Self-assembly of virus-like particles of rabbit hemorrhagic disease virus capsid protein expressed in Escherichia coli and their immunogenicity in rabbits

- Soluble RHDV-VP60 protein was expressed in Escherichia coli by a pSMK vector containing a SUMO tag.
- The VP60 protein of RHDV has self-assembled into VLPs after the cleavage of the SUMO tag.
- RHDV specific responses were obviously induced in rabbits by RHDV-VLPs.
- VLPs-based RHDV vaccine can be used as a promising RHDV vaccine candidate.

In this study, virus-like particles (VLPs) derived from rabbit hemorrhagic disease virus (RHDV) were evaluated for the development of a vaccine against RHDV infection. The VP60 gene was cloned and inserted into a pSMK expression vector containing a small ubiquitin-like modifier (SUMO) tag that can promote the soluble expression of heterologous proteins in Escherichia coli cells. After expression and purification of His-SUMO-VP60 and cleavage of the SUMO tag, we found that the RHDV VP60 protein had self-assembled into VLPs with a similar shape and smaller size compared with authentic RHDV capsid. Next, the antigenicity and immunogenicity of the VLPs were examined. The results showed that RHDV-specific responses were clearly induced in rabbits and that all rabbits in the VLP group survived while those in the negative control group died within 72 h post-infection. These results suggest that VLP-based RHDV could be a promising RHDV vaccine candidate.