Discovery of Novel Benzimidazole Resistance Mechanisms

项目概要： 寄生线虫给许多发展中国家带来了巨大的健康和经济负担， 感染了全球超过十亿人这些毁灭性的疾病造成的发病率和死亡率 大规模药物管理（MDA）计划部分减少了病原体，这些计划依赖于持续的 有限的驱虫药组合的有效性。苯并咪唑（BZ）化合物是一类广泛使用的化合物， 广谱驱虫药是这种有限的化学治疗武器库的不可或缺的组成部分。 BZ抗性的前景对线虫防治计划的未来成功构成严重威胁。 这些前景已经在兽医领域实现了密集使用BZ，预计 在人类医学中实现，增加了由扩展的MDA引起的选择。早期发现 线虫寄生虫种群中的抗性相关等位基因对于减缓驱虫药的目标是必不可少的。 耐药性和延长这类关键药物的寿命。基于对自由生活的线虫的研究 从三十年前的秀丽隐杆线虫开始，寄生线虫研究人员专注于一个BZ目标， 线虫特异性β-微管蛋白。尽管有这些知识，它仍然是一个完全的谜（1）是否有任何等位基因 引起抗性（即超越相关性），（2）对BZ中毒敏感的线虫组织， 以及（3）引起耐药性的药物-靶标相互作用。在捻转血矛线虫中， 经验证的敏感和耐药性样品，以及耐药性已发展超过 时间这些样本在任何人类寄生线虫种属中均不可用。使用定量 在这些资源上的抗性测定中，我们已经表明BZ抗性远远超出了这种单一的β- 微管蛋白靶点然而，我们不知道这些独立的耐药机制在C。线虫或寄生虫 物种在目标1中，我们将明确测试与寄生虫抗性相关的等位基因是否真的导致了 抗性，测试这些等位基因的适合性效应，鉴定BZ靶向的组织，并表征 β-微管蛋白如何受苯并咪唑类影响的分子机制。在目标2中，我们将发现beta- 微管蛋白独立的耐药机制使用易处理的C.线虫模式线虫在目标3中， 将结果推广到H.基因组和经验证的菌株资源能够发现 保守的抗性机制。在任何寄生线虫物种中都不可能实现这些 目标.只有通过模式线虫C.线虫和 兽用寄生线虫H.扭曲我们的研究结果将直接影响到 施用治疗并监测人寄生线虫的抗性。

Project summary: Parasitic nematodes impose a massive health and economic burden across much of the developing world, infecting over one billion people worldwide. The morbidity and mortality inflicted by these devastating pathogens is partly curtailed by mass drug administration (MDA) programs that depend on the continued efficacy of a limited portfolio of anthelmintic drugs. Benzimidazole (BZ) compounds are a widely used class of broad-spectrum anthelmintics that are an indispensable component of this limited chemotherapeutic arsenal. The prospects of BZ resistance pose a serious threat to the future success of nematode control programs. These prospects have been realized in the veterinary domain following intensive BZ use and are predicted to materialize in human medicine with increased selection caused by expanded MDA. Early detection of resistance-associated alleles in nematode parasite populations is essential to the goal of slowing anthelmintic resistance and extending the lifespan of this critical drug class. Based on research in the free-living nematode Caenorhabditis elegans from thirty years ago, parasitic nematode researchers focus on one BZ target, a nematode-specific beta-tubulin. Despite this knowledge, it is still a complete mystery (1) whether any alleles cause resistance (i.e. go beyond correlation), (2) the nematode tissues that are sensitive to BZ poisoning, and (3) the drug-target interactions that cause resistance. In Haemonchus contortus, we have collected both validated sensitive and resistance samples, and longitudinal samples where resistance has developed over time. These samples are not available in any human parasitic nematode species. Using quantitative resistance assays on these resources, we have shown that BZ resistance goes well beyond this single beta- tubulin target. However, we do not know these independent resistance mechanisms in C. elegans or parasite species. In Aim 1, we will test explicitly whether alleles correlated with resistance in parasites actually cause resistance, test the fitness effects of these alleles, identify the tissues targeted by BZ, and characterize the molecular mechanism for how beta-tubulin in affected by benzimidazoles. In Aim 2, we will discover beta- tubulin independent mechanisms of resistance using the tractable C. elegans model nematode. In Aim 3, we will expand our results to H. contortus where genomic and validated strain resources enable discoveries of conserved resistance mechanisms. It is not possible in any parasitic nematode species to accomplish these goals. New discoveries are possible only through this interplay between the model nematode C. elegans and the tractable veterinary parasitic nematode H. contortus. Our results will have direct impacts on how treatments are administered and resistance is monitored in human parasitic nematodes.