Hepatitis C virus E1 and modified E2 delivered from an mRNA vaccine induces protective immunity.

Hepatitis C virus (HCV) is characterized by a high number of chronic cases due to an impairment of protective innate and adaptive immune responses. Here, we examined the contribution of the individual ectodomains of E1, E2, or a modified E2 with reduced CD81 binding and an inserted N-linked glycosylation site in combination as vaccine antigen mRNA-lipid nanoparticles (LNPs). The induction of a protective immune response to surrogate recombinant vaccinia virus (VV) expressing homologous HCV glycoprotein(s) challenge infection in a BALB/c mouse model was observed. Vaccination with a mRNA-LNP expressing soluble E1 (sE1) significantly reduced vv/HCV titer in the mouse ovary. However, the addition of sE2 mRNA-LNP for immunization impaired the efficacy of the sE1 construct. Further analysis showed that Th1 related cytokine responses to the sE1 mRNA-LNP were significantly altered in the presence of sE2 following co-immunization. Evaluation of immunogenicity revealed that the use of modified sE2 nucleoside mRNA-LNP vaccine results in an improved cellular immune response, IgG2a isotype switching, enhanced total IgG, and an increase in the neutralizing antibody response against HCV pseudotype virus. HCV cross genotype specific reactivity to peptides representing conserved E2 specific linear epitopes were enhanced in modified E2 vaccinated animal sera. In the absence of a suitable immunocompetent small animal model for HCV infection, protection from surrogate HCV vaccinia challenge infection model was observed in the immunized mice as compared to sE1 alone or an unmodified sE2 mRNA-LNP vaccine. Inclusion of sE1 with modified sE2 as mRNA-LNP vaccine candidate appeared to be beneficial for protection.