Electron microscopy images and morphometric data of SARS-CoV-2 variants in ultrathin plastic sections.

Conventional thin section electron microscopy of viral pathogens, such as the pandemic SARS-CoV-2, can provide structural information on the virus particle phenotype and its evolution. We recorded about 900 transmission electron microscopy images of different SARS-CoV-2 variants, including Alpha (B.1.1.7), Beta (B.1.351), Delta (B.1.617.2) and Omicron BA.2 (B.1.1.529) and determined various morphometric parameters, such as maximal diameter and spike number, using a previously published measurement method. The datasets of the evolved virus variants were supplemented with images and measurements of the early SARS-CoV-2 isolates Munich929 and Italy-INMI1 to allow direct comparison. Infected Vero cell cultures were cultivated under comparable conditions to produce the viruses for imaging and morphometric analysis. The images and measurements can be used as a basis to analyse the morphometric changes of further evolving viruses at the particle level or for developing automated image processing workflows and analysis.