Fetal CMV Infection: Role of the Human Placenta

先天性巨细胞病毒(CMV)感染每年影响美国1%的婴儿，导致 死亡率和永久性残疾。胎盘的病毒感染在传播给胎儿之前，以及 感染途径与子宫-胎盘界面的细胞滋养细胞(CTB)相互作用有关。 对妊娠早期胎盘活检标本的研究表明，CMV感染子宫和 传播到锚定绒毛中的分化/侵袭性CTB和漂浮绒毛中的祖细胞。受感染的 CTB下调关键分化分子，削弱侵袭性。最近的研究表明，免疫球蛋白- 病毒粒子复合体跨细胞转运(由新生儿Fc受体介导)穿过合体滋养层细胞 并感染潜在的四氯苯。免疫组织化学染色显示病毒在发育中的胎盘中复制的位置 与细胞分化时上调的功能性受体的表达有关。令人惊讶的是，CMV GB 在合体滋养层细胞中与含有小凹蛋白-1的隔室共定位，形成小凹小体 病毒粒子可在中性pH条件下积累。Gb中的Caveolin-1结合基序表明病毒诱导的内化。 这些新的观察结果证实，病毒粒子内化在自然感染组织的小窝中，并可能 解释为什么感染会发生在整个妊娠过程中。长期目标是了解机制 通过胎盘传播，防止病毒感染胎盘并传播到胎儿。这个 GB促进小窝中的病毒粒子内吞和病毒粒子跨细胞作用的假设将被用 特化细胞和绒毛外植体，并在自然感染的胎盘中得到证实。具体的 目标如下。目的1.检测整合素异常与膜近端细胞功能 CMV临床株感染CTB的黏附、迁移和侵袭鉴别目标2. 完成对CTB和特殊细胞中作为CMV受体的分子的分析。评估 小窝蛋白-1-脂筏和GB在病毒粒子摄取中的作用。感染胎盘中相关的病毒复制部位 与发育和空间调节的受体。目标3.研究病毒粒子在空泡中的运输 极化细胞中的小泡，并评估病毒粒子在细胞间的传输。检视从中国分离的凹陷体 自然感染的胎盘。这些研究将揭示CMV用来破坏 胎盘！形成屏障，到达胎儿隔室。了解这些过程是以下步骤的第一步 设计新的方法来阻止病毒的传播和增强病毒的屏障功能 预防胎盘这种重要的人类病原体在先天性疾病中造成的损害。

Congenital cytomegalovirus (CMV) infection affects 1% of babies in the United States annually, causing mortality and permanent disabilities. Virus infection of the placenta precedes transmission to the fetus, and the routes of infection are linked to cytotrophoblast (CTB) interactions at the uterine-placental interface. Studies of biopsy specimens from early-gestation placentas revealed that CMV infects the uterus and spreads to differentiating/invading CTBs in anchoring villi and to progenitor cells in floating villi. Infected CTBs downregulate key differentiation molecules and impair invasiveness. Recent studies showed that IgG- virion complexes are transcytosed (mediated by the neonatal Fc receptor) across the syncytiotrophoblast and infect underlying CTBs. Immunostaining showed that sites of viral replication in the developing placenta correlate with expression of functional receptors upregulated as the cells differentiate. Surprisingly, CMV gB colocalized with caveolin-1 containing compartments in the syncytiotrophoblast, forming caveosomeswhere virions could accumulate at neutral pH. Caveolin-1-binding motifs in gB suggest virus-induced internalization. These novel observations establish that virions internalize in caveolae in naturally infected tissues and could explain why infection occurs throughout gestation. The long-term objectives are to understand mechanisms of transplacental transmission and prevent virus infection of the placenta and spread to the fetus. The hypothesis that gB promotes virion endocytosis in caveolae and virion transcytosis will be tested using specialized cells and chorionic villus explants and confirmed in naturally infected placentas. The specific aims are as follows. Aim 1. Examine dysregulated integrins and membrane-proximalfunctions¿cell adhesion, migration and invasion¿in differentiating CTBs infected with clinical CMV strains. Aim 2. Complete the analysis of molecules that function as CMV receptors in CTBs and specialized cells. Assess the role of caveolin-1-lipid rafts and gB in virion uptake. Correlate viral replication sites in infected placentas with developmental^ and spatially regulated receptors.Aim 3. Investigate virion transport in caveolar vesicles in polarized cells and evaluate cell-cell transmission of virions. Examine caveosomes isolated from naturally infected placentas. These studies will uncover mechanisms used by CMVto breach the placenta! barrier and reach the fetal compartment. Understanding these processes is the first step in the design of novel approaches to block viral spread and enhance the barrier function of the placenta to prevent damage caused by this important human pathogen in congenital disease.