CELLULAR INVASION BY GROUP B STREPTOCOCCI

B组链球菌(GBS)是细菌性败血症最常见的原因 以及新生儿的脑膜炎。尽管这是一部内容广泛的文献 描述GBS感染的免疫学和流行病学的现有文献 新生儿，关于这一具体机制的信息很少 有机体用来引发疾病。我们已经开发出了一种子宫内模型 在亚人灵长类动物中由GBS引起的新生儿败血症--M.nememstrina或 辫子猕猴。这些婴儿表现出人类所有的圣痕 婴儿在宫内感染GBS。婴幼儿肺超微结构的研究 患有GBS肺炎的灵长类动物表明GBS能够入侵 肺泡上皮细胞。基于这些数据，我们在体外开发了 GBS法检测上皮细胞侵袭能力。这项提案旨在界定 GBS进入上皮细胞的特性。这个 调查将首先确定细菌和细胞因素的特征 GBS侵袭原发呼吸道上皮细胞所需 台词。其次，我们将调查GBS进入和 从根尖到基底侧面的横行(细胞分裂) 上皮细胞的极单分子层。这些实验应该提供 洞察GBS用于穿透和遍历的机制 真核细胞。 我们建议确定由GBS产生的可能的毒力因子 是侵袭表型的罪魁祸首。转座子突变体 胶囊和溶血素的生产已经在以前进行过，并将于 对它们入侵上皮细胞的能力进行了筛选。转座子 将使用诱变技术获得新的B|GBS等基因突变株 在体外不能进入上皮细胞。病毒的致命性 入侵突变体将被测试其诱导GBS感染的能力， 首先是在新生大鼠败血症模型中，随后是特异性侵袭 突变体将在GBS新生儿灵长类败血症模型中进行宫内测试。 那些不能入侵并随后被证明是无毒的突变体 在动物模型中将进一步利用分子生物学来表征 技巧。对入侵决定因素很重要的基因，由 转座子诱变，将被克隆并鉴定基因产物 使用标准化的基因表达分析。这些研究应该开始 使用标准化的基因表达分析进行鉴定。这些研究应该 开始确定在早期步骤中重要的细菌特性 新生儿B群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.