Abstract
BackgroundDespite recent advancements, limitations in the treatment and control of hepatitis C virus (HCV) infection reprioritized the studies for invention of an efficient HCV vaccine to elicit strong neutralizing antibodies (NAbs) and cellular responses.MethodsHerein, we report molecular construction of a BacMam virus-based surface display for a subtype-1a HCV gpE2 (Bac-CMV-E2-gp64; Bac) that both expressed and displayed gpE2 in mammalian cells and bacouloviral envelope, respectively.ResultsAssessments by western blotting, Immunofluorescence and Immunogold-electron microscopy indicated the proper expression and incorporation in insect cell and baculovirus envelope, respectively. Mice immunized in three different prime-boost immunization groups of: Bac/Bac, Bac/Pro (bacoulovirus-derived gpE2) and Bac/DNA (plasmid DNA (pCDNA)-encoding gpE2) developed high levels of IgG and IFN-γ (highest for Bac/Bac group) indicating the induction of both humeral and cellular immune responses. Calculation of the IgG2a/IgG1 and IFN-γ/IL-4 ratios indicated a Th1 polarization of immune responses in the Bac/Bac and Bac/DNA groups but a balanced Th1-Th2 phenotype in the Bac/Pro group. Sera of the mice in the Bac/Bac group provided the highest percentage of cross-NAbs against a subtype-2a HCVcc (JFH1) compared to Bac/Pro and Bac/DNA groups (62% versus 41% and 6%).ConclusionsResults indicated that BacMam virus-based surface display for gpE2 might act as both subunit and DNA vaccine and offers a promising strategy for development of HCV vaccine for concurrent induction of strong humoral and cellular immune responses.
Highlights
Despite recent advancements, limitations in the treatment and control of hepatitis C virus (HCV) infec‐ tion reprioritized the studies for invention of an efficient HCV vaccine to elicit strong neutralizing antibodies (NAbs) and cellular responses
Confirmation of the generated recombinant baculovirus The constructed recombinant baculovirus (Bac-CMVE2-gp64; Bac) for simultaneous expression/display of the HCV E2 protein consisted of pCMV-IE, gp64 SP, His6 tag, E2 ectodomain, gp64 TM and cytoplasmic terminal domain (CTD) under the control of polyhedron promoter (PPH) (Fig. 1a)
Results of the Enzyme linked immunosorbent assay (ELISA) for HCV gpE2-specific IgG measurements on sera of the mice immunized by different immunization regimens indicated that there was statistically significant difference in the total IgG levels between Bac/Bac and Bac/Pro compared to Bac/DNA group (p < 0.017, p < 0.0007) (Fig. 2a)
Summary
Limitations in the treatment and control of hepatitis C virus (HCV) infec‐ tion reprioritized the studies for invention of an efficient HCV vaccine to elicit strong neutralizing antibodies (NAbs) and cellular responses. Despite extensive studies for development of a HCV vaccine by use of HCV proteins in various antigen formulations and modalities, no approved vaccine for human use is available to date. Results of the studies indicated that for being effective, an HCV vaccine needs to elicit strong neutralizing antibodies (NAbs) and potent T-cell responses [6, 7]. HCV gpE2 harbors several dominant T-cell epitopes for induction of strong cellular responses that further endorse it as a candidate vaccine antigen [10, 11]. Search for better adjuvants and vaccine platforms/modalities for induction of broad spectrum NAbs and cellular responses were undertaken [6]
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