Use of an Organophosphorus (OP) Hydrolase for Acute OP Poisoning

描述（由申请人提供）：有机磷农药中毒是许多发展中国家过早死亡的主要原因，仅在亚太地区每年就造成约20万人死亡。在北美和欧洲，情况大不相同。虽然农药中毒确实会发生，但OP中毒的主要风险来自对平民的恐怖袭击-通过在拥挤的空间释放OP神经毒气或可能将剧毒农药引入供水系统。OPs的急性毒性主要是由于对乙酰胆碱酯酶（AChE）的抑制作用。目前对OP中毒的治疗需要复苏和使用阿托品，然后给予肟来重新激活乙酰胆碱酯。然而，这些解毒剂的有效性有限，根据负责的OP，即使在重症监护支持下仍有10%至40%的患者死亡。尽管有机磷农药作为一个临床问题已经存在了50年，但自20世纪60年代以来就没有引入新的治疗方法。由于早期治疗干预可改善OP中毒后的预后，因此安全高效且可由中毒部位的急救人员给予的治疗应能显著改善预后。细菌和人类都能产生酶来水解OP化合物。重组细菌OP水解酶有潜力提供一种可负担得起的、广泛可用的、安全的治疗方法，对多种OPs快速有效。澳大利亚的昆虫学CSIRO开发了一种细菌酶，称为OpdA，对许多目前使用的OPs具有出色的体外催化活性。在概念验证研究中，我们已经证明OpdA在对硫磷和敌敌畏中毒的大鼠模型中单独使用或与2- PAM一起使用具有极好的疗效。然而，在对OP中毒的人类进行临床试验之前，还需要采取一些进一步的步骤，包括拟议的非人类灵长类动物研究。这笔拨款的目的是开发一种新的非人灵长类动物（NHP）对硫磷中毒模型，并在该NHP模型中测试OpdA的安全性和有效性。证明该酶对对硫磷安全有效，将为进一步开发人类使用提供必要的动力。我们的中心假设是OpdA是安全的，可以提高对硫磷中毒后的生存率。如果成功，这项研究有望通过减轻意外、故意或自杀中毒后农药的急性毒性作用来改善公众健康。这项研究也对神经毒气中毒后军人和平民的治疗有启示。

DESCRIPTION (provided by applicant): Organophosphorus (OP) pesticide poisoning is a leading cause of premature death in many developing countries, killing an estimated 200,000 people every year in the Asia-Pacific region alone. In North America and Europe, the situation is quite different. While pesticide poisoning does occur, the main risk of OP poisoning is from terrorist attacks on civilian populations - through the release of OP nerve gases in crowded spaces or perhaps introduction of highly toxic pesticides into water supplies. The acute toxicity of OPs is primarily due to inhibition of acetylcholinesterase (AChE). Current therapy for OP poisoning requires resuscitation and use of atropine, followed by administration of oximes to reactivate AChE. However, these antidotes have limited effectiveness and between 10 and 40% of patients, depending on the responsible OP, still die even with intensive care support. Although OP pesticides have been a clinical problem for 50 years, no new therapies have been introduced since the 1960s. Because early therapeutic interventions lead to improved outcomes after OP poisoning, a treatment that is safe and highly effective, and that can be given by first responders at the site of poisoning, should markedly improve outcome. Both bacteria and humans make enzymes that hydrolyze OP compounds. Recombinant bacterial OP hydrolases have the potential to provide an affordable, widely available, and safe treatment that is rapidly effective against a wide variety of OPs. CSIRO, Entomology, in Australia has developed a bacterial enzyme, called OpdA, with excellent in vitro catalytic activity against many currently used OPs. In proof-of-concept studies, we have shown that OpdA has excellent efficacy when used alone or with 2- PAM in rat models of parathion and dichlorvos poisoning. However, a number of further steps, including the proposed non-human primate studies, are required before clinical trials in humans with OP poisoning. The purposes of this grant are to develop a new non-human primate (NHP) model of parathion poisoning and to test the safety and efficacy of OpdA in this NHP model. Proof that the enzyme is safe and effective against parathion should provide the necessary impetus for further development for human use. Our central hypothesis is that OpdA is safe and improves survival after poisoning with parathion. If successful, the proposed research promises to improve public health by mitigating the acute toxic effects of pesticides after accidental, intentional, or suicidal poisoning. The research also has implications for the treatment of military personnel and civilians after nerve gas poisoning.