title: Amelioration of Cryptosporidium parvum infection in vitro and in vivo by targeting parasite fatty acyl-coenzyme A synthetases.
abstract: BACKGROUND
  Cryptosporidium is emerging as 1 of the 4 leading diarrheal pathogens in children in developing countries. Its infections in patients with AIDS can be fatal, whereas fully effective treatments are unavailable. The major goal of this study is to explore parasite fatty acyl-coenzyme A synthetase (ACS) as a novel drug target.
  
  
  METHODS
  A colorimetric assay was developed to evaluate biochemical features and inhibitory kinetics of Cryptosporidium parvum ACSs using recombinant proteins. Anticryptosporidial efficacies of the ACS inhibitor triacsin C were evaluated both in vitro and in vivo.
  
  
  RESULTS
  Cryptosporidium ACSs displayed substrate preference toward long-chain fatty acids. The activity of parasite ACSs could be specifically inhibited by triacsin C with the inhibition constant Ki in the nanomolar range. Triacsin C was highly effective against C. parvum growth in vitro (median inhibitory concentration, 136 nmol/L). Most importantly, triacsin C effectively reduced parasite oocyst production up to 88.1% with no apparent toxicity when administered to Cryptosporidium-infected interleukin 12 knockout mice at 8-15 mg/kg/d for 1 week.
  
  
  CONCLUSIONS
  The findings of this study not only validated Cryptosporidium ACS (and related acyl-[acyl-carrier-protein]-ligases) as pharmacological targets but also indicate that triacsin C and analogues can be explored as potential new therapeutics against the virtually untreatable cryptosporidial infection in immunocompromised patients.
authors.affiliation: Department of Veterinary Pathobiology, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station.
authors.forename: Fengguang
authors.initials: F
authors.lastname: Guo
authors.forename: Haili
authors.initials: H
authors.lastname: Zhang
authors.forename: Jason M
authors.initials: JM
authors.lastname: Fritzler
authors.forename: S Dean
authors.initials: SD
authors.lastname: Rider
authors.forename: Lixin
authors.initials: L
authors.lastname: Xiang
authors.forename: Nina N
authors.initials: NN
authors.lastname: McNair
authors.forename: Jan R
authors.initials: JR
authors.lastname: Mead
authors.forename: Guan
authors.initials: G
authors.lastname: Zhu
mesh_terms: D000818:Animals; D018929:Cell Culture Techniques; D019976:Cloning, Organism; D003066:Coenzyme A Ligases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D003457:Cryptosporidiosis / Q000201:enzymology / Q000517:prevention & control*; D016785:Cryptosporidium parvum / Q000201:enzymology*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006801:Humans; D051379:Mice; D014226:Triazenes / Q000494:pharmacology*
chemical_list: D004791:Enzyme Inhibitors; D014226:Triazenes; C034613:triacsin C; D003066:Coenzyme A Ligases
keywords: Cryptosporidium parvum; anti-cryptosporidial efficacy; cryptosporidiosis; long chain fatty acyl-CoA synthetase; triacsin C