Abstract:

Object To establish a infection dog model with RH strain of Toxoplasma gondii. Method Three specific pathogen-free 76 day-old Beagles were intraperitoneal injected with 1. 5 × 107 tachyzoites of Toxoplasma gondii. The dogs had been growing in positive pressure isolators under barrier environment and fed with artificial milk. The experiment was carried out under negative pressure barrier environment. After inoculation, anal temperatures, oral and anal swabs were collected twice daily to detect B1 gene of T. gondii by PCR. At 8 days post inoculation ( dpi ) all animals were euthanized, and nucleotide copies of Rep529 nt at various tissues were quantified by real-time PCR method. Histopathology and immunohistochemical stains changes were observed. Result The result showed that the three dogs had fever and diarrhea at 4 dpi-5 dpi; much ascites was appeared when the abdomens were opened; B1 gene of T. gondii was detected in oral or anal swabs at 2 dpi - 6 dpi by a routine PCR method, and the PCR result positive rate of the anal swabs was higher than that of the oral swabs totally, there was obvious inflammatory reaction in the liver tissue in histopathological observation with HE stain. Among all the detected tissues sampled on autopsy using the Taqman real-time PCR, the copy number of the Rep529 nt was high in cecum and liver. Conclusion The infectious experiment shows that there merely causes a mild infection model on SPF Beagles when inoculated with RH strain of T. gondii, with transient increase of body temperature and diarrhea, liver degeneration and necrosis.

Key words: Toxoplasma gondii, laboratory beagles, disease model

摘要： 目的 建立实验用犬人工感染人源强毒力型弓形虫的发病模型。 方法 将 3 只 76 日龄人工哺乳、正压隔离器内生长的实验用比格犬腹腔注射 1. 5×107 个 RH 株速殖子,每日 2 次检测直肠体温、采集口腔拭子、直肠拭子,感染 8 d 后(8 dpi)安乐死所有动物。 利用 PCR 检测拭子和血液中的弓形虫 B1 基因,利用荧光定量法检测 8 dpi 犬主要组织脏器中弓形虫 529 bp 重复片段的拷贝数,并对主要脏器进行组织病理学检测。 结果 结果表明 3 只实验犬在 4 ~ 5 dpi 均出现了一过性体温升高,轻微腹泻;2 ~ 6 dpi 的咽拭子或肛拭子中能检测到弓形虫 B1 基因的核酸,且肛拭子阳性率高于咽拭子;8 dpi 剖检后,均产生较多腹水;肝组织均出现明显的炎性变化;盲肠和肝中的弓形虫529 bp 片段的核酸拷贝数最高。 结论 利用 SPF 级比格犬腹腔接种弓形虫 RH 株,主要引起一过性体温升高和短时腹泻,可导致肝组织变性和坏死,发病模型较温和。

关键词: 刚地弓形虫, 比格犬, 发病模型