Toxoplasma dye test using cell culture derived tachyzoites

Area of Science:

• Medical Parasitology
• Cell Biology
• Diagnostic Immunology

Background:

• Toxoplasma gondii tachyzoites are crucial for the dye test, a standard diagnostic method for toxoplasmosis.
• Current production methods involve animal cultures, which are costly and time-consuming.
• Alternative production methods are needed to improve efficiency and reduce costs.

Purpose of the Study:

• To evaluate the diagnostic utility of Toxoplasma gondii tachyzoites produced via serial passage in HeLa cell culture.
• To compare the cost-effectiveness of cell culture production versus traditional animal culture methods.

Main Methods:

• Tachyzoites were cultured and serially passaged in HeLa cells for use in the dye test.
• Human sera were assessed for accessory factor suitability, with sodium citrate optimization.
• The dye test performance using cell culture-derived tachyzoites was compared against animal-derived tachyzoites using 105 patient sera.

Main Results:

• 84% of cell culture harvests yielded usable tachyzoites, with consistent yield and viability during serial passage.
• Optimized accessory factor with sodium citrate improved dye test performance.
• 92 of 105 sera (87.6%) showed agreement or within-one-dilution concordance between the two methods.
• Cell culture production demonstrated significantly lower start-up (2.5x) and maintenance (3x) costs compared to animal culture.

Conclusions:

• Cell culture-derived tachyzoites are suitable for routine use in the Toxoplasma gondii dye test.
• Cell culture production is more economical than animal culture.
• Implementing cell culture methods can empower general hospitals to perform the dye test, leading to quicker and more precise diagnoses.