Virus Infections In The Eye

我们对病毒和寄生虫在眼睛微环境中复制时发生的各种病毒学和免疫病理过程的研究包括四个方面：(1)病毒诱导的视网膜退化过程；(2)病毒在人类疾病中的可能作用；(3)人类巨细胞病毒(CMV)感染的分子诊断和发病机制；(4)眼睛的疱疹病毒感染。我们已经建立了一个研究视网膜退行性疾病的模型系统-实验性冠状病毒视网膜病变(EcoR)。该病毒能够在存在轻度视网膜血管炎症的情况下引发急性感染。最初的视网膜损伤之后是感染性病毒的清除和进行性的视网膜变性。这是第一个显示病毒引起的变性、病毒持久性、对病毒引起的组织损伤的遗传易感性和病毒引发的自身免疫反应的视网膜模型。我们的目标是确定视网膜退行性疾病的病理生理机制，并确定与之相关的基因。在过去的一年里，我们继续评估非常早期的细胞因子和趋化因子谱，作为衡量冠状病毒感染的小鼠免疫反应强度的指标，这些小鼠具有视网膜变性易感性和视网膜变性抵抗背景。这些研究发现，这两个小鼠品系产生的早期免疫反应有明显的差异。这些差异体现在干扰素-伽马和由干扰素-伽马引发的两种趋化因子CXCL9和CXCL10的产生上。在第2天和第3天，BALB/c小鼠的血清中有较高水平的干扰素-γ、CXCL9和CXCL10。与此同时，在CD-1小鼠的血清中检测到的这些分子的水平要低得多。此外，实时荧光定量聚合酶链式反应分析证实，CXCL9和CXCL10基因在Babl/c小鼠的视网膜中的表达显著高于CD-1小鼠。这些研究确定了可能的机制，使BALB/c小鼠具有强大的免疫反应，可能触发自身免疫成分。CXCL9和CXCL10是一种强大的趋化因子，它们与活化的T细胞和NK细胞上的CXCR3相互作用。这些T细胞参与对视网膜内感染和自身靶点的免疫反应。 角膜疱疹感染引起强烈的炎症反应，最终导致威胁视力的间质角膜炎，这是潜伏病毒频繁重新激活的后遗症。疱疹间质角膜炎(HSK)的病因学被认为是一种异常的TH1细胞因子介导的免疫病理。最近，我们发现HSV-DNA和HSV-Ig G IC在眼部微环境中的持续存在可能有助于HSK的血管生成和炎症反应，细胞因子和TLR可能是干预的潜在靶点。在过去的一年里，我们利用聚合酶链式反应(PCR)确定了HHV-6和/或其他人类疱疹病毒与角膜炎症的相关性。我们对22例角膜炎症患者进行了评估。其中，HHV-6阳性14例，HSV-1阳性9例。仅5例疱疹病毒DNA阴性。这些结果表明，大多数角膜炎症与疱疹病毒有关，HHV-6与疾病的相关性比其他疱疹病毒更常见。而在47例正常人泪液标本中未检出HHV-6DNA。当HSV-1引发角膜炎症时，渗入的T细胞或巨噬细胞可能携带HHV-6。HHV-6诱导的免疫抑制作用可能进一步促进HSV-1的复制。我们还在12名患者中的5名患者的涂片样本中观察到HHV-6，但没有观察到HSV-1DNA。后者的数据表明，HHV-6本身可能是角膜炎症的另一种病原体。HHV-6是旁观者还是真正的病原体，这一问题还有待进一步澄清。

Our studies of various virologic and immunopathologic processes that occur when viruses and parasites replicate in the ocular microenvironment comprise four areas: (1) virus induced retinal degenerative processes; (2) the possible roles of viruses in human diseases; (3) molecular diagnosis and pathogenesis of cytomegalovirus (CMV) infections in man; and (4) herpesvirus infections of the eye. We have established a model system for studying retinal degenerative diseases, experimental coronavirus retinopathy (ECOR). The virus is capable of inducing an acute infection in the presence of mild retinal vascular inflammation. Initial retinal damage is followed by clearance of infectious virus and progressive retinal degeneration. This is the first retinal model to demonstrate a virus induced degeneration, viral persistence, a genetic predisposition to virus induced tissue damage and a virus triggered autoimmune response. Our goal is to determine the pathophysiological mechanisms and to identify genes involved in the retinal degenerative disease. During the past year we have continued to evaluated very early cytokine and chemokine profiles as a measure of intensity of immune reactivity in coronavirus infected mice with a retinal degeneration susceptible and a retinal degeneration resistant background. These studies identified a distinct difference in the early immune response that is generated by the two mouse strains. These differences are noted in the production of IFN-gamma and the two chemokines triggered by IFN-gamma, CXCL9 and CXCL10. At day 2 and 3 PI, BALB/c mice have high levels of IFN-gamma, CXCL9 and CXCL10 in their sera. At the same time, significantly lower levels of these molecules are detected in sera from CD-1 mice. Moreover, real time PCR analysis of retinas identified that CXCL9 and CXCL10 gene expression is significantly greater in retinas from BABL/c mice in comparison to CD-1 mice. These studies identify possible mechanisms that allow the BALB/c mouse to have a robust immune response that could trigger an autoimmune component. CXCL9 and CXCL10 are potent chemokines that interact with CXCR3 present on activated T cells and NK cells.These T cells participate in immune reactivity against infected and self targets within the retina. Corneal herpes infection elicits a robust inflammatory response and eventually leads to a vision-threatening stromal keratitis as a sequela of frequent reactivation of latent virus. The aetiology of herpetic stromal keratitis (HSK) is thought to be an aberrant TH1 cytokine mediated immunopathology. Recently, we identified that the continued presence of HSV-DNA and HSV-IgG IC within the ocular microenvironment may contribute to angiogenesis and inflammation observed in HSK, and cytokines and TLRs may be potential targets for intervention. During the past year we have determined the association of HHV-6 and/or other human herpesviruses in corneal inflammation using polymerase chain reaction (PCR). We evaluated 22 patients with corneal inflammation. Among them, HHV-6 was positive in 14 out of 22 patients, and HSV-1 was found in 9 of those patients. Only 5 patients were negative for herpesvirus DNA. These results indicated that the majority of the corneal inflammation was related to herpesviruses, and that the association of HHV-6 with disease was more frequent that with other herpesviruses. In contrast, HHV-6 DNA was not detected in 47 tear samples obtained from normal individuals. When HSV-1 triggers corneal inflammation, infiltrated T cells or macrophages may carry HHV-6. The immune suppressive activities induced by HHV-6 may further facilitate HSV-1 replication. We also observed HHV-6 but not HSV-1 DNA in smear samples from 5 of 12 patients. These latter data indicate that HHV-6 may be another causative agent by itself in corneal inflammation. The issue of whether HHV-6 is a bystander or true pathological agent remains to be further elucidated.