Combining sample expansion and light sheet microscopy for the volumetric imaging of virus-infected cells with optical super-resolution

Abstract

Expansion microscopy is a sample preparation technique that enables the optical imaging of biological specimens at super-resolution owing to their physical magnification, which is achieved through water-absorbing polymers. The technique uses readily available chemicals and does not require sophisticated equipment, thus offering super-resolution to laboratories that are not microscopy-specialised. Here we present a protocol combining sample expansion with light sheet microscopy to generate high-contrast, high-resolution 3D reconstructions of whole virus-infected cells. The results are superior to those achievable with comparable imaging modalities and reveal details of the infection cycle that are not discernible before expansion. An image resolution of approximately 95 nm could be achieved in samples labelled in 3 colours. We clearly resolve the concentration of viral nucleoprotein on the surface of vesicular structures within the cell and their positioning relative to cellular organelles. We provide detailed guidance and a video protocol for the optimal application of the method and demonstrate its potential to study virus-host cell interactions.