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. 1996 Dec;40(12):2781–2784. doi: 10.1128/aac.40.12.2781

Cryptosporidium parvum metalloaminopeptidase inhibitors prevent in vitro excystation.

P C Okhuysen 1, C L Chappell 1, C Kettner 1, C R Sterling 1
PMCID: PMC163621  PMID: 9124840

Abstract

Cryptosporidium parvum arginine aminopeptidase (RAP) was studied during in vitro excystation. Specific RAP inhibitors were identified by using C. parvum extracts. Amastatin, a series of alpha-aminoboronic acids, and the chelating agents EDTA and 1,10-phenanthrolene, but not endoproteinase inhibitors, blocked enzymatic activity. RAP inhibitors found to be effective in soluble enzymatic assays were then studied for their effect on in vitro excystation. 1,10-Phenanthrolene, amastatin, and H-boronorleucine (pinacol) inhibited excystation by 84, 57, and 61%, respectively, compared with solvent-treated control oocysts. Sporozoites remained viable within the oocyst as determined by propidium iodide and fluorescein diacetate dye uptake, suggesting that alpha-aminoboronic acids were not directly lethal to the parasite.

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Selected References

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