Deng Shu-Xuan, Cheng An-Chun, Wang Ming-Shu, Cao Ping
Avian Diseases Research Center, College of Veterinary Medicine of Sichuan Agricultural University, Yaan, Sichuan 625014, China.
Avian Dis. 2008 Mar;52(1):88-93. doi: 10.1637/8102-090107-Reg.
The objective of this study was to identify and understand the regular distribution pattern and primary penetration site for Salmonella Enteritidis (SE) in the gastrointestinal tract of ducks. An assay based on the serovar-specific DNA sequence of SE from GenBank, a serovar-specific real-time, fluorescence-based quantitative polymerase chain reaction, was developed for the detection of SE. We used this assay to detect genomic DNA of SE in the blood and gastrointestinal tract, including duodenum, jejunum, ileum, cecum, rectum, esophagus, stomach muscularis, and stomach glandularis, from ducks after oral challenge at different time points. The results showed that SE was consistently detected in all segments of the gastrointestinal tract. The jejunum and ileum were positive 8 hr postinoculation (PI). The organism was detected in blood 12 hr PI, while the final organ to show a positive result was the stomach at 24 hr PI. The copy number of SE DNA in each tissue reached a peak at 24-36 hr PI, with the jejunum, ileum, and cecum containing high concentrations of SE, whereas the blood, duodenum, rectum, stomach, and esophagus had low concentrations. SE populations began to decrease and were not detectable at 2 days PI, but were still present up to 9 days PI in the jejunum, ileum, and cecum without causing apparent symptoms. By 3 days PI the cecum had significantly higher numbers of SE than any of the other areas (P < 0.01), and this appeared to reflect its function as a repository for SE. In conclusion, the results provided significant data for understanding the life cycle of SE in the gastrointestinal tract and showed that the jejunum, ileum, and cecum were the primary sites of invasion in normal ducks after oral challenge. This study will help to understand the mechanisms of action of SE infection in vivo.
本研究的目的是确定并了解肠炎沙门氏菌（SE）在鸭胃肠道中的分布规律及主要侵入部位。基于GenBank中SE的血清型特异性DNA序列，开发了一种血清型特异性实时荧光定量聚合酶链反应检测方法，用于检测SE。我们利用该方法在不同时间点对经口攻毒后的鸭的血液及胃肠道（包括十二指肠、空肠、回肠、盲肠、直肠、食管、胃肌层和胃腺层）中的SE基因组DNA进行检测。结果显示，在胃肠道的所有节段均能持续检测到SE。接种后8小时，空肠和回肠呈阳性。接种后12小时在血液中检测到该菌，而最后显示阳性结果的器官是胃，在接种后24小时呈阳性。各组织中SE DNA的拷贝数在接种后24 - 36小时达到峰值，空肠、回肠和盲肠中SE浓度较高，而血液、十二指肠、直肠、胃和食管中的浓度较低。SE菌量在接种后2天开始下降且无法检测到，但在接种后9天，空肠、回肠和盲肠中仍有SE存在，且未引起明显症状。到接种后3天，盲肠中的SE数量显著高于其他任何部位（P < 0.01），这似乎反映了其作为SE储存库的功能。总之，这些结果为了解SE在胃肠道中的生命周期提供了重要数据，并表明空肠、回肠和盲肠是经口攻毒后正常鸭的主要入侵部位。本研究将有助于了解SE体内感染的作用机制。
