CELLULAR INVASION BY GROUP B STREPTOCOCCI

B族链球菌（GBS）是细菌性脓毒症的最常见原因 和脑膜炎 虽然大量的文献 存在描述GBS感染的免疫学和流行病学， 新生儿，很少有信息存在的具体机制， 微生物用于诱发疾病。 我们在子宫内建立了一个 新生儿败血症，诱导GBS，在亚人灵长类- M。内梅斯特里纳湖 猪尾猕猴 这些婴儿身上有人类的所有印记 子宫内感染GBS的婴儿。 婴幼儿肺超微结构研究 患有GBS肺炎的灵长类动物表明，GBS能够侵入 肺泡上皮细胞 基于这些数据，我们在体外开发了 GBS对上皮细胞侵袭的测定。 该提案旨在界定 GBS进入上皮细胞的特征。 的 研究将首先描述细菌和细胞因子的特征 GBS侵袭主要是呼吸道上皮细胞所需的 线 其次，我们将调查GBS进入的能力， 从顶端到基底外侧表面的横向（穿细胞作用） 上皮细胞的极性单层。 这些实验应该提供 深入了解GBS用于渗透和穿越 真核细胞 我们建议鉴定由GBS产生的假定毒力因子， 负责入侵表型。 转座子突变体 胶囊和溶血素的生产以前已经完成， 筛选它们侵入上皮细胞的能力。 转座子 诱变将用于衍生B的新的同基因突变株|GBS 其不能在体外进入上皮细胞。 的毒力 将测试入侵突变体诱导GBS感染的能力， 首先在新生大鼠脓毒症模型中，随后， 突变体将在子宫内在GBS新生灵长类动物脓毒症模型中进行测试。 那些不能入侵的突变体，后来被证明是无毒的 将使用分子生物学方法进一步表征 技术. 对入侵决定因素很重要的基因， 转座子诱变，将被克隆和基因产物鉴定 使用标准化的基因表达分析。 这些研究应该开始， 使用标准化基因表达测定鉴定。 这些研究应 开始鉴定在早期步骤中重要的细菌特性， 新生儿B组链球菌感染的发病机制。

Group B streptococci (GBS) are the most common cause of bacterial sepsis and meningitis in the newborn infant. Although an extensive literature exists describing the immunology and epidemiology of GBS infection in neonates, very little information exists on the specific mechanisms this organism uses to induce disease. We have developed an in utero model of neonatal sepsis, induced by GBS, in subhuman primates - M. nemestrina or pigtail macaques. These infants display all of the stigmata of human infants infected by GBS in utero. Lung ultrastructural studies of infant primates with GBS pneumonia have shown that GBS are capable of invading alveolar epithelial cells. Based on this data, we have developed in vitro assays of epithelial cell invasion by GBS. This proposal seeks to define the characteristics of entry by GBS into epithelial cells. The investigation will first characterize the bacterial and cellular factors required by GBS for invasion of primarily respiratory epithelial cell lines. Secondly, we will investigate the ability of GBS to enter and traverse (trancytosis) from the apical to the basoloateral surface of a polar monolayer of epithelial cells. These experiments should provide insight into the mechanisms GBS use to penetrate and traverse across eukaryotic cells. We propose to identify the putative virulence factors produced by GBS that are responsible for the invasion phenotype. Transposon mutants in production of capsule and hemolysin have been made previously and will be screened for their ability to invade epithelial cells. Transposon mutagenesis will be used to derive new isogenic mutant strains of B|GBS which are unable to enter epithelial cells in vitro. The virulence of invasion mutants will be tested for their ability to induce GBS infections, first in a neonatal rat sepsis model, and subsequently, specific invasion mutants will be tested in utero in the GBS neonatal primate sepsis model. Those mutants incapable of invasion and subsequently shown to be avirulent in animal models will be further characterized using molecular biologic techniques. The genes important for invasion determinants, identified by transposon mutagenesis, will be cloned and the gene products identified using standardized gene expression assays. These studies should begin to identify using standardized gene expression assays. These studies should begin to identify the bacterial traits important in the early steps in the pathogenesis of neonatal infections caused by Group B streptococci.