vaccine Accelerates Viral Antigen Clearance by Mobilizing Monocyte Infiltration Into the Liver in HBV Carrier Mice
Jau-Hau Horng 1 , Wei-Hsiang Lin 2 , Chang-Ru Wu 1 , You-Yu Lin 3 , Li-Ling Wu 4 , Ding-Shinn Chen 3 5 6 , Pei-Jer Chen 7 8 9 10
Affiliations
Affiliations
1
Graduate Institute of Microbiology, National Taiwan University College of Medicine, No. 1 Jen Ai Road Section 1, Taipei, Taiwan (R.O.C.).
2
TheVax Genetics Vaccine Company Limited, 5F, No. 25, Jen Ai Road Section 4, Taipei, Taiwan (R.O.C.).
3
Graduate Institute of Clinical Medicine, National Taiwan University College of Medicine, No. 1, Jen Ai Road Section 1, Taipei, Taiwan (R.O.C.).
4
Department & Institute of Physiology, National Yang-Ming University, No. 155, Section 2, Linong Street, Taipei, Taiwan (R.O.C.).
5
Division of Gastroenterology, Department of Internal Medicine, National Taiwan University Hospital, No. 1, Changde Street, Taipei, Taiwan (R.O.C.).
6
Hepatitis Research Center, National Taiwan University Hospital, No. 1, Changde Street, Taipei, Taiwan (R.O.C.).
7
Graduate Institute of Microbiology, National Taiwan University College of Medicine, No. 1 Jen Ai Road Section 1, Taipei, Taiwan (R.O.C.). [email protected].
8
Graduate Institute of Clinical Medicine, National Taiwan University College of Medicine, No. 1, Jen Ai Road Section 1, Taipei, Taiwan (R.O.C.). [email protected].
9
Division of Gastroenterology, Department of Internal Medicine, National Taiwan University Hospital, No. 1, Changde Street, Taipei, Taiwan (R.O.C.). [email protected].
10
Hepatitis Research Center, National Taiwan University Hospital, No. 1, Changde Street, Taipei, Taiwan (R.O.C.). [email protected].
PMID: 32466788 DOI: 10.1186/s12929-020-00662-x
Abstract
Background: Hepatitis B virus (HBV) persistently infected about 250 million people worldwide, and a curative treatment remains an unmet medical need. Among many approaches to treat chronic hepatitis B (CHB), therapeutic vaccines have been developed for two decades, but none have yielded promising results in clinical trials. Therefore, dissection of HBV clearance mechanisms during therapeutic vaccination in appropriate models, which could give rise to new curative therapies, is urgently needed. Growing evidence indicates that prolonged and intensive exposure of antigen-specific T cells to viral antigens is a major cause of T cell exhaustion, and decreases anti-HBV immunity efficacy of therapeutic vaccination. HBV X protein (HBx) is expressed at low levels, and the understanding of its immunogenicity and potential in therapeutic CHB vaccines is limited.
Methods: HBV genome sequences from CHB patients were cloned into a pAAV plasmid backbone and transfected into immunocompetent mouse hepatocytes through hydrodynamic injection. Mice carrying > 500 IU/mL serum HBV surface antigen (HBs) for more than 4 weeks were considered HBV carriers mimicking human CHB and received 3 doses of weekly HBx vaccine by subcutaneous immunization. Serum HBV clearance was evaluated by monitoring serum HBs and HBV-DNA titers. Residual HBV in the liver was evaluated by western blotting for HBV core antigen. The splenic antigen-specific T cell response was quantified by a 15-mer overlapping peptide-stimulated interferon-γ enzyme-linked immunospot assay. Blood and hepatic immune cells were quantified by flow cytometric analysis.
Results: Our HBx-based vaccine induced systemic HBx-specific CD4+ and CD8+ T cell responses in HBV carrier mice and demonstrated significant HBs and HBV-DNA elimination. The protective effect persisted for at least 30 days without additional booster immunization. Different infiltrating myeloid cell subsets, each with distinctive roles during immune-mediated HBV clearance, were found in the liver of vaccinated mice. During vaccine therapy, inflammatory monocyte depletion resulted in sustained HBV clearance inhibition, whereas phagocytic monocyte-derived macrophage and Kupffer cell elimination resulted in only transient inhibition of vaccine-induced HBV clearance.
Conclusions: We report the potential role of HBx as a major immunogen in an HBV therapeutic vaccine and the significance of a liver-infiltrating monocyte subset during hepatic viral clearance.
方法：将来自CHB患者的HBV基因组序列克隆到pAAV质粒骨架中，并通过流体动力注射转染到具有免疫功能的小鼠肝细胞中。携带大于500 IU / mL血清HBV表面抗原（HBs）超过4周的小鼠被认为是模仿人CHB的HBV携带者，并通过皮下免疫每周接种3剂HBx疫苗。通过监测血清HBs和HBV-DNA滴度评估血清HBV清除率。通过蛋白质印迹法评估HBV核心抗原在肝脏中的残留HBV。通过15聚体重叠肽刺激的干扰素-γ酶联免疫斑点测定法定量脾抗原特异性T细胞应答。通过流式细胞术分析定量血液和肝免疫细胞。