p-values from correlation matrices.

Albendazole (a benzimidazole) and ivermectin (a macrocyclic lactone) are the two most commonly co-administered anthelmintic drugs in mass-drug administration programs worldwide. Despite emerging resistance, we do not fully understand the mechanisms of resistance to these drugs nor the consequences of delivering them in combination. Albendazole resistance has primarily been attributed to variation in the drug target, a beta-tubulin gene. Ivermectin targets glutamate-gated chloride channels (GluCls), but it is unknown whether GluCl genes are involved in ivermectin resistance in nature. Using Caenorhabditis elegans, we defined the fitness costs associated with loss of the drug target genes singly or in combinations of the genes that encode GluCl subunits. We quantified the loss-of-function effects on three traits: (i) multi-generational competitive fitness, (ii) fecundity, and (iii) development. In competitive fitness and development assays, we found that a deletion of the beta-tubulin gene ben-1 conferred albendazole resistance, but ivermectin resistance required the loss of two GluCl genes (avr-14 and avr-15). The fecundity assays revealed that loss of ben-1 did not provide any fitness benefit in albendazole conditions and that no GluCl deletion mutants were resistant to ivermectin. Next, we searched for evidence of multi-drug resistance across the three traits. Loss of ben-1 did not confer resistance to ivermectin, nor did loss of any single GluCl subunit or combination confer resistance to albendazole. Finally, we assessed the development of 124 C. elegans wild strains across six benzimidazoles and seven macrocyclic lactones to identify evidence of multi-drug resistance between the two drug classes and found a strong phenotypic correlation within a drug class but not across drug classes. Because each gene affects various aspects of nematode physiology, these results suggest that it is necessary to assess multiple fitness traits to evaluate how each gene contributes to anthelmintic resistance.阿苯达唑（Albendazole，苯并咪唑类化合物）与伊维菌素（Ivermectin，大环内酯类化合物）是全球范围内群体给药项目中最常联合应用的两种驱虫药物。尽管耐药性问题日益凸显，但目前学界尚未完全阐明这两类药物的耐药机制，也未明晰联合给药的潜在后果。阿苯达唑耐药性主要归因于其药物靶点——β微管蛋白基因（beta-tubulin gene）的序列变异。伊维菌素的作用靶点为谷氨酸门控氯离子通道（GluCls），但目前仍不清楚自然环境中GluCl基因是否参与伊维菌素的耐药进程。本研究以秀丽隐杆线虫（Caenorhabditis elegans）为模式生物，明确了单个或联合缺失编码GluCl亚基的药物靶点基因所对应的适合度代价。我们对三类性状的功能丧失效应进行了量化分析：（1）多代竞争适合度；（2）繁殖力；（3）发育水平。在竞争适合度与发育检测实验中，我们发现β微管蛋白基因ben-1的缺失可赋予宿主阿苯达唑耐药性，但伊维菌素耐药性需要同时缺失两个GluCl基因（avr-14与avr-15）。繁殖力实验结果显示，ben-1的缺失无法在阿苯达唑处理条件下为宿主带来适合度优势，且所有GluCl缺失突变体均未产生伊维菌素耐药性。随后，我们针对上述三类性状探寻多药耐药性的相关证据。结果表明，ben-1的缺失不会赋予宿主伊维菌素耐药性，同时任一单个或组合的GluCl亚基缺失也不会赋予宿主阿苯达唑耐药性。最后，我们对124株秀丽隐杆线虫野生菌株在6种苯并咪唑类药物与7种大环内酯类药物中的发育情况进行了检测，以探究两类药物间是否存在多药耐药性关联。结果显示，同一药物类别内存在显著的表型相关性，但跨药物类别则未出现此类关联。鉴于单个基因可影响线虫生理活动的多个方面，本研究结果提示，若要评估各基因对驱虫药耐药性的贡献，需同时评估多个适合度相关性状。