Hepatitis C virus (HCV) is highly diverse and has multiple immune evasion mechanisms, underscoring the need for innovative vaccination strategies. In recent years, mRNA-technology has allowed more rapid, flexible and cost-effective vaccine design than conventional approaches. This study utilises mRNA-technology in conjunction with a minimised form of E2 (E2Δ123) to create a vaccine for HCV.
Previous research has shown that the removal of the hypervariable regions of the E2 glycoprotein can generate an antigen (E2Δ123) with enhanced immunogenicity that is focused towards the neutralising epitopes of E2. Additionally, a cysteine modified variant, E2Δ123A7, offers a consistent monomeric structure that facilitates standardisation and manufacturing at scale. Here we show the expression, antigenicity and biophysical characterisation of mRNA-produced antigens through in vitro transient expression, purification using IMAC and size exclusion chromatography, SDS-PAGE and analysis with broadly neutralising (bNAbs) and non-neutralising antibodies via ELISA. To analyse the immunogenicity, vaccination studies in small animals were performed using mRNA formulations of E2Δ123, E2Δ123A7 and wildtype E1E2 heterodimer, as well as their purified protein counterparts.
The findings demonstrated that mRNA-produced antigens were successfully expressed and maintained their structural integrity. They effectively presented neutralising epitopes, as evidenced by the binding of bNAbs to these proteins. Immunogenicity studies in small animals demonstrated the mRNA-derived vaccine induced a comparable or enhanced immune responses compared to the purified protein, suggesting the potential of the mRNA platform for HCV vaccine development.
Overall, the study suggests that mRNA-produced E2Δ123 and E2Δ123A7 exhibit potential as vaccine candidates in clinical trials due to their ability to elicit targeted immune responses, maintain structural integrity, and present neutralising epitopes effectively. This work represents a critical step toward developing a potent mRNA-based HCV vaccine, leveraging the rapid development, scalability, and strong immune response characteristics of mRNA technology to address a significant public health need.