Innate immune mechanisms in dengue infection

描述（由申请人提供）：关于登革热病毒感染的最令人困惑的问题之一是发现，尽管一种血清型的原发感染导致针对相同血清型的长期保护，但异源血清型的感染导致从轻度到重度的广泛疾病，并且在某些情况下是致命的。这种结果的机制还远不清楚，并且为生产有效的登革热疫苗提供了重大挑战，因为疫苗实际上可能增强严重疾病的可能性。我们的实验室一直在研究登革热（DF）和登革出血热（DHF）患者对登革病毒的急性反应，试图描绘出可以在流行人群中区分DF和DHF的生物标志物。在此过程中，我们的实验室记录了以下内容：a）登革热感染早期（第1-3天），这些患者的血浆含有许多细胞因子和趋化因子，我们认为它们驱动记忆B细胞的动员，所述记忆B细胞发育成血浆母细胞并代表血液中>50%的B细胞; b）血浆母细胞对晚期细胞因子引起的细胞凋亡高度敏感，（第7-10天）这些患者的血清和/或通过它们与表达Fas-L的NK细胞的相互作用，c）表达未成熟表型的浆细胞样树突细胞（pDC）的频率显著增加，d）在这些患者中存在针对异源登革热病毒的沉默记忆B细胞应答。基于这些初步发现，我们的实验室制定了一系列问题，旨在更详细地定义急性登革热感染期间发生的免疫事件链，旨在定义与疾病严重程度相关的事件。因此，在本发明中，该建议的目的是进行以下的详细研究：a）在急性感染期间存在于登革热患者血清中的趋化因子/细胞因子的水平，并鉴定血浆母细胞上的归巢标记物，并将轻度无症状与严重疾病相关联，B）试图定义导致血浆母细胞凋亡增强的机制，c）检查KIR/细胞因子之间的关系，有助于NK细胞与单核细胞和树突细胞（DC）之间相互作用质量的MHC多态性和d）与疾病严重程度相关的单核细胞/DC的表型和功能异质性的研究。我们已经组建了一支由免疫学家，病毒学家和儿科登革热临床医生组成的优秀团队，他们在登革热病毒性疾病方面有着长期的工作记录，以解决所概述的每一个具体目标，并提交这些研究的结果不仅有助于了解登革热感染的发病机制，还可能为有效的疫苗制剂提供线索。

DESCRIPTION (provided by applicant): One of the most perplexing issues with regards to dengue virus infection is the finding that whereas primary infection with one serotype leads to long term protection against the same serotype, infection with a heterologous serotype leads to a wide spectrum of illness ranging from mild to severe and in some cases fatal. The mechanisms for this outcome are far from clear and provide for a major challenge to produce an effective dengue vaccine since the potential exists that the vaccine may in fact potentiate severe disease. Our lab has been studying the acute response to dengue virus in patients with dengue fever (DF) and dengue hemorrhagic fever (DHF) in attempts to delineate biological markers that can distinguish DF from DHF in an endemic population. During this process our lab has documented the following: a) early (day 1-3) during dengue infection, the plasma of these patients contain a number of cytokines and chemokines that we submit drive the mobilization of memory B cells which develop into plasma blasts and represent >50% of the B cells in the blood b) the plasma blasts are highly susceptible to apoptosis by factors in the late (day 7-10) sera of these patients and/or by their interaction with Fas-L expressing NK cells c) there is a marked increase in the frequencies of plamacytoid dendritic cells (pDC's) which express immature phenotype d) there is a muted memory B cell response against the heterologous dengue virus in these patients. Based on these preliminary findings, our lab has formulated a series of questions, which are aimed at defining in more detail the chain of immunological events that occur during acute dengue infection with the aim to define the events that are associated with disease severity. Thus, the objectives of this proposal are to carry out detailed studies of a) levels of the chemokines/cytokines that are present in the sera of dengue patients during acute infection and identify homing markers on the plasma blasts and correlate mild asymptomatic v/s severe disease b) attempt to define the mechanisms that lead to enhanced apoptosis of the plasma blasts c) examine the relationships between KIR/MHC polymorphisms that contribute to the quality of interactions between NK cell and monocytes and dendritic cells (DC's) and d) studies of the phenotypic and functional heterogeneity of monocytes/DC's that correlates with disease severity. We have assembled an outstanding team of immunologists, virologists and pediatric dengue clinicians with a long track record of working on dengue viral disease to address each of the specific aims outlined and submit that the results from these studies will not only contribute to the understanding of the pathogenesis of dengue infection but may also provide clues to effective vaccine formulation.