Single-molecule imaging reveals stages of virus-like particle assembly

Researchers at the University of Oxford studied how an engineered virus-like particle, made of 60 protein units, assembles. Using mass photometry alongside a method to confine and continuously observe individual molecules, they tracked changes in particle mass as proteins joined. The Nature study was designed to capture intermediate stages that are difficult to observe with methods that examine only starting materials or finished particles.

The team found that early protein connections are weak and can break apart, allowing unsuccessful arrangements to be retried. A key stable intermediate forms when five larger building blocks close into a pentagonal ring. After this structure appears, subsequent stable stages require fewer additional building blocks, and assembly proceeds more quickly.

The findings provide a molecular model for assembly in this engineered particle and may inform future research on disrupting viral capsids or designing virus-like particles for vaccines. However, the study did not test antiviral drugs, vaccine candidates, or clinical outcomes. Its findings should not be interpreted as evidence that a new treatment or vaccine is available; applicability to other viruses also remains to be established.