A Hepatitis C Virus DNA Vaccine Encoding a Secreted, Oligomerized Form of Envelope Proteins Is Highly Immunogenic and Elicits Neutralizing Antibodies in Vaccinated Mice

Abstract

Hepatitis C virus (HCV) persistently infects approximately 71 million people globally. To prevent infection a vaccine which elicits neutralizing antibodies against the virus envelope proteins (E1/E2) which are required for entry into host cells is desirable. DNA vaccines are cost-effective to manufacture globally and despite recent landmark studies highlighting the therapeutic efficacy of DNA vaccines in humans against cervical cancer, DNA vaccines encoding E1/E2 developed thus far are poorly immunogenic. We now report a novel and highly immunogenic DNA vaccination strategy that incorporates secreted E1 and E2 (sE1 and sE2) into oligomers by fusion with the oligomerization domain of the C4b-binding protein, IMX313P. The FDA approved plasmid, pVax, was used to encode sE1, sE2, or sE1E2 with or without IMX313P, and intradermal prime-boost vaccination studies in BALB/c mice showed that vaccines encoding IMX313P were the most effective in eliciting humoral and cell-mediated immunity against the envelope proteins. Further boosting with recombinant E1E2 proteins but not DNA nor virus-like particles (VLPs) expressing E1E2 increased the immunogenicity of the DNA prime-boost regimen. Nevertheless, the antibodies generated by the homologous DNA prime-boost vaccinations more effectively inhibited the binding of VLPs to target cells and neutralized transduction with HCV pseudoparticles (HCVpp) derived from different genotypes including genotypes 1, 2, 3, 4, 5, and 6. This report provides the first evidence that IMX313P can be used as an adjuvant for E1/E2-based DNA vaccines and represents a translatable approach for the development of a HCV DNA vaccine.

Enhanced T Cell Responses Induced by a Necrotic Dendritic Cell Vaccine, Expressing HCV NS3

“…NS3-specific cellular immune responses were assessed by IFN-γ ELISpot assay as we described ( Grubor-Bauk et al, 2015 , 2019 ; Masavuli et al, 2019 ). Briefly, multiscreen-IP HTS plates (Millipore) were coated with anti-mouse IFNγ (clone AN18, MabTech) and secreted IFNγ was detected with anti-mouse IFNγ -biotin (clone R4-6A2, MabTech), streptavidin-AP (Sigma Aldrich) and SigmaFast BCIP/NBT (Sigma Aldrich).…”

Hepatitis C Virus Vaccine: Challenges and Prospects

“…Despite the challenges faced in HCV vaccine design, there have been a variety of different vaccine approaches investigated with a small number of these candidates reaching human trials (summarized in Table 1). Currently, DNA and peptide-based vaccine candidates are actively being investigated in murine models [154][155][156][157][158]. One recently reported peptide candidate consisted of overlapping peptides derived from the p7 protein which induced antigen-specific CD4+ T cells and cytotoxic CD8+ T cells capable of targeting p7 expressing hepatocytes in vivo [154].…”

Innate Immune Response against Hepatitis C Virus: Targets for Vaccine Adjuvants

“…A DNA vaccine encoding secreted HCV E1/E2 oligomers by fusion with the oligomerization domain of the chicken complement inhibitor C4b-binding protein (IMX313P) was designed and evaluated in BALB/c mice [ 184 ]. The sE1/sE2-IMX313P vaccine elicited an enhanced nAbs and cell-mediated responses against the envelope proteins when compared to separate (E1 or E2) immunogens.…”