Protective Immune Responses to Blastomyces Dermatitidis

芽孢霉病是一种主要的系统性真菌病，通常会导致进行性肺部疾病，但在皮炎芽孢杆菌感染过程中导致免疫失败和耐药性的因素尚不清楚。在原发肺部感染的小鼠模型中，我们创建了一个WI-1基因敲除的皮炎芽孢杆菌，该基因被减弱并得到控制。给小鼠注射它可以为它们接种疫苗，防止再次感染，并激发灭菌免疫。在此，我们建议使用上一个资助期建立的等基因减毒野生型菌株和小鼠模型来确定实验性肺芽生菌病免疫失败和耐药的细胞和分子基础。我们假设：皮炎芽孢杆菌在非免疫宿主中破坏免疫T细胞的产生，导致进行性感染。在接种疫苗的宿主中，T细胞介导抵抗力，并在产生和维持疫苗免疫和记忆所需的T细胞亚群中表现出可塑性。我们的具体目的是：(1)破译免疫抑制细胞因子转化生长因子-β在进行性初次感染时T细胞免疫失败中的作用，以及T细胞激活的负调节因子CTLA-4在转化生长因子-β诱导的细胞免疫抑制过程中的参与。(2)描述了细胞因子(干扰素-γ、肿瘤坏死因子-α)、细胞溶解和直接抗微生物活性等不同机制，以及CD28共刺激和IL-12信号在产生和维持这些回忆性免疫反应中的要求。(3)从皮炎假单胞菌c DNA文库的表达产物和一种粗制的保护性细胞壁膜抗原的T细胞免疫印迹中鉴定并克隆保护性T细胞识别的抗原，证明克隆的重组抗原对皮炎假单胞菌具有体内保护性免疫作用。了解免疫失败和对真菌耐药的机制将有助于规划健康人以及艾滋病等宿主防御受损患者的疫苗和治疗策略。

Blastomycosis, one of the principal systemic mycoses, often produces a progressive pulmonary disease, but the factors that account for immune failure and resistance during infection with Blastomyces dermatitidis infection are ill defined. We created a WI-1 knockout of B. dermatitidis that is attenuated and controlled in a murine model of primary pulmonary infection. Its administration to mice vaccinates them against re-infection and evokes sterilizing immunity. We propose here to use the isogenic attenuated and wild-type strains and mouse models developed in the last funding period to define the cellular and molecular bases of immune failure and resistance in experimental pulmonary blastomycosis. We hypothesize: that B. dermatitidis subverts generation of immune T-cells in a nonimmune host, leading to progressive infection. In a vaccinated host, T-cells mediate resistance, and show plasticity in the requirements of T-cell subsets for generation and maintenance of vaccine immunity and memory. Our specific aims are to: (1) Decipher the role of the immunosuppressive cytokine transforming growth factor-beta (TGF- beta) in failure of T-cell immunity during progressive primary infection, and the participation of CTLA-4, a negative regulator of T-cell activation, during TGF-beta-induced cellular immune suppression. (2) Delineate differential mechanisms - cytokines (IFN-gamma, TNF-alpha), cytolysis, and direct antimicrobial activity - by which CD4+ and CD8+ T-cells mediate vaccine immunity to B. dermatitidis, and requirements for CD28 co- stimulation and IL-12 signaling in generating and maintaining these recall immune responses. (3) Identify and clone antigens that protective T-cells recognize in vitro from expressed products of a B. dermatitidis cDNA library, and in T-cell immunoblots of a crude, protective cell-wall membrane antigen, and demonstrate that the cloned recombinant antigens confer protective immunity in vivo to B. dermatitidis. Understanding mechanisms of immune failure and resistance to fungi will assist in planning vaccine and treatment strategies in healthy people, and in patients with impairments of host defense such as AIDS.