PHOSPHOLIPASE: A TARGET TO DIAGNOSE INVASIVE CANDIDIASIS

描述（由申请人提供）：免疫功能低下的患者是侵袭性念珠菌病最易感的个体之一。即使接受治疗，念珠菌性免疫功能低下患者的死亡率估计在38-50%之间。目前可用的诊断测试包括常规血培养缺乏敏感性和特异性。因此，必须开发能够提供感染早期证据和/或补充现有培养和血清学检测的创新实验室方法。我们小组最近的研究结果表明，白色念珠菌分泌的磷脂酶B可能是念珠菌病的一个新的诊断靶点。当我们在两种不同的念珠菌病小鼠模型中测试白色念珠菌的等基因菌株对时，这一点很明显，并且表明caplb1突变体的毒力显着减弱。本实验旨在开发和评估基于plb1的侵袭性念珠菌病诊断测试。该建议的总体假设是Plb1可以作为一种有用的诊断标记物。为了支持这一假设，我们已经证明Plb1是分泌的，并且在体内的宿主组织入侵过程中可以检测到。重要的是，我们还发现侵袭性念珠菌病患者（n=33）的血清中抗plb1抗体水平明显高于健康对照组（P = 0.042）。我们将通过以下具体目标进一步检验这一假设：1)鉴定、表达和纯化Plb1p推断的氨基酸区域的特异性区域。这些多肽将用于评估Plb1作为特定诊断标记物的潜力。2)兔血清循环抗Plb1p抗体及Plb1p抗原检测。3)利用人血清评价Plb1p的诊断效用。每种方法的有效性将在已建立的侵袭性和粘膜念珠菌病实验动物模型、培养证实的侵袭性念珠菌病患者和对照组中进行评估。

DESCRIPTION (provided by applicant): Immunocompromised patients are among the most susceptible individuals to develop invasive candidiasis. Mortality rates among candidemic immunocompromised patients have been estimated at between 38-50%, even with therapy. Currently available diagnostic tests including routine blood cultures lack sensitivity and specificity. Thus, development of innovative laboratory methods capable of providing early evidence of infection and/or complement current cultural and serological tests is imperative. Recent findings from our group suggest that phospholipase B, secreted by Candida albicans may be a novel diagnostic target for candidiasis. This was evident when we tested an isogenic strain pair of C. albicans differing only in their ability to secret PLB, in two different murine models of candidiasis, and showed that the virulence of caplb1 mutants is significantly attenuated. The experiments described in this proposal aim at developing and evaluating Plb1-based diagnostic tests for invasive candidiasis. The overall hypothesis of this proposal is that Plb1 could be useful as a diagnostic marker. In support of this hypothesis, we have shown that Plb1 is secreted and is detectable during host tissue invasion in vivo. Importantly, we also showed that sera from patients with invasive candidiasis (n=33) contained significantly higher levels of anti-Plb1 antibody compared to sera obtained from healthy controls (P = 0.042). We will examine this hypothesis further by pursuit of the following specific objectives: 1) Identification, expression and purification of regions specific to Plb1p deduced amino acid regions. These peptides will be used to evaluate the potential of Plb1 as a specific diagnostic marker. 2) Detection of circulating anti-Plb1p antibody and Plb1p antigen in rabbit sera. 3) Evaluations of diagnostic utility of Plb1p using human sera. The effectiveness of each approach will be evaluated in established experimental animal models of invasive and mucosal candidiasis and patients with culture-proven invasive candidiasis and controls for the study.