Altered Glycosylation Patterns Increase Immunogenicity of a Subunit Hepatitis C Virus Vaccine, Inducing Neutralizing Antibodies Which Confer Protection in Mice

Abstract

Hepatitis C virus (HCV) infection is a global health problem for which no vaccine is available. HCV has a highly heterogeneous RNA genome and can be classified into seven genotypes. Due to the high genetic and resultant antigenic variation among the genotypes, inducing antibodies capable of neutralizing most of the HCV genotypes by experimental vaccination has been challenging. Previous efforts focused on priming humoral immune responses with recombinant HCV envelope E2 protein produced in mammalian cells. Here, we report that a soluble form of HCV E2 (sE2) produced in insect cells possesses different glycosylation patterns and is more immunogenic, as evidenced by the induction of higher titers of broadly neutralizing antibodies (bNAbs) against cell culture-derived HCV (HCVcc) harboring structural proteins from a diverse array of HCV genotypes. We affirm that continuous and discontinuous epitopes of well-characterized bNAbs are conserved, suggesting that sE2 produced in insect cells is properly folded. In a genetically humanized mouse model, active immunization with sE2 efficiently protected against challenge with a heterologous HCV genotype. These data not only demonstrate that sE2 is a promising HCV vaccine candidate, but also highlight the importance of glycosylation patterns in developing subunit viral vaccines. IMPORTANCEA prophylactic vaccine with high efficacy and low cost is urgently needed for global control of HCV infection. Induction of broadly neutralizing antibodies against most HCV genotypes has been challenging due to the antigenic diversity of the HCV genome. Here, we refined a high-yield subunit HCV vaccine that elicited broadly neutralizing antibody responses in preclinical trials. We found that soluble HCV E2 protein (sE2) produced in insect cells is distinctly glycosylated and is more immunogenic than sE2 produced in mammalian cells, suggesting that glycosylation patterns should be taken into consideration in efforts to generate antibody-based recombinant vaccines against HCV. We further showed that sE2 vaccination confers protection against HCV infection in a genetically humanized mouse model. Thus, our work identified a promising broadly protective HCV vaccine candidate that should be considered for further preclinical and clinical development. I t is estimated that over 2% of the world's population is chronically infected with hepatitis C virus (HCV) (1). Although recently approved direct-acting antiviral (DAA) drugs (2) have greatly improved upon the curing efficacy of the previous interferon (IFN)-based regimen, these new therapies are very expensive and thus unaffordable for the majority of HCV-infected individuals who live in developing countries, where most new infections occur. Since the approval of these highly effective DAAs, the number of chronic HCV carriers has not significantly declined. Furthermore, there is little evidence that patients cured of their chronic infections with DAAs retain antiviral immunity that is protective against future HCV exposures. Therefore, the...

Leishmania-Derived Trimannose Modulates the Inflammatory Response To Significantly Reduce Leishmania major-Induced Lesions

“…Antigen glycosylation has become increasingly recognized as a critical component of immune modulation by pathogens (6)(7)(8)(9). However, the glycan portion of the glycoconjugate was mainly considered a modulatory component with little to no antigenic properties independent of the lipid or protein that it was conjugated to.…”

A trivalent HCV vaccine elicits broad and synergistic polyclonal antibody response in mice and rhesus monkey

“…Here, we designed a trivalent formulation that includes sE2 from Con1 (GT1b), H77 (GT1a) and S52 (GT3a) to increase the antigenic coverage. These three sE2 proteins were expressed and purified from Drosophila S2 cell supernatants (figure 1A–C) as previously reported27 and mixed in an equal ratio and compared with each individual sE2 protein. ELISA analysis shows that these E2 proteins reacted in a dose-dependent manner with E2 receptor CD81 (figure 1D) or E2-specific antibodies AR3A9 and AP33,31 which recognise a conformational and linear E2 epitope, respectively (figure 1E), suggesting that the three sE2 proteins were properly folded.…”

“…HCV E2-specific antibodies in sera were quantified by ELISA as previously described 27. For neutralisation assay, around 100 focus-forming units of HCVcc were incubated for 1 hour with serially diluted sera or purified IgG.…”

“…The E2 protein is expressed from Drosophila S2 cells at a remarkably high yield (up to 100 mg/L) and has been shown to be highly immunogenic possibly due to its distinct glycosylation patterns in insect cells 27 28. Importantly, active immunisation with the E2 vaccine efficiently protected genetically humanised mice from heterologous HCV challenge 27. The objective of this study was to improve the breadth and potency of immunity induced by E2, particularly to the HCV strains that were inefficiently neutralised by the Con1sE2-induced antibodies, such as H77 (GT1a) and S52 (GT3a) which are prevalent subgenotypes in the world 29…”

Biotechnologies Applied in Biomedical Vaccines

“…The antigen protein is harvested and puriied to be used for the vaccine. This technique is also being used to explore a vaccine against hepatitis C [4].…”