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Determination of Giardia cyst viability in environmental and faecal samples by immunofluorescence, fluorogenic dye staining and differential interference contrast microscopy
Author(s) -
Thiriat,
Sidaner,
Schwartzbrod
Publication year - 1998
Publication title -
letters in applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.698
H-Index - 110
eISSN - 1472-765X
pISSN - 0266-8254
DOI - 10.1046/j.1472-765x.1998.00282.x
Subject(s) - propidium iodide , immunofluorescence , staining , giardia , dapi , differential interference contrast microscopy , biology , fluorescence microscope , fluorescein isothiocyanate , fluorescein , differential staining , microbiology and biotechnology , fluorescence , pathology , microscopy , antibody , biochemistry , immunology , medicine , apoptosis , genetics , physics , quantum mechanics , programmed cell death
Amongst the techniques suggested for the determination of Giardia cyst viability, the use of the fluorogenic dyes, fluorescein diacetate (FDA) and propidium iodide (PI) is the most often recommended, even though it appears to overestimate the number of viable cysts. In the present study, the replacement of FDA with 4′,6‐diamidino‐2‐phenylindole (DAPI) allowed simultaneous direct immunofluorescence with monoclonal antibody labelled with fluorescein isothiocyanate (MAb‐FITC). Under these conditions, it was possible both to quantify the cysts according to the immunofluorescence technique, and to appreciate their viability by using fluorogenic dye staining (DAPI and PI) and differential interference contrast (DIC) microscopy. This method proved to be significantly better than the counting methods normally suggested. The technique has been applied to Giardia cysts recovered from faeces and wastewater sludge.