Vaccine-mediated Targeting of Viral IL10 to Control HCMV Shedding and Reinfection

描述(由申请人提供)：在有免疫能力的宿主中对人类巨细胞病毒(HCMV)感染的免疫反应呈现悖论，对那些没有免疫能力的人具有潜在的破坏性影响。对保护性HCMV疫苗的长期追求受到多种因素的阻碍，其中包括关于HCMV自然历史的两个矛盾。(1)在具有免疫功能的宿主中，HCMV被认为是一种低致病潜力的病毒。然而，在那些限制临床结果的免疫反应存在的情况下，病毒有效地维持了终生持久性。人巨细胞病毒持续存在的一个特点是潜伏的病毒基因组重新激活和病毒脱落。水平传播对原发巨细胞病毒感染的高危人群是一种传染病威胁，尤其是未对巨细胞病毒免疫的母亲所生的胎儿。越来越多的证据突显了关于巨细胞病毒免疫的另一个模棱两可的问题。(2)在初次和长期感染过程中产生的针对病毒后遗症的免疫反应，对水平传播的病毒粒子再次感染的保护作用不完全。众所周知，具有先前免疫力的妇女可以再次感染HCMV的抗原变异体，然后将其传播给胎儿。这一建议假设存在一个关键的联系，将病毒与宿主的相互作用、持久性和再感染联系在一起，容易受到疫苗介导的干预。具体地说，HCMV通过HCMV编码的白介素10蛋白(CmvIL10)的功能调节宿主免疫，使病毒重新激活和病毒粒子系统传播到再感染部位以外。假设：HCMV感染者暴露后cmvIL10的中和抗体(NAB)滴度的增加将(1)减少HCMV的脱落，(2)增加对再次感染的抵抗力。这项研究扩展了我们关于cmvIL10的体外功能和恒河猴巨细胞病毒(RhCMV)编码的IL-10(RhcmvIL10)对宿主免疫的体内调节作用的工作。目的1)用功能失活的重组人巨细胞病毒白细胞介素10免疫感染的猴，定量检测其分泌的重组人巨细胞病毒。目的2)比较不同NAB滴度的重组人巨细胞病毒免疫猕猴对重组人巨细胞病毒IL10的再感染情况。目的3)rhcmvIL-10诱导的宿主免疫改变的特征。 公共卫生相关性：这项建议的目标是通过扩大巨细胞病毒疫苗的目标人群，使其不仅仅限于没有预先获得巨细胞病毒免疫的妇女，从而改变预防先天性巨细胞病毒感染的范式。以那些传播病毒的人为目标来减少脱落，也以那些具有先天免疫力的妇女为目标来减少再感染，这将大大降低先天性感染率。

DESCRIPTION (provided by applicant): Immune responses to human cytomegalovirus (HCMV) infection in immunocompetent hosts present paradoxes with potentially devastating ramifications for those without immune competency. The long quest for a protective HCMV vaccine has been impeded by multiple factors, including two contradictions about HCMV natural history. (1) HCMV is considered to be a virus with low disease potential in immunocompetent hosts. Yet, the virus efficiently maintains a lifelong persistence in the presence of those immune responses that limit clinical outcomes. A hallmark of HCMV persistence is the reactivation of latent viral genomes and shedding of virus. Horizontal transmission represents an infectious threat to those at-risk for primary HCMV infection, particularly fetuses borne by mothers without prior HCMV immunity. Accumulating evidence highlights another ambiguity about HCMV immunity. (2) The immune responses to HCMV generated during primary and long-term infection, which protect against viral sequelae, are incompletely protective against reinfection with horizontally transmitted virions. It is well- established that women with prior immunity can be reinfected with antigenic variants of HCMV that can then be transmitted to their fetuses. This proposal hypothesizes that there is a key nexus linking virus-host interactions, persistence, and reinfection that is susceptible to vaccine- mediated intervention. Specifically, HCMV modulation of host immunity through the functionality of the HCMV-encoded interleukin-10 protein (cmvIL10), enables both viral reactivation and systemic spread of virions beyond sites of reinfection. HYPOTHESIS: post-exposure increases of neutralizing antibody (NAb) titers to cmvIL10 in HCMV-infected individuals will (1) reduce HCMV shedding and (2) increase resistance to reinfection. This study extends our work on the in vitro functionality of cmvIL10 and the in vivo modulation of host immunity by rhesus CMV (RhCMV)-encoded IL-10 (rhcmvIL10). Aim 1) Quantification of RhCMV shedding in RhCMV- infected monkeys following immunization with functionally inactive rhcmvIL10. Aim 2) Comparison of RhCMV reinfection in RhCMV-immune monkeys that differ in their NAb titers to rhcmvIL10. Aim 3) Characterization of rhcmvIL-10-induced alterations to host immunity. PUBLIC HEALTH RELEVANCE: The goal of this proposal is the shift the paradigm for the prevention of congenital HCMV infection by expanding the target population for an HCMV vaccine beyond just women without preconceptional HCMV immunity. Targeting those who shed virus to reduce shedding and also targeting those women with preconceptional immunity to reduce reinfection would greatly reduce the rate of congenital infection.