When viruses travel through the air in tiny droplets, they can quickly start to dry out. Yet many viruses remain infectious after rehydration—something that is still not fully understood. Now, an international team of researchers has directly observed at the European XFEL how the protein shells of viruses can change shape during dehydration, offering new clues to viral resilience and opening new possibilities for virology research. The results, published in Light: Science & Applications, lay the groundwork for potential applications in virology and public health and can, for instance, help develop antiviral strategies.

At the SPB/SFX instrument of the European XFEL, Abhishek Mall from the Max Planck Institute for the Structure and Dynamics of Matter in Hamburg (MPSD) and his colleagues explored the structural dynamics of the protein shells—called capsids—that enclose the genetic material of viruses. Specifically, they examined the behavior of capsids of the bacteriophage MS2 under conditions of dehydration. MS2 is an icosahedral, i.e., shaped by 20 triangular surfaces that form a sphere, single-stranded RNA virus that infects the bacterium Escherichia coli and is widely used as a model system in virology.

The capsid’s design is critical for protecting the viral genome and helping the virus interact with host cells. However, viruses are often confronted with environments that challenge their structural integrity, for example through dehydration. Theoretical studies have long suggested that capsids may undergo low-energy “buckling transitions”—sudden changes in shape—to adapt to such stresses, but direct experimental evidence has been lacking.