Virus-Like Particles Containing the E2 Core Domain of Hepatitis C Virus Generate Broadly Neutralizing Antibodies in Guinea Pigs

Abstract

A vaccine to prevent hepatitis C virus (HCV) infection is urgently needed for use alongside direct acting antiviral drugs to achieve elimination targets. We have previously shown that a soluble recombinant form of the glycoprotein E2 ectodomain (residues 384-661), that lacks three variable regions (Δ123) is able to elicit a higher titer of broadly neutralizing antibodies (bnAbs) in comparison to the parental form (receptor-binding domain; RBD). In this study, we engineered a viral nanoparticle that displays HCV glycoprotein E2 on a duck hepatitis B virus (DHBV) small surface antigen (S) scaffold. Four variants of E2-S virus-like particles (VLPs) were constructed: Δ123-S and RBD-S, and Δ123A7-S and RBDA7-S in which 7 cysteines were replaced with alanines. While all four E2-S VLPs display E2 as a surface antigen, the Δ123A7-S and RBDA7-S VLPs were the most efficiently secreted from transfected mammalian cells, and displayed epitopes recognized by cross-genotype broadly neutralizing monoclonal antibodies (bnmAbs). Both Δ123A7-S and RBDA7-S VLPs were immunogenic in guinea pigs, generating high titers of antibodies reactive to native E2 and able to prevent the interaction between E2 and the cellular receptor CD81. Four out of eight animals immunized with Δ123A7-S elicited neutralizing antibodies (nAbs), with three of those animals generating bnAbs against 7 genotypes. Immune serum generated by animals with nAbs mapped to major neutralization epitopes located at residues 412-420 (epitope I) and antigenic region 3. VLPs that display E2 glycoproteins represent a promising vaccine platform for HCV and could be adapted to large-scale manufacturing in yeast systems. IMPORTANCE There is currently no vaccine to prevent hepatitis C virus infection, which affects more than 71 million people globally and is a leading cause of progressive liver disease including cirrhosis and cancer. Broadly neutralizing antibodies that recognise the E2 envelope glycoprotein can protect against heterologous viral infection and correlate with viral clearance in humans. However, broadly neutralizing antibodies are difficult to generate due to conformational flexibility of the E2 protein and epitope occlusion. Here we show that a VLP vaccine using the duck hepatitis B virus S antigen fused to HCV glycoprotein E2 assembles into virus like particles that display epitopes recognised by broadly neutralizing antibodies and elicit such antibodies in guinea pigs. This platform represents a novel HCV vaccine candidate amenable to large-scale manufacture at low cost.

Yeast and Virus-like Particles: A Perfect or Imperfect Couple?

“…Concerning post-translational modifications, N-glycans derived from H. polymorpha are similar to those of P. pastoris described in the previous paragraph and thereby are less hyper-mannosylated than the N-glycans produced by S. cerevisiae (Figure 3) [109]. VLPs composed of glycosylated proteins have been effectively produced in H. polymorpha [110][111][112]. A recombinant strain carrying a deletion in two main yeast genes belonging to hyper-mannosylation pathways, α-1,6-mannosyltransferase (∆hpoch1) and α-1,3-mannosyltransferase (∆hpalg3) was constructed in order to produce human hybrid-type N-glycans.…”

Two-component vaccine consisting of virus-like particles displaying hepatitis C virus envelope protein 2 oligomers

“…Statistical significance testing was done using non-parametric Mann-Whitney tests (Graphpad Prism 9.2.0) and the significance threshold was set at 95%. protein) 30,33 . Importantly, the two-component (i.e., modular) nature of the employed cVLP vaccine design permits the comparison of monomeric and multimeric antigens.…”

“…While many research groups have contributed ways to improve immunogenicity of sE2 [26][27][28][29][30][31] , it remains challenging to produce HCV vaccine antigens that are both immunogenic and adaptable to proven vaccine modalities. In the attempt to overcome this barrier, sE2 has been genetically fused to different proteins, which can self-assemble into nanoparticles (NP) displaying multiple copies of monomeric sE2 30,32,33 . This offers a way to boost the immunogenicity of sE2, by allowing the antigen to be delivered in a multivalent and highly repetitive format 34 .…”

Advances in Tumor Antigen‐Based Anticancer Immunotherapy: Recent Progress, Prevailing Challenges, and Future Perspective

“…These particles exhibited epitopes recognized by widely neutralizing antibodies and elicited such antibodies in guinea pigs. [88] EBV and KSHV belong to the same herpesvirus subfamily. There are some common challenges in developing these two vaccines, such as concerns about the safety of potential infections and the lack of animal models.…”

“…These particles exhibited epitopes recognized by widely neutralizing antibodies and elicited such antibodies in guinea pigs. [ 88 ]…”