Spike 1 trimer subunit vaccines against porcine epidemic diarrhea virus effectively induce protective immunity...

PEDV poses a significant threat to the sustainable development of the global swine industry, resulting in substantial economic losses. Current commercially available vaccines exhibit limited efficacy in controlling the disease. Therefore, the development of an effective vaccine for the prevention and control of PEDV is critically important. This study employed Trimer-Tag technology to express a native-like trimeric S1 subunit fusion protein using a eukaryotic expression system as a candidate vaccine, and evaluated its immunogenicity and protective efficacy in comparison with the full-length S protein. The results demonstrated that the S1-Trimer vaccine was safe, as no mortality was observed in mice and no abortions occurred in sows during the immunization period. In mouse, sow and piglet models, S1-Trimer elicits immunological responses comparable to those of the full-length S protein and induces high levels of PEDV-specific antibodies, including serum IgG, IgA, and neutralizing antibodies (Nabs). The results of the piglet challenge study demonstrated that, compared with the control group, immunization with both S1-Trimer and the full-length S protein significantly reduced diarrhea index scores, intestinal viral loads, and intestinal pathological lesions. These findings indicate that the S1-Trimer vaccine elicits strong protection against the highly pathogenic strain of PEDV, with clinical efficacy comparable to that of the full-length S protein. S1-Trimer, a promising and competitive candidate vaccine based on Trimer-Tag technology, represents a potentially significant platform for the rapid development and production of safe and effective subunit vaccines in the future.