Study Finds Imbalance in Viral Shape Helps Drives Infection

Viruses are often portrayed as perfectly symmetrical shells that hold genetic material with precision, but new research from Penn State reveals that subtle asymmetry is central to their ability to infect hosts. The study shows that this imbalance provides viruses with a directional bias that helps them release their genetic material efficiently, offering insights useful for antiviral drug design, vaccine development, and therapeutic delivery technologies. The findings were published in Science Advances.

“A virus lacks sensory organs, so it uses chemical cues to determine how it replicates its genetic material into new viral packages or assemblies with precise polarity,” said Ganesh Anand, lead author of the study. “This polarity guides the RNA, its genetic material that allows the virus infection to spread, and our research shows that asymmetry is what gives the virus this essential polarity.”

The team investigated Turnip Crinkle Virus (TCV), a plant pathogen with an icosahedral, or 20-sided, shell like many human viruses, including enteroviruses, noroviruses, and poliovirus. Using advanced imaging techniques at Penn State’s Core Facilities, the researchers discovered that TCV relies on a single chemical bond called an isopeptide link to create a slight imbalance inside its protein shell. The link connects two structural proteins, clustering the virus’s RNA on one side of the particle so it exits in a controlled direction when infecting cells.

Anand compared this mechanism to a “loaded die,” explaining that the imbalance ensures RNA bursts out rapidly through a specific exit when the virus begins to disassemble. This structural feature positions the RNA near the host’s ribosomes, allowing viral protein production to start almost immediately.

To visualize this process, the researchers combined cryo-electron microscopy and hydrogen-deuterium exchange mass spectrometry. “We were able to see the polarity of the particle and it appeared to be positioned somewhere very close to where the RNA looked like it was wanting to get out,” said co-author Varun Venkatakrishnan.

The team suggests that asymmetry may be a widespread viral strategy. By targeting structural links like the isopeptide bond, scientists could potentially disrupt RNA release, design improved RNA-based vaccines, or develop antivirals that prevent viruses from maintaining their infection-ready state.