Isolation, Passage, and Pathogenicity of a Newly Isolated Lawsonia intracellularis Strain From Hubei, China

IF 3.5 2区农林科学 Q2 INFECTIOUS DISEASES

Transboundary and Emerging Diseases Pub Date : 2025-07-01 DOI:10.1155/tbed/2501719

Rui Xie, Yajuan Luo, Changjiang Peng, Wenqing Wu, Yucong Cui, Xinru Sun, Lin Hua, Bin Wu, Zhong Peng

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Abstract

Lawsonia intracellularis is the causative agent of porcine proliferative enteropathy (PPE)—a disease of great economic impact to the global pig industry, but the isolation and continuous passage culture of this bacterial species is very difficult which limits the development of inactivated or live vaccines. While China is the largest pig rearing country in the world, only one study has reported the isolation of L. intracellularis. In this study, we examined 1574 ileal samples collected from 10 slaughterhouses in Hubei Province, China, and obtained 104 samples tested positive for L. intracellularis. From these positive samples, we successfully isolated a L. intracellularis strain designated LI-HuB23, which could be continuously passaged in IEC-18 cells. The successful isolation of LI-HuB23 was confirmed by transmission electron microscopy (TEM), indirect immunofluorescence assay (IFA), PCR amplifying, and Sanger sequencing of the marker gene (aspA). LI-HuB23 exhibited stable proliferation over 10 passages and it was still being passaged for over 30 generations. Oral inoculation of 28-day-old pigs with LI-HuB23 containing 6.9 × 10⁸ bacterial microorganisms induced loose stools and watery diarrhea between Days 14 and 28 postinfection. Challenging pigs showed an average daily gain (ADG) lowered than the control pigs (206.05 ± 23.48 g/day vs. 241.43 ± 16.78 g/day). All challenging were serologically positive for L. intracellularis IgG at 21 days postinoculation. Histological examination detected crypt hyperplasia, characterized by a reduction in goblet cells within the hyperplastic crypts. Colonization of L. intracellularis in ileal crypts was confirmed by immunohistochemical examination.

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湖北一株胞内Lawsonia的分离、传代及致病性研究

Lawsonia intracellularis是猪增生性肠病的病原体(PPE)——疾病全球养猪业的经济影响,但这种细菌物种的隔离和连续通过文化是非常困难的,限制发展的灭活或活疫苗。虽然中国是世界上最大的养猪国，但只有一项研究报道了胞内乳杆菌的分离。本研究对湖北省10个屠宰场的1574份回肠样本进行了检测，其中104份样本检测出胞内乳杆菌阳性。从这些阳性样本中，我们成功分离出一株可在IEC-18细胞中连续传代的胞内乳杆菌，命名为LI-HuB23。通过透射电镜（TEM）、间接免疫荧光法（IFA）、PCR扩增和标记基因（aspA）的Sanger测序证实了LI-HuB23的成功分离。LI-HuB23在10代传代后增殖稳定，并可传代30代以上。口服含有6.9 × 108个细菌微生物的LI-HuB23可导致28日龄猪在感染后第14 ~ 28天出现稀便和水样腹泻。挑战猪的平均日增重（ADG）低于对照组（206.05±23.48 g/d vs. 241.43±16.78 g/d）。接种21天后，所有攻鼠血清细胞内乳杆菌IgG阳性。组织学检查发现隐窝增生，其特征是增生性隐窝内杯状细胞减少。免疫组化检查证实胞内乳杆菌在回肠隐窝中定植。

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来源期刊

Transboundary and Emerging Diseases 农林科学-传染病学

CiteScore

8.90

自引率

9.30%

发文量

350

审稿时长

1 months

期刊介绍： Transboundary and Emerging Diseases brings together in one place the latest research on infectious diseases considered to hold the greatest economic threat to animals and humans worldwide. The journal provides a venue for global research on their diagnosis, prevention and management, and for papers on public health, pathogenesis, epidemiology, statistical modeling, diagnostics, biosecurity issues, genomics, vaccine development and rapid communication of new outbreaks. Papers should include timely research approaches using state-of-the-art technologies. The editors encourage papers adopting a science-based approach on socio-economic and environmental factors influencing the management of the bio-security threat posed by these diseases, including risk analysis and disease spread modeling. Preference will be given to communications focusing on novel science-based approaches to controlling transboundary and emerging diseases. The following topics are generally considered out-of-scope, but decisions are made on a case-by-case basis (for example, studies on cryptic wildlife populations, and those on potential species extinctions): Pathogen discovery: a common pathogen newly recognised in a specific country, or a new pathogen or genetic sequence for which there is little context about — or insights regarding — its emergence or spread. Prevalence estimation surveys and risk factor studies based on survey (rather than longitudinal) methodology, except when such studies are unique. Surveys of knowledge, attitudes and practices are within scope. Diagnostic test development if not accompanied by robust sensitivity and specificity estimation from field studies. Studies focused only on laboratory methods in which relevance to disease emergence and spread is not obvious or can not be inferred (“pure research” type studies). Narrative literature reviews which do not generate new knowledge. Systematic and scoping reviews, and meta-analyses are within scope.