PDF(Pubmed)
Abstract：
There are several Entamoeba species that colonize humans, but only Entamoeba histolytica causes severe disease. E. histolytica is transmitted through the fecal-oral route to colonize the intestinal tract of 50 million people worldwide. The current mouse model to study E. histolytica intestinal infection directly delivers the parasite into the surgically exposed cecum, which circumvents the natural route of infection. To develop a fecal-oral mouse model, we screened our vivarium for a natural murine Entamoeba colonizer via a pan-Entamoeba PCR targeting the 18S ribosomal gene. We determined that C57BL/6 mice were chronically colonized by Entamoeba muris. This amoeba is closely related to E. histolytica, as determined by 18S sequencing and cross-reactivity with an E. histolytica-specific antibody. In contrast, outbred Swiss Webster (SW) mice were not chronically colonized by E. muris. We orally challenged SW mice with 1 × 105 E. muris cysts and discovered they were susceptible to infection, with peak cyst shedding occurring between 5 and 7 days postinfection. Most infected SW mice did not lose weight significantly but trended toward decreased weight gain throughout the experiment compared to mock-infected controls. Infected mice treated with paromomycin, an antibiotic used against noninvasive intestinal disease, do not become colonized by E. muris. Within the intestinal tract, E. muris localizes exclusively to the cecum and colon. Purified E. muris cysts treated with bovine bile in vitro excyst into mobile, pretrophozoite stages. Overall, this work describes a novel fecal-oral mouse model for the important global pathogen E. histolytica. IMPORTANCE Infection with parasites from the Entamoeba genus are significantly underreported causes of diarrheal disease that disproportionally impact tropical regions. There are several species of Entamoeba that infect humans to cause a range of symptoms from asymptomatic colonization of the intestinal tract to invasive disease with dissemination. All Entamoeba species are spread via the fecal-oral route in contaminated food and water. Studying the life cycle of Entamoeba, from host colonization to infectious fecal cyst production, can provide targets for vaccine and drug development. Because there is not an oral challenge rodent model, we screened for a mouse Entamoeba species and identified Entamoeba muris as a natural colonizer. We determine the peak of infection after an oral challenge, the efficacy of paromomycin treatment, the intestinal tract localization, and the cues that trigger excystation. This oral infection mouse model will be valuable for the development of novel therapeutic options for Entamoeba infections.
摘要：
有几种在人类中定居的Entamoeba物种，但只有溶组织内阿米巴会导致严重的疾病。溶组织大肠杆菌通过粪便-口腔途径传播，在全球5000万人的肠道定植。目前研究溶组织大肠杆菌肠道感染的小鼠模型直接将寄生虫递送到手术暴露的盲肠中，从而规避了自然的感染途径.为了建立粪便-口腔小鼠模型，我们通过靶向18S核糖体基因的泛-内阿米巴PCR筛选了我们的动物的天然鼠内阿米巴定植剂。我们确定C57BL/6小鼠被内阿米巴长期定殖。这种变形虫与溶组织大肠杆菌密切相关，如通过18S测序和与溶组织大肠杆菌特异性抗体的交叉反应性所确定的。相比之下,瑞士韦伯斯特（SW）小鼠未被E.muris长期定殖。我们用1×105个E.muris囊肿口服攻击SW小鼠，发现它们容易感染，囊肿高峰脱落发生在感染后5到7天之间。与模拟感染的对照相比，大多数感染的SW小鼠在整个实验中体重并未显着减轻，但体重增加趋势下降。用巴龙霉素治疗的感染小鼠，一种用于治疗非侵入性肠道疾病的抗生素，不要被E.muris殖民。在肠道内，E.muris仅位于盲肠和结肠。纯化的E.muris囊肿用牛胆汁体外处理，前滋养体阶段。总的来说,这项工作描述了一种新的粪便-口腔小鼠模型的重要的全球病原体溶组织大肠杆菌。重要性来自内阿米巴属的寄生虫的感染是腹泻病的严重报道原因，对热带地区造成不成比例的影响。有几种感染人类的Entamoeba引起一系列症状，从无症状的肠道定植到具有传播的侵袭性疾病。所有Entamoeba物种都通过粪便-口腔途径在受污染的食物和水中传播。研究Entamoeba的生命周期，从宿主定植到感染性粪便囊肿的产生，可以为疫苗和药物开发提供靶点。因为没有口腔挑战啮齿动物模型，我们筛选了小鼠Entamoeba物种，并将Entamoebamuris鉴定为天然定殖者。我们确定口腔攻击后的感染高峰，巴龙霉素治疗的疗效，肠道定位，以及引发兴奋的线索。这种口腔感染小鼠模型对于开发Entamoeba感染的新型治疗选择将是有价值的。
