IMMUNE PROPHYLAXIS AGAINST AMEBIASIS

肠道原生动物溶组织内阿米巴是发病的主要原因 和死亡率。 一般来说，感染的传播和 卫生条件差导致阿米巴结肠炎和肝脓肿 在这种情况下，没有疫苗可用。 通过定义 寄生虫和溶解的组织和人体免疫反应，实质上 疫苗的研制已经取得了进展。 体液和细胞- 介导的机制在保护免受阿米巴肝中起作用 脓肿 粘膜免疫在相关肠粘膜损伤模型中的作用 阿米巴病尚未定义。 一种260 kDa半乳糖降解的寄生虫 粘附蛋白（GIAP）介导滋养体与结肠的结合 粘蛋白、上皮细胞和宿主炎性细胞。 GIAP绑定是 E.溶组织剂 GIAP由一个170 kDa的重亚基和一个35 kDa的轻亚基组成， 重亚基是抗原性的并具有碳水化合物结合活性。 纯化的天然GIAP在沙鼠中作为疫苗是高度有效的 阿米巴肝脓肿模型;来自GIAP重亚基的基因具有 被克隆和测序。 侵袭性阿米巴病治愈的患者 唾液sIgA到GIAP。 本提案的目标是：1） 确定粘膜抗GIAP分泌型伊加（sIgA）在免疫中的作用 肠阿米巴病; 2）构建重组GIAP亚单位疫苗 在肠道阿米巴病和阿米巴肝的灵长类动物模型中有效 脓肿; 3）确定是否选用E.溶组织重组体 抗原与GIAP亚单位组合将增强疫苗效力。 本建议的具体目标和方法是：1）定义sIgA 对GIAP重亚基的应答在人类感染和实验中的作用 用ELISA法检测狒狒肠道阿米巴病的唾液和 肠分泌物; 2）确定GIAP的哪些部分重 亚基通过产生粘附而引起保护性sIgA应答， 抑制性伊加单克隆抗体可以是重亚基， 用选择GIAP亚单位免疫小鼠，测定sIgA 免疫反应和被动免疫狒狒伊加单克隆抗体 重组GIAP对狒狒的抗体和主动免疫 亚单位，以确定对实验性肠 阿米巴病;和3）在狒狒和沙鼠模型中确定 实验性肠道和肝脏阿米巴病的疗效的重组 含有GIAP亚单位和主要半胱氨酸的阿米巴病亚单位疫苗 蛋白酶或肝脓肿特异性29 kDa表面抗原。 先前 研究和初步数据表明，拟议的研究将 大大提高了我们对大肠杆菌粘膜免疫的了解。histolytica 并导致有效的阿米巴病亚单位疫苗的开发。

The enteric protozoan Entamoeba histolytica is a major cause of morbidity and mortality worldwide. In general, transmission of infection and resultant amebic colitis and liver abscess is due to poor sanitary conditions, there is no vaccine available. By defining the mechanisms of parasite and lysis of tissue and the human immune response, substantial progress is vaccine development has occurred. Both humoral and cell- mediated mechanisms are operative in protection against amebic liver abscess. The role of mucosal immunity in a relevant model of intestinal amebiasis has not been defined. A parasite 260kDa galactose-inhibitable adherence protein (GIAP) mediates binding of trophozoites to colonic mucins, epithelial cells and host inflammatory cells. GIAP binding is required for the CA ++ dependent lysis of host tissues by E. histolytica. The GIAP consists of a 170kDa heavy subunit and a 35kDa light subunit, the heavy subunit is antigenic and possesses carbohydrate binding activity. Purified native GIAP is highly efficacious as a vaccine in the gerbil model of amebic livery abscess; the gene from the GIAP heavy subunit has been cloned and sequenced. Patients cured of invasive amebiasis possess salivary sIgA to the GIAP. The objectives of this proposal are: 1) to define the role of mucosal anti-GIAP secretory IgA (sIgA) in immunity intestinal amebiasis; 2) to construct a recombinant GIAP subunit vaccine effective in primate models of intestinal amebiasis and amebic liver abscess; 3) to determine if use of selected E. histolytica recombinant antigens in combination with GIAP subunits will enhance vaccine efficacy. The specific aims and methods of this proposal are: 1) to define the sIgA response to the GIAP heavy subunit in human infection and experimental intestinal amebiasis in the baboon by ELISA assay of salivary and intestinal secretions; 2) to identify which portions of the GIAP heavy subunit elicit protective sIgA responses by production of adherence- inhibitory IgA monoclonal antibodies to may the heavy subunit, immunization of mice with selected GIAP subunits with assay of sIgA responses, and passive immunization of baboons with IgA monoclonal antibodies and active immunization of baboons with recombinant GIAP subunits to determine protection against experimental intestinal amebiasis; and 3) to determine in the baboon and gerbil models of experimental intestinal and liver amebiasis the efficacy of a recombinant amebiasis subunit vaccine containing GIAP subunits and the major cysteine proteinase or the liver abscess specific 29kDa surface antigen. Previous studies and preliminary data indicate that the proposed studies will greatly enhance our understanding of mucosal immunity to E. histolytica and lead to development of an effective amebiasis subunit vaccine.