| Enterotoxigenic E.coli(ETEC)is one of the most common pathogens in the breeding industry that can cause diarrhea in piglets.Newborn piglets are vulnerable to various pathogens due to their weak intestines and incomplete development of immune function.ETEC-induced diarrhea in piglets caused by ETEC is accompanied by a variety of symptoms,mainly manifested as yellow and white diarrhea in piglets.Piglets affected by diarrhea often also suffer from dehydration,mental depression,and slow development.Piglet diarrhea seriously affects the health and performance of piglets.Inadequate treatment can lead to a decline in piglet performance and,in severe cases,piglet death.Incomplete treatment of piglet diarrhea can cause pathogens to spread quickly in the breeding environment,affect the scale of pig breeding,and cause huge economic losses to the breeding industry.Piglet diarrhea causes increased breeding costs,affects the supply of live pigs,and the price of pork products rises,bringing economic burden to consumers.In this experiment,enterotoxin-producing Escherichia coli F4,F5,F6,F18,F41 fimbriae and STa-LTB-STb recombinant enterotoxin were used as antigens to jointly prepare a multivalent vaccine against the two major targets of fimbria and enterotoxin.Sexual IgY,to achieve double blocking of two major virulence factors.Immunize laying hens,collect yolk fluid and separate and purify yolk antibodies by water dilution-ammonium sulfate precipitation method combined with ultrafiltration concentration.The experimental results show that the final purity of the antibody reaches 84.8%,the potency of IgY for the five fimbriae antigens exceeds 1:10000,the highest potency can reach 1:32000,and the potency for recombinant enterotoxin up to 1:8000,indicating that Multivalent antigen has good immunogenicity,suitable for IgY production and preparation.In the in vitro experiment,the rabbit anti-chicken IgG labeled with colloidal gold specifically adsorbed yolk antibody,and the binding effect of the yolk antibody to each antigen was observed under transmission electron microscope.The results showed that the specific yolk antibody can tightly bind to the cell surface and be bound at the same time Structural changes on the cell surface.The multivalent specific egg yolk antibody in the liquid environment can effectively inhibit the proliferation of five enterotoxigenic Escherichia coli such as K88,K99,987 p,F18 and F41.The inhibitory effect is concentration-dependent,and the bacteriostatic effect is more significant with the increase of the yolk antibody concentration.Using xylene and hexadecane as the organic phase,the effect of egg yolk antibody on the hydrophobicity of each strain of ETEC was tested by means of a hydrocarbon adsorption experiment.The results showed that the surface hydrophobicity of each cell was significantly enhanced,which was different from the previous research results.The actual mechanism of action of yolk antibodies provides a reference.In animal experiments,weaned SD rats were used as the object to establish a model,and the rats were challenged and administered by intragastric administration.The specific yolk antibody and non-specific yolk antibody were tested for the prevention and treatment of ETEC.Specific IgY effectively reduces the rate of diarrhea in rats,promotes weight gain,improves growth and development,significantly reduces the levels of TNF-?,IL-1?,and IL-6 in blood and tissues(P<0.05),relieving ETEC Inflammatory reaction,protect the intestinal villi from the destruction of ETEC enterotoxin,exemplify a good prevention and treatment effect,realize the double blocking of fimbria and enterotoxin,and play a comprehensive role in protecting the intestine of rats.To further explore the mechanism of yolk antibodies in animals and to promote the application in breeding animals to provide experimental reference. |
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