Lectin-Carbohydrate Interactions in the Host-Parasite System

描述(申请人提供)：寄生虫是一些昆虫传播的传染病的病原体，如疟疾和丝虫病。昆虫对寄生虫的感染有细胞免疫和体液免疫两种反应。然而，寄生虫已经发展出逃避或抑制其媒介的免疫反应的策略。昆虫必须首先识别病原体，然后才能产生免疫反应，而对非自身感染性病原体的识别是由模式识别受体(PRRs)介导的。我们对昆虫中作为PRR的蛋白质有一些了解，这些蛋白质可以刺激对细菌或真菌感染的免疫反应。然而，昆虫免疫系统如何识别真核寄生虫，以及这些寄生虫如何逃避宿主免疫系统，人们知之甚少。我们认为寄生虫表面的分子特征存在差异，这决定了宿主蛋白与寄生虫的选择性结合和寄生虫的命运。C型凝集素是一个蛋白质家族，在先天免疫中起PRRs的作用。我们已经从烟草角虫Manduca sexta中鉴定出一组C型凝集素(免疫凝集素)，它们作为PRRs刺激免疫反应。免疫凝集素-2(IML-2)直接与线虫、线虫和马来丝虫结合，IML-2与线虫结合刺激线虫黑化。然而，蚊子的C型凝集素还没有得到很好的表征，特别是在生化功能方面。因此，我们将使用两个系统，即六线虫和蚊虫信天翁-丝虫线虫，研究IML-2和ArMiceres C型凝集素与微丝虫的相互作用，并研究IML-2和ArMiceres凝集素在微丝虫黑化包裹中的作用。这两个特定的目的是：1)研究昆虫C型凝集素原型Manduca imulectin-2与线虫(B.marayi、B.paangi、D.immitis和Celegans)的分子相互作用，作为了解潜在的凝集素-寄生虫相互作用的指南，这些相互作用影响模式识别和先天免疫反应的结果。2)研究筛选出的9种Armieres C型凝集素与微丝虫(马来丝虫、帕汉氏丝虫和钩端螺旋体)的配体结合特异性和亲和力，并研究这些凝集素在Ar中对微丝虫黑化包埋的作用。信天翁。鉴定线虫和马来线虫表面蛋白或表面多糖可被Manduca imulectin-2或Armieres C型凝集素识别。与公共卫生相关的寄生虫是一些昆虫传播的传染病的病原体，如疟疾和丝虫病。昆虫对寄生虫的感染有细胞免疫和体液免疫两种反应。然而，昆虫必须首先识别病原体，然后才能产生免疫反应，而对非自身感染性病原体的识别是由模式识别受体(PRRs)介导的。我们对昆虫中作为PRR的蛋白质有一些了解，这些蛋白质可以刺激对细菌或真菌感染的免疫反应。然而，人们对昆虫免疫系统如何识别非真菌真核寄生虫知之甚少：这些生物上与病原体相关的分子模式是什么，PRR与它们结合在一起的是什么？C型(钙依赖)凝集素是一个蛋白质家族，在脊椎动物和无脊椎动物的天然免疫系统中具有PRR的功能。本项目旨在研究寄主蛋白与寄生虫的选择性结合如何通过两个系统来决定寄生虫的命运，这两个系统分别是烟草角虫六线虫和蚊虫亚信天翁-丝虫线虫。

DESCRIPTION (provided by applicant): Parasites are causative agents of some insect-borne infectious diseases such as malaria and filariasis. Insects respond to infection by parasites with both cellular and humoral immune responses. However, parasites have developed strategies to evade or suppress immune responses of their vectors. Insects must first recognize pathogens before they can mount an immune response, and recognition of nonself infective agents is mediated by pattern recognition receptors (PRRs). We have some understanding of the proteins that serve as PRRs in insects to stimulate immune responses to bacterial or fungal infection. However, very little is known about how insect immune systems recognize eukaryotic parasites and how these parasites evade the host immune system. We propose that parasites have variations in the molecular character of their surface, which determine selective binding of host proteins to parasites and the fate of parasites. The C-type lectins are a family of proteins with functions as PRRs in innate immunity. We have identified a group of C-type lectins (immulectins) from the tobacco hornworm Manduca sexta, which function as PRRs to stimulate immune responses. Immulectin-2 (IML-2) directly binds to nematodes Caenorhabditis elegans and Brugia malayi, and binding of IML-2 to C. elegans stimulates melanization of the worms. However, C-type lectins from mosquitoes have not been well characterized, particularly with regard to biochemical functions. Thus, we will use two systems, M. sexta - nematodes and the mosquito Armigeres subalbatus - filarial nematodes, to study interactions of IML-2 and Armigeres C-type lectins with microfilariae, and to study the roles of IML-2 and Armigeres lectins in melanotic encapsulation of microfilariae. The two specific aims are: 1) Investigate molecular interaction of an insect prototype C-type lectin, Manduca immulectin-2, with nematodes (B. malayi, B. pahangi, D. immitis, and C. elegans) as a guide to understanding potential lectin-parasite interactions that influence the outcome of pattern recognition and innate immune responses. 2) Investigate the ligand-binding specificity and affinity of nine selected Armigeres C-type lectins for microfilariae (B. malayi, B. pahangi, and D. immitis), and study functions of these lectins in melanotic encapsulation of microfilariae in Ar. subalbatus. Identify surface proteins or surface polysaccharides of C. elegans and B. malayi that can be recognized by Manduca immulectin-2 or Armigeres C-type lectins. PUBLIC HEALTH RELEVANCE Parasites are causative agents of some insect-borne infectious diseases such as malaria and filariasis. Insects respond to infection by parasites with both cellular and humoral immune responses. However, insects must first recognize pathogens before they can mount an immune response, and recognition of nonself infective agents is mediated by pattern recognition receptors (PRRs). We have some understanding of the proteins that serve as PRRs in insects to stimulate immune responses to bacterial or fungal infection. However, very little is known about how insect immune systems recognize non-fungal eukaryotic parasites: what are the pathogen-associated molecular patterns on such organisms and what PRRs bind to them? The C-type (calcium-dependent) lectins are a family of proteins with functions as PRRs in innate immune systems of vertebrates and invertebrates. This project is to investigate how selective binding of host proteins to parasites determines the fate of parasites using two systems, the tobacco hornworm Manduca sexta - nematodes and the mosquito Armigeres subalbatus - filarial nematodes.