Measles virus infection of the respiratory tract

麻疹作为全世界发病率和死亡率的一个原因正在增加。麻疹病毒（MeV）， 麻疹的病原体，通过呼吸道传播，是人类最具传染性的病毒之一 估计基本生殖率（R 0）为12-18，这推动了对高水平人口的需求 免疫力，以防止疫情。麻疹是一种人类疾病，但猕猴可以通过 与人类接触，产生类似人类麻疹的疾病，并已有效地用于研究 麻疹的发病机制。了解MeV的极其有效的空中传输需要 了解病毒气溶胶或飞沫接触呼吸道后感染的开始， 病毒的控制和释放机制。呼吸道上皮细胞长期以来被认为是第一个网站， MeV感染，随后扩散至淋巴组织。然而，研究人员使用增强型绿色 表达荧光蛋白（eGFP）的重组报告基因MeV不能检测感染的呼吸道感染。 上皮细胞感染后早期猕猴或证明感染从顶端表面 在培养物中分化呼吸道上皮细胞，并推断它们没有被感染。因为 另一种观点是，在基础感染培养的上皮细胞后观察到表达eGFP的细胞， 肺上皮细胞感染是通过基底外侧暴露于受感染的淋巴细胞而开始的， 直到病毒血症建立后才发生。后一项研究得出结论，骨髓细胞 而不是上皮细胞是肺中MeV感染的初始部位。然而，我们的数据显示， 呼吸道上皮细胞的感染实际上是相当有效的，但是暴露于MeV会诱导MeV的脱落， 从上皮表面产生多核巨细胞，并且使其没有可检测到的感染细胞。 因此，上皮细胞可能是重要的启动以及传播的MeV感染。 识别呼吸道中允许非常有效地启动感染的易感细胞， 确定MeV进入分化上皮细胞的机制是理解 有效的MeV传播和使用雾化疫苗进行麻疹免疫接种。为了解决这一关键问题， 我们将使用恒河猴的体外和体内研究来鉴定野生型和非野生型 MeV的疫苗株通过以下途径感染原代分化的呼吸道上皮细胞 具体目的：（1）确定原代肺泡巨噬细胞对MeV感染的相对易感性 以及来自上呼吸道和下呼吸道的分化细胞的培养物，包括肺成纤维细胞， 树突细胞和基底、纤毛和产生粘液的上皮细胞。(2)确定使用的宿主受体 以及MeV感染并诱导初级分化的呼吸道上皮脱落的机制 细胞在顶面相互作用后。(3)识别分化的呼吸系统的先天反应 上皮细胞对MeV感染的作用及其在限制病毒复制中的作用。

Measles is increasing as a cause of morbidity and mortality worldwide. Measles virus (MeV), the causative agent of measles, is spread by the respiratory route and is one of the most highly infectious viruses of humans with an estimated basic reproductive rate (R0) of 12-18 that drives the need for high levels of population immunity to prevent outbreaks. Measles is a human disease, but macaques can contract measles through contact with humans, develop disease that mimics human measles and have been effectively used for studies of measles pathogenesis. Understanding the extremely efficient airborne transmission of MeV requires knowledge of both the initiation of infection after viral aerosol or droplet contact with the respiratory tract and mechanisms of virus control and release. Respiratory epithelial cells were long assumed to be the first site of MeV infection with subsequent spread to lymphoid tissue. However, investigators using enhanced green fluorescent protein (eGFP)-expressing recombinant reporter MeVs were not able to detect infected respiratory epithelial cells early after infection of macaques or to demonstrate infection from the apical surface of differentiated respiratory epithelial cells in culture and deduced that they had not become infected. Because eGFP-expressing cells were observed after basal infection of cultured epithelial cells, an alternate view emerged that lung epithelial cell infection is initiated through basolateral exposure to infected lymphocytes and does not occur until after the viremia is established. These latter studies have concluded that myeloid cells rather than epithelial cells are the initial sites of MeV infection in the lung. However, our data show that apical infection of respiratory epithelial cells is actually quite efficient, but exposure to MeV induces shedding of MeV- producing multinucleated giant cells from the epithelial surface and leaves it without detectable infected cells. Therefore, epithelial cells may be important for the initiation as well as dissemination of MeV infection. Identification of the susceptible cells in the respiratory tract that allow for very efficient initiation of infection and determination of the mechanism of MeV entry into differentiated epithelial cells are key to understanding efficient MeV transmission and use aerosolized vaccine for measles immunization. To address this critical area we will use in vitro and in vivo studies of rhesus macaques to identify the mechanisms by which both wild type and vaccine strains of MeV infect primary differentiated respiratory tract epithelial cells through the following specific aims: (1) Determine the relative susceptibility to infection with MeV of primary alveolar macrophages and cultures of differentiated cells from the upper and lower respiratory tract that include lung fibroblasts, dendritic cells and basal, ciliated and mucous-producing epithelial cells. (2) Determine the host receptors used and mechanisms by which MeV infects and induces shedding of primary differentiated respiratory epithelial cells after interaction at the apical surface. (3) Identify the innate responses of differentiated respiratory epithelial cells to MeV infection and their role(s) in restricting virus replication.