| As one of the most common and harmful diseases in poultry breeding，coccidiosis is aseriousparasitic diseases in the world.Coccidiosis brings about enormous economic losses.Due to its pathogenesis are mixed, which is infected by two or more kinds of coccidian atthe same time, damage to different parts of the chicken’s intestines, there are greatdifficulties in terms of prevention and control.For a long time, both of the treatment andprevention of this disease depend on the chemical synthetic drugs, however, it is seriousthat drug resistance and drug residues phenomenon are caused by chemical synthetic andthe effect of the chemical synthetic drugs for the diseaseis worse and worse, not living upto expectations.Lactic acid bacteria are a kind of important probiotics that exists in nature, and theyplay an important role in intestinal micro-ecological balance. At present, there have beensome studies about probiotics like the lactic acid bacteria have the certain effectagainstparasites, but there is little research associated withcoccidiosis in chickens.Therefore, this study aims to through genetic engineering to construct the recombinantlactic acid bacteria which have the function of immune enhancement and examines theeffect on Eimeria tenella, providing theory reference fordevelopment ofLactic acidbacteriapreparationagainstcoccidiosis.This studyconnected IL-2, pSIP409and coccidian SO7genes together to construct therecombinant plasmid ofPsip409-SO7-IL-2. Convert the new structure toescherichiacoli byelectro transformation. Afterpurification, the plasmid was verified. Convert the plasmid toLb.plantarum NC8by electro transformation, and thenit was indicated by extraction ofrecombinant plasmid, double digested and PCRand the successful transformation had beenmade and the protein expressed.And then test the performance of the recombinant lactic acid bacteriaprotective’seffect for Eimeria tenella in chicken. Chickensexperiments were randomly divided intofour groups:Recombinant lactic acid bacteria group,Empty vector group, Non-immune&no-inflectiongroup (red), Non-immune&inflectiongroup (white).Respectivelyfed thechicks in the first day with PCMV-Neo-Bam and recombinant lactic acid bacteria diluents1m（lconcentration of1x109CFU/ml） in the empty vector group andrecombinant lactic acid bacteria group.Seven days later, the chicks were infected with coccidian, andthequantity of coccidian per chick is5×104.Daily test weight and according to the weight change, the chickens fed recombinantlactic acid bacteria lose the least weight. There is a difference between recombinant lacticacid bacteria group and inflection group which has obvious weight change, but notsignificant (p>0.05),thenslaughtered8days later after inflection. Detect the indexesofanimals’ spleen, cecum and peripheral blood.Theresults show that the group with recombinant lactic acid bacteria is the leastserious in the pathological changes of cecumcompared with other experimental group, andno bleeding and enlargement symptoms. H&E staining results showed thatexperimentalanimals’ epithelial cells of appendix contain a lot of the coccidiosis in the inflectiongroup,and it is difficult to find coccidiosis in the recombinant lactic acid bacteria group.According the results of OPG counting,the oocysts of cecum contentdecreased, OPGof recombinant lactic acid bacteria group is1.3×105and it is3.9×105in inflectiongroup(P＜0.05). Detecting spleen lymphocyte CD4+and CD8+content, the recombinantlactic acid bacteria group of experimental animals in vivo CD4+and CD8+weresignificantly higher than the inflection group.ACI is greater than180in recombinant lacticacid bacteria group.The results show thatthe recombinant lactic acidbacteriapSIP409-SO7-IL2has a good performanceagainstcoccidiosis. |
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