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Toxoplasma and Brain Vesicles

43:52 recording · AUTO · 2 speakers

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Brief overview

Toxoplasma cysts in neurons alter extracellular vesicles that make astrocytes inflammatory and cut GLT-1, risking excitotoxicity.

  1. Infected neurons make fewer, different vesiclesConcentration dropped more than in half, with clear separation in both protein and microRNA content.
  2. GLT-1 falls through vesicle-borne communicationAstrocytes exposed to vesicles from infected neurons decreased GLT-1, the transporter clearing 90% of extracellular glutamate.
  3. Lifelong cysts are not dormantBradyzoite cysts persist for the host's life and keep affecting neurons, astrocytes and glutamate levels.
Executive Summary AI
  • On TWIP 264, recorded 15 August 2025, Vincent Racaniello and Daniel Griffin discuss a PLOS Pathogens paper from the University of California, Riverside (Emily Tabayi first author, Emma Wilson lead) on how Toxoplasma gondii infection of neurons changes extracellular vesicles and astrocyte phenotype.2:18
  • Daniel frames the stakes with the paper's opening line: nearly one-third of the world's population carries this obligate intracellular parasite, acquired mainly through undercooked meat, mother-to-child transmission or cat litter, and the neuronal cysts stay for life.4:04
  • In the data, infected cortical neurons at an MOI of 0.5 produced extracellular vesicles at less than half the concentration of uninfected ones, with principal component analysis showing clearly altered protein and microRNA cargo, including a shift from pro-inflammatory to anti-inflammatory microRNAs.21:46
  • Astrocytes still took those vesicles up, but vesicles from infected neurons changed astrocyte gene expression and decreased GLT-1 protein, the transporter responsible for 90% of extracellular glutamate uptake, which links the infection to excitotoxic states such as seizures.28:19
  • They close on prevalence and behaviour: over 80% in Brazil and France, CDC says 11% in the US though Daniel guesses nearer half, and Daniel argues slowing a mouse down so a feline eats it is the evolutionary logic behind the brain changes.37:40
Key Quote
“Nearly one-third of the world's population is infected with the obligate intracellular parasite toxoplasma gondii.”
— Daniel Griffin3:56
Key Quote
“The extracellular space is actually, dare I say, infested.”
— Daniel Griffin15:52
Key Quote
“The infected concentration is really dropping more than in half.”
— Daniel Griffin21:46