Combining herbal fermentation with Lactobacillus expressing recombinant PEDV-S1 protein offers protection against PEDV infection

The porcine epidemic diarrhea virus (PEDV) causes porcine epidemic diarrhea, an acute, highly contagious infectious disease that has caused significant economic losses in the global pig industry. Due to the high variability of PEDV, vaccines based on classical strains no longer provide effective immune protection, and no specific antiviral drugs have been developed. In this study, we successfully developed a novel recombinant Lactobacillus strain that expresses the PEDV-LJX01-S1 protein. This was achieved using a laboratory-constructed S-layer-anchored expression system, along with CRISPR-Cas9 and other technologies. Additionally, we screened the traditional Chinese medicine Andrographis paniculata and co-fermented it with the recombinant Lactobacillus , leading to a significant enhancement of the immune response. The findings demonstrated that the new recombinant Lactobacillus enhanced the quantity of macrophages and natural killer cells in the piglets' peripheral blood. Additionally, it increased the activation of CD4 + T cells in the spleen and stimulated the release of interleukin-4. Furthermore, in the intestines and spleen, the recombinant Lactobacillus promoted the activation of T cells, B cells, and myeloid cells, which in turn enhanced the activation of CD3 + T cells, CD21 + B cells, and certain myeloid cells in the small intestine. Piglets that received the vaccination demonstrated improved intestinal health, a reduction in viral load, and a considerable increase in serum-specific antibodies. This work offers important insights into managing PEDV by introducing a novel vaccination approach for the prevention and control in pigs. • A recombinant Lactobacillus expressing PEDV-LJX01-S1 was developed using CRISPR-Cas9 gene editing. • Co-fermentation with Andrographis paniculata enhanced the immune response in piglets. • Inoculated piglets showed strong resistance to PEDV infection after challenge.