Innate immune mechanisms in dengue infection

描述(申请人提供)：关于登革热病毒感染，最令人困惑的问题之一是发现，虽然一种血清型的初次感染会导致对同一血清型的长期保护，但感染异种血清型会导致从轻微到严重的广泛疾病，在某些情况下甚至是致命的。造成这一结果的机制远不清楚，并为生产有效的登革热疫苗提供了一个重大挑战，因为存在疫苗实际上可能加剧严重疾病的可能性。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，试图在流行人群中描述可以区分DF和DHF的生物标志物。在这个过程中，我们的实验室记录如下：a)在登革热感染的早期(第1-3天)，这些患者的血浆中含有许多细胞因子和趋化因子，我们提交这些细胞因子和趋化因子来驱动记忆B细胞的动员，这些B细胞发育成浆母细胞并代表&GT；血液中50%的B细胞b)这些患者晚期(第7-10天)血清中的因素和/或它们与表达NK细胞的Fas-L的相互作用对血浆母细胞高度敏感；c)表达未成熟表型d的造板细胞样树突状细胞(plamacytoid Dendritic cell，PDC)的频率显著增加)这些患者对异种登革热病毒的记忆B细胞反应减弱。根据这些初步发现，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，以确定与疾病严重程度相关的事件。因此，这项建议的目的是：a)对急性感染期间登革热患者血清中存在的趋化因子/细胞因子水平进行详细研究，并确定血浆母细胞上的归巢标志物并与轻度无症状的v/S重症疾病相关；b)尝试确定导致血浆母细胞凋亡增加的机制；c)检测导致NK细胞与单核细胞和树突状细胞(DC‘s)相互作用质量的KIR/MHC基因多态性之间的关系；d)研究单核细胞/DC的表型和功能异质性与疾病严重程度的关系。我们召集了一支由免疫学家、病毒学家和登革热儿科临床医生组成的优秀团队，他们在登革热病毒疾病方面有着长期的工作记录，以解决所概述的每个具体目标，并认为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定提供线索。

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.