Naegleriafowleri(N.fowleri)通过上呼吸道感染会导致致命的CNS疾病,称为原发性阿米巴脑膜脑炎(PAM)。对禽N.fowleri感染的强烈的体内免疫应答是表征该疾病的免疫病理学的基础。然而,对这种病原体逃避免疫控制的原因知之甚少。感染发生在看似健康的个体中,缺乏有效的临床选择,因此死亡率接近98%。尚不清楚宿主因素如何或是否可能导致易感性或疾病恶化。然而,缺乏工具阻碍了体内免疫反应和疾病进展的机理研究。在这项研究中,我们已经产生了单克隆抗体,以N.fowleri表面抗原,并证明他们是很好的工具,用于研究体内免疫应答。我们还鉴定了一个单克隆,2B6,在体外具有有效的固有抗变形虫活性。这种抗体还能够在体内治疗上延长宿主的存活时间,具有更能够指导免疫效应物活性的同种型的重组抗体在治疗性给予时进一步提高了存活率。因此,我们报道了一种新的单克隆抗体的产生,该抗体可以增强有益的免疫功能。即使在疾病期间给予治疗。我们相信这为PAM中治疗性抗体治疗的潜力提供了证据。IMPORTANCENaegleriafowleri(N.fowleri)是一种自由生活的变形虫,在温暖的淡水中无处不在。虽然人类接触很常见,它很少导致发病机制。然而,当N.Fowleri进入上呼吸道时,特别是嗅觉粘膜,感染导致称为原发性阿米巴脑膜脑炎(PAM)的致命疾病。作为一个自由生活的变形虫,N.fowleri不需要哺乳动物宿主;事实上,它可以准确地描述为偶然的机会病原体。虽然大多数机会性感染发生在免疫功能低下的人类中,没有报道的免疫功能障碍与鸡传染性猪瘟感染相关。因此,N.Fowleri机会主义的基础尚不清楚,以及为什么有些人开发PAM而另一些人不开发PAM的原因根本没有得到很好的理解。有理由推测局部或急性免疫衰竭,甚至可能缺乏先前的适应性免疫,与疾病易感性有关。在哺乳动物宿主中仔细的免疫分析和体内对福氏N.fowleri免疫反应的表征是迫切需要的,以了解哪些宿主因素对防御至关重要。以及这些反应如何以导致致命感染的方式受损。为了确定基因和途径,提供抵抗体内鸡的感染,我们产生了表面反应性单克隆抗体(Abs),可在体内快速检测和定量变形虫。有趣的是,在人和动物的血清和唾液中很容易检测到N.fowleri结合抗体,这表明非致死性暴露会引起针对变形虫的体液免疫反应。然而,目前尚不清楚Abs如何在体内与Naegleria相互作用或有助于预防致死性感染.在这项研究中,我们已经产生并表征了单克隆抗体(Ab),克隆2B6,其识别存在于体外培养的家禽猪链球菌以及小鼠传代的家禽猪链球菌中的糖基化表面抗原。当克隆2B6与家禽N.Fowleri结合时,抑制阿米巴的运动性和摄食行为,导致强烈的生长抑制作用。用Ab全身和脑内处理的小鼠表现出延迟的疾病发作和延长的存活。此外,我们发现,通过抗体同种型增强免疫定向效应子活性可以进一步增强生存率,而没有明显的免疫致病性副作用.这些发现显示了抗体治疗作为目前在PAM中使用的那些的额外治疗剂的潜力。
Naegleria fowleri (N. fowleri) infection via the upper respiratory tract causes a fatal CNS disease known as primary amoebic meningoencephalitis (PAM). The robust in vivo immune response to N. fowleri infection underlies the immunopathology that characterizes the disease. However, little is known about why this pathogen evades immune control. Infections occur in seemingly healthy individuals and effective clinical options are lacking, thus a nearly 98% fatality rate. It is unclear how or if host factors may contribute to susceptibility or disease exacerbation, yet mechanistic studies of the in vivo immune response and disease progression are hampered by a lack of tools. In this study, we have generated monoclonal antibodies to N. fowleri surface antigens and shown them to be excellent tools for studying the in vivo immune response. We also identified one monoclonal, 2B6, with potent inherent anti-amoebastatic activity in vitro. This antibody is also able to therapeutically prolong host survival in vivo and furthermore, recombinant antibodies with an isotype more capable of directing immune effector activity further improved survival when given therapeutically. Thus, we report the generation of a novel monoclonal antibody to N. fowleri that can enhance beneficial immune functions, even when given therapeutically during disease. We believe this provides evidence for the potential of therapeutic antibody treatments in PAM.IMPORTANCENaegleria fowleri (N. fowleri) is a free-living amoeba that is found ubiquitously in warm freshwater. While human exposure is common, it rarely results in pathogenesis. However, when N. fowleri gains access to the upper airway, specifically the olfactory mucosa, infection leads to a lethal disease known as primary amoebic meningoencephalitis (PAM). As a free-living amoeba, N. fowleri does not need a mammalian host; indeed, it can be accurately described as an accidental opportunistic pathogen. While most opportunistic infections occur in humans who are immunocompromised, there are no reported immune dysfunctions associated with N. fowleri infection. Therefore, the basis for N. fowleri opportunism is not known, and the reasons why some humans develop PAM while others do not are simply not well understood. It is reasonable to speculate that local or acute immune failures, potentially even a lack of prior adaptive immunity, are related to disease susceptibility. Careful immune profiling and characterization of the in vivo immune response to N. fowleri in a mammalian host are desperately needed to understand which host factors are critical to defense, and how these responses might be compromised in a way that results in lethal infection. To identify genes and pathways that provide resistance against in vivo N. fowleri infection, we generated surface reactive monoclonal antibodies (Abs) that provide rapid amoeba detection and quantification in vivo. Interestingly, N. fowleri binding Abs have been readily detected in the serum and saliva of humans and animals suggesting that non-lethal exposure drives a humoral immune response against the amoeba. Yet, how Abs might interact with Naegleria in vivo or contribute to preventing lethal infection is not well understood. In this study, we have generated and characterized a monoclonal antibody (Ab), Clone 2B6, that recognizes a glycosylated surface antigen present in cultured in vitro N. fowleri as well as mouse passaged N. fowleri. When clone 2B6 binds to N. fowleri, it inhibits amoeba motility and feeding behavior, leading to strong growth inhibition. Mice treated systemically and intracerebrally with Ab displayed a delayed disease onset and prolonged survival. In addition, we found that enhancing immune-directed effector activity via antibody isotype could further enhance survival without obvious immunopathogenic side effects. These findings show the potential for antibody treatment as an additional therapeutic to those used currently in PAM.