Understanding BK virus in kidney transplantation

每年，全世界有超过90，000名患有肾脏疾病的患者接受改变生命的肾脏移植。这些患者服用免疫抑制药物以防止移植肾的排斥反应，但这些药物会增加感染的风险。在这方面，BK病毒的重要性日益增加。BK病毒对健康人无害，但可导致肾移植患者发生严重疾病。不受控制的BK感染可引发服用免疫抑制剂的患者的肾脏严重损伤，限制移植功能，并可能导致过早的肾功能丧失和再次透析。对于BK感染没有有效的治疗方法，除了减少抗排斥药物以允许免疫系统对抗BK，这增加了移植排斥和损失的风险。随着肾移植随着时间的推移变得越来越复杂，越来越多的患者需要强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，我们对BK病毒的分子机制有一个清晰的了解并利用它来开发新的治疗方法越来越重要。BK病毒在绝大多数人成年时就存在。我们最近发现，BK病毒产生的一种蛋白质（称为未知蛋白）形成了一个通道，并且通过我们不了解的机制，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“病毒孔蛋白”。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它可能给肾移植带来的问题的关键。该项目将研究病毒离开细胞的方式中未知蛋白的结构和功能，并寻求确定药物的靶点，以阻止BK病毒损害肾移植。该项目的具体目标是：1）了解未知蛋白viroporin的结构和功能：o使用先进的电子显微镜确定未知蛋白病毒孔蛋白的3D分子结构。定义结构中的分子靶位点，创建用于功能分析和筛选具有破坏病毒孔蛋白功能能力的化合物的平台2）利用我们对未知蛋白viroporin的新结构知识来了解已知低效力的未知蛋白的结合。利用这些信息来筛选高效力抑制剂的化合物的虚拟库。功能研究和潜在的未来临床用途3）原代细胞培养模型中的病毒孔蛋白功能和新型抑制剂因此使用两种互补的细胞培养系统来模拟高效抑制剂化合物的抗病毒活性我们将与结构生物学和药物化学方面的专家合作者以及使用不同细胞培养模型的其他BK研究人员合作，以确保我们的结果是稳健的，并可用于寻找BK病毒的新疗法。最终，这将通过减少BK病毒引起的问题而使患者受益，这将使受BK病毒影响的肾移植持续更长时间。

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.