The blood fluke Schistosoma is a parasitic trematode that is
responsible for more than 200,000 human deaths per year. Most Schistosoma species are located in
tropical and subtropical areas of the delveloping world. The state of the art
to detect Schistosoma viability involves microscopy and knowledge of parasite
morphology. The lack of appropriate methods for quantifying Schistosoma
viability blocks the development of new anthelmintics.
In this application note we present a fluorescence
intensitybased microtiter plate assay to reproducibly detect schistosomal viability
using the POLARstar Omega from BMG LABTECH (Fig.1). The principle of the assay
is based on differential membrane permeabilities of the dyes, fl uorescein
diacetate (FDA) and propidium iodide (PI). Fluorescein diacetate is able to
cross the membrane of living cells. Once inside the cell, esterases will cut
the diacetate and fluorescein is released resulting in a measurable fluorescence
signal that is directly related to the number of living cells. In contrast,
propidium iodide cannot enter a viable cell. This dye will only stain the DNA
of dead cells when the membrane has been compromised. The simultaneous detection
of both propidium iodide and fluorescein diacetate measures allowed us to
develop a fluorescence-based, microplate bioassay to improve detection of
schistosomal viability. The assay is adaptive to 96-well and 384-well format,
quantitative and provides objective readouts (relative fluorescence units) of parasite
viability during in vitro culture. Using this flexible bioassay, we demonstrate
its versatility in detecting schistosomal viability in response to a known
inhibitor of thioredoxin glutathione reductase (auranofin).
The blood fluke Schistosoma is a parasitic trematode that is
responsible for more than 200,000 human deaths per year. Most Schistosoma species are located in
tropical and subtropical areas of the delveloping world. The state of the art
to detect Schistosoma viability involves microscopy and knowledge of parasite
morphology. The lack of appropriate methods for quantifying Schistosoma
viability blocks the development of new anthelmintics.