Role of a Galactose-Binding Insect Lectin in Defense Response (s) Against Invading Pathogens

本研究的目的是进一步阐明昆虫凝集素在抵抗病原体的防御反应中的作用。甜菜夜蛾（Spodoptera exigua）的半乳糖结合凝集素将用于这些研究。这种凝集素很容易从幼虫的血淋巴中提取，并已被证明对具有表面半乳糖残基的潜在真菌病原体具有调理作用。将制备针对该凝集素的单克隆抗体，以便在昆虫组织中定位该分子。光学和电子显微镜将用于这些研究，并在实验中使用直接探针来定位选定微生物细胞壁上的凝集素受体。凝集素的抗菌特性将被评估，以及被宿主粒细胞吞噬的调理微生物的命运。摄取细胞的活力将通过传统的电镀方法和亚甲基蓝染色测定来确定。最后，将检查凝集素受体在免疫活性和免疫抑制粒细胞上的分布。凝集素是一种特殊的糖结合蛋白，已在许多动物的体液中检测到。尽管人们对这些分子的功能知之甚少，但根据各种粗略的证据，人们已经提出，在昆虫中，它们可能通过包裹微生物并促进昆虫血液中的清除细胞清除细菌或真菌，从而起到防御细菌或真菌的作用。这项研究将更彻底地检验这一假设，并应阐明凝集素在昆虫防御入侵微生物中的作用。

The purpose of the proposed research is further to elucidate the role of insect lectins in the defense response against pathogens. A galactose binding lectin from Spodoptera exigua (beet armyworm) will be used in these studies. This lectin is easily extracted from larval hemolymph and has been shown to opsonize potential fungal pathogens which have surface galactose residues. Monoclonal antibodies against the lectin will be prepared in order to localize the molecule in insect tissues. Light and electron microscopy will be used for these studies and in experiments using direct probes to localize lectin receptors on cell walls of selected microorganisms. Antimicrobial properties of the lectin will be assessed as well as the fate of opsonized microbes phagocytosed by host granulocytes. Viability of ingested cells will be determined by conventional plating methods and by use of a methylene blue staining assay. Finally, the distribution of lectin receptors on both immunocompetent and immunosuppressed granulocytes will be examined. Lectins are specific sugar-binding proteins that have been detected in the body fluids of numerous animal species. Although little is known about the function of these molecules, it has been suggested on the basis of a variety of sketchy evidence that in insects they may function in defense against bacteria or fungi by coating the microorganisms and promoting their removal by scavenger cells in the insect's blood. This research will examine this hypothesis more thoroughly and should elucidate the role(s) of lectins in an insect's defense against invading microorganisms.