Oligosaccharide moieties of human milk glycans that inhibit pathogens

描述（由申请方提供）：目前有强有力的数据支持我们的早期假设，即母乳喂养婴儿肠道疾病的发生率降低部分是由于母乳聚糖的保护。聚糖，包括糖蛋白、糖脂、粘蛋白和糖胺聚糖，含有与蛋白质、脂质和其他分子主链连接的复杂寡糖结构。这些复杂的碳水化合物部分由乳腺中的许多糖基转移酶合成;与细胞表面糖缀合物病原体受体具有同源性的那些聚糖可以抑制病原体结合，从而保护哺乳期婴儿。婴儿轮状病毒和HIV感染主要通过口服接种引入，我们发现这些致病病毒在体外被特定的高分子量人乳聚糖强烈抑制。人乳糖胺聚糖的一个子集、硫酸软骨素和人乳硫酸化鞘糖脂部分的一种组分各自在固相测定和人白细胞中强烈抑制HIV。人乳糖蛋白，乳粘附素（46 kDa），强烈抑制MA 104细胞的轮状病毒感染，该分子占人乳体外抗轮状病毒的所有抑制活性。该提案的重点是使用最近可用的最先进的仪器分析技术来表征这些活性抗病毒聚糖，这些技术可以提供对复杂聚糖部分分子结构的详细了解。将研究分子机制，包括通过整个分子抑制病原体的多个菌株。随后将进行研究，以确定活性分子的最小活性部分，并确认其抑制病原体的机制。这些研究旨在通过乳酸克鲁维酵母（人类饮食中许多乳制品中天然存在的酵母）的基因工程合成活性部分，并已证明其适合合成其他活性人乳聚糖。可抑制HIV或轮状病毒的适合口服的合成人乳聚糖的可用性可能对这些对公共卫生的重要威胁产生重大影响。

DESCRIPTION (provided by applicant): There is now strong data supporting our early hypothesis that the reduced incidence of enteric diseases in breastfeeding infants is due, in part, to protection by human milk glycans. Glycans, including glycoproteins, glycolipids, mucins, and glycosaminoglycans, contain complex oligosaccharide structures attached to proteins, lipids, and other molecular backbones. These complex carbohydrate moieties are synthesized by the many glycosyltransferases in the mammary gland; those glycans with homology to cell surface glycoconjugate pathogen receptors may inhibit pathogen binding, thereby protecting the nursing infant. Rotavirus and HIV infections in infants are introduced primarily through oral inoculation, and we discovered that these pathogenic viruses are strongly inhibited by specific high molecular weight human milk glycans in vitro. A subset of the human milk glycosaminoglycans, a chondroitin sulfate, and a component of the human milk sulfated glycosphingolipid fraction each strongly inhibit HIV in solid phase assays and in human leukocytes. A human milk glycoprotein, lactadherin (46 kDa), strongly inhibits rotavirus infection of MA 104 cells, and this molecule accounts for all of the inhibitory activity of human milk against rotaviruses in vitro. This proposal focuses on characterizing these actively antiviral glycans, using state-of-the-art instrumental analytical techniques that have recently become available and can provide detailed understanding of the molecular structure of complex glycan moieties. The molecular mechanisms will be studied to include the inhibition of multiple strains of the pathogens by the whole molecules. This will be followed by research to identify the smallest active moieties of the active molecules, and confirming their mechanism of pathogen inhibition. These studies are designed to culminate in a plan to synthesize the active moieties through genetic engineering of Kluyveromyces lactis, yeast occurring naturally in many dairy products of the human diet, and which has proved amenable to synthesis of other active human milk glycans. The availability of synthetic human milk glycans suitable for oral consumption that inhibit HIV or rotavirus could have large impact on these important threats to public health.