title: Inhibition of Plasmodium falciparum proliferation in vitro by double-stranded RNA nanoparticle against malaria topoisomerase II.
abstract: The need to develop new effective antimalarial agents is urgent due to the rapid emergence of drug resistance to all current drugs by the most virulent human malaria parasite, Plasmodium falciparum. A promising avenue is in the development of antimalarials based on RNA interference targeting expression of malaria parasite vital genes, viz. DNA topoisomerase II gene (PfTOP2). Biodegradable chitosan nanoparticle system has proven to be effective in delivering DNA and small double-stranded interfering RNA to target cells. We have employed a long double-stranded (dsRNA) targeting the coding region of PfTOP2 that is complexed with chitosan nanoparticles in order to interfere with the cognate mRNA expression and examined its effect on P. falciparum growth in culture. Exposure of ring stage-infected erythrocytes to 10 μg/ml PfTOP2 chitosan/dsRNA nanoparticles for 48 h resulted in 71% growth inhibition as determined by [(3)H] hypoxanthine incorporation and microscopic assays, compared with 41% inhibition using an equivalent amount of free PfTOP2 dsRNA or 12% with unrelated chitosan/dsRNA nanoparticles. This inhibition was shown to occur during maturation of trophozoite to schizont stages. RT-PCR analysis indicated 56% and 38% decrease in PfTOP2 transcript levels in P. falciparum trophozoites treated with PfTOP2 dsRNA nanoparticles and free PfTOP2 dsRNA respectively. These results suggest that chitosan-based nanoparticles might be a useful tool for delivering dsRNA into malaria parasites.
authors.affiliation: Institute of Molecular Biosciences, Mahidol University, Salaya, Nakornpathom 73170, Thailand.
authors.forename: Pongsopee
authors.initials: P
authors.lastname: Attasart
authors.affiliation: Department of Biochemistry, Faculty of Science, Mahidol University, Bangkok 10400, Thailand.
authors.forename: Siriwan
authors.initials: S
authors.lastname: Boonma
authors.affiliation: Department of Chemistry, Faculty of Science, Mahidol University, Bangkok 10400, Thailand.
authors.forename: Panya
authors.initials: P
authors.lastname: Sunintaboon
authors.affiliation: Department of Chemistry, Faculty of Science, Mahidol University, Bangkok 10400, Thailand.
authors.forename: Dolpawan
authors.initials: D
authors.lastname: Tanwilai
authors.affiliation: Department of Microbiology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand.
authors.forename: Jinrapa
authors.initials: J
authors.lastname: Pothikasikorn
authors.affiliation: Department of Biochemistry, Faculty of Science, Mahidol University, Bangkok 10400, Thailand. Electronic address: wilai.noo@mahidol.ac.th.
authors.forename: Wilai Tienrungroj
authors.initials: WT
authors.lastname: Noonpakdee
mesh_terms: D002478:Cells, Cultured; D048271:Chitosan; D004250:DNA Topoisomerases, Type II / Q000235:genetics / Q000276:immunology*; D004912:Erythrocytes / Q000469:parasitology; D006801:Humans; D053758:Nanoparticles; D010963:Plasmodium falciparum / Q000201:enzymology / Q000235:genetics / Q000254:growth & development* / Q000276:immunology; D034622:RNA Interference; D012330:RNA, Double-Stranded / Q000276:immunology*; D012333:RNA, Messenger / Q000032:analysis; D034741:RNA, Small Interfering / Q000276:immunology*
chemical_list: D012330:RNA, Double-Stranded; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D048271:Chitosan; D004250:DNA Topoisomerases, Type II
keywords: Double-stranded RNA; Malaria; Nanoparticles; PfTOP2; Plasmodium falciparum; Topoisomerase II