Immune System's Secret Weapon Against Brain Parasite Revealed

UVA researchers uncover how the body fights back against the widespread Toxoplasma gondii infection

Published on Feb. 17, 2026

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A new study from the University of Virginia School of Medicine has shed light on a key strategy the immune system uses to combat the Toxoplasma gondii parasite, which infects an estimated one-third of the global population. Researchers found that specialized immune cells called CD8+ T cells can become infected with the parasite themselves, but then trigger a self-destruct mechanism using an enzyme called caspase-8 to eliminate both the infected cell and the parasite within it.

Why it matters

Understanding how the body controls Toxoplasma gondii infections is crucial, as the parasite can remain dormant in the brain for life and pose serious risks for those with weakened immune systems. This discovery sheds new light on the complex evolutionary arms race between pathogens and the immune system, and could lead to new therapeutic strategies for treating toxoplasmosis.

The details

The Toxoplasma gondii parasite is commonly transmitted through contact with cats, contaminated food, or undercooked meat. Once inside the body, it can travel to various organs and settle in the brain. Researchers led by Dr. Tajie Harris at the University of Virginia focused on how CD8+ T cells, which are designed to eliminate infected cells, respond when the parasite invades them. Surprisingly, they found that these T cells don't just fight the parasite - they can become infected themselves. However, the infected T cells then activate the caspase-8 enzyme, triggering programmed cell death and eliminating both the cell and the parasite within it.

  • The research was led by a team at the University of Virginia School of Medicine.

The players

Toxoplasma gondii

A microscopic parasite found in warm-blooded animals that infects an estimated one-third of the global population, often remaining dormant in the brain for life.

Dr. Tajie Harris

Director of the Center for Brain Immunology and Glia (BIG Center) at the University of Virginia School of Medicine and the lead researcher on this study.

CD8+ T cells

Specialized immune cells designed to eliminate infected cells.

Caspase-8

An enzyme that regulates immune responses and can trigger programmed cell death.

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What they’re saying

“We found that these very T cells can secure infected, and, if they do, they can opt to die. Toxoplasma parasites need to live inside cells, so the host cell dying is game over for the parasite.”

— Dr. Tajie Harris, Director of the Center for Brain Immunology and Glia (BIG Center) at the University of Virginia School of Medicine (newsy-today.com)

“Prior to our study, we had no idea that Caspase-8 was so important for protecting the brain from Toxoplasma.”

— Dr. Tajie Harris, Director of the Center for Brain Immunology and Glia (BIG Center) at the University of Virginia School of Medicine (newsy-today.com)

What’s next

Researchers plan to further investigate the role of caspase-8 and its broader implications for controlling intracellular pathogens, which could lead to new therapeutic strategies for treating toxoplasmosis and other infectious diseases.

The takeaway

This discovery highlights the complex evolutionary battle between pathogens and the immune system, and demonstrates the immune system's sophisticated mechanisms for fighting back against even the most persistent infections like Toxoplasma gondii. Understanding these processes is crucial for developing effective treatments, especially for those with weakened immune systems.