Research On The Protect Effect Of FimH Recombinant Lactobacillus On Avian Pathogenic Escherichia Coli

Avian pathogenic Escherichia coli has caused huge economic losses, also seriously harmthe healthy development of the poultry industry. The chemical composition of E. coli fimbriaeswas proteins, containing a variety of amino acids and having a good immunogenicity, stimulatethe body to produce antibodies. Studies have shown that E. coliⅠtype pilus can karyokinesisand stimulate lymphocytes to multiply and differentiation. We also hope to develop a subunitvaccine of avian pathogenic Escherichia coli and genetic engineering, in order to effectivelycontrol the avian pathogenic Escherichia coli. However, in order to effective control avianpathogenic Escherichia coli, economical, effective and convenient oral vaccine has been as adesirable objective. We previously prepared with Lactobacillus (Lactobacillus plantarum NC8)of viable cells as antigen presenting carrier E. coli fimbriae major immune protective antigengene FimH protein as a target gene, the recombinant expression system Lactobacillus FimH, theoral immunization of mice was found to have good immunogenicity in our laboratory.To further assess the oral recombinant lactobacillus NC8-pSIP409-FimH protective effectpathogenic to chickens infected chickens, following researches were carried out in thisexperiment. The chicks were randomly grouped in PBS, NC8-pSIP409and NC8-pSIP409-FimH.Then we detected IgG antibody levels in serum at different times to assess humoral immunityand detected tracheal secretions sIgA antibody levels in intestinal contents to assess mucosalimmunity; detected spleen lymphocyte proliferation after oral administration of Lactobacillus,Th1/Th2cytokine expression levels and the change of T cell subsets; determine oralrecombinant lactobacillus chicken pathogenic E. coli infection after liver chicks in each group,pericardium and airbag score index. Finally, we confirmed that oral recombinant lactobacilluschicken pathogenic E. coli infection in chicken weight loss rate and protection rate case.Experimental results show that oral administration of recombinant lactobacillusNC8-pSIP409-FimH produce a good immune effects in vivo in chicks. Experimental resultsshow that oral administration of recombinant lactobacillus NC8-pSIP409-FimH chicken IgGantibody levels began to rise at28d，when it turn to42d we can see more significant difference(*P <0.05); oral NC8-pSIP-409-FimH recombinant lactic acid bacteria in the intestinal contentsof chicks matter and tracheal lavage sIgA antibody levels were higher than control group (*P<0.05); chicken peripheral immune organs lymphocyte proliferation results were higgher thanother control group (*P <0.05); oral recombinant lactobacillus NC8-pSIP409-FimH spleen chicks secretion cytokines and T cell subsets were also significantly higher than the othercontrol group (*P <0.05); pathogenic E. coli infected chickens, chicks oral recombinantlactobacillus organ lesion index was significantly lower than the other control group (*P <0.05),weight loss rate is lower than the other group, the survival rate of60%, similar to the effect ofthe inactivated vaccine.