Herpes Simplex Virus-Cell Interactions Studied by Low-Fading Contrasted Immunofluorescence

The low-fading immunofluorescence with propidium iodide contrast described here is recommended for light and confocal viral antigen identification and other cell biology studies because: (1 ) it is a simple, rapid, sensitive, and reproducible technique; (2 ) phase-contrast microscopy is unnecessary; (3 ) contrast is optimal without blurring the fluorescent labeling; (4 ) autofluorescence is minimal, even in fixed cells; (5 ) background staining is minimal; (6 ) fading is invisible for at least 5-min exposures, even in preparations with weak antigen presentation; (7 ) fluorescence is stable after storage in the dark at -20�C; (8 ) fluorochromes are small-sized markers without steric hindrance; and (9 ) there is no need for silver enhancement or substrate solutions, which increase the risk of diffusion and other artifacts.