PATHOGENESIS OF HAEMOPHILUS DUCREYI INFECTIONS

杜热氏嗜血杆菌是一种生殖器溃疡--下巴的病原体。 促进人类免疫缺陷病毒传播的疾病 (艾滋病毒)。我们对软下巴、毒力的发病机制的认识 决定因素和对H.ducreyi的免疫反应受到一种 完全缺乏从自然环境中纵向收集的临床标本 被感染的病人。杜氏杆菌是一种严格的人类病原体，它能表达 模仿人类抗原的细胞表面成分。为了研究 为了探讨软骨病的发病机制，我们建立了一种实验性的软骨病模型。 人类志愿者的皮肤感染。我们对模型进行了改进，以便 实验性感染过程模仿自然发生的疾病。这个 本应用的重点是开发和研究模型，使我们 可以测试关于发病机制、宿主免疫反应和 候选毒力决定因素。 在实验模型中，丘疹病变可能是自发的 分解或进展为脓疱疹的形成。我们的数据表明， 感染的结果是由当地因素调节的，这是第一次 人类宿主能对病毒产生有效免疫反应的证据 H.Dureyi。免疫反应的焦点是皮肤 CD4+细胞的浸润性。我们的第一个假设是T细胞 实验性皮损中产生的浸润物和细胞因子发生变化 时间和影响感染结局的模型。 杜氏嗜血杆菌黏附于人类角质形成细胞，并黏附，有时甚至 体外培养的人成纤维细胞。我们的第二个假设是H。 Ducreyi黏附于角质形成细胞和成纤维细胞，其中一些 细菌成功入侵真核细胞，使有机体能够 躲避宿主的防御。 细菌表面结构，如外膜蛋白(OMPS)和 菌毛在革兰氏阴性杆菌发病机制中起重要作用 感染。我们的实验室已经刻画了几个守恒面 杜氏嗜血杆菌主要外膜蛋白的组成 (MOMP)和PILI。使用遗传学方法，我们希望评估MOMP的作用 和菌毛在发病机制中的作用。我们的第三个假设是，实验 感染模式可以区分父母的毒力 候选毒力决定因素中的菌株和同基因突变体。 为了检验这些假设，我们的具体目标包括：标准化 实验感染杜氏嗜血杆菌的人类挑战模型； 实验性皮损的免疫组织病理学和细胞因子分析 在感染过程中的不同时间进行的；定位的 皮损中细菌的数量；构建同源突变体 毛发或与毛发相关的粘连.能力评估 人类挑战模型来区分亲本品系 和候选毒力决定因素中的同源突变。

Haemophilus ducreyi is the etiologic agent of chancroid, a genital ulcer disease that facilitates transmission of the Human Immunodeficiency Virus (HIV). Our understanding of the pathogenesis of chancroid, virulence determinants, and immune responses to H.ducreyi has been hampered by a total lack of longitudinally collected clinical specimens from naturally infected patients. H. ducreyi is a strict human pathogen that expresses cell surface components that mimic human antigens. To study the pathogenesis of chancroid, we have developed an experimental model of skin infection in human volunteers. We have refined the model so that the course of experimental infection mimics naturally occurring disease. The focus of this application is to develop and study the model so that we can test hypotheses about pathogenesis, host immune responses and candidate virulence determinants. In the experimental model, papular lesions may either spontaneously resolve or progress to pustule formation. Our data suggests that the outcome of infection is modulated by local factors, and this is the first evidence that the human host can mount an effective immune response to H. ducreyi. The focal point of the immune response is a cutaneous infiltrate of CD4+ cells. Our first hypothesis is that the T Cell infiltrate and cytokines produced in the experimental lesions change over time and influence the outcome of infection in the model. H. ducreyi adheres to human keratinocytes and adheres to and sometimes in vades human fibroblasts in vitro. Our second hypothesis is the H. ducreyi adheres to keratinocytes and to fibroblasts and that some of the bacteria successfully invade eukaryotic cells, allowing the organism to evade host defenses. Bacterial surface structures such as outer membranes proteins (OMPs) and pili have important roles in the pathogenesis of gram negative bacterial infections. Our laboratory has characterized several conserved surface components of H. ducreyi including the major outer membrane protein (MOMP) and pili. Using a genetic approach, we wish to asses the role MOMP and pili in pathogenesis. Our third hypothesis is that the experimental infection model can discriminate between the virulence of the parental strain and isogeneic mutants in candidate virulence determinants. To test these hypotheses, our specific aims include: standardization of the human challenge model of experimental H. ducreyi infection; immunohistopathological and cytokine analysis of experimental lesions biopsied at different times during the course of infection; localization of the bacteria in the lesions; construction of isogeneic mutants in the MOMP, pilus, or a pilus associated adhesion; assessment of the ability of the human challenge model to discriminate between the parental strain and isogeneic mutants in candidate virulence determinants.