Mycoplasma genitalium variation in longitudinally infected men

描述(申请人提供)：生殖支原体(MG)是男性尿道炎的一种病因，在女性的子宫颈炎症、子宫内膜炎、盆腔炎、输卵管因素不孕和早产中的病因学作用越来越得到认可。不幸的是，这种细菌对靶向细胞壁的抗生素和许多目前用于治疗原发病和可能严重的生殖道疾病后遗症的抗生素具有抗药性。无论是男性还是女性，MG感染在人类中都可能持续数月至数年，尽管在感染期间会诱导炎症反应和特异性抗体。我们和其他人假设，这种持久性是基于MG通过其复杂而独特的末端细胞器中的两种表面蛋白--MgpB和MgpC的抗原变异来逃避宿主免疫反应的能力。支持这一假设的是，我们已经证明了编码这些蛋白的相邻基因mgpB和mgpC在体内都存在广泛的变异，并且在宫颈/阴道感染中随着时间的推移而演变。然而，到目前为止，我们还不能通过评估感染诱导的抗体对当代和时间匹配的患者分离株的基因变异和抗原选择的作用来检验这一假设。我们最近由美国国立卫生研究院资助的生殖支原体治疗试验为我们提供了这样一个机会。在这项完成的试验中，确定了感染生殖支原体的男性，并要求他们每隔三周返回三到四次访问，在此期间收集血清和他们的生殖支原体菌株。 进行了培养和鉴定。这些实验是史无前例的，因为TURE研究将使用最近的临床分离株，而不是实验室适应的菌株。因此，我们建议1)描述在整个纵向研究中不同时间点的mgpB序列变异的演变，2)将mgpB中特定变量序列的清除与感染男性对这些序列的抗体的产生联系起来，以及3)确定这些变异序列的抗体是否增强了补体介导的对生殖器分枝杆菌的杀伤。这项研究的创新之处在于，它经济地使用了一组极其有价值和特征良好的患者标本，以评估基因变异在这种新发现的病原体持续存在中的作用。这项研究具有重要意义，因为它将部分揭示这种新发现的生殖器病原体的免疫逃避机制。我们对这种未被研究的细菌的免疫病理机制的关注的潜在影响是巨大的，因为可以确定干预和治疗的新靶点。

DESCRIPTION (provided by applicant): Mycoplasma genitalium (MG) is a cause of urethritis in men and is becoming increasingly recognized for its etiologic role in cervicitis, endometritis, pelvic inflammatory disease, tubal factor infertility, and preterm birth in women. Unfortunately, this bacterium is resistant to cell wall-targeting antibiotics and to many of the antibiotics curretly used to treat primary disease and possible serious reproductive tract disease sequelae. MG infection may persist in humans for months to years in both men and women despite the induction of an inflammatory response and specific antibodies during infection. We and others have hypothesized that this persistence is based on the ability of MG to evade the host immune response by antigenic variation in two of its surface proteins, MgpB and MgpC located in its complex and unique terminal organelle. Supporting this hypothesis, we have shown that variation in mgpB and mgpC, the adjacent genes encoding these proteins, is extensive both in vivo and evolves over time in cervical/vaginal infections. However, up to this point, we have not been able to test this hypothesis by assessing the role of antibodies induced by infection on gene variation and antigenic selection of contemporary and temporally matched patient isolates. Our recent NIH-funded treatment trial for M. genitalium has given us such an opportunity. In this completed trial, M. genitalium infected men were identified and asked to return at three week intervals for three to four visits at which time sera was collected and their M. genitalium strains were cultured and characterized. These experiments are unprecedented because recent clinical isolates, not laboratory-adapted strains will be used in tour study. Thus we propose to 1) characterize the evolution of mgpB sequence variation of at different time points throughout the longitudinal study, 2) correlate the clearance of specific variable sequences in mgpB with the development of antibodies to these sequences in the infected men, and 3) determine if the antibodies to these variant sequences enhance complement-mediated killing of M. genitalium. This study is innovative in its economical use of an extremely valuable and well-characterized set of patient specimens to assess the role of gene variation on persistence of this newly recognized pathogen. This study is significant in that it will reveal, in part, the mechanisms of immune evasion in this newly recognized genital pathogen. The potential impact of our focus on the immunopathogenesis of this understudied bacterium is great in that novel targets for intervention and treatment may be identified.