酵母甘露聚糖肽对致病性大肠杆菌感染小鼠的保护作用

本试验旨在研究酵母甘露聚糖肽（MTY）对致病性大肠杆菌（PEC）感染小鼠的保护作用。选取无特定病原体（SPF级）昆明小鼠40只，随机分为4组，分别为空白组、模型组、阳性药物组、MTY组（每组10个重复，每个重复1只小鼠），其中，空白组和模型组灌服生理盐水，阳性药物组灌服抗生素阿莫西林，MTY组灌服酵母甘露聚糖肽。4周后，对模型组、阳性药物组、MTY组昆明小鼠进行致病性大肠杆菌（PEC）攻毒试验，通过对攻毒试验前小鼠肠道微生物分析以及PEC感染后小鼠死亡率、脏器指数、肠道组织以及各器官切片组织病理分析，同时观察体内试验过程小鼠体质变化，综合评价MTY对PEC感染小鼠的保护效果。结果表明，MTY对PEC有抑制作用。与空白组相比，MTY组小鼠肠道微生物菌群有显著性差异（P<0.05），主要表现为有益菌丰度增加，菌群多样性增加；与模型组相比，MTY处理能有效降低小鼠感染PEC后的死亡率；MTY显著提高了小鼠胸腺指数（P<0.05），降低脾指数（P>0.05），并极显著降低肝指数（P<0.01）；MTY抑制了小鼠空肠杯状细胞的减少（P>0.05）；MTY抑制了小鼠肠道中MUC2及ZO-1表达下调（P<0.05）；MTY对感染PEC后的小鼠肠道、肝、脾和肺等器官均起显著的保护作用。由此可见，灌服酵母甘露聚糖肽能减轻PEC对机体的损害，进而对小鼠起保护作用。

Protective Effect of Yeast Mannatide on Mice Infected with Pathogenic Escherichia coli

The objective of this study was to investigate the protective effect of yeast mannatide (MTY) on mice infected with pathogenic Escherichia coli (PEC). Firstly,40 SPF male KM mice were randomly divided into 4 groups:control group, model group, positive drug group and MTY group (10 replicates per group and 1 mouse per replicate). Control group and model group were given normal saline, while the positive drug group and the MTY group were given antibiotic amoxicillin and MTY, respectively. In this paper, the Kunming mice were gavaged MTY for 4 weeks before the challenge experiments with PEC. By analysing enteric microorganism of mice that before challenge test, mortality of mice after PEC infection, organ index, intestinal structure, organs histopathological analysis, and at the same time, observing the physical change of mice in vivo testing, the protective effect of MTY on PEC infected mice was comprehensively evaluated. The results showed that MTY could inhibit PEC proliferation. Compared with blank group, MTY group had significant difference in intestinal microflora (P<0.05), which mainly showed that beneficial bacteria increased and bacterial diversity increased. Compared with model group, MTY treatment can effectively reduce the mortality of mice infection with PEC. MTY significantly increased thymus index (P<0.05), decreased spleen index (P>0.05) and extremely significantly decreased liver index (P<0.01). MTY inhibited the decrease of goblet cells in jejunum of mice (P>0.05). MTY inhibited the down-regulation of MUC2 and ZO-1 expression in intestinal of mice (P<0.05). Therefore, MTY has a good protective effect on intestinal, liver, spleen and lung organs of mice infected with PEC, which has a wide application future in animal feed.In conclusion, oral administration of MTY can reduce the damage of PEC to the body and then play a protective role in mice.