Mechanisms of Immune Avoidance by Haemophilus ducreyi

描述(申请人提供)：下巴是一种细菌性生殖器溃疡疾病，流行于撒哈拉以南非洲和东亚地区。对杜氏嗜血杆菌的免疫反应，无论是从感染者身上清除微生物，还是在防止杜氏嗜血杆菌再次感染方面都不是很有效。本文描述的三个具体目标旨在利用和扩展猪下巴模型来测试与这种免疫反应较差的机制相关的假说。目的1通过检验杜氏嗜血杆菌主要诱导细胞免疫的假说来评估宿主对杜氏杆菌的反应，该假说在清除感染细菌方面无效。将检测从感染皮损分离的杜氏杆菌特异性CD4和CD8淋巴细胞的细胞因子表达模式。在目标2中，将通过检验杜氏嗜血杆菌CDT和溶血素毒素通过其对免疫效应细胞的细胞毒作用来阻止免疫发育的假设来解决细菌对免疫反应的抑制作用。这一目标将通过比较CDT/HEM双重突变体和野生型H.ducreyi接种后的免疫发育动力学和强度，同时评估突变体与野生型生物在T细胞细胞因子表达和抗原特异性方面的差异来实现这一目标。这些毒素对免疫反应的具体贡献将通过测试它们对鸡蛋溶菌酶产生抗体和细胞毒性T细胞的影响来检验。目的2提出这样的假设，即对杜氏杆菌产生强有力的杀菌抗体反应将导致更有效地清除感染组织中的生物体，并防止随后杜氏杆菌的再次感染。杜氏杆菌外膜蛋白已被鉴定为杀菌抗体的靶标。这种蛋白质将被测试是否有能力诱导对杜氏杆菌的保护性免疫反应。

DESCRIPTION (provided by applicant): Chancroid is a bacterial genital ulcer disease endemic to sub-Saharan Africa and Eastern Asia. The immune response to Haemophilus ducreyi, the etiologic agent of chancroid, is not very effective at either clearing organisms from an infected individual or at preventing subsequent H. ducreyi re-infections. The three specific aims described herein are designed to utilize and extend the swine model of chancroid to test hypotheses that relate to the mechanisms underlying this poor immune response. Aim 1 assesses the host response to H. ducreyi by testing the hypothesis that H. ducreyi elicit predominantly cellular immunity, which is ineffective at clearing the infecting bacteria. The cytokine expression pattern of H. ducreyi specific CD4 and CD8 lymphocytes isolated from infected lesions will be examined. In Aim 2 the bacterial contribution to inhibiting the immune response will be addressed by testing the hypothesis that the H. ducreyi CDT and hemolysin toxins block immunity development through their cytotoxic effect on immune effector cells. This aim will be accomplished by comparing the kinetics and strength of immune development following inoculation with cdt/hem double mutants and wild type H. ducreyi, while also assessing differences in T cell cytokine expression and antigen specificity effected by mutant as compared to wild type organisms. The specific contribution of the toxins on the immune response will be examined by testing their effect on the development of antibody and cytotoxic T cells to hen egg lysozyme. Aim 2 addresses the hypothesis that a vigorous bactericidal antibody response to H. ducreyi would result in more efficient clearing of organisms from infected tissue and prevent subsequent H. ducreyi re infection. An H. ducreyi outer membrane protein that is a target for bactericidal antibody has been identified. This protein will be tested for the ability to elicit a protective immune response to H. ducreyi.