FCGRIIIA and IGHG (GM) Genotypes and Immunity to HSV1 in Herpes Stromal Keratitis

由1型单纯疱疹病毒(HSV1)引起的疱疹间质角膜炎(HSK)是引起 美国的传染性失明。HSV1是一种常见的病毒，并不是所有感染HSV1的人都是 同样有可能发生HSK，提示宿主遗传因素参与了HSK的发展 无序。免疫球蛋白GM(g标记)同种异型，由IGHG1、IGHG2和IGHG3基因编码 14号染色体，是参与HSK发病的优秀候选基因，因为它们 调整HSV1免疫逃避策略。HSV1编码的诱骗FCG受体(FcgR，GE-g1) 糖蛋白复合体，病毒用来阻断宿主Fc介导的效应器功能，如抗体- 依赖细胞细胞毒性(ADCC)，与表达不同GM同种异型的抗体结合不同。 表达GM1、17等位基因的IgG1蛋白与病毒诱骗FcgR的亲和力显著高于 表达替代的GM1-，3等位基因。此外，GM基因与细胞FcgR基因上位， 与HSV1感染细胞ADCC的大小有关。基于这些观察结果，我们假设 GM和FcgRIIa基因是HSK的危险因素，其潜在机制包括它们的贡献 对HSV1蛋白的体液免疫和对HSV1感染的角膜上皮细胞的ADCC免疫。这个 以下具体目标将检验我们的假设：目的1：确定GM和FcgRIIIa基因是否为危险因素 为HSK准备的。HSK患者和对照组的DNA将被表征为几个GM和FcgRIIa等位基因 评估这些基因是否单独或上位是HSK的危险因素；目标2：确定 抗体对特定HSV1蛋白的反应性大小与GM和FcgRIIIa等位基因有关。 我们将定量检测猪血清中HSV1-gD(一种主要糖蛋白和候选疫苗)的抗体反应。 HSK患者和对照组，并确定抗体反应性的大小是否与GM相关 和FcgRIIa基因；目标3：确定Fc(GM)和细胞FcgR等位基因的特定等位基因组合 影响ADCC水平。免疫球蛋白抗体介导的ADCC在FcγR(表达于 效应细胞)与抗病毒抗体的Fc区结合。由此推断，Fc、γR和Fc的遗传变异， 几乎所有的GM等位基因都表达了，这可能是ADCC大小差异的原因。 以HSV-gD转染的角膜上皮细胞为靶细胞，亲和力纯化，异型异型抗HSV1- HSK患者的gD抗体，以及NK细胞(表达不同的FcgRIIIa等位基因)作为效应器，我们将 确定ADCC水平是否与FCG(GM)和FcgRIIIa的特定组合有关 等位基因。这一研究结果将加深我们对Fc介导的效应器的遗传学的理解 HSV1-HSK关联的潜在机制。这将为病毒设计的改进提供信息 可产生保护性抗体Fc效应反应的免疫原以及在Fc的设计中 治疗这种疾病的治疗性单抗的区域。

Herpes stromal keratitis (HSK), induced by herpes simplex virus type 1 (HSV1), is the most common cause of infectious blindness in the United States. HSV1 is a common virus and not all HSV1-infected people are equally likely to develop HSK, suggesting the involvement of host genetic factors in the development of this disorder. Immunoglobulin GM (g marker) allotypes, encoded by IGHG1, IGHG2, and IGHG3 genes on chromosome 14, are excellent candidate genes for involvement in HSK etiopathogenesis because they modulate HSV1 immunoevasion strategies. The HSV1-encoded decoy Fcg receptor (FcgR), the gE-gl glycoprotein complex, which the virus uses to thwart host’s Fc-mediated effector functions, such as antibody- dependent cellular cytotoxicity (ADCC), binds differentially to IgG antibodies expressing different GM allotypes. IgG1 proteins expressing GM 1,17 alleles have strikingly higher affinity for the viral decoy FcgR than those expressing the alternative GM 1-,3 alleles. In addition, GM genes, epistatically with cellular FcgR genes, contribute to the magnitude of ADCC of HSV1-infected cells. Based on these observations, we hypothesize that GM and FcgRIIIa genes are risk factors for HSK, and the underlying mechanisms include their contribution to the humoral immunity to HSV1 proteins and to the ADCC of HSV1-infected corneal epithelial cells. The following specific aims will test our hypothesis: Aim1: Determine if GM and FcgRIIIa genotypes are risk factors for HSK. DNA from HSK patients and controls will be characterized for several GM and FcgRIIIa alleles to assess whether these genes—individually or epistatically—are risk factors for HSK; Aim 2: Determine if the magnitude of antibody responsiveness to particular HSV1 proteins is associated with GM and FcgRIIIa alleles. We will quantitate antibody responses to HSV1-gD (a major glycoprotein and vaccine candidate) in the sera of HSK patients and controls and determine if the magnitude of antibody responsiveness is associated with GM and FcgRIIIa genotypes; Aim 3: Determine if particular allelic combinations of Fc (GM) and cellular FcgR alleles influence the level of ADCC. IgG antibody mediated ADCC is triggered upon ligation of FcγR (expressed on effector cells) to the Fc region of anti-viral IgG antibodies. It follows that genetic variation in FcγR and Fc, where virtually all GM alleles are expressed, could contribute to the differences in the magnitude of ADCC. Using HSV-gD-transfected corneal epithelial cells as target, affinity purified, allotypically disparate anti-HSV1- gD antibodies from HSK patients, and NK cells (expressing different FcgRIIIa alleles) as effectors, we will determine whether the level of ADCC is associated with particular combinations of Fcg (GM) and FcgRIIIa alleles. The results of this investigation will enhance our understanding of the genetics of Fc-mediated effector mechanisms underlying the HSV1-HSK association. This will inform improvements in the design of viral immunogens that may generate protective antibody Fc effector responses as well as in the design of the Fc region of therapeutic monoclonal antibodies for the treatment of this disorder.