Expression and Evaluation of a Novel PPRV Nanoparticle Antigen Based on Ferritin Self-Assembling Technology.

Peste des Petits Ruminants (PPR) is a highly pathogenic disease that is classified as a World Organization for Animal Health (OIE)-listed disease. PPRV mainly infects small ruminants such as goats and sheep. In view of the global and high pathogenicity of PPRV, in this study, we proposed a novel nanoparticle vaccine strategy based on ferritin (Fe) self-assembly technology. Using Helicobacter pylori ( H. pylori ) ferritin as an antigen delivery vector, a PPRV hemagglutinin (H) protein was fused with ferritin and then expressed and purified in both Escherichia coli ( E. coli ) and silkworm baculovirus expression systems. Subsequently, the nanoparticle antigens' expression level, immunogenicity and protective immune response were evaluated. Our results showed that the PPRV hemagglutinin-ferritin (H-Fe) protein was self-assembled in silkworms, while it was difficult to observe the correctly folded nanoparticle in E. coli . Meanwhile, the expression level of the H-Fe protein was higher than that of the H protein alone. Furthermore, the immunogenicity and protective immune response of H-Fe nanoparticle antigens expressed by silkworms were improved compared with the H antigen alone. Particularly, the protective immune response of H-Fe antigens expressed in E. coli did not change, as opposed to the H antigen, which was probably due to the incomplete nanoparticle structure in E. coli . This study indicated that the use of ferritin nanoparticles as antigen delivery carriers could increase the expression of antigen proteins and improve the immunogenicity and immune effect of antigens.