STRUCTURE OF THE HUMAN MILK INHIBITOR OF HIV BINDING

我们发现母乳可以抑制人的gp120蛋白的结合。 免疫缺陷病毒(HIV)包膜糖蛋白，对人类 宿主细胞受体；这种结合被认为是必不可少的第一个 介入艾滋病毒的传染性。在牛体内未发现抑制活性。 牛奶也不在人类血清中，但其他物种的牛奶展示了 可变活动。我们建议纯化HIV抑制因子(S)。 并准确地定义其生化、免疫学和 生物物理特性。初步的生化和免疫学 研究表明，这种天然状态的抑制物质是一种 大分子大于250kD，等电点为9.3-9.6， 可能是硫酸盐和糖基化的，但既不含甘露糖，也不含甘露糖 唾液酸。抑制剂的比活性至少是一个数量级 比葡聚糖硫酸盐更大的量级，意味着高度特异 和强大的机制。活性因子与牛奶有关 糖蛋白、粘蛋白或糖胺聚糖等大分子。我们 最近发现从人乳脂肪小球中分离出一种粘蛋白复合体 膜阻断了CD4的结合。抑制活性将通过以下方式确定 样本抑制HIV包膜结合的能力 CD4糖蛋白gp120(或其单抗替代物OKT4A)， 并抑制HIV在培养细胞中的复制。结构性的 与之相关的活性大分子的特征 保护性活动将被确定。我们将开发一种固相 用于检测和测量活性因子的分析方法，以便 寻找含有抑制物的替代材料来源 分子(S)。从而鉴定了一类新的化合物 抗HIV治疗潜力是该项目的主要目标。这个 研究还将为风险评估提供信息。 围产期HIV感染的相关因素。 艾滋病毒的围产期传播正在迅速成为新的 艾滋病病例。儿童艾滋病通常会导致精神上的失败 智障和死亡。尽管已知的母乳中含有 免疫球蛋白和非免疫球蛋白因子抑制 微生物病原体，也是已知的垂直致病因子 某些病毒的传播。母乳被认为是一种 艾滋病毒传播者，引发了人们对母乳喂养的担忧 艾滋病毒发病率高的人群；然而，大多数流行病学 有证据表明，与母乳喂养相关的发病率没有增加 艾滋病毒感染母亲人群的垂直传播。因此， 在母乳中定义一种特定的艾滋病毒传播抑制剂可能会 提供对制订公共卫生政策有用的信息，在 除了它的潜在效用之外，它还为开发 新型治疗或预防药物家族，具有低潜在的 寄主毒性。

We have found that human milk inhibits the binding of gp120, the human immunodeficiency virus (HIV) envelope glycoprotein, to CD4, the human host cell receptor; this binding is thought to be an essential first step in HIV infectivity. The inhibitory activity was not found in bovine milk nor in human sera, but the milks of some other species exhibit variable activity. We propose to purify the HIV inhibitory factor(s) in human milk and to define precisely its biochemical, immunological, and biophysical characteristics. Preliminary biochemical and immunological studies indicate that this inhibitory material in its native state is a macromolecular larger than 250 Kd with an isoelectric point of 9.3-9.6, possibly sulfated and glycosylated, but containing neither mannose nor sialic acid. The specific activity of the inhibitor is at least an order of magnitude greater than dextran sulfate, implying a highly specific and potent mechanism. The active factor is associated with milk macromolecules such as glycoproteins, mucins or glycosaminoglycans. We recently found that a mucin complex isolated from human milk fat globule membrane blocks CD4 binding. Inhibitory activity will be determined by the ability of a sample to inhibit binding of the HIV envelope glycoprotein gp120 (or its monoclonal antibody surrogate, OKT4A) to CD4, and to inhibit the replication of HIV in cultured cells. The structural features of the active macromolecules that are associated with the protective activity will be determined. We will develop a solid phase assay for detection and measurement of the active factor in order to seek alternate sources of materials containing the inhibitory molecule(s). Thus the identification of a new class of compounds with anti-HIV therapeutic potential is the major goal of this project. The studies will also provide information for the assessment of the risk factors associated with perinatal HIV infection. Perinatal transmission of HIV is rapidly becoming a major source of new AIDS cases. Pediatric AIDS usually results in failure to thrive, mental retardation, and death. Although human milk is known to contain immunoglobulin and non-immunoglobulin factors that inhibit several microbial pathogens, it is also known to act as the agent of vertical transmission for certain viruses. Breast milk has been suggested as an agent of HIV transmission, raising concerns regarding breast feeding in populations with high incidence of HIV; however, most epidemiologic evidence indicates no breast-feeding-related increase in the rate of vertical transmission by populations of HIV infected mothers. Thus, defining a specific inhibitor of HIV transmission in human milk might contribute information useful in formulating public health policy, in addition to its potential utility for providing a basis for developing a novel family of therapeutic or prophylactic agents with low potential of host toxicity.