Chimeric hepatitis B core virus-like particles displaying the receptor-binding domain of porcine deltacoronavirus elicit protective immunity in piglets.

As an emerging porcine enteric coronavirus, porcine deltacoronavirus (PDCoV) poses a serious threat to the swine industry and has the potential to infect humans. Thus, the development of effective vaccines is crucial for the prevention and control of PDCoV. In this study, RBD-HBc chimeric virus-like particles (VLPs) were accomplished by inserting the receptor binding domain (RBD) of PDCoV spike protein into the major immunodominant region of the truncated hepatitis B virus core protein (HBc; amino acids 1-149), and the protective efficacy of RBD-HBc chimeric VLPs was evaluated in piglets. Compared to the RBD protein, RBD-HBc chimeric VLPs induced higher levels of PDCoV-specific sIgA, neutralizing antibodies, and increased the secretion of IFN-γ and IL-4. Furthermore, virus challenge tests demonstrated that RBD-HBc chimeric VLPs effectively reduced virus shedding and alleviated pathological damage. These data indicate that RBD-HBc chimeric VLPs is a promising vaccine candidate for combating PDCoV infection.