Adenoviral Delivery of Recombinant Hepatitis B Virus Expressing Foreign Antigenic Epitopes for Immunotherapy of Persistent Viral Infection

Abstract

We previously reported a proof-of-concept study for curing chronic hepatitis B virus (HBV) infection using a foreign-antigen recombinant HBV (rHBV) as a gene therapy vector. Targeted elimination of wild-type HBV (wtHBV)-infected cells could be achieved by functionally activating an in situ T-cell response against the foreign antigen. However, as chronic HBV infection spreads to all hepatocytes, specific targeting of virus-infected cells is thought to be less critical. It is also feared that rHBV may not induce active immunization in a setting resembling natural infection. For this immunotherapeutic approach to be practically viable, in the present study, we used a recombinant adenovirus (rAd) vector for rHBV delivery. The rAd vector allowed efficient transduction of wtHBV-producing HepG2 cells, with transferred rHBV undergoing dominant viral replication. Progeny rHBV virions proved to be infectious, as demonstrated in primary tupaia hepatocytes. These results greatly expanded the antiviral capacity of the replication-defective rAd/rHBV in wtHBV-infected liver tissue. With prior priming in the periphery, transduction with rAd/rHBV attracted a substantial influx of the foreign-antigen-specific T-effector cells into the liver. Despite the fully activated T-cell response, active expression of rHBV was observed for a prolonged time, which is essential for rHBV to achieve sustained expansion. In a mouse model of HBV persistence established by infection with a recombinant adeno-associated virus carrying the wtHBV genome, rAd/rHBV-based immunotherapy elicited a foreign-antigen-specific T-cell response that triggered effective viral clearance and subsequent seroconversion to HBV. It therefore represents an efficient strategy to overcome immune tolerance, thereby eliminating chronic HBV infection. IMPORTANCEAdenovirus-delivered rHBV activated a foreign-antigen-specific T-cell response that abrogated HBV persistence in a mouse model. Our study provides further evidence of the potential of foreign-antigen-based immunotherapy for the treatment of chronic HBV infection.

A dendritic cell receptor-targeted chimeric immunotherapeutic protein (C-HBV) for the treatment of chronic hepatitis B

“…Many novel therapies that target the HBV life cycle and host immune response are currently in various stages of clinical development. 19,62 Strategies to develop agents for functional cure of hepatitis B include the use of novel adjuvants and routes of administration, 63 HBV antigens produced in situ using vector plasmids, 64,65 various RNAi technologies, 66 Tolllike receptor (TLR) effectors, 67 mAbs 68 and inhibitors of core capsid assembly. 69 The mechanisms HBV uses to avoid immune surveillance are not well understood.…”

CRISPR/Cas9 nickase-mediated disruption of hepatitis B virus open reading frame S and X

“…Clearly, for clinical application other delivery vehicles, providing a high vector to target cell ratio 56 , should be considered. Since HBV infection is primarily confined to a single organ, the liver, non-integrating vectors that reach high titres, such as adeno-associated virus (AAV) vectors 57 58 or adenoviral vectors 59 60 , may be suitable tools for direct and repeated delivery of the CRISPR/Cas9n nuclease system to achieve HBV clearance over time.…”

Engineering Hepadnaviruses as Reporter-Expressing Vectors: Recent Progress and Future Perspectives

“…In a study aimed at liver-targeting delivery of immunogenic peptides, Deng et al attempted to alleviate this problem by optimizing sequences surrounding HBV polymerase start codon according to Kozak’s rules [ 34 ], while replacing the upstream central part of C ORF with sequences encoding a polyepitope peptide (180 nt) in a fashion similar to the design of Wang et al above. The recombinant HBV apparently replicated better than wild-type HBV in the presence of a trans -complemented core, and in a follow-up study, mature virions infectious for primary tupaia hepatocytes (PTH) were demonstrated to be produced at levels lower than the wild-type [ 35 ]. Expression of the cargo peptide, however, was only shown using plasmid or recombinant adenovirus as delivery vectors [ 34 , 35 ].…”

“…The recombinant HBV apparently replicated better than wild-type HBV in the presence of a trans -complemented core, and in a follow-up study, mature virions infectious for primary tupaia hepatocytes (PTH) were demonstrated to be produced at levels lower than the wild-type [ 35 ]. Expression of the cargo peptide, however, was only shown using plasmid or recombinant adenovirus as delivery vectors [ 34 , 35 ].…”