Anti-viral Mechanisms of Defensins

项目摘要 先天免疫反应是宿主防御感染的关键组成部分。α-防御素，1 抗微生物肽家族，是进化上保守的一类先天免疫效应物， 描述了抗菌活性;然而，它们在病毒免疫中的作用还不太清楚。强效 在体外和细胞培养中已经描述了α-防御素对多种病毒的中和作用。通过专注 在人类腺病毒和乳头瘤病毒上，我们已经确定了一种共同的机制， 与病毒衣壳结合，并在进入细胞时改变外壳，以阻断感染。最近，我们发现， 通过口腔/粪便途径传播的病毒（例如，轮状病毒和肠道腺病毒）选择性地抵抗 来自其宿主物种的α-防御素的抗病毒活性，同时保持对非宿主α-防御素的敏感性， 防御素在某些情况下，宿主α-防御素甚至增加或增强这些病毒的感染， 这使我们假设肠道病毒已经进化到逃避或劫持这些宿主防御 肽来增加感染和传播。为了验证这一假设，我们将研究增强和 通过宿主和非宿主α-防御素中和轮状病毒。轮状病毒是重要的人类病原体 更深入地了解决定其向性的宿主因素对于理解 传输这些研究将结合联合收割机生物化学和遗传学方法来鉴定α-防御素 病毒衣壳上的结合决定簇，并鉴定α-防御素特性， 加强活动。我们还将确定轮状病毒中和和增强的机制。 最后，我们将确定这些机制是否改变体内病毒感染。 为了确定我们在腺病毒和HPV研究中发现的抗病毒机制是否 一般来说，我们还将剖析细小病毒抑制的机制。细小病毒，特别是腺病毒- 相关病毒是重要的病毒载体。此外，还有众所周知的（例如，B19）和新兴（例如， 博卡病毒）细小病毒，它们是重要的人类病原体。这些研究将由高 临床相关病毒载体的解析结构研究。从这两个比较研究中， 结合我们先前对人类腺病毒的认识， 乳头状瘤病毒，我们将获得更深入的了解免疫的一个关键组成部分的功能， 这可能是许多病毒发病机制中的共同因素。这些研究也可能有助于 开发α-防御素作为治疗剂并为疫苗设计提供信息。

Project Summary The innate immune response is a critical component of host defense against infection. Alpha-defensins, one family of antimicrobial peptides, are an evolutionarily conserved class of innate immune effectors with well- described anti-bacterial activity; however, their role in viral immunity is less well understood. The potent neutralization of diverse viruses by alpha-defensins has been described in vitro and in cell culture. By focusing on human adenovirus and papillomavirus, we have identified a common mechanism whereby alpha-defensins bind to the viral capsid and alter uncoating during cell entry to block infection. Recently, we have found that viruses transmitted by the oral/fecal route (e.g., rotavirus and enteric adenovirus) are selectively resistant to the antiviral activity of alpha-defensins from their host species while remaining sensitive to non-host alpha- defensins. In some cases, the host alpha-defensins even increase or enhance the infection of these viruses, leading us to hypothesize that enteric viruses have evolved to either evade or hijack these host defense peptides to increase infection and transmission. To test this hypothesis, we will study the enhancement and neutralization of rotavirus by host and non-host alpha-defensins. Rotaviruses are important human pathogens and a deeper understanding of host factors that dictate their tropism is important for understanding transmission. These studies will combine biochemical and genetic approaches to identify alpha-defensin binding determinants on the viral capsids and to identify alpha-defensin properties that differentiate neutralizing and enhancing activities. We will also identify the mechanisms of rotavirus neutralization and enhancement. Finally, we will determine whether or not these mechanisms alter viral infection in vivo. To determine whether the antiviral mechanism that we have uncovered in our studies of adenovirus and HPV is general, we will also dissect the mechanism of parvovirus inhibition. Parvoviruses, particularly adeno- associated virus, are important viral vectors. In addition, there are well known (e.g., B19) and emerging (e.g., bocavirus) parvoviruses that are important human pathogens. These studies will be facilitated by high resolution structural studies of clinically relevant viral vectors. From these comparative studies of two disparate families of non-enveloped viruses in combination with our prior insights from human adenovirus and papillomavirus, we will gain a deeper understanding of the function of a critical component of the immune system that may be a common factor in the pathogenesis of many viruses. These studies may also aid in the development of alpha-defensins as therapeutics and inform vaccine design.