Thiazole orange: a new dye for Plasmodium species analysis

Area of Science:

• Biomedical science
• Parasitology
• Cell biology

Background:

• Accurate quantification of Plasmodium falciparum is crucial for antimalarial drug development and understanding parasite biology.
• Traditional methods like Giemsa staining can be labor-intensive and subjective.
• There is a need for rapid, sensitive, and objective methods for assessing parasite levels in vitro.

Purpose of the Study:

• To develop and validate a rapid, sensitive, and objective method for determining Plasmodium falciparum levels in in vitro cultures.
• To utilize fluorescent flow cytometry and thiazole orange (TO) staining for parasite detection.

Main Methods:

• A fluorescent flow cytometer with a 15-mW argon laser (488 nm) was employed.
• Thiazole orange (TO), a membrane-permeable fluorochrome that stains RNA, was used for labeling.
• Parasitized red blood cells were incubated with TO in phosphate-buffered saline (PBS) and analyzed fresh or after fixation.

Main Results:

• The method demonstrated high sensitivity and rapidity in detecting Plasmodium falciparum.
• Excellent correspondence was observed between the counts of fluorescent-labeled parasitized cells and Giemsa-stained cells.
• The staining protocol could be applied before or after cell fixation.

Conclusions:

• Fluorescent flow cytometry with TO staining provides a reliable and efficient method for quantifying Plasmodium falciparum in vitro.
• This technique offers an objective alternative to traditional microscopy-based methods.
• The developed assay is suitable for malaria research, including drug screening and basic parasite studies.