New research from the USF Health Morsani College of Medicine adapts a fluorescent imaging system to study Toxoplasma gondii and produces the first detailed map of its cell cycle. Toxoplasma spreads through uncooked meat and contaminated produce and causes toxoplasmosis, which is usually mild but can be serious for pregnant women and for people with weakened immune systems. Acute infection can be treated if caught early, but long-term treatment carries toxicity risks and there are currently no cures for brain cysts that form in the chronic stage.
Mapping was difficult because Toxoplasma does not follow the standard cell cycle and lacks many common human proteins. The team tested many markers and fluorescent tags, trying red and green labels by trial and error, until a reliable signal emerged. They identified a protein called PCNA1 in the parasite nucleus and strengthened its visibility by attaching two copies of a bright neon green tag.
The resulting map shows the parasite moves through an ordinary early phase but then enters overlapping later stages. Investigators describe these stages as fork-like: a straight handle followed by several prongs that allow as many as three phases to occur at once. This arrangement helps rapid multiplication and immune evasion before cyst formation.
With the cell cycle mapped by fluorescence, researchers are now looking for vulnerable stages that could stop parasite multiplication and are testing how drugs affect specific phases. The study appears in mBio. Source: University of South Florida.
Difficult words
- cell cycle — Sequence of stages when a cell grows.
- fluorescent — Emitting light after absorbing other light.fluorescent tags, fluorescent imaging system
- toxoplasmosis — Infection caused by the Toxoplasma parasite.
- chronic — Continuing for a long time.
- parasite — Organism that lives and feeds on another.Toxoplasma, parasite nucleus, parasite multiplication
- immune evasion — Ways a pathogen avoids the body's immune response.
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Discussion questions
- Which stage or feature of the parasite cell cycle would you prioritise for new drug development, and why? Use reasons from the article.
- What risks of long-term treatment for toxoplasmosis are mentioned in the text?
- Besides testing drugs, how might mapping the parasite cell cycle help researchers understand or control the infection?
