The Trichomonas vaginalis pseudocyst is a viable cell stage with a distinct transcriptome and an intact membrane.

T. vaginalis pseudocysts induced by acidic or iron-depleted culture maintain intact membranes and remain transcriptionally active for several days, supporting viability.

• Why it matters: Trichomoniasis is a neglected STI, and it has been unclear whether pseudocysts are quiescent viable stages or merely degenerate forms, limiting understanding of persistence.
• What they did: The study induced pseudocysts from trophozoites using acidic media or iron-depleted media, then assessed membrane integrity, flow cytometry/FACS subpopulations, transcriptomics, and reversion using pure live cultures.
• The result: Pseudocysts showed intact membranes, phosphatidylserine on the surface, distinct transcriptional programs with reduced metabolism gene expression, and viability for days, implying a stress-induced stage linked to persistent infections.