Molecular Mechanism of IMD (NF-kB) Inhibition by Dengue Virus in the Mosquito Aedes Aegypti, and Implications for Transmission and Emergence

登革热病毒是导致人类疾病的最重要的蚊媒病毒。世界上几乎一半的人口面临感染登革热病毒的风险，主要发生在热带低收入和中等收入国家。每年约有4亿人受到感染，其中约有1亿例严重的流感样登革热和50万例更严重、可能致命的登革热出血热。登革热疾病的主要影响除了造成重大痛苦和生命损失和经济生产力损失外，还在于在许多国家几乎每年都经历的流行病期间，不发达的医疗保健系统不堪重负，影响到常规和紧急医疗护理。目前还没有治疗登革热的药物，唯一获得许可的疫苗也不完美，不建议在全球广泛使用。登革热病毒通过蚊子传播，不能在人与人之间直接传播。当蚊子以感染者为食时，它也会感染登革热病毒。当蚊子以另一个人为食时，病毒就会传播，导致另一个人被感染。因此，防止通过蚊子传播是减轻全球疾病负担的有效方法。通常传播登革热病毒的蚊子是黄热病蚊子(拉丁文名称为埃及伊蚊)。像人类一样，蚊子有一种免疫系统，可以保护它们免受病毒疾病的侵袭。当黄热病蚊子感染病毒时，这种蚊子的免疫反应就会启动，但并不是所有的免疫系统都能对抗登革热病毒。我们发现，这是因为登革热病毒主动阻断了免疫反应的某些部分。这笔赠款将调查登革热病毒是如何从免疫系统的这些手臂中逃脱的，这在任何蚊媒病毒中都是第一次。最终，这将使我们能够开发出加强蚊子免疫系统的方法，以防止它们感染登革热病毒，这将减少传播，保护人们免受登革热疾病的侵袭。我们的首要目标是找出登革热病毒如何阻止蚊子的免疫反应。登革热病毒感染蚊子时会产生10种蛋白质，我们预测其中一种蛋白质会扰乱蚊子的免疫反应。我们将确定哪些蛋白质可以做到这一点，以及如何做到这一点。我们的第二个目标将从不同的角度来看待这个问题，我们将询问蚊子免疫反应的某些手臂对抗击登革热感染有多重要。我们将通过观察病毒在缺乏这些免疫反应的蚊子细胞中生长时会发生什么来实现这一点。前两个目标将使用从蚊子中提取的细胞进行研究，这些细胞很容易在实验室中使用，有助于找出登革热病毒如何隐藏在蚊子免疫系统中的细节。然而，我们不能用这些细胞来研究传播。出于这个原因，这笔赠款的第三个也是最后一个目标是在实验室中重复前两个目标中的关键实验，以检查我们的结果是否与实际蚊子中发生的情况相关。登革热病毒有四种不同的毒株，其中一些病毒的表现非常不同，所以我们还将检查我们的结果是否可以外推到所有四种登革热病毒株。此外，我们的实验将告诉我们，登革热病毒是如何阻止蚊子的免疫反应的，以及逃脱某些蚊子免疫反应的能力对登革热病毒的传播有多重要。未来，这些信息将使黄热病蚊子的免疫反应更强，更能对抗登革热病毒，从而减轻全球登革热疾病的负担，以防止疾病传播。

Dengue virus is the most important mosquito-borne virus causing human disease. Almost half the world's population is at risk of dengue virus infection, mostly in tropical low and middle-income countries. Approximately 400 million people are infected each year, with about 100 million cases of the severe flu-like dengue fever and 500,000 cases of the more severe and potentially fatal dengue haemorrhagic fever. The major impact of dengue disease, on top of significant suffering and loss of life and economic productivity, is that underdeveloped healthcare systems are overwhelmed during the almost annual epidemics experienced by many countries, affecting routine and emergency medical care. There are no medicines to treat dengue and the only licensed vaccine is imperfect and not recommended for widespread global use.Dengue virus is transmitted by mosquitoes and cannot spread directly between humans. When a mosquito feeds on an infected person, it too becomes infected with dengue virus. The virus is passed on when the mosquito feeds on another person, causing that second person to become infected. Preventing transmission through the mosquito is therefore an effective way of reducing the global disease burden.The mosquito that usually transmits dengue virus is the 'yellow fever mosquito' (Latin name Aedes aegypti). Like humans, mosquitoes have an immune system that protects them against viral diseases. The immune response of the yellow fever mosquito springs into action when the insect is infected with viruses, but not all arms of the immune system are able to fight dengue virus. We discovered that this is because dengue virus actively blocks certain parts of the immune response. This grant will investigate how dengue virus escapes from these arms of the immune system, a first for any mosquito-borne virus. Ultimately, this will allow us to develop ways of strengthening the immune system of mosquitoes to stop them from being infected with dengue virus, which will reduce transmission and protect people from dengue disease.Our first goal is to work out how dengue virus blocks mosquito immune responses. Dengue virus makes ten proteins when it infects a mosquito, and we predict that one of these proteins disrupts mosquito immune responses. We will identify which protein can do this, and how. Our second goal will look at this question from a different angle by asking how important certain arms of the mosquito's immune response are for fighting dengue infection. We will do this by looking at what happens to the virus when we grow it in mosquito cells that lack these parts of the immune response. These first two goals will be researched using cells taken from mosquitoes, which are easy to work with in the lab and useful for finding out the fine details of how dengue virus hides from the mosquito immune system. However, we cannot use these cells to study transmission. For this reason, the third and final goal of this grant is to repeat key experiments from the first two goals in yellow fever mosquitoes in the laboratory to check that our results are relevant to what happens in an actual mosquito. There are four different strains of dengue virus, some of which behave very differently from one another, so we will also check whether our results can be extrapolated to all four dengue strains.Together, our experiments will tell us how dengue virus blocks mosquito immune responses, and how important the ability to escape certain mosquito immune responses is for the transmission of dengue virus. In the future, this information will allow us to reduce the global burden of dengue disease by making the yellow fever mosquito's immune response stronger and better able to fight dengue virus in order to prevent disease transmission.