Abstract
Enterovirus71 (EV71) has posed a serious threat to children health and caused the death of more than 200 children since 1998, thus entailing the need to develop an effective vaccine to prevent the endemic. Since the assembly of enterovirus requires the cleavage of P1 polyprotein by protease 3CD into individual structural proteins and baculovirus holds promise as a vector for gene delivery into mammalian cells, we constructed recombinant baculovirus encoding P1 and 3CD of EV71 (Bac-P1-E3CD) to co-express the proteins in mammalian cells, hoping that P1 is cleaved correctly and stimulate stronger immunity in vivo. We demonstrated that Bac-P1-E3CD transduction of mammalian cells resulted in the cleavage of P1 into individual structural proteins (VP1, VP3 and VP0) and formation and aggregation of virus like particles (VLPs) within the transduced RD cells. To explore whether prolonged antigen expression can ameliorate the vaccine efficacy, we constructed the hybrid Sleeping Beauty-baculovirus (SB-P1-E3CD-V/SB100X-V) for sustained P1/3CD expression and demonstrated that the hybrid baculovirus prolonged the VP1 expression to 21 days in HEK 293 cells. Immunization of mice with SB-P1-E3CD-V/SB100X-V elicited the anti-EV71 antibodies with high neutralization titers and the antibody response persisted for up to 12 weeks. More importantly, the baculovirus-based vaccine could elicit stronger cellular immunity. In a long time, the SB-P1-E3CD-V group indeed observed a higher immune response especially injected single-dose group. In this study, we introduce a new platform: Combine baculovirus with long-term expression system as a vaccine vector, and propose ‘’single-dose strategy’’. Hope this new idea could contribute the development of baculovirus-based vaccine.