不同猪源受体菌表达猪流行性腹泻病毒保护性抗原S1诱导免疫应答的比较研究OA北大核心CSTPCD

The aim was to compare the strength of Lacticaseibacillus paracasei of porcine origin,Limosilactobacillus reuteri of porcine origin,and Lactobacillus johnsonii of porcine origin as oral vaccine vectors to express exogenous proteins to stimulate immunity production in piglets with a view to selecting suitable lactic acid bacteria as receptor vectors.In this study,the acid and bile salt tolerance of recombinant porcine Lacticaseibacillus paracasei(pPG-T7g10-S1/L.paracasei 27-2),Limosilactobacillus reuteri(pPG-T7g10-S1/L.reuteri J31)and Lactobacillus johnsonii(pPG-T7g10-S1/L.johnsonii 6332)were measured in vitro to investigate the resistance of the three strains expressing PEDV S1 protein.The results showed that all the three recombinant strains could tolerate acid and bile salt environment,and there was no significant difference with their wild type strains.Then to compare the immune effects,the newborn piglets were orally immunized with the three recombinant strains,separately.Indirect ELISA and neutralization test were used to detect the specific antibodies and neutralizing activity of the piglets,and the levels of each cytokine in serum and intestinal mucosa of the immunized piglets were measured.The results showed that after oral immunization,compared with the control group,the levels of serum IgG antibody and SIgA antibody in nasal swabs,anal swabs and intestinal mucus of piglets in the three recombinant strains groups were significantly increased,lasted to the 28th day.The antibody level induced by pPG-T7g10-S1/L.paracasei 27-2 group was significantly higher than that of the other two groups(P＜0.05).Pigley-produced specific IgG and SIgA both showed neutralizing activity against PEDV.The levels of IFN-γ,IL-2,IL-4 and IL-10 in the serum of piglets were significantly higher than those in the control group(P＜0.05),but there was no significant difference in the levels of cytokines among the three recombinant strains.The levels of cytokines IFN-γ,IL-2,IL-4,IL-5,IL-6,IL-17,IL-21,TGF-β,APRIL and BALL in the jejunal mucosa of piglets were higher than those in the control group.The levels of IL-4,IL-5,IL-6,TGF-β,IL-17,IL-21 and BALL in pPG-T7g10-S1/L.paracasei 27-2 group were significantly higher than those in other groups(P＜0.05).In conclusion,in this study,oral immunization of piglets with recombinant L.paracasei,L.reuteri and L.johnsonii,constitutively expressing the major protective antigen S1 of PEDV,showed that they could stimulate mucosal immunity,humoral immunity and cellular immunity against PEDV.Compared with the other two recombinant strains,the recombinant porcine pPG-T7g10-S1/L.paracasei 27-2 had the best oral immunization effect.The results of this experiment provide scientific data for the construction of a more effective oral vaccine for lactic acid bacteria.