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 degrees 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.