title: Use of bacterially expressed dsRNA to downregulate Entamoeba histolytica gene expression.
abstract: BACKGROUND
  Modern RNA interference (RNAi) methodologies using small interfering RNA (siRNA) oligonucleotide duplexes or episomally synthesized hairpin RNA are valuable tools for the analysis of gene function in the protozoan parasite Entamoeba histolytica. However, these approaches still require time-consuming procedures including transfection and drug selection, or costly synthetic molecules.
  
  
  RESULTS
  Here we report an efficient and handy alternative for E. histolytica gene down-regulation mediated by bacterial double-stranded RNA (dsRNA) targeting parasite genes. The Escherichia coli strain HT115 which is unable to degrade dsRNA, was genetically engineered to produce high quantities of long dsRNA segments targeting the genes that encode E. histolytica beta-tubulin and virulence factor KERP1. Trophozoites cultured in vitro were directly fed with dsRNA-expressing bacteria or soaked with purified dsRNA. Both dsRNA delivery methods resulted in significant reduction of protein expression. In vitro host cell-parasite assays showed that efficient downregulation of kerp1 gene expression mediated by bacterial dsRNA resulted in significant reduction of parasite adhesion and lytic capabilities, thus supporting a major role for KERP1 in the pathogenic process. Furthermore, treatment of trophozoites cultured in microtiter plates, with a repertoire of eighty-five distinct bacterial dsRNA segments targeting E. histolytica genes with unknown function, led to the identification of three genes potentially involved in the growth of the parasite.
  
  
  CONCLUSIONS
  Our results showed that the use of bacterial dsRNA is a powerful method for the study of gene function in E. histolytica. This dsRNA delivery method is also technically suitable for the study of a large number of genes, thus opening interesting perspectives for the identification of novel drug and vaccine targets.
authors.affiliation: Institut Pasteur, Unité Biologie Cellulaire du Parasitisme, Paris, France.
authors.forename: Carlos F
authors.initials: CF
authors.lastname: Solis
authors.forename: Julien
authors.initials: J
authors.lastname: Santi-Rocca
authors.forename: Doranda
authors.initials: D
authors.lastname: Perdomo
authors.forename: Christian
authors.initials: C
authors.lastname: Weber
authors.forename: Nancy
authors.initials: N
authors.lastname: Guillén
mesh_terms: D000818:Animals; D019295:Computational Biology; D015536:Down-Regulation / Q000235:genetics*; D042783:Endothelial Cells / Q000166:cytology / Q000469:parasitology; D004748:Entamoeba histolytica / Q000235:genetics* / Q000254:growth & development / Q000472:pathogenicity; D005247:Feeding Behavior; D017125:Genes, Protozoan / Q000235:genetics*; D005821:Genetic Techniques; D006801:Humans; D008099:Liver / Q000166:cytology; D010641:Phenotype; D017434:Protein Structure, Tertiary; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D012329:RNA, Bacterial / Q000235:genetics*; D012330:RNA, Double-Stranded / Q000235:genetics*; D053058:Trophozoites / Q000502:physiology; D014404:Tubulin / Q000378:metabolism; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism
chemical_list: C503280:KERP1 protein, Entamoeba histolytica; D015800:Protozoan Proteins; D012329:RNA, Bacterial; D012330:RNA, Double-Stranded; D014404:Tubulin; D037521:Virulence Factors