Electron microscopy of virus particles in ultrathin frozen sections

A procedure with the use of polyethylene glycol (PEG) 600 to support biological materials for ultracryotomy was developed. Developing and mature virions were demonstrated by electron microscopy in negatively stained frozen sections of vaccinia virus-infected human diploid cells and of herpes simplex virus (HSV) type 1 infected primary rabbit kidney cells. Approximate localisation of the virus particles in the cells was possible.