NATURAL IMMUNITY TO ENTAMOEBA HISTOLYTICA

溶组织内阿米巴是一种肠道原虫，感染10%的 它是以下主要寄生原因之一 世界范围内的死亡。最近，一些重要的阿米巴抗原已经 被分离、鉴定和克隆，包括170 kDa的重链 半乳糖抑制黏附蛋白(GIAP)的一个亚基，一个29 kDa 肝脓肿特异性表面抗原，主要的半胱氨酸蛋白酶 E.组织溶解和高度保守的125 kDa表面抗原。然而， 在阿米巴病疫苗的开发工作开始之前，我们必须 进一步了解对这种寄生虫的自然免疫力。这个 这项提案的总体目标是确定自然免疫力 发生于侵袭性阿米巴病和无症状肠道 感染，如果是的话，来表征特定的免疫反应 关联的。需要检验的假设是：1)侵袭性疾病的治愈 阿米巴病之后是对侵袭性阿米巴病的保护性免疫。 和无症状的肠溶血性肠杆菌感染。2)淘汰 无症状致病性和非致病性肠溶组性埃希菌 感染之后，对复发的免疫可持续数月至数年。 感染；3)对侵袭性阿米巴病的免疫力依赖于 持续抗原特异性细胞免疫(CMI)反应，免疫 肠道感染需要类似的特异性SIgA反应。 这项建议的具体目的是确定：1)发生 侵袭性阿米巴病与血清阳性无症状肠道感染 治愈的阿米巴肝脓肿患者和对照组；2)如果有 阿米巴感染或疾病之间的联系；3)宿主 无症状溶血性肠杆菌感染过程中的免疫应答及其意义 与清除感染的关系；4)复发的发生率 无症状感染及其与宿主免疫反应的相关性 免疫力是否具有菌株特异性。这将通过以下方式实现 100例阿米巴肝脓肿治愈及900例随访 在医学研究理事会(纳塔尔)和 南非德班的爱德华七世国王医院。1000个人中的每一个 受试者将每三个月进行一次有决心的随访 临床状态、发生肠溶血性肠炎的情况 猪链球菌粪便抗原培养、直接检测及酵母菌分析 感染性菌株。此外，血清黏附蛋白的测定 抗原血症、血清免疫球蛋白抗体四大重组体 前面提到的抗原，唾液中的IgA去免疫球蛋白和可溶性 将进行阿米巴抗原检测。所有受试者都将进行CMI研究 淋巴细胞转化和γ-射线测定 有丝分裂原、可溶性阿米巴抗原和 4株具有较好特性的重组E。初步 研究支持了注册和遵循这一规则的高度可行性 受试者数量。考虑到地方性疾病的已知感染率 在德班地区，已确定研究的规模是足够的。 以解决所提出的问题。这项提案将解决一个令人难以置信的 阿米巴病研究中的重要问题和对疫苗的重大影响 该领域的开发和临床实践。

Entamoeba histolytic is an enteric protozoan that infects 10% of the world's population and is one of the following leading parasitic causes of death worldwide. Recently, a number of important amebic antigens have been isolated, characterized and cloned, including the 170kDa heavy subunit of the galactose-inhibitable adherence protein (GIAP), a 29kDa liver abscess-specific surface antigen, the major cysteine proteinase of E. histolytic, and a highly conserved 125kDa surface antigen. However, before work can proceed on development of an amebiasis vaccine we must gain a further understanding of natural immunity to this parasite. The overall objective of this proposal is to determine if natural immunity develops following invasive amebiasis and asymptomatic intestinal infection, and if so, to characterize the specific immune responses associated. They hypotheses to be tested are: 1) Cure of invasive amebiasis is followed by protective immunity against invasive amebiasis and asymptomatic intestinal infection with E. histolytic. 2) Elimination of asymptomatic pathogenic and nonpathogenic E. histolyatica intestinal infection is followed by immunity for months to years against recurrent infection; and 3) Immunity to invasive amebiasis is dependent on sustained antigen-specific cell mediated immune (CMI) responses, immunity to intestinal infection requires a similarly specific sIgA response. The specific aims of this proposal are to determine: 1) the incidence of invasive amebiasis and asymptomatic intestinal infection in seropositive individuals cured of amebic liver abscess and controls; 2) if there is an association between the amebic infection or disease; 3) the host immune response during asymptomatic E. histolytic infection and its relation to clearance of the infection; and 4) the incidence of recurrent asymptomatic infection, its correlation to host immune response, and whether immunity is strain specific. This will be accomplished by following 100 patients cured of amebic liver abscess and their 900 close associates for > 3 years at the Medical Research Council (Natal) and the King Edward VII Hospital in Durban, South Africa. Each of the 1000 subjects will have the follow-up every three months with determination of clinical status, occurrence of E. histolytic intestinal infection by culture and direct detection of fecal antigen and zymodeme analysis of infecting strain. In addition, assays of serum adherence protein antigenemia, serum IgG antibodies to each of the four major recombinant antigens previously mentioned, and salivary IgA to the GIAP and soluble amebic antigen will be performed. All subjects will have CMI studies consisting of lymphocyte blastogenesis and determination of gamma interferon production in response to mitogen, soluble amebic antigen and the 4 well characterized recombinant E. histolytic antigens. Preliminary studies support the high feasibility for enrolling and following this number of subjects. Considering known infection rates in the endemic area of Durban, the size of the study has been determined to be adequate to address the questions posed. This proposal will address an incredibly important issues in amebiasis research and have a major impact on vaccine development and clinical practice in the field.