A THERAPEUTIC DNA VACCINE IN NONHUMAN PRIMATE AGAINST CHAGAS DISEASE

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 以前的研究表明，在克氏锥虫感染的急性期或慢性期接种表达克氏锥虫抗原Tsa1和Tc24的DNA疫苗，至少可以部分控制几个品系的小鼠的疾病发展。因此，在这项初步研究中，我们旨在评估这种DNA疫苗在恒河猴身上的安全性和有效性。6只动物(6.5~14.8 kg)经静脉感染500,000只克鲁兹毛滴虫/kg(Y株)，其中3只分别于感染后3、4、5个月分别肌注含Tsa1和Tc24的DNA疫苗500g，佐剂为磷酸铝。三只对照动物接受相同剂量的空质粒。治疗和未治疗的动物在感染后总共被跟踪6个月。通过每月监测血细胞计数和化学成分来评估DNA疫苗治疗的安全性，除了一只变成糖尿病的动物外，所有这些都没有显示出任何变化。通过比较治疗动物和未治疗动物之间的疾病发展情况来评估治疗效果。感染2个月后，所有动物均为克氏毛滴虫血清阳性和/或血样中克氏毛滴虫聚合酶链式反应阳性的寄生虫血症。感染后4个月和6个月时，两组猴子的心电图记录均正常。然而，与接受治疗的动物相比，未经治疗的动物的QT间期似乎更长。所有动物在感染后6个月断头取材。尸检表明所有器官外观正常，证实了疫苗治疗的安全性。组织切片的组织病理学分析表明，两组猴子的心脏都有轻微的炎症。一只接受治疗的猴子肝脏也出现了轻微的炎症，另一只猴子的胃也出现了轻微的炎症。另一方面，所有未经治疗的动物在几个组织中表现出轻微到轻微的炎症，如结肠、胃、肝脏、肺和骨骼肌，这表明这些动物患有更严重的疾病。进一步的分析，包括用于分析免疫反应的体外PBMC刺激，用于检测组织样本中寄生虫DNA的PCR分析，以及免疫组织化学，仍在进行中。这些初步结果表明，所使用的治疗性疫苗是安全的，并对控制非人类灵长类疾病的进展有一定的治疗效果。美国国立卫生研究院将在下学期提交一份关于扩大这项先导研究的完整项目的拨款提案。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Previous studies showed that a DNA vaccine expressing Trypanosoma cruzi antigens TSA1 and Tc24, administered during the acute or chronic phase of the infection with T. cruzi could control at least partially the development of the disease in several strains of mice. In this pilot study, we thus aimed at evaluating the safety and efficacy of this DNA vaccine in rhesus monkeys. Six animals (6.5-14.8 kg) were infected via IV with 500,000 T. cruzi parasites/kg (Y strain), and three were treated with three IM injections of 500 ¿g of DNA vaccine encosing TSA1 and Tc24 with aluminium phosphate as an adjuvant at 3, 4, and 5 months post-infection. Three control animals received the same doses of empty plasmid. Treated and untreated animals were followed for a total of 6 months post-infection. Safety of the DNA vaccine treatment was assessed by monthly monitoring of blood counts and chemistry, all of which did not show any alteration, except for one animal which turned diabetic. Treatment efficacy was assessed by comparing disease development between treated and untreated animals. Two months after infection, all the animals were seroposivive for T. cruzi and/or presented parasitemia as indicated by a positive T. cruzi PCR in blood samples. Electrocardiographic reccordings at 4 and 6 months post infection were normal in both groups of monkeys. However, QT interval appeared longer in untreated animals compared to that of treated animals. All animals were sacrified at 6 months post infection. Necropsies indicated that all organs had a normal appearance, confirming the safety of the vaccine treatment. Histopathologic analysis of tissue sections indicated that there was minimal inflammation in the heart of monkeys from both groups. One treated monkey also presented minimal inflammation in the liver, and anonther one mild inflammation in the stomach. On the other hand, all the untreated animals presented minimal to mild inflammation in several tissues, such as colon, stomach, liver, lung, and skeletal muscle, suggesting a more severe disease in these animals. Further analysis, including in vitro PBMC stimulation for the analysis of the immune response, PCR assays to detect parasite DNA in tissue samples, and immunohistochemistry, are still underway. These first results indicate that the therapeutic vaccine used was safe and had some therapeutic effect on the control of disease progression in non-human primates. A NIH grant proposal for a full project expanding this pilot study will be submitted next semester.