Parasite Hides by Stealing Human Cell Proteins

Parasites are infamous for their resourceful ways of infecting human cells, often developing complex tactics to slip past immune defenses unnoticed. One particularly crafty organism, Entamoeba histolytica, has evolved a remarkable method to stay hidden: it tears off fragments of human cells and uses their proteins to disguise itself.

Life Cycle of a Deadly Parasite

E. histolytica is a unicellular parasite responsible for amoebiasis—a serious disease that spreads via contaminated food and water. Its resilient cyst form can survive the acidic environment of the stomach, eventually releasing active amoebic trophozoites in the small intestine. These trophozoites then move to the large intestine, where they reproduce and form new cysts, continuing the infectious cycle when expelled in feces.

This pathogen infects around 50 million people globally each year and is linked to approximately 70,000 deaths. In many cases, it only causes mild symptoms like diarrhea, but in severe instances, it can destroy liver tissue and spread to the brain or lungs. Despite its widespread impact, E. histolytica remains largely understudied, with many aspects of its biology still not fully understood.

“All parasites are understudied, but E. histolytica is especially mysterious,” notes Katherine Ralston, an associate professor in microbiology and molecular genetics. “It has the ability to kill virtually any human cell.”

A New Understanding of Immune Evasion

While it was previously known that this amoeba could eliminate immune cells to avoid detection, the exact mechanism had remained elusive. Earlier theories suggested the parasite released toxins to kill its targets.

But Ralston’s research uncovered something far more unusual. Instead of killing cells outright, the parasite nibbles off small portions, leaving the host cell damaged but not entirely destroyed. It doesn’t consume these bits for nourishment—instead, it hijacks surface proteins such as CD46 and CD55, incorporating them into its own outer layer. These proteins normally help human cells avoid immune attacks, so when the parasite wears them, it becomes effectively invisible to the immune system.

Scientists call this method of stealing and using host proteins for camouflage trogocytosis.

New Hope for Treatment

Researchers initially reported the breakthrough in a preprint at the end of 2024. Now, they are actively exploring the parasite’s already-sequenced RNAi library to identify the genes responsible for its protein-stealing behavior. When paired with CRISPR gene-editing tools, it could open the door to treatments that specifically target these molecular interactions and neutralize the parasite.

We’re finally seeing a promising path forward,” says graduate student Wesley Huang. “And it feels like a real possibility.

Read the original article on: New Atlas

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