Molecular Recognition of Complex Glycans by Antibodies and Dendritic Cell C-type Lectins

布鲁氏菌病会导致牛的自然流产和与受感染动物接触的人的严重虚弱不适。在加拿大，在野生动物种群(野牛、麋鹿、驯鹿)中有布鲁氏菌的储存库，疾病可以从那里传播到家养牛群或人类。由于对养牛业的经济影响以及人类潜在的疾病，美国已花费35亿美元试图为其牛群接种疫苗，并对追踪牛群中的潜在病例保持警惕。目前的动物疫苗是布鲁氏菌的减毒株，但这造成了一种不切实际的情况。布鲁氏菌病在动物和人类中的推定诊断依赖于对布鲁氏菌细胞表面多糖抗原抗体的检测，但由于接种疫苗的动物表现出与感染布鲁氏菌强毒株的牛相似的抗体反应，因此令人困惑。多糖包被细菌和它们的抗体以防止感染，正如前面提到的布鲁氏菌，抗体的检测用于诊断感染。我们对合成碳水化合物的研究使我们能够理解多种抗体识别细菌抗原的分子基础。我们将利用这一基础来指导设计和合成布鲁氏菌A和M多糖抗原的活性亚片段，目的是创造对兽医重要的精确诊断抗原。这项研究的第二个目标是找到更简单、更有效的方法将抗原输送到树突状细胞，树突状细胞处理外来抗原并确保有效的免疫反应。树突状细胞上的C型凝集素是结合碳水化合物的蛋白质。我们将合成寡糖并以多个副本展示它们，使它们与C型凝集素Dectin-1紧密结合，从而刺激这一途径的效应器，导致抗原摄取和强大的免疫反应。拟议的基础化学发现研究是必要的，并支持我们努力了解细胞控制对碳水化合物抗原的免疫反应。

Brucellosis causes spontaneous abortion in cattle and a serious debilitating malaise in humans who come in contact with infected animals. In Canada there are repositories of Brucella in wild animal populations (bison, elk, caribou) from which the disease can be spread to domestic cattle herds or humans. Because of the economic effect on the cattle business and the disease potential in humans, the US has spent $3.5 billion trying to vaccinate its cattle herds and is vigilant in tracking potential cases within herds. The current animal vaccine is an attenuated strain of Brucella but this creates an impractical situation. Presumptive diagnosis of brucellosis in animals and humans depends on detection of antibodies to Brucella cell surface polysaccharide antigens but is confounded because vaccinated animals manifest an antibody response similar to that observed in cattle infected by a virulent strain of Brucella. Polysaccharides coat bacteria and antibodies to them protect against infection, and as mentioned for Brucella, detection of antibodies is used for diagnosis of infection. Our synthetic carbohydrate research has enabled us to understand the molecular basis for bacterial antigen recognition by a wide range of antibodies. We will use this foundation to guide the design and synthesis of active sub-fragments of Brucella A and M polysaccharide antigens, with the objective of creating precise diagnostic antigens important to veterinary medicine.A second objective of this research is to discover simpler and more effective ways to deliver antigens to dendritic cells, the cells that process foreign antigens and ensure an effective immune response. C-type lectins on dendritic cells are proteins that bind carbohydrates. We will synthesize oligosaccharides and display them in multiple copies so that they bind the C-type lectin, Dectin-1 sufficiently tightly to stimulate effectors of this pathway leading to antigen uptake and a robust immune response. The proposed fundamental chemistry discovery research is necessary and underpins our efforts to understand cellular control of the immune response to carbohydrate antigens.