Viruses that evolved in the unique environment of the International Space Station (ISS) demonstrate enhanced effectiveness at killing bacteria when returned to Earth. The findings, published in PLOS Biology on January 13, reveal how microgravity fundamentally alters the evolutionary race between bacteria and the viruses that infect them (phages). This research isn’t just about space biology; it has direct implications for developing more potent treatments against antibiotic-resistant bacteria on Earth.
The Evolutionary Shift in Microgravity
Bacteria and phages engage in a constant arms race: bacteria evolve defenses, phages evolve ways to bypass them. But this competition unfolds differently in space, where the lack of gravity creates a slower, more deliberate evolutionary process. Researchers at the University of Wisconsin-Madison compared E. coli populations infected with the T7 phage on the ISS versus identical control groups on Earth.
The study confirms earlier hypotheses that phage infection cycles are slower in microgravity due to reduced fluid mixing. On Earth, gravity stirs fluids, ensuring constant contact between bacteria and viruses. In space, this mixing doesn’t happen naturally, forcing phages to adapt to a slower pace and become more efficient at attaching to bacteria.
Genetic Mutations Boost Viral Potency
Whole-genome sequencing revealed that both the bacteria and phages on the ISS accumulated unique genetic mutations not seen in Earth-grown samples. Space-based viruses evolved mutations that increased their ability to infect bacteria and bind to bacterial receptors. Simultaneously, E. coli developed defenses against these attacks, including altering their receptors to resist phage infection and improving survival in microgravity.
Researchers then used deep mutational scanning to analyze changes in the viruses’ receptor-binding proteins. Surprisingly, the space-adapted phages, when brought back to Earth, exhibited increased activity against antibiotic-resistant E. coli strains – specifically those commonly causing urinary tract infections. This unexpected result demonstrates that the evolutionary pressures of space can yield viruses with enhanced killing power in terrestrial environments.
“It was a serendipitous finding,” said lead study author Srivatsan Raman. “We were not expecting that the [mutant] phages that we identified on the ISS would kill pathogens on Earth.”
Implications for Phage Therapy
These findings have significant implications for phage therapy, an emerging treatment that uses viruses to kill bacteria or enhance the effectiveness of antibiotics. Experts suggest that understanding how phages adapt to microgravity at the genetic level could help optimize antibiotic strategies on Earth.
Charlie Mo, an assistant professor at the University of Wisconsin-Madison, notes that while the research shows promise, the cost of space experiments or simulating microgravity remains a challenge. However, the potential benefits extend beyond Earth-bound applications; more effective phage therapies could be crucial for astronaut health during long-duration space missions.
In conclusion, this study highlights the unexpected benefits of space research for terrestrial medicine. By studying how viruses evolve in microgravity, scientists are uncovering new ways to combat antibiotic resistance and improve phage therapies, both on Earth and in the cosmos.
