Transmission electron microscopy surveillance of retroviruses in tissue culture cells prepared by the critical-point drying method.

Tissue culture cells grown on grids were processed by the critical-point drying whole-cell method. With the use of a conventional transmission electron microscope operating at 100 kV, this technique permitted visualization of intracytoplasmic organelles of unsectioned whole cells. The morphology of type C virus in the process of budding and also in extracellular locations closely resembled that revealed in thin sections. Prelimininary results of virus surveillance of tissue culture cells prepared by this technique was corroborated by the levels of reverse transcriptase activity in culture media and by immunofluorescence staining of viral antigens on the cell surface.