Micro-evolution of Arthritogenic Mycoplasma hominis in a Single Patient

 描述(由申请人提供)：在健康和免疫受损的宿主中，多种人类支原体会引起慢性和机会性感染。人支原体是第一个被发现的与人类相关的支原体，它与泌尿生殖道定植广泛相关，可导致细菌性阴道病、盆腔炎和发烧(产后或流产后)。还报告了生殖器外感染，包括慢性关节炎、骨髓炎、新生儿的各种并发症和播散性感染，在免疫功能低下的宿主中，这些感染可能是致命的。我们对人类支原体在关节形成过程中的致病因素和宿主适应策略的了解在很大程度上是未知的。此外，在慢性关节炎的病例中，人们知之甚少。 尽管面临反复的抗菌治疗和宿主免疫系统的挑战，但允许长期定居的潜在基因变化。我们的知识库目前受到以下因素的限制：缺乏对这种病原体的明确遗传系统，缺乏任何关节致病分离物的基因组序列信息，以及只有两个基因组数据集可用于该物种的任何分离物。因此，比较基因组测序被建议用于(I)纵向系列的12个人分枝杆菌分离株，这些分离株是从一名感染性关节炎患者身上在5年内恢复的，以及(Ii)一个由12个临床分离株组成的小组，其中包括另外6个血清型，来自不同大陆的两个尿道炎株，两个创伤相关分离株，一个四环素耐药分离株和一个已报道的基因转移的临床分离株。对纵向序列中两个表面脂蛋白表达的分析表明，由于同源多聚体内插入/缺失(INDel)突变而导致抗原的高频变异，以及一种新的基因表达机制，即40kb的大基因组复制导致表面抗原基因与rRNA基因启动子并置。虽然这种“自下而上”的方法提供了对表面抗原变异的重要洞察，但该提案的两个具体目标旨在使用“自上而下”的策略，使用下一代测序来全面描述代表宿主内微进化的突变和基因组重排，这些突变和重排代表了人类关节5年生态位适应期间的微进化。由于目前只有两个人类支原体基因组序列可用，将这些数据与关节炎菌株和12个额外的临床分离株产生的数据进行比较基因组分析，将提炼该物种的核心和泛基因组，潜在地揭示与不同疾病病理分离株不同相关的基因、基因岛或可移动的遗传元件。这些数据还应该提供不同血清型之间的抗原性差异，以及获得性四环素耐药性的机制和获得。最终，完成这些特定目标所产生的数据应该提供一个平台，从这个平台可以制定和实施改进免疫或化疗干预的战略。

 DESCRIPTION (provided by applicant): Multiple human mycoplasma species cause chronic and opportunistic infections in both healthy and immunocompromised hosts. Mycoplasma hominis, the first human-associated mycoplasma to be identified, is widely associated with urogenital tract colonization that can lead to bacterial vaginosis, pelvic inflammatory disease and fever (post-partum or post-abortion). Extragenital tract infections including chronic arthritis osteomyelitis, assorted complications in newborn infants and disseminated infections have also been reported, which in immunocompromised hosts are potentially fatal. Our understanding of pathogenicity factors and strategies for host adaptation employed by M. hominis during arthritogenesis are largely unexplored. Furthermore, in cases of chronic arthritis, little is known of the underlying genetic changes that permit long term colonization despite the challenges of repeated antimicrobial therapy and the host immune system. Our knowledge base is currently limited by the lack of a defined genetic system for this pathogen, the absence of genome sequence information for any arthritogenic isolate and only two genomic datasets available for any isolates of the species. Accordingly, comparative genome sequencing is proposed for (i) a longitudinal series of twelve M. hominis isolates that were recovered over a 5-year period from a single patient with septic arthritis and (ii) a panel of twelve clinical isolates including an additional six serotypes, two urethritis strains from different continents, two wound-associated isolates, a tetracycline resistant isolate and a clinical isolate for which gene transfer has been reported. Analysis of the expression of two surface lipoproteins in the longitudinal series has demonstrated high frequency antigenic variation by insertion/deletion (indel) mutation within a homopolymeric tract and a novel mechanism of gene expression whereby a large, 40-kb genome duplication results in juxtaposition of a surface antigen gene with a rRNA gene promoter. Although such "bottom up" approaches have provided significant insight into surface antigen variation, two of the Specific Aims of this proposal are designed to use a "top down" strategy employing next generation sequencing to comprehensively delineate mutations and genomic re- arrangements that represent within-host micro-evolution during the 5-year niche adaptation in a human joint. As only two genome sequences are currently available for M. hominis, the comparative genomic analyses of these data to those generated for the arthritis strains and 12 additional clinical isolates will refine the core and pangenomes for the species, potentially revealing genes, gene islands or mobile genetic elements that are differentially associated with isolates from different disease pathologies. These data should also provide insight antigenic variation between different serotypes and the mechanism and acquisition of acquired tetracycline resistance. Ultimately, the data generated by completion of these Specific Aims should provide a platform from which strategies for improved immune or chemotherapeutic intervention can be devised and implemented.