Development of Virus-Like Particles (VLPs) for Hepatitis C Virus genotype 4: a novel approach for vaccine development in Egypt.

Background: Egypt has the highest global prevalence of Hepatitis C Virus (HCV) infection, particularly of genotype 4. The development of a prophylactic vaccine remains crucial for HCV eradication, yet no such vaccine currently exists due to the vaccine development challenges. The ability of Virus-Like Particles (VLPs) to mimic the native virus and incorporate neutralizing and conformational epitopes, while effectively engaging both humoral and cellular immune responses, makes them a promising approach to addressing the challenges in HCV vaccine development.

Methods: Lentiviral-based vectors were constructed and employed to integrate the full-length sequence of Core, E1, E2, and P7 genes of HCV genotype 4 into the genome of Human Embryonic Kidney cells (HEK293T). Upon the expression, HCV structural proteins can oligomerize and self-assemble into VLPs mimicking the structure of HCV native virus. VLPs were purified and characterized for the development of a potential VLPs-based vaccine.

Results: In this study, mammalian cells were successfully engineered to stably express HCV structural proteins and generate non-infectious VLPs for HCV genotype 4. The expression of HCV-integrated genes resulted in a successful production of HCV structural proteins, which oligomerized and self-assembled into two layers enveloped VLPs. Electron microscopy analysis of purified VLPs revealed spherical particles with an average diameter of 60-65 nm, closely resembling mature HCV virions. These results highlighted the potential of these VLPs as a vaccine candidate for HCV genotype 4.

Conclusions: HCV genotype 4 remains an underexplored target in vaccine development, despite its significant public health burden, especially in Egypt. The successful generation of VLPs for this genotype represents a promising avenue for further vaccine development. The established system provides a robust platform for the production and study of VLP-based vaccines targeting HCV genotype 4.