Biosafety level‐3 cryo‐electron tomography of active severe acute respiratory syndrome coronavirus 2 virions

Abstract

Understanding the structural properties of pathogenic viruses in their native, infectious state is critical for rational vaccine and drug development. However, conducting cryo-electron microscopy (cryo-EM) under biosafety level 3 (BSL-3) containment presents significant challenges. Here, we established and validated a high-end cryo-EM workflow within a BSL-3 facility, comprehensively integrating facility design, containment measures, sample handling, cryo-transfer systems, and decontamination protocols. To demonstrate the utility and reproducibility of this workflow, we applied cryo-electron tomography to investigate severe acute respiratory syndrome coronavirus 2 in its native, active state. Our observations confirm that unfixed viral particles display pleomorphic features comparable to those previously reported in fixed or inactivated preparations, validating that these structural characteristics represent native features rather than artifacts of chemical fixation. Furthermore, spatial redistribution of surface spikes was observed. The establishment of this robust BSL-3 cryo-EM workflow provides a practical blueprint for the structural characterization of emerging high-consequence pathogens, supporting pandemic preparedness, vaccine development, and antiviral discovery.

The authors' abstract, as published at the source. Protein Science, 2026 · DOI ↗