Department of Microbiology and Immunology, Medical College of Virginia Campus of Virginia Commonwealth University, Richmond, VA 23298, USA.
BMC Genomics. 2010 Jun 11;11:375. doi: 10.1186/1471-2164-11-375.
Worldwide, bacterial vaginosis (BV) is the most common vaginal disorder. It is associated with risk for preterm birth and HIV infection. The etiology of the condition has been debated for nearly half a century and the lack of knowledge about its cause and progression has stymied efforts to improve therapy and prevention. Gardnerella vaginalis was originally identified as the causative agent, but subsequent findings that it is commonly isolated from seemingly healthy women cast doubt on this claim. Recent studies shedding light on the virulence properties of G. vaginalis, however, have drawn the species back into the spotlight.
In this study, we sequenced the genomes of a strain of G. vaginalis from a healthy woman, and one from a woman with bacterial vaginosis. Comparative analysis of the genomes revealed significant divergence and in vitro studies indicated disparities in the virulence potential of the two strains. The commensal isolate exhibited reduced cytotoxicity and yet the cytolysin proteins encoded by the two strains were nearly identical, differing at a single amino acid, and were transcribed at similar levels. The BV-associated strain encoded a different variant of a biofilm associated protein gene and demonstrated greater adherence, aggregation, and biofilm formation. Using filters with different pore sizes, we found that direct contact between the bacteria and epithelial cells is required for cytotoxicity.
The results indicated that contact is required for cytotoxicity and suggested that reduced cytotoxicity in the commensal isolate could be due to impaired adherence. This study outlines two distinct genotypic variants of G. vaginalis, one apparently commensal and one pathogenic, and presents evidence for disparate virulence potentials.
在全球范围内，细菌性阴道病（BV）是最常见的阴道疾病。它与早产和 HIV 感染的风险有关。这种疾病的病因已经争论了将近半个世纪，由于缺乏对其病因和发病机制的了解，阻碍了改善治疗和预防的努力。加德纳菌最初被确定为病原体，但随后发现它通常从看似健康的女性中分离出来，这对这一说法提出了质疑。然而，最近的一些研究揭示了加德纳菌的毒力特性，使该物种重新成为关注焦点。
在这项研究中，我们对一名健康女性和一名细菌性阴道病女性的阴道加德纳菌菌株进行了基因组测序。对基因组的比较分析显示出显著的差异，体外研究表明两种菌株的毒力潜力存在差异。共生分离株表现出降低的细胞毒性，但两种菌株编码的细胞毒素蛋白几乎相同，仅在单个氨基酸处存在差异，转录水平相似。与 BV 相关的菌株编码了一种不同的生物膜相关蛋白基因，表现出更强的粘附、聚集和生物膜形成能力。使用具有不同孔径的过滤器，我们发现细菌和上皮细胞之间的直接接触是细胞毒性所必需的。
结果表明接触是细胞毒性所必需的，并表明共生分离株的细胞毒性降低可能是由于粘附能力受损所致。本研究概述了两种不同的加德纳菌基因型变体，一种显然是共生的，一种是致病的，并提供了证据表明其具有不同的毒力潜力。
