Intact Cryptosporidium parvum oocysts isolated after in vitro excystation are infectious to neonatal mice

摘要

In vitro excystation is often used as a measure of viability of encysted protozoan parasites. Parasites that do not excyst in vitro are assumed to be non-viable anal non-infectious, whereas those that do excyst are assumed viable. To test the validity of these assumptions, Cryptosporidium parvum oocysts were excysted in vitro using two different excystation protocols, and the non-excysted intact oocysts were isolated using flow cytometry. Non-excysted sorted oocysts readily infected neonatal CD-1 mice. Increasing the duration of the excystation assays from 1 h to 3 h resulted in a higher percent of excysted oocysts, but the remaining non-excysted parasites were still capable of infecting neonatal CD-1 mice. Our results suggest that in vitro excystation is not an accurate measure of the viability or infectious potential of C. parvum oocysts. (C) 2000 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved. [References: 22]