摘要： 研究重组大肠杆菌不耐热肠毒素B亚单位(rLTB)在鸭体内的吸收代谢及组织分布,为rLTB的临床应用安全性提供依据。试验鸭分别肌注1,50,100 mg/kg rLTB后,以神经节苷脂GM1酶联免疫吸附法(GM1-ELISA)测定注射后不同时间点鸭血清中的rLTB含量;连续3次肌注rLTB后,观察临床症状和剖检病理变化,并采集心脏、肝脏、脾脏、肺脏、肾脏和大脑制备组织切片,HE染色观察组织病理学变化,免疫酶组织化学染色观察rLTB在各脏器内的分布及含量变化。结果表明:鸭血清中的rLTB含量变化及维持时间与rLTB注射剂量呈正相关。1 mg/kg注射组2 h达到峰值,维持至6 h开始下降,24 h后基本检测不到;50,100 mg/kg注射组分别于2 h和1 h达到峰值,并均维持至12 h才开始下降,48 h后基本检测不到。HE染色切片显示50 mg/kg注射组肝细胞轻度浊肿变性,肺脏轻微炎症;100mg/kg注射组肝细胞浊肿变性明显、肺脏重度炎症、脑组织出现局灶性坏死。免疫组化染色结果显示,在被检脏器中均检出rLTB,以大脑含量最高,脾脏和肝脏次之,心脏和肺脏检出量低。rLTB大剂量肌肉注射可引起鸭一定的组织学病变,对鸭的安全使用剂量应不超过50 mg/kg。

关键词: 大肠杆菌不耐热肠毒素B亚单位, 鸭, 吸收代谢, 组织分布

Abstract: E. coli heat-labile enterotoxin B subunit (rLTB) exerts most effective adjuvant effects on mucosal immune responses. In order to elucidate the dynamic and the safety of rLTB for clinical use in duck, the concentra- tions of rLTB in sera, histopathological changes and tissue distribution of rLTB were examined. Ducks were bled pri- or to injection and at different time intervals post-intramuscular injection (IM) with 1,50,100 mg/kg rLTB, respec- tively. GM1-ELISA was applied for the determination of rLTB concentration in sera. The autopsy of ducks was con- ducted at different time points after IM of rLTB once a day,3 times in a row. Samples of heart, liver, spleen, lung, kidney and brain were fixed in 10% paraformaldehyde and the tissue sections were examined after coloration with haematoxylin and eosin(HE) or immunohistochemical(IHC) staining. The result showed that there was positive correlation between concentration and duration of rLTB in sera and the dosages of application. In 1 mg/kg group the amount of rLTB peaked at 2 hour post injection (HPI),and started to decline at 6 HPI,and could not be detected at 24 HPI. In 50 mg/kg group and 100 mg/kg group the peak were achieved at 2 HPI and 1 HPI,respectively and began to decrease at 12 HPI,and beyond the detection limit at 48 HPI. The slight cloudy swelling and degeneration of hepa- tocellular,inflammatory cell infiltration in lung were observed in 50 mg/kg group ducks. Obvious cloudy swelling and degeneration of hepatocellular,severe inflammatory cell infiltration in lung and focal necrosis in brain tissue were ob- served in 100 mg/kg group. IHC staining results showed that rLTB was deteceted in all 6 kinds of examined organs and the highest amount rLTB was observed in brain. The conclusion is that the high dosage of rLTB may cause histo- logical lesions and the rLTB should be used under 50 mg/kg for safe in duck.

Key words: E. coli heat-labile enterotoxin B subunit(LTB), Duck, Dynamic, Distribution

中图分类号: 

• S834