Key result
PDCoV RBD dimer vaccine elicits ~2.8-fold higher neutralizing antibody titers vs inactivated vaccine in piglets.
Why the study?
Commercial vaccines for porcine deltacoronavirus are scarce, and while the spike protein receptor binding domain is a key target for neutralizing antibodies, the monomer exhibits weak immunogenicity.
Does a tandem dimeric RBD subunit vaccine improve immunogenicity and protective efficacy against PDCoV compared to monomer and inactivated vaccines in mice and piglets?
Does a tandem dimeric RBD subunit vaccine improve immunogenicity and protective efficacy against PDCoV compared to monomer and inactivated vaccines in mice and piglets?
A novel tandem dimeric RBD subunit vaccine for PDCoV demonstrated superior immunogenicity and protective efficacy compared to monomer and inactivated vaccines in animal models.
RBD dimer shows stronger immunogenicity than inactivated vaccine in piglets; extends preclinical platform but leaves open field efficacy and translation.
Porcine deltacoronavirus (PDCoV) is an emerging swine enteric coronavirus that has caused global epidemics and substantial economic losses, posing a potential risk of cross-species transmission, including to humans. However, commercial vaccines are currently scarce. The receptor binding domain (RBD) of the spike (S) protein is a key target for inducing neutralizing antibodies, but the RBD monomer typically exhibits low molecular weight and weak immunogenicity. This study aimed to develop a tandem dimeric RBD subunit vaccine and evaluate its immunogenicity and protective efficacy in comparison with the RBD monomer and an inactivated vaccine. A PDCoV RBD dimer protein was successfully expressed and purified using a mammalian expression system. In mice, the RBD dimer vaccine elicited significantly higher RBD specific IgG levels, and induced a mixed Th1/Th2 type immune response, while simultaneously inducing numerically higher neutralizing antibody titers compared with the monomer and inactivated vaccines, despite non-significant differences. Post-challenge histopathological analysis revealed that the intestinal villi of mice in the dimer group remained largely intact, with significantly less damage than those in the control groups. In piglets, the peak neutralizing antibody titer induced by the RBD dimer was approximately 2.8 times that induced by the inactivated vaccine, and antibody levels remained relatively high until day 72, accompanied by significantly stimulated lymphocyte proliferation. In mice, the RBD dimer subunit vaccine demonstrated superior antibody titers and protective efficacy compared with both the monomer and inactivated vaccines. In piglets, the dimer vaccine elicited higher and more durable antibody and neutralizing activity than the inactivated vaccine. These findings indicate the considerable potential of this candidate vaccine and warrant further in‑depth evaluation of its clinical protective efficacy in piglets.
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Tian et al. (2026) studied Porcine deltacoronavirus (PDCoV) infection (n=48). PDCoV RBD dimer subunit vaccine vs. RBD monomer vaccine, inactivated PDCoV vaccine, and PBS was evaluated on Neutralizing antibody titers and PDCoV RBD-specific IgG levels. The PDCoV RBD dimer subunit vaccine elicited significantly higher RBD-specific IgG levels and approximately 2.8-fold higher peak neutralizing antibody titers compared to the inactivated vaccine in piglets.
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