Dark-field focus assay: an improved method for the quantification of transforming retroviruses.
Dark-field optics were used for the counting of foci in cultures infected with transforming retroviruses. This method greatly increases counting efficiency and reduces operator fatigue.
D000818:Animals; D002472:Cell Transformation, Viral; D007708:Kirsten murine sarcoma virus / Q000302:isolation & purification; D008828:Microbiological Techniques; D008858:Microscopy, Phase-Contrast; D012190:Retroviridae / Q000302:isolation & purification*