Eckmann Lars
Department of Medicine, University of California, San Diego, La Jolla, California 92093, USA.
Parasite Immunol. 2003 May;25(5):259-70. doi: 10.1046/j.1365-3024.2003.00634.x.
Giardia lamblia (syn. G. duodenalis or G. intestinalis), the causative agent of giardiasis, is one of the most common causes worldwide of intestinal infections in humans. Symptomatic infection is characterized by diarrhoea, epigastric pain, nausea, vomiting, and weight loss, yet many infections are asymptomatic. The protozoan, unicellular parasite resides in the lumen and attaches to the epithelium and overlying mucus layers but does not invade the mucosa and causes little or no mucosal inflammation. Giardiasis is normally transient, indicating the existence of effective host defences, although re-infections can occur, which may be related to differences in infecting parasites and/or incomplete immune protection. Mucosal defences against Giardia must act in the small intestinal lumen in the absence of induction by classical inflammatory mediators. Secretory IgA antibodies have a central role in anti-giardial defence. B cell-independent mechanisms also exist and can contribute to eradication of the parasite, although their identity and physiological importance are poorly understood currently. Possible candidates are nitric oxide, antimicrobial peptides such as Paneth cell alpha-defensins, and lactoferrin. Elucidation of the key anti-giardial effector mechanisms will be important for selecting the best adjuvants in the rational development of vaccination strategies against Giardia.
蓝氏贾第鞭毛虫（同义词：十二指肠贾第虫或肠道贾第虫）是贾第虫病的病原体，是全球人类肠道感染最常见的病因之一。有症状的感染表现为腹泻、上腹部疼痛、恶心、呕吐和体重减轻，但许多感染是无症状的。这种原生动物单细胞寄生虫存在于肠腔内，附着于上皮细胞和覆盖的黏液层，但不侵入黏膜，几乎不引起或不引起黏膜炎症。贾第虫病通常是短暂的，这表明存在有效的宿主防御机制，尽管可能会再次感染，这可能与感染的寄生虫差异和/或不完全的免疫保护有关。针对蓝氏贾第鞭毛虫的黏膜防御必须在小肠腔内发挥作用，且不受经典炎症介质的诱导。分泌型IgA抗体在抗贾第虫防御中起核心作用。不依赖B细胞的机制也存在，并且有助于根除寄生虫，尽管目前对它们的特性和生理重要性了解甚少。可能的候选物质包括一氧化氮、抗菌肽（如潘氏细胞α-防御素）和乳铁蛋白。阐明关键的抗贾第虫效应机制对于在合理制定抗蓝氏贾第鞭毛虫疫苗接种策略时选择最佳佐剂至关重要。
