中文摘要：

为研究鸡白痢沙门菌（S．pullorum）分离株对雏鸡的致病性，通过筛选2010至2012年期间中国华东部分地区的78株鸡白痢沙门菌，选择具有代表性的12株在雏鸡上进行致死性感染试验，并对其中的2株强毒分离株进行半数致死量测定和细菌定殖研究，运用组织病理学和免疫组化方法研究其引起的组织病变和细菌分布情况。结果显示：鸡在接种2株强毒分离株后第3天组织即可出现病变，第7—14天病变最为严重，第21天后明显好转。感染过程中各组织中沙门菌数量有不同程度的变化。结果表明这2株鸡白痢沙门菌分离株对雏鸡具有较强的致病性，且不同分离株对雏鸡脏器的定殖能力、分布情况有所不同。鸡白痢沙门菌分离株对雏鸡致病性的研究为揭示其感染机理及疫苗研制提供了相关的依据。

英文摘要：

To investigate the pathogenicity of Salmonella pullorum （S. pullorum） to young chickens, fatal infection experiment was conducted in young chickens by inoculating 12 S. Pul lorum, which were chosen from 78 S. pullorum isolates in Eastern China during 2010 and 2012. LD50 and colonization of two virulent S. pullorum isolates was tested in young chickens, while histopathology and immunohistochemistry were applied to analyze pathological lesions and distri bution of S. pullorum in tissues at different time point. Results were as follows： Lesions early appeared in tissues at day 3 after inoculation; The most serious lesions appeared during day 7 and 14, and decreased obviously after day 21. The quantity of S. pullorum colonization in different tissues varied during the infection. The two S. pullorum isolates were high pathogenic to young chickens, and different isolates had different ability of colonization and distribution in tissues. This research provided experimental evidence for analyzing the mechanisms and developing vac- cine of S. pullorum.