Modified Alphavirus-Vesiculovirus Hybrid Vaccine Vectors for Homologous Prime-Boost Immunotherapy of Chronic Hepatitis B

Abstract

Virus-like vesicles (VLV) are hybrid vectors based on an evolved Semliki Forest virus (SFV) RNA replicon and the envelope glycoprotein (G) from vesicular stomatitis virus (VSV). Previously, we showed that VLV can be used to express protein antigens and generate protective antigen-specific CD8+ T cells. This report describes VLV vectors designed for enhanced protein expression and immunogenicity. Expressing hepatitis B virus (HBV) middle S antigen (MHBs) from VLV using a dual subgenomic promoter significantly increased MHBs-specific CD8+ T cell and antibody production in mice. Furthermore, envelope glycoprotein switch from VSV Indiana to the glycoprotein of Chandipura virus enabled prime-boost immunization and further increased responses to MHBs. Therapeutic efficacy was evaluated in a mouse model of chronic HBV infection initiated by HBV delivery with adeno-associated virus. Mice with lower or intermediate HBV antigen levels demonstrated a significant and sustained reduction of HBV replication following VLV prime-boost immunization. However, mice with higher HBV antigen levels showed no changes in HBV replication, emphasizing the importance of HBV antigenemia for implementing immunotherapies. This report highlights the potential of VLV dual promoter vectors to induce effective antigen-specific immune responses and informs the further development and evaluation of hybrid viral vaccine platforms for preventative and therapeutic purposes.

Therapeutic vaccination for treatment of chronic hepatitis B

“…One strategy is to enrol groups of patients with lower baseline HBV antigen load, whose HBV-specific T cells are more susceptible to functional recovery. This is supported by animal models of chronic HBV in which therapeutic vaccination is more successful when HBsAg titres are low (115)(116)(117) and in people with chronic HBV stopping nucleos(t)ide therapy, in whom low HBsAg titres at time of nucleos(t)ide withdrawal are associated with subsequent HBsAg loss during follow-up (118). Pretreatment with therapies to reduce HBsAg, such as small interference RNA (siRNA) or nucleic acid polymers (NAPs) (119)(120)(121), might be useful to reduce HBsAg levels prior to therapeutic vaccination.…”

Immune modulation of innate and adaptive responses restores immune surveillance and establishes anti-tumor immunological memory

“…The VLV double promoter (dp) vector was for cloning was prepared by linearizing it with Asc I and Sbf I restriction enzymes in order to insert VSV G glycoprotein fragment from New Jersey (NJ) serotype downstream of the second sub-genomic promoter (27). The resulting VLVdp VSV G NJ vector was then digested with BamH I and Pac I enzymes and the resulting vector was used to insert cytokines and shRNA downstream of the first sub-genomic promoter.…”

“…VLV are a capsid-free, self-replicating virus-like vaccine platform carrying positive-strand capped and polyadenylated RNA encoding an in vitro evolved SFV RNA-dependent RNA replicase and the VSV glycoprotein. VLV can be engineered to express foreign antigens, proteins, or microRNAs (miRNA) that can modulate the immune response (27,28). The VLV platform replicates like a virus, but its only structural protein is the VSV glycoprotein (VSV-G), and unlike many other viral vectors, lacks pathogenicity (29,30).…”

Cancer immunotherapy with enveloped self-amplifying mRNA CARG-2020 that modulates IL-12, IL-17 and PD-L1 pathways to prevent tumor recurrence

“…The virus-like vesicle (VLV) is a hybrid of components from two unrelated animal viruses, the alphavirus Semliki Forest virus (SFV) RNA-dependent polymerase and rhabdovirus vesicular stomatitis virus glycoprotein (VSV-G), that produces infectious replication-competent enveloped vesicles at high titers in vitro 7 , 8 , 9 . VLVs can express multiple proteins, such as reporters, antigens, and/or membrane proteins, by employing sub-genomic promoters or 2A self-cleaving peptides 10 , 11 , 12 , 13 . Delivery of VLVs in vivo results in transient expression of VLV-encoded proteins and induction of antigen-specific immune responses 7 , 8 , 9 , 10 , 12 , 13 .…”

“…VLVs can express multiple proteins, such as reporters, antigens, and/or membrane proteins, by employing sub-genomic promoters or 2A self-cleaving peptides 10 , 11 , 12 , 13 . Delivery of VLVs in vivo results in transient expression of VLV-encoded proteins and induction of antigen-specific immune responses 7 , 8 , 9 , 10 , 12 , 13 . Prior applications of VLVs were focused on developing prophylactic vaccines or immunotherapy for chronic infections such as HBV or HIV 8 , 10 , 12 , 13 , 14 , but VLVs have not been explored before for use as oncolytic artificial viruses.…”