Visualizing a viral genome with contrast variation small angle X-ray scattering.

Area of Science:

• Structural biology
• Virology
• Biophysics

Background:

• Single-stranded RNA viruses pose significant health threats, yet their assembly mechanisms remain poorly understood.
• Understanding viral assembly is crucial for developing antiviral strategies and therapies.

Purpose of the Study:

• To introduce and validate a novel technique for observing viral RNA genome packaging and encapsidation.
• To monitor structural dynamics of viral RNA during assembly using a new biophysical tool.

Main Methods:

• Contrast variation small-angle X-ray scattering (CV-SAXS) was employed to exclusively detect the viral RNA signal.
• The structure of encapsidated MS2 RNA was determined using CV-SAXS.
• Cryo-electron microscopy (cryo-EM) reconstructions were used for comparative analysis.

Main Results:

• CV-SAXS successfully detected the structure of encapsidated MS2 RNA, aligning with cryo-EM data.
• Comparisons revealed significant structural rearrangements in RNA upon binding with capsid proteins.
• The study demonstrates the feasibility of using CV-SAXS for viral genome studies.

Conclusions:

• CV-SAXS is a promising tool for studying viral RNA structure and assembly dynamics.
• The technique can reveal critical protein-RNA interactions during viral formation.
• Future applications include time-resolved CV-SAXS to elucidate efficient viral assembly processes.