Hepatitis B virus as a gene delivery vector activating foreign antigenic T cell response that abrogates viral expression in mouse models

Abstract

Chronic hepatitis B virus (HBV) infection is characterized by functionally impaired T cell responses.To ensure active immunotherapy, the immune response must be switched from exhausted T cells to functional effectors that can attain the liver and cure the viral infection. We thus designed a recombinant HBV (rHBV) containing a modified viral core gene that specifically delivers a foreign antigenic polyepitope to the liver. This recombinant virus could only be self-maintained in hepatocytes already infected by HBV through capsid complementation. A strong foreign epitope-specific T cell response was first primed in the periphery by way of DNA immunization in human leukocyte antigen ( In order to treat chronic HBV infection, intrahepatic T cell responses need to be switched from a state of dysfunction to fully efficient effector T cells. Previous studies have shown that HBV-based therapeutic vaccination might specifically activate T cell responses in chronic HBV carriers, although these appear to be transient and followed by a gradual decline. 2,3 For this reason, escape from built-up tolerance seems to be one of the most crucial points in active immunotherapy for persistent viral infection. 4 To achieve this goal, we propose an innovative strategy based on a non-HBV antigen-mediated functional T cell response that is intended to specifically target HBV and HBV-infected liver cells. Briefly, the non-HBV antigen consists of a portion of a foreign antigenic polyepitope that has been engineered in the HBV genome to create a recombinant hepatitis B virus (rHBV). Thus, HBV is used as a gene therapy vector to deliver the foreign antigenic polyepitope to the liver.Abbreviations: ALT, alanine aminotransferase; EBV, HBc, hepatitis B virus core protein; HBsAg, hepatitis B virus surface antigen; HBV, hepatitis B virus; HIV, human immunodeficiency virus; HLA, human leukocyte antigen; hyd., hydrodynamic; i.m., intramuscular injection; ORF, open reading frame; pCMV, cytomegalovirus plasmid; pgRNA, pregenomic RNA; prHBV1.3, recombinant hepatitis B virus plasmid; pwtHBV, rHBc, recombinant hepatitis B virus core protein; rHBV, recombinant hepatitis B virus; SEM, standard

Human Hematopoietic Reconstitution and HLA-Restricted Responses in Nonpermissive Alymphoid Mice

“…Two weeks after the last immunization, an HLA-A2-restricted anti-HBV splenic hCD8 T cell response was detected directly using specific MHC pentamers (Fig. 6B) (19). HLA-A2-restricted HBVspecific pentamer + CD8 + T cells were detected only in immunized CH1-2hSa chimeras and not in nonimmunized chimeras or in the original HLA-A2 + CB cells (Fig.…”

“…Spleen cells from immunized mice were incubated for 10 min with Fc block, as described in the previous section. Cells were stained for 10 min at RT in FACS buffer with a mix of three HBV-specific pentamers, HLA-A2-env peptides (peptides 183-191 and 348-357) and HLA-A2-core peptide (peptides [18][19][20][21][22][23][24][25][26][27], all the three pentamers being conjugated with allophycocyanin (ProImmune, Oxford, U.K.). As controls, cells were incubated with hepatitis C virus (HCV)-specific pentamers HLA-A2 NS3 peptide (1073-1081).…”

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

“…The plasmid carrying rHBV, named prHBV1.3s, was constructed as previously described (1), except that an HLA-A2-restricted epitope from the HIV gag protein was removed from the polyepitope sequence due to its hyporesponsiveness (1) (Fig. 1A).…”

“…It is therefore important to establish whether the rHBV vector facilitates active immunization, albeit with high expression of the foreign polyepitope. In this regard, surrogate delivery of rHBV DNA via hydrodynamic injection, as used in our previous study (1), could not be applied in humans, although it triggered a potent T-cell response in the murine liver (9). (iv) For sustained expansion, rHBV vector has to survive the functionally activated T-cell response, rather than be largely suppressed in the liver, as suggested in our previous study (1).…”

“…We previously described a novel strategy based on a T-cell response against a foreign antigen that specifically targets HBV-infected cells (1). In brief, the coding sequence for a cluster of immunodominant foreign epitopes was inserted into the HBV core gene to create a recombinant virus (rHBV).…”