title: Plasmodium yoelii: correlation of up-regulated prophenoloxidase and phenoloxidases with melanization induced by the antimalarial, nitroquine.
abstract: Although knowledge of the mosquito immune response has recently improved, less is known about the impact of antimalarial drugs on mosquito immunity. In the present study, we found that nitroquine, an effective antimalaria drug, could also induce melanotic encapsulation of Plasmodium by Anopheles stephensi. The melanization rate of the nitroquine treated group was 60.8%. To explore the effect of nitroquine on mosquito immunity, we determined the increase in activity of phenoloxidases (PO) enzyme, the main component of melanotic encapsulation, with nitroquine treatment. Moreover, we cloned prophenoloxidase (PPO) gene, which is accepted as the inactive phenoloxidase form and observed inducible expression of this gene with nitroquine treatment by real-time PCR. Our data implied that up-regulation of PPO gene and PO activity might be correlated with nitroquine. Nevertheless, nitroquine had no effect on the transcription of PPO gene or the activity of PO enzyme in the mosquito fed on a normal blood meal. In our study, we also observed the degenerative effect of 0.1% nitroquine on Plasmodium in the mosquito. This suggests that the degeneration of Plasmodium induced by nitroquine might result in the exposure of pattern-recognition ligands which can active the immune reaction, up-regulate PPO gene expression and PO activity, and induce the melanization.
authors.affiliation: Department of Parasitology, The Third Military Medical University, Chongqing 400038, PR China. zhangjianss567@sohu.com <zhangjianss567@sohu.com>
authors.forename: Jian
authors.initials: J
authors.lastname: Zhang
authors.forename: Fu Sheng
authors.initials: FS
authors.lastname: Huang
authors.forename: Wen Yue
authors.initials: WY
authors.lastname: Xu
authors.forename: Peng
authors.initials: P
authors.lastname: Song
authors.forename: Jian Hua
authors.initials: JH
authors.lastname: Duan
authors.forename: Song
authors.initials: S
authors.lastname: Yang
authors.forename: Zong Wen
authors.initials: ZW
authors.lastname: Qiu
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000852:Anopheles / Q000201:enzymology / Q000276:immunology / Q000469:parasitology*; D000962:Antimalarials / Q000494:pharmacology*; D004156:Catechol Oxidase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D004792:Enzyme Precursors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005260:Female; D006458:Hemolymph / Q000201:enzymology; D008543:Melanins / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D014442:Monophenol Monooxygenase / Q000378:metabolism*; D010967:Plasmodium yoelii / Q000187:drug effects / Q000276:immunology* / Q000502:physiology; D016133:Polymerase Chain Reaction; D011799:Quinazolines / Q000494:pharmacology*; D011897:Random Allocation; D015854:Up-Regulation
chemical_list: D000962:Antimalarials; D004792:Enzyme Precursors; D008543:Melanins; D011799:Quinazolines; C021126:nitroquine; C038451:pro-phenoloxidase; D004156:Catechol Oxidase; D014442:Monophenol Monooxygenase