Killed But Metabolically Active Leishmania: a novel protozoan vaccine technology

描述(申请人提供)：虫媒原生动物利什曼原虫导致生活在发展中国家和前往发展中国家的数百万人死亡和发病。战争和经济全球化使更多的美国人受到这些感染。尽管世界各地的许多科学家做出了努力，但针对利什曼原虫和其他原生动物的免疫保护仍然是一个难以实现的目标，而且仍然没有被批准用于预防原生动物疾病的有效疫苗。几千年来，原生动物寄生虫进化了复杂的生命周期，促进了宿主免疫系统的传播和逃避。这些适应在许多情况下都得到了很好的描述，但到目前为止，在人类身上产生保护性免疫已被证明是一个不可逾越的挑战。使用灭活疫苗、减毒疫苗或亚单位疫苗进行了许多尝试，但均未成功。理想的疫苗将最大限度地提高免疫刺激和安全性，同时最大限度地减少毒性或对最广泛的接种者造成不慎疾病的能力。我们正在寻求一种创新的方法来解决这个问题，有可能影响到全世界数百万人。最近，我们已经产生了概念验证数据来支持一种全新的疫苗技术，该技术实现了这些目标，并可以应用于许多原生动物疾病。该策略利用了一种名为S-59的新型化学灭菌，当暴露在UVA辐射下时，这种灭菌会导致DNA交联。我们和其他人已经成功地利用这项技术开发了安全有效的重组细菌疫苗。最近，我们在内脏利什曼病(感染内脏器官的利什曼病)模型中证明，S-59/长波紫外线治疗利什曼原虫产生了一种具有代谢活性的灭活型生物体，能够保护啮齿动物免受感染。我们还证明了这一策略与新型Toll样受体激动剂的强大互补性，当仅将其应用于皮肤时，这些激动剂可以增强对感染病原体的免疫反应。在这项提案中，我们将扩大这些概念验证研究，并将它们扩展到皮肤利什曼病的啮齿动物模型，以确定这项技术对抗这些毁灭性寄生虫病的潜力。我们还将确定与该疫苗诱导的保护性免疫相关的基本免疫机制。这里概述的实验将提供进一步的概念证明，最终目标是开发针对利什曼病的新型预防和治疗性疫苗。这项技术如果成功，也可能适用于感染人类的其他寄生原虫，如疟疾、查加斯病(美国锥虫病)和睡病(非洲锥虫病)。这些研究可能导致针对具有复杂生命周期的其他细胞内生物的安全、全细胞疫苗，例如分枝杆菌疾病(结核病、麻风病和布鲁里溃疡)，在这些疾病中，抗生素耐药性是一个紧迫的全球威胁，疫苗可能提供最佳的长期解决方案。这种方法是创新的，但基于一个强大而简单的理由。如果这些疫苗取得成功，它们对人类的影响将是巨大的。此外，目前的研究旨在回答有关对寄生虫感染的免疫力的基本问题，这将有助于推进疫苗的发现，无论采用何种方法。与公共卫生相关：利什曼病是一种寄生虫感染，在生活在发展中国家和前往发展中国家旅行的数百万人中导致死亡和疾病。战争和经济全球化使更多的美国人受到这些感染。尽管世界各地的许多科学家做出了努力，但针对利什曼原虫和其他原生动物的疫苗保护仍然是一个难以实现的目标，而且仍然没有被批准用于治疗这些疾病的有效疫苗。我们正在寻求一种创新的方法来解决这个问题，开发一种全新的利什曼病疫苗技术，有可能影响全球数百万人。如果有效，这项技术未来可能会应用于其他传染病，如疟疾和结核病。

DESCRIPTION (provided by applicant): The insect-borne protozoa Leishmania causes death and morbidity in millions of humans living in and traveling to the developing world. Wars and economic globalization expose even more Americans to these infections. Despite the efforts of many scientists throughout the world, immunoprotection against Leishmania and other protozoa remains an elusive target, and there are still no effective vaccines approved for use against protozoan diseases. Over many millennia protozoan parasites have evolved complex life cycles that facilitate transmission and evasion of host immune systems. These adaptations have been well described in many cases, but generating protective immunity in humans has so far proven an insurmountable challenge. Many attempts have been made using killed, attenuated, or subunit vaccines without success. The ideal vaccine would maximize immune stimulation and safety while minimizing toxicity or the capacity to cause inadvertent disease for the widest range of vaccinees. We are pursuing an innovative approach to this problem with the potential to impact millions of people worldwide. Recently, we have generated proof-of-concept data to support a completely novel vaccine technology which accomplishes these goals and could be applied to many protozoan diseases. The strategy utilizes a novel type of chemical sterilization called S-59 that results in DNA crosslinks when exposed to UVA radiation. We and others have successfully used this technology to develop safe and effective recombinant bacterial vaccines already. Most recently, we have demonstrated that S-59/UVA treatment of Leishmania results in a Killed But Metabolically Active (KBMA) organism capable of protecting rodents from infection in a model of visceral leishmaniasis (Leishmania that infects the visceral organs). We have also demonstrated a powerful complementarity of this strategy with novel Toll-like receptor agonists that enhance immune responses against infectious agents when simply applied to the skin. In this proposal we will amplify these proof-of-concept studies and expand them to rodent models of cutaneous leishmaniasis to determine the potential of this technology against these devastating parasitic diseases. We will also determine the fundamental immune mechanisms associated with the protective immunity induced by this vaccine. The experiments outlined here will provide further proof of concept with the ultimate goal of developing novel prophylactic and therapeutic vaccines against leishmaniasis. This technology, if successful, may also apply to other parasitic protozoa infecting humans, such as malaria, Chagas' disease (American Trypanosomiasis), and Sleeping Sickness (African Trypanosomiasis). These studies could potentially lead to safe, whole cell vaccines against other intracellular organisms with complex life cycles, such as mycobacterial diseases (Tuberculosis, Leprosy, and Buruli ulcer) in which antibiotic resistance is an urgent global threat and vaccines may provide the best long term solution. The approach is innovative, but based on a strong, yet simple rationale. The impact of these vaccines on humanity would be enormous if they are successful. Additionally, the current studies are designed to answer fundamental questions about immunity to parasitic protozoan infections that will help advance vaccine discovery regardless of approach. PUBLIC HEALTH RELEVANCE: Leishmaniasis is a parasitic infection that causes death and illness in millions of humans living in and traveling to the developing world. Wars and economic globalization expose even more Americans to these infections. Despite the efforts of many scientists throughout the world, vaccine protection against Leishmania and other protozoa remains an elusive target, and there are still no effective vaccines approved for use against these diseases. We are pursuing an innovative approach to this problem by developing a completely novel vaccine technology against Leishmaniasis with the potential to impact millions of people worldwide. If effective, this technology could potentially be applied to other infectious agents such as malaria and tuberculosis in the future.