Space Viruses Evolve | Unexpected Findings

A recent study showed that viruses that infect bacteria, known as phages, maintained their ability to infect their hosts from E. coli in microgravity conditions aboard the International Space Station (ISS). However, interactions between viruses and bacteria behaved differently than they do on Earth. The work, led by Phil Huss of the University of Wisconsin-Madisonwas published on January 13 in the open access journal PLOS Biology.

Interactions between phages and their hosts are critical to microbial ecosystems. They are often described as an evolutionary arms race, where bacteria develop defenses against phages, while the latter find new ways to evade those defenses. Although these interactions have been widely studied on Earth, microgravity conditions alter bacterial physiology and the physics of virus-bacteria collisions, disrupting typical interactions.

However, few studies have explored how the dynamics between phages and bacteria differ in microgravity. To address this issue, Huss and his team compared two sets of samples of E. coli infected with a phage known as T7: one incubated on Earth and another aboard the ISS.

Analysis of samples obtained on the space station showed that, after an initial delay, the T7 phage managed to infect E. coli. However, whole genome sequencing revealed marked differences in the genetic mutations of both bacteria and viruses between the Earth and microgravity samples.

The ISS phages gradually accumulated specific mutations that could increase their infectivity or their ability to bind to receptors on bacterial cells. Meanwhile, the E. coli of the ISS accumulated mutations that could protect them against phages and improve their survival success in near-weightlessness conditions.

The researchers applied a high-throughput technique known as deep mutational scanning to more closely examine changes in the phage receptor-binding protein T7, which plays a key role in infection, revealing significant differences between microgravity conditions and those on Earth. Additional experiments on Earth linked these microgravity-associated changes in the receptor-binding protein to increased activity against strains of E. coli which cause urinary tract infections in humans and are usually resistant to T7.

Overall, this study highlights the potential of phage research aboard the ISS to reveal new insights into microbial adaptation, with relevance to both space exploration and human health.

The authors stated: “Space fundamentally changes how phages and bacteria interact: infection slows down and both organisms evolve on a different trajectory than on Earth. By studying these space-driven adaptations, we identified new biological insights that allowed us to engineer phages with much greater activity against drug-resistant pathogens on Earth.”

To access the full article at PLOS Biologyyou can use the following link: https://plos.io/4q4S9AO.

Cita: Huss P, Chitboonthavisuk C, Meger A, Nishikawa K, Oates RP, Mills H, et al. (2026) Microgravity reshapes bacteriophage-host coevolution aboard the International Space Station. PLoS Biol 24(1): e3003568. https://doi.org/10.1371/journal.pbio.3003568

Authors’ countries: USA. Financing: This work was supported by the Defense Threat Reduction Agency (Grant HDTRA1-16-1-0049) to SRCC received a graduate training fellowship from the Anandamahidol Foundation (Thailand). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.