IMMUNODOMINANT TARGETS OF CMI TO CRYPTOSPORIDIUM

描述（由申请人提供）：免疫功能低下个体的细小隐孢子虫感染通常发展为慢性，严重的隐孢子虫病，可危及生命。与低CD4+细胞水平相结合，其他免疫系统因素的不足预计会导致免疫缺陷宿主的慢性感染。相反，细胞因子如γ干扰素（ifn - γ）在成人和儿童感染的控制中都有牵连。阐明免疫应答和识别免疫失调的特征，如细胞因子异常或t细胞对关键隐孢子虫抗原的增殖能力低下，可能会识别出隐孢子虫病的高危患者。据推测，免疫能力强的宿主的感染消退与负责激活淋巴细胞群和诱导细胞因子的特定抗原有关，并允许保护免受后续感染。因此，缺乏对这些关键抗原的反应和某些细胞因子谱的发展可能导致慢性，难治性感染和有限的保护反应，如果有的话。我们最近开发了一个模型，用于评估成年实验动物对小孢子虫感染的保护性免疫。该模型使用IL-12缺陷或“敲除”小鼠，是一项重要的进展，因为以前的工具不足以有效评估免疫。我们现在计划使用这个模型来确定产生和维持保护性免疫反应所需的细胞类型和细胞因子。淋巴细胞亚群的必要性将由IL-12敲除小鼠原发感染和激发感染期间特定细胞群（如CD4+、CD8+和IEL细胞）以及关键细胞因子（ifn - γ、IL-15和IL-4）的消耗来决定。为了确定这些实验确定的保护反应是否可以通过免疫诱导，免疫优势抗原（Cp40、Cp23、Cp17、Cp15、CpPO、CpP1和CpP2）将被评估，以确定它们是否可以在我们的小鼠疫苗模型中产生保护反应。这将通过用这些抗原的DNA结构免疫小鼠，评估其引发免疫反应的能力，并用小孢子虫挑战小鼠来确定达到的保护程度来实现。

DESCRIPTION (provided by applicant): Cryptosporidium parvum infections in immunocompromised individuals often develop into chronic, severe cryptosporidiosis that can become life-threatening. In conjunction with low CD4+ cell levels, insufficiency of other immune system factors are expected to contribute to infection chronicity in the immunodeficient host. In contrast, cytokines such as gamma interferon (IFN-gamma) have been implicated in control of infection in both adults and children. Elucidation of immune responses and identification of features of immune dysregulation, such as cytokine abnormalities or inability of T-cells to proliferate in response to key cryptosporidial antigens, might identify patients at high risk for cryptosporidiosis. It is hypothesized that infection resolution in the immunocompetent host is linked to specific antigens responsible for the activation of lymphocyte populations and induction of cytokines and allows for protection from subsequent infections. Consequently, a lack of response to these key antigens and development of certain cytokine profiles may lead to chronic, intractable infections and limited, if any, protective responses. We have recently developed a model useful for evaluating protective immunity to C. parvum infection in adult experimental animals. This model, which uses IL-12 deficient or "knockout" mice, is an important advance as previous tools were inadequate to effectively assess immunity. We now plan to use this model to determine the cell types and cytokines necessary for the generation and maintenance of protective immune responses. The necessity of subpopulation of lymphocytes will be determined by depletion of specific cell populations (e.g. CD4+, CD8+, and IEL cells) as well as key cytokines (IFN-gamma, IL-15 and IL-4) during primary and challenge infection of IL-12 knockout mice. To determine if protective responses identified by these experiments can be induced through immunization, immunodominant antigens (Cp40, Cp23, Cp17, Cp15, CpPO, CpP1, and CpP2) will be evaluated to determine if they can generate protective responses in our mouse vaccine model. This will be accomplished by immunizing mice with a DNA construct of these antigens, assessing their ability to elicit immune responses, and challenging mice with C. parvum to determine the degree of protection achieved.