Schistosoma mansoni resistance to Praziquantel treatment

描述（由申请人提供）：血吸虫病是由血吸虫属寄生虫引起的，曼氏血吸虫是南美洲唯一发现的物种。该病在世界各地的流行地区造成严重的人类发病率和死亡率。主要的控制策略包括用吡喹酮药物对受感染人群进行大规模治疗。然而，鉴于在一些流行地区报告了寄生虫对吡喹酮的耐药性，这种方法存在问题。该项目的长期目标是鉴定参与抗吡喹酮治疗的曼氏血吸虫基因。特异性目标#1的目标是：1)确定曼氏链球菌对吡喹酮敏感性的自然变异；2)分离耐药菌株；3)比较耐药菌株与敏感菌株的遗传谱。特异性目标#2的目标是：1)通过比较易感蠕虫和抗性蠕虫的转录组来识别与抗性表型相关的基因；2)通过控制基因表达水平来调节抗性表型。拟议的工作将使用从受感染个体的粪便中获得的寄生虫卵进行。将通过确定在小鼠模型中杀死50%感染寄生虫（ED50）所需的药量来评估寄生虫对吡喹酮的敏感性。此外，这种方法将使我们能够识别耐药分离株。寄生虫将利用合作小组已经开发的多态微卫星位点进行基因分型。我们预测，抗性蠕虫将表现出不同的基因转录谱相对于易感个体。为了确定造成这些差异的基因，将采用基因表达序列分析（SAGE）。将通过改变基因表达模式，在耐药和易感蠕虫中进一步研究已鉴定的基因；RNA干扰（RNAi）将用于下调基因表达，而质粒构建（包含感兴趣的基因）将用于上调表达模式。利用这些方法和技术，我们希望能够阐明曼氏血吸虫耐药的机制，并根据我们的研究结果提出新的治疗和控制措施。这项研究将主要在巴西的Rene Rachou - FIOCRUZ中心与Guilherme Oliveira合作进行，作为NIH拨款# 2R01AI042768-05A2的延伸。

DESCRIPTION (provided by applicant): Schistosomiasis is caused by parasites of the Schistosoma genus, and Schistosoma mansoni is the only species found in South America. The disease causes significant human morbidity and mortality in endemic areas worldwide. The main control strategy involves mass-treating infected human populations with the drug Praziquantel. However, this methodology is problematic given that parasite resistance to Praziquantel has been reported from a number of endemic areas. The long-term objective of this project is to identify Schistosoma mansoni genes involved in resistance to Praziquantel treatment. The objectives of Specific Aim #1 are to 1) determine natural variation of S. mansoni sensitivity to Praziquantel treatment, 2) isolate resistant strains and 3) compare genetic profiles of resistant versus susceptible strains. The objectives of Specific Aim #2 are to 1) identify genes involved in the resistant phenotype by comparing the transcriptome of susceptible versus resistant worms, and 2) modulate the resistance phenotype by controlling gene- expression levels. The proposed work will be performed using parasite eggs obtained from the feces of infected individuals. Parasite susceptibility to Praziquantel will be assessed by determining the amount of drug necessary to kill 50% of the infecting parasites (ED50) in a mouse model. In addition, this approach will allow us to identify resistant isolates. Parasites will be genotyped using polymorphic microsatellite loci already developed by the collaborating groups. We predict that resistant worms will demonstrate different gene-transcription profiles relative to susceptible individuals. To identify the genes responsible for these differences, Serial Analysis of Gene Expression (SAGE) will be employed. Identified genes will be further investigated in both resistant and susceptible worms by altering gene-expression patterns; RNA interference (RNAi) will be used to down-regulate gene expression, whereas plasmid constructs (containing the genes of interest) will used to up-regulate expression patterns. By utilizing these methods and techniques, we expect to clarify the mechanism(s) underlying drug resistance in Schistosoma mansoni, and to propose novel treatments and control measures based on our results. This research will be done primarily in Brazil at the Centra de Pesquisas Rene Rachou - FIOCRUZ in collaboration with Guilherme Oliveira as an extension of NIH grant # 2R01AI042768-05A2.