Hepatitis B core antigen-based trivalent VLP vaccine against porcine viral diarrhea.

Porcine viral diarrhea imposes substantial economic burdens on the swine industry. The commercial triplex-attenuated vaccine against TGEV, PEDV, and PoRV infections has limitations in preparation and efficacy. The Hepatitis B virus core antigen (HBcAg), known for its ability to self-assemble into virus-like particles (VLPs) in vitro and stably present exogenous antigens, serves as a critical technical foundation for the development of innovative nano-vaccines. In this study, we strategically concatenated truncated and full-length monomers of HBcAg, with the conserved linear neutralizing epitopes from TGEV, PEDV, and PoRV being respectively integrated exclusively into the truncated variants to develop a trivalent-VLP (triVLP) vaccine candidate for porcine viral diarrhea. The immunogenicity of triVLPs at two distinct dosages (25 μg and 50 μg) was then evaluated in BALB/c mice following their administration. Notably, the higher dosage of 50 μg triVLP was found to significantly enhance cellular immunity compared to the 25 μg triVLP group, as evidenced by the substantial increase in serum levels of IFN-γ and IL-4 observed at 35 days post-immunization (dpi). Furthermore, at 35 dpi, the IgG and virus neutralizing (VN) antibody titers against TGEV, PEDV, and PoRV in the 50 μg triVLP group were significantly higher than those observed in the group receiving the commercial triplex-attenuated vaccine, indicating a pronounced humoral immune response. Collectively, our data indicate that HBcAg-based trivalent VLPs elicit potent cellular and humoral immunity, positioning them as a prospective vaccine candidate for porcine viral diarrhea.