The porcine epidemic diarrhea virus, PEDV, which causes diarrhea, vomiting and death in piglets, causes huge economic losses. Therefore, understanding how to induce mucosal immune responses in piglets is essential in the mechanism and application against PEDV infection with mucosal immunity. A method of treatment in our research was used to make an oral vaccine that packaged the inactive PEDV with microencapsulation, which consisted of sodium alginate and chitosan, and adapted the condition of the gut in mice. The in vitro release experiment of microcapsules showed that inactive PEDV was not only easily released in saline and acid solutions but also had an excellent storage tolerance, and was suitable for use as an oral vaccine. Interestingly, both experimental groups with different doses of inactive virus enhanced the secretion of specific antibodies in the serum and intestinal mucus, which caused the effective neutralization against PEDV in the Vero cell by both IgG and IgA, respectively. Moreover, the microencapsulation could stimulate the differentiation of CD11b+ and CD11c+ dendritic cells, which means that the microencapsulation was also identified as an oral adjuvant to help phagocytosis of dendritic cells in mice. Flow cytometry revealed that the B220+ and CD23+ of the B cells could significantly increase antibody production with the stimulation from the antigens’ PEDV groups, and the microencapsulation could also increase the cell viability of B cells, stimulating the secretion of antibodies such as IgG and IgA in mice. In addition, the microencapsulation promoted the expression of anti-inflammatory cytokines, such as IL-10 and TGF-β. Moreover, proinflammatory cytokines, such as IL-1, TNF-α, and IL-17, were inhibited by alginate and chitosan in the microencapsulation groups compared with the inactivated PEDV group. Taken together, our results demonstrate that the microparticle could play the role of mucosal adjuvant, and release inactivated PEDV in the gut, which can effectively stimulate mucosal and systemic immune responses in mice.

Background Lactobacillus casei had four possible probiotic roles, such as antimicrobial antagonism, competitional adhesion, immunoregulation and inhibition of bacterial toxin. The complex environment of gut microbe blocked to explore the antimicrobial scheme through genetics, metabolomics, proteomics, and signal transduction wth Lactobacillus casei. The genome editing Lactobacillus and germ-free animal provided the similar studying model of cell signal pathways to fully elucidate the probiotic mechanisms in animal. Results To delineate the metabolic reactions of nucleotides from L. casei associated with mechanisms of inhibiting pathogens and immunoregulation, we report the PyrR gene which was an important regulon to promote the pyrimidine biosynthesis, and PyrR deficient L. casei strain was successfully constructed with CRISPR-Cas9D10A tool. There were some changes with the basic biological characterization, such as decreasing the growth, auxotroph and morphological damage in the PyrR deficient strain. The metabolic profiles of supernatant between PyrR deficient and wild strain revealed a complementary regulation from other metabolic pathways within decreasing pyrimidine biosynthesis. Besides, the PyrR deficient strain significantly lost the character of inhibiting the growth of pathogens. We further identify PyrR regulating pyrimidine biosynthesis, which further improved the internalization and colocalization with the development of macrophages. Conclusions Evidence shows that PyrR gene is an active key for regulating pyrimidine biosynthesis in L. casei supernatant against a wide range of pathogens. The complementary regulation for the PyrR deficient could no inhibit the growth of pathogens, and immune regulation in the macrophages from mice. Thus, the deletion of PyrR in L. casei lost the probiotic character of antimicrobial antagonism and immunoregulation.

Lactobacillus is one of the predominant microorganisms in gut from human and animal, and the lactobacillus have effective applications against the viral diarrhea of piglets in the farm. However, the function and the concrete cell single pathways of the active ingredient from lactobacillus was not clear within anti-infection in the postbiotics research. Here, we compared the biological function of extracellular polysaccharides (EPS) purified from Lactobacillus casei and gene editing Lactobacillus casei with the CRISPER-Cas9 technology, which were with the ability of antioxidation and anti-inflammation, and the EPS could also inhibit the ROS production within the IPEC-J2. Interestingly, we found that both of EPS and genome editing Lactobacillus casei could specifically target the IFN-λ expression in the IPEC-J2, which was beneficial against the PEDV infection in the virus replication and production with the qRT-PCR and indirect immunofluorescence methods. Finally, the STAT3 cell single pathway was stimulated to transcribe IFN-λ with the EPS to elucidate the detailed mechanism of activating type III IFN signals receptor of IL-10R2, which play the function between anti-inflammation and anti-virus in the PEDV infection. Taken together, our research linked a postbiotics of EPS with the antiviral infection of PEDV, which suggest that the lactobacillus itself still have displayed the potential immunomodulatory activities, and highlight the immunomodulatory potential of EPS-producing microbes.

Seneca Valley Virus (SVV) infection was recently spread the pig farm in the Canada, American and China, human, mice and housefly have been the host and reservoirs. Although such cross-species transmission events result in limited onward in the new cross-species transmission, sustained outbreak have posed a new mammalian host. Thus, to determine whether mink was one of a new mammalian host in our study with the molecular characteristics of isolated SVA genomes, challenge, pathological study, and immune respond. Here, our research was the first systemic analysis on a new isolation strain of SVV from pig, the new strain infected the mink in oral and intestine, which produced the pathological change in the intestine. And the SVV could stimulate the specific neutralizing antibody. This study highlights the importance of identifying SVV infection in the mink and host as a mutational pressure for the virus evolution that could threaten livestock, public health and economic growth.