Self-assembling Rotavirus VP6 Nanoparticle Vaccines Expressed in Escherichia coli Elicit Systemic and Mucosal Responses in Mice

Background: Rotavirus is the most common cause of infectious diarrhea in infants and young children around the world. The inner capsid protein VP6 has been discussed as alternative vaccine as it can induce cross-protective immune responses against different RV strai. The use of ferritin nanoparticle may enhance the immunogenicity of the subunit vaccine. Objective: In this article, our motivation is to design and obtain a self-assemble rotavirus nanoparticle vaccine which can induce efficiency immune response. Methods: The VP6 protein was fused with ferritin and expressed in the Escherichia coli expression system. The recombinant VP6-ferritin (rVP6-ferritin) protein was purified by His-tag affinity chromatography and fast protein liquid chromatography. Transmission electron micrographic analysis was used to detect the nanostructure of the self-assembled protein. Mice were gavage with the protein and ELISA was used to detect the titer of the VP6 specific antibody. Results: The recombined VP6-ferritin was expressed in the Escherichia coli as an inclusion body form and the purified protein has similar antigenicity to rotavirus VP6. Transmission electron micrographic analysis of rVP6-ferritin exhibited spherical architecture with a uniform size distribution, which is similar to the ferritin nanocage. Immune response analysis showed that mice immunized by rVP6-ferritin protein induced 8000 (8000±1093) anti-VP6 IgG titers or 1152 (1152±248.8) anti-VP6 IgA titers. Conclusion: According to the above research, the rotavirus VP6-ferritin protein can be easily express and self-assemble to the nano-vaccine and induce efficiency humoral and mucosal immunity. Our research makes a foundation for the development of oral rotavirus vaccine.