THE OSMIUM AMMINE-SO2 STAINING METHOD FOR STUDYING THE IN-SITU CONFIGURATION OF VIRAL GENOMES IN ULTRATHIN SECTIONS OF DNA VIRUS-INFECTED CELLS

The Feulgen-like osmium ammine-SO, method developed by Cogliati and Ga utier (CR Acad Sci Ser D 1973, 276, 3041-3044) stains the DNA at the u ltrastructural level. Compared to several other techniques for detecti ng DNA, this method remains the only one revealing the configuration o f the DNA molecules within the cell whatever their compactness. In the present article we summarize the results we obtained with the osmium ammine method in the study of the fate of viral genomes along the infe ctious cycles in several DNA virus infected cells including adenovirus , herpes simplex virus, simian virus 40 and poxvirus. The results are discussed in relation to the replicative and transcribing activities o f viral DNA.