Space travel supercharges the ability of viruses to infect bacteria

Space travel supercharges the ability of viruses to infect bacteria

By KR Callaway edited by Sarah Lewin Frasier

Bacteria and the viruses that infect them are perpetually at war. Their deadly clash is pushing both types of microbes to develop new traits that meet the challenges of every environment they inhabit, from the human digestive tract to the hydrothermal vents of the ocean floor – and even the harsh conditions of space.

To see how microgravity changes certain microbes, researchers sent bacteria-infected viruses called bacteriophages to the International Space Station, and they found that the viruses adapted in ways that made them even more effective at infection.

In the experiment, detailed in PLOS Biologythe team incubated samples of common laboratory bacteriophage T7 with the enemy, Escherichia coli bacteria, for varying durations. They ran the same experiment on Earth and in space; the terrestrially grown viruses infected bacteria within two to four hours, but those in space took more than four hours to breach the bacteria’s defenses. The infection took longer in orbit because microgravity is an unknown stressor that both microbes must adapt to, the researchers suggest.

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However, once the viruses adapted to microgravity by subtly changing their shape, they became even more effective germ killers. “A simple microgravity experiment reveals these mutations that have much higher efficacy against pathogens,” said senior study author Srivatsan Raman, a chemical and biological engineer at the University of Wisconsin–Madison.

The difference between Earth and space may have to do with mixing. “Under normal gravity, fluid movement continuously stirs the environment, increasing the chances of viruses and bacteria meeting,” explains Ester Lázaro, an astrobiologist who was not involved in the study. “In microgravity, this natural mixture is drastically reduced or disappears entirely.” To overcome this lack of mixing, microbes grown in low gravity changed at a genetic level. The bacteriophages acquired mutations that slightly change the shape and structure of their outer membranes, for example, helping them to grip the bacteria they attack.

When they returned to Earth, the space viruses were placed alongside another strain of E.coli which is responsible for particularly stubborn urinary tract infections and often resistant to bacteriophages. The engineered viruses were able to kill that bacterium, which Raman says is “actually quite promising.” If exposing these bacteria-targeted viruses to new environmental stressors makes them more potent, researchers may be able to create versions strong enough to help the body fight off treatment-resistant bacteria.

“T7 is one of our iconic model organisms, so a lot is known about this bacteriophage,” says Evelien Adriaenssens, a researcher at the Quadram Institute in England, who was not involved in the study. “It was cool to see that if you go into a different environment, there’s still new knowledge that comes up.”

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