Understanding BK virus in kidney transplantation

每年，全世界有超过9万名肾脏疾病患者接受肾脏移植手术。这些患者服用免疫抑制药物来防止移植肾的排斥反应，但这些药物增加了感染的风险。在这方面，越来越重要的是BK病毒，这种病毒对健康人无害，但对肾移植患者却可能导致严重疾病。不受控制的BK感染可能会对服用免疫抑制药物的人的肾脏造成严重损害，限制移植功能，并可能导致肾脏过早丢失并重新进行透析。目前还没有有效的治疗BK感染的方法，除了减少抗排斥药物，让免疫系统对抗BK，这增加了移植排斥和丧失的风险。随着时间的推移，肾移植变得越来越复杂，越来越多的患者需要强大的免疫抑制组合来防止他们的肾移植排斥。这意味着受BK病毒影响的肾移植患者数量预计会增加，因此，我们清楚地了解BK病毒的分子机制并利用它来开发新的治疗方法变得越来越重要。绝大多数人成年后都会感染BK病毒。我们最近发现，由BK病毒产生的一种蛋白质（称为agnoprotein）形成一个通道，通过一种我们尚不了解的机制，这种通道形成能力是允许病毒从感染细胞中退出所必需的——这被称为“毒孔蛋白”。由于几乎每个接受肾移植的人体内都存在这种病毒，因此它如何离开细胞被认为是导致肾移植问题的关键。该项目将在病毒离开细胞的过程中检查agnoprotein的结构和功能，并寻求确定可以阻止BK病毒破坏肾移植的药物靶点。该项目的具体目标是：1)了解agnoprotein viroporin的结构和功能；o使用先进的电子显微镜确定agnoprotein viroporin的3D分子结构；确定结构中的分子靶点，为功能分析和筛选具有破坏病毒孔蛋白功能的化合物提供平台；2)开发有效的agnoprotein inhibitor或利用我们对agnoprotein viroporin的新结构知识来了解其结合利用这些信息筛选高效抑制剂化合物的虚拟文库，在体外和细胞培养模型中测试这些抑制剂，以生成一套化合物，用于进一步的功能研究和潜在的未来临床应用。我们将与结构生物学和药物化学的专家以及其他使用不同细胞培养模型的BK研究人员合作，以确保我们的结果是稳健的，并可以向前推进，以寻找BK病毒的新治疗方法。最终，这将减少BK病毒引起的问题，从而使患者受益，这将使受BK病毒影响的肾脏移植持续更长时间。

Each year, over 90,000 patients worldwide suffering from kidney disease receive a life transforming kidney transplant. These patients take immunosuppression medications to prevent rejection of the transplanted kidney, but those medications increase the risk of infection. Of growing importance in this regard is BK virus, a harmless virus in a healthy person, but one that can cause severe disease in kidney transplant patients.Uncontrolled BK infection can trigger serious damage to the kidney in a person taking immunosuppression, limiting transplant function and potentially leading to premature kidney loss and return to dialysis. There are no effective treatments for BK infection, other than reducing anti-rejection medications to allow the immune system to fight BK, which increases the risk of transplant rejection and loss.As kidney transplantation has become more complex over time, an increasing number of patients need strong immunosuppression combinations to prevent their kidney transplant from rejecting. This means the number of patients with kidney transplants affected by BK virus is expected to grow, For this reason it is increasingly important that we have a clear understanding of the molecular mechanisms of BK virus and use this to develop new treatments.BK virus is present in the vast majority of people by the time they are adults. We recently showed that a protein made by BK virus (called agnoprotein) forms a channel and that by a mechanism that we do not understand, this channel-forming ability is necessary to allow the virus to exit from infected cells - this is referred to as a "viroporin". Since the virus is present in almost every person receiving a kidney transplant, how it leaves the cells is thought to be critical to the problems it can cause for a kidney transplant.This project will examine the structure and function of agnoprotein in the way the virus leaves the cells and seek to identify targets for medications that could stop the BK virus from damaging the kidney transplant. Specific aims of the project are:1) Understand agnoprotein viroporin structure and function:o Determine the 3D molecular structure of the agnoprotein viroporin using advanced electron microscopyo Define molecular target sites in the structure creating a platform for functional analysis and for screening of compounds for the ability to disrupt the viroporin function2) Develop potent agnoprotein inhibitorso Use our novel structural knowledge of the agnoprotein viroporin to understand the binding of known low potency inhibitorso Use this information to screen virtual libraries of compounds for high potency inhibitors o Test these inhibitors in vitro and in cell culture models to generate a suite of compounds for further functional studies and potential future clinical use3) Validate viroporin function, and novel inhibitors in primary cell culture modelso Use two complementary cell culture systems to model the antiviral activity of the high potency inhibitor compoundsWe will work with expert collaborators in Structural Biology and Medicinal Chemistry, and other BK researchers who use different cell culture models, to ensure our results are robust and can be taken forward to find new treatments for BK virus.Ultimately, this will benefit patients by reducing the problems caused by BK virus, which will make kidney transplants affected by BK virus last longer.