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， 死亡率和永久性残疾。胎盘的病毒感染先于胎儿传播， 感染途径与子宫-胎盘界面的细胞滋养层（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， 扩散到锚定绒毛中的分化/侵入CTB和漂浮绒毛中的祖细胞。感染 CTB下调关键分化分子并损害侵袭性。最近的研究表明，IgG- 病毒体复合物通过合体滋养层被转胞吞（由新生儿Fc受体介导 并感染潜在的CTB。免疫染色显示病毒在胎盘发育中的复制位点 与随着细胞分化而上调的功能性受体的表达相关。令人惊讶的是，CMV gB 与合体滋养层中含有小窝蛋白-1的隔室共定位，形成小窝体， 在中性pH值下，病毒粒子可以积累。gB中的Caveolin-1结合基序表明病毒诱导的内化。 这些新的观察结果表明，病毒粒子在自然感染组织中的小窝中内化， 解释为什么感染发生在整个妊娠期。长期目标是了解机制 预防病毒经胎盘传播，防止病毒感染胎盘并传播给胎儿。的 gB促进小窝中病毒粒子内吞作用和病毒粒子转胞吞作用的假设将使用 专门的细胞和绒毛膜绒毛外植体，并在自然感染的胎盘中得到证实。具体 目标如下。目标1.检查失调的整合素和膜近端功能 粘附、迁移和侵袭的能力，以区分临床CMV株感染的CTB。目标二。 完成对CTB和特化细胞中作为CMV受体的分子的分析。评估 小窝蛋白-1-脂筏和gB在病毒体摄取中的作用。感染胎盘中的相关病毒复制位点 与发育和空间调节受体。目的3.研究小窝中病毒粒子的运输 极化细胞中的囊泡，并评估病毒体的细胞间传递。检查分离自 自然感染的胎盘这些研究将揭示CMV用于破坏 胎盘！屏障到达胎儿室。了解这些过程是 设计新的方法来阻断病毒传播和增强细胞的屏障功能， 胎盘，以防止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.