People Behind the Science
862: Understanding How the Brain Battles Infection - Dr. Tajie Harris
Why It Matters
Understanding brain‑immune interactions is crucial for developing treatments for neuro‑inflammatory diseases and infections that can cause lasting neurological damage. As Toxoplasma infects roughly one‑third of the global population, insights from Dr. Harris’s work have direct relevance to public health and to patients with compromised immune systems.
Key Takeaways
- •Neuroimmunology explores brain immune responses to Toxoplasma infection
- •Brain's immune privilege limits strong inflammation, risking neuron loss
- •Caspase‑8 triggers clean cell death, targeting parasites without damage
- •Unexpectedly, T cells become infected, revealing new immune pathways
- •Cross‑disciplinary mentorship drives breakthroughs in brain‑immune research
Pulse Analysis
Dr. Tajie Harris, an associate professor at the University of Virginia, bridges microbiology, immunology and neuroscience to decode how the brain defends itself against infection. Her laboratory focuses on Toxoplasma gondii, a single‑cell parasite that silently resides in up to one‑third of the global population and can reactivate when immunity wanes. Because the central nervous system is considered an immune‑privileged site, inflammatory responses are deliberately muted; excessive immunity risks irreversible loss of irreplaceable neurons. Understanding this delicate balance is critical for developing therapies that protect brain tissue while clearing pathogens.
In a recent series of experiments, Harris’s team investigated whether programmed cell death could be harnessed to eliminate the parasite without collateral damage. By genetically deleting caspase‑8 in neurons, astrocytes and microglia, they discovered that the enzyme was not essential in those cells, prompting a broader search. Using a fluorescent reporter introduced by the parasite, they visualized infected immune cells and were surprised to find that T cells themselves become hosts for Toxoplasma. This unexpected route suggests that adaptive immune cells may inadvertently aid pathogen persistence, opening new avenues for targeted interventions that modulate cell‑death pathways.
The findings illustrate why interdisciplinary collaboration is a strategic asset for biotech firms and research institutions. Combining expertise in neuroanatomy, molecular immunology and advanced genetics accelerates the translation of basic discoveries into drug candidates, such as caspase‑8 modulators or T‑cell‑focused therapies. For investors, the emerging field of neuro‑immunology promises a pipeline of novel treatments for neurodegenerative diseases, brain infections, and immune‑mediated disorders. Harris’s career trajectory—leveraging mentorship, cross‑departmental networks, and a willingness to pivot—offers a roadmap for building high‑impact scientific teams that can deliver commercializable breakthroughs.
Episode Description
Dr. Tajie Harris is an Associate Professor in the Department of Neuroscience in the School of Medicine at the University of Virginia. Tajie's research is at the intersection of immunology, microbiology, and neuroscience. She's interested in understanding how the immune system functions in the brain, particularly when someone is infected with a single-celled parasite called Toxoplasma gondii. When she's not working, Tajie enjoys going for walks and spending time with her two rescue dogs. She is also a fan of traveling, cooking, and putting together jigsaw puzzles. She received her B.S. degree in biology from Bemidji State University in Minnesota and her Ph.D. in microbiology from the University of Wisconsin-Madison. Afterwards, Tajie conducted Postdoctoral Research in immunoparasitology at the University of Pennsylvania before joining the faculty at the University of Virginia where she is today. In this interview, Tajie shares more about her life and science.
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