关键词: 海藻糖比伯斯坦杆菌, 致病性, 临床症状, 病理变化, 细菌载量

Abstract:

To thoroughly evaluate the pathogenic characteristics of Bibersteinia trehalosi (B. trehalosi) in experimental animals (mice) and target animals (sheep), this study will inoculate mice and sheep with varying doses of the B. trehalosi GD01 strain, which was isolated from a sheep that died of pneumonia. Key indicators, including clinical symptoms, pathological changes, and pathogen load post-inoculation, will be assessed to provide a detailed understanding of the virulence of the strain. In the mouse experiment, intraperitoneal inoculation of the bacteria resulted in a dose-dependent lethal effect. As the dose increased, the mortality rate gradually rose, accompanied by severe pulmonary lesions and a significant increase in bacterial load. In the sheep experiment, intratracheal inoculation of the bacterium at different doses induced acute fever, coughing, nasal discharge, and anorexia, with more severe symptoms at higher doses. Necropsy results showed varying degrees of congestion, consolidation, fibrinous exudation, pleuropulmonary adhesions, and purulence in the lungs, with pathological changes typical of fibrinous pneumonia and pleuropneumonia. The severity of these changes was positively correlated with the infection dose. Histopathological observations revealed fibroblast proliferation and inflammatory cell infiltration, and immunohistochemistry showed significant pathogen aggregation within the alveoli. qPCR analysis showed that sheep continued to shed bacteria through the nasal cavity after infection, with high viral loads detected in the lungs, indicating that the bacterium successfully colonized the sheep's lungs and caused disease. In conclusion, this study characterized the clinical symptoms, pathological changes, and pathogen load after B. trehalosi infection in mice and sheep, confirming that B. trehalosi induces a dose-dependent pathogenic response in both species. These findings provide important experimental data for further understanding the pathogenic mechanisms of this bacterium, establishing animal infection models, and developing prevention and control strategies.

Key words: Bibersteinia trehalosi, pathogenicity, clinical symptoms, pathological changes, bacterial load