猪胞内劳森菌中国分离株感染模型的建立

doi:10.3864/j.issn.0578-1752.2026.15.016

摘要/Abstract

摘要：

【目的】利用中国分离的胞内劳森菌（Lawsonia intracellularis, LI）菌株及不同来源临床组织毒，建立稳定的猪增生性肠病（porcine proliferative enteritis, PPE）模型，构建一套涵盖排菌、粪便评分、日增重、料肉比、血清抗体和病理变化的系统性评价指标体系，明确最佳攻毒剂量与优选菌株，为LI的致病机制研究、疫苗评价及防控策略提供标准化模型与数据支撑。【方法】选用28日龄断奶仔猪，分为阴性对照组和多个感染组。试验一：比较JX703、GX301、HN312和LI-HuB23 4种组织毒（1×10⁹ LI/头）的致病性。试验二：选择综合致病性最强的JX703组织毒及体外培养的LI-HuB23分离株，以不同剂量（10¹⁰ LI/头、10⁸ LI/头、10⁶ LI/头）口服感染28日龄猪只，感染后监测28 d，观察粪便排菌、粪便评分、日增重、料肉比、血清抗体及病理学变化。【结果】试验一：不同LI菌株的组织毒感染组均成功复制出典型PPE临床症状与病理表现：感染后第4天即可从粪便中检出LI，排菌持续至第28天。感染组于感染后第4天开始出现腹泻症状，第19—21天症状最为严重。各感染组平均日增重均低于阴性对照组，料肉比升高。血清抗体监测显示感染建立的第14天起血清抗体转阳，并持续至第28天。病理变化见感染组肠黏膜褶皱增厚，H.E染色显示肠隐窝增生，杯状细胞减少，免疫组化染色在肠隐窝胞质内见LI。综合来看JX703组织毒的症状最突出，毒力最强。试验二：不同剂量结果显示：LI-HuB23分离株以10⁶ LI/头剂量即可建立感染，出现排菌、腹泻与病理变化。随着感染剂量升高，症状加重，10¹⁰ LI/头组排菌峰值、粪便评分、病理评分及平均日增重降低程度最为典型。【结论】成功利用LI中国分离株和收集的组织毒建立了PPE模型，选定的排菌、粪便评分、日增重、料肉比、血清抗体、病理变化指标具有参考价值；使用10¹⁰ LI/头作为感染菌量建立的感染模型更为典型。

关键词: 猪增生性肠病, 胞内劳森菌, 猪, 感染模型, 攻毒剂量

Abstract:

【Objective】This study aimed to establish a stable porcine proliferative enteropathy (PPE) model using Chinese isolates of Lawsonia intracellularis (LI) and clinical infected intestinal tissue homogenates from different sources, construct a systematic evaluation index system covering fecal bacterial shedding, fecal score, average daily gain, feed conversion ratio, serum antibody level and histopathological changes, and identify the optimal challenge dose and preferred strain, so as to provide the standardized model and data support for the research on LI pathogenic mechanism, vaccine efficacy evaluation and prevention and control strategies.【Method】Twenty-eight-day-old weaned piglets were selected and divided into a negative control group and multiple infection groups. In Experiment 1, the pathogenicity of four LI tissue homogenates (JX703, GX301, HN312, and LI-HuB23) was compared at the dose of 1×10⁹ LI per piglet. In Experiment 2, JX703 tissue homogenate with the strongest comprehensive pathogenicity and the in vitro cultured LI-HuB23 isolate were selected to orally inoculate 28-day-old piglets at gradient doses (10¹⁰ LI per pig, 10⁸ LI per pig, and 10⁶ LI per pig). The piglets were monitored for 28 days after inoculation, during which fecal bacterial shedding, fecal score, average daily gain, feed conversion ratio, serum antibody level and histopathological changes were observed and recorded.【Result】In Experiment 1, typical clinical symptoms and pathological manifestations of PPE were successfully reproduced in all infection groups inoculated with tissue homogenates of different LI strains. LI was detectable in feces from day 4 post-inoculation, and bacterial shedding persisted until day 28 post-inoculation. Diarrhea occurred in the infection groups from day 4 post-inoculation, with the most severe symptoms observed from day 19 to 21 post-inoculation. All infection groups showed lower average daily gain and higher feed conversion ratio compared with the negative control group. Serum antibody monitoring showed that seroconversion occurred from day 14 after the establishment of infection and lasted until day 28 post-inoculation. Pathological examination revealed thickened intestinal mucosal folds in the infection groups; hematoxylin-eosin (HE) staining showed intestinal crypt hyperplasia and decreased goblet cells, and LI was detected in the cytoplasm of intestinal crypt epithelial cells by immunohistochemical staining (IHC). Overall, JX703 tissue homogenate induced the most prominent symptoms with the strongest virulence. In Experiment 2, the results of gradient dose test showed that inoculation with LI-HuB23 in 10⁶ LI per piglet was sufficient to establish effective infection, accompanied by fecal bacterial shedding, diarrhea, and corresponding pathological changes. The severity of symptoms increased with the elevation of infection dose, and the 10¹⁰ LI per pig group exhibited the most typical patterns in terms of peak fecal scores, pathological scores, and reductions in average daily gain.【Conclusion】A PPE infection model was successfully established using Chinese LI isolates and field-derived infected tissue homogenates in this study. The selected evaluation indexes had an important reference value for related research, including fecal bacterial shedding, fecal score, average daily gain, feed conversion ratio, serum antibody level and histopathological changes. The infection model established with an inoculation dose of 10¹⁰ LI per pig presented more typical clinical and pathological characteristics of PPE.

Key words: porcine proliferative enteropathy, Lawsonia intracellularis, swine, infection model, challenge dose

谢锐, 谷正全, 刘思雯, 罗亚娟, 崔玉琮, 华琳, 宋文博, 黄超, 汤细彪, 徐高原, 陈焕春, 吴斌, 彭忠. 猪胞内劳森菌中国分离株感染模型的建立[J]. 中国农业科学, 2026, 59(15): 3452-3464.

XIE Rui, GU ZhengQuan, LIU SiWen, LUO YaJuan, CUI YuCong, HUA Lin, SONG WenBo, HUANG Chao, TANG XiBiao, XU GaoYuan, CHEN HuanChun, WU Bin, PENG Zhong. Establishment of an Infection Model in Pigs for Chinese Clinical Strains of Lawsonia intracellularis[J]. Scientia Agricultura Sinica, 2026, 59(15): 3452-3464.

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