New Tool Alters Pneumocystis Fungi

Researchers use extracellular vesicles to deliver gene-editing technology into the difficult-to-study fungal pathogen.

Jan. 29, 2026 at 4:15am

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Pneumocystis fungi are difficult to study and culture, making it challenging to develop new treatments. Researchers have now harnessed extracellular vesicles (EVs) to deliver CRISPR-Cas9 gene-editing technology inside the fungus. Tests on mice showed that the method worked to modify genes in the fungus associated with treatment resistance.

Why it matters

Pneumocystis is an unwieldy genus of fungal pathogens that cause severe pneumonia, particularly in immunocompromised people. However, the mechanisms by which it infects a host organism and develops resistance to treatments remain largely unknown, making it difficult to devise new therapeutics. This new tool offers a way to genetically modify the fungus and study its inner workings, which could lead to the development of better drugs.

The details

Researchers at the University of Cincinnati College of Medicine used EVs from mouse lungs to deliver gene-modifying molecules inside Pneumocystis murina, a species that infects mice. Results from both lab and animal tests showed that the modified fungus expressed the introduced genomic modifications. This approach allows researchers to use mouse models to understand the genetic workings of the fungi, particularly those related to infection and drug resistance. One of the mutations they targeted has been connected to the development of resistance to a common prophylactic drug among immunocompromised people.

  • The study was recently published in the journal mBio.

The players

A. George Smulian, M.D.

An infectious disease researcher and senior author on the study who has studied the genetic machinery of Pneumocystis for decades.

Steve Sayson, Ph.D.

A molecular biologist who led the study and had been examining extracellular vesicles within the host environment where Pneumocystis lives.

Pneumocystis

An unwieldy genus of fungal pathogens that cause severe pneumonia, particularly in immunocompromised people.

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What they’re saying

“This really is the first use of host EVs as a transport mechanism to introduce DNA and nucleic acid material into pathogenic organisms.”

— A. George Smulian, M.D., Infectious disease researcher and senior author

“So, now we're able to interrogate that process to say what's causing resistance. Maybe we can develop a better drug.”

— Steve Sayson, Ph.D., Molecular biologist and lead author

What’s next

The researchers say the next step is to find ways to better understand the genetic transformation initiated by the EVs, including controlling more genes and the level of expression.

The takeaway

This new tool offers a promising approach to genetically modify the difficult-to-study Pneumocystis fungi, which could lead to a better understanding of the mechanisms behind infection and drug resistance, and ultimately the development of more effective treatments for severe pneumonia caused by this pathogen.