Endogenous reverse transcription of wild type and mutant viruses. The endogenous reverse transcription assay was performed as described in the Materials and Methods. Autoradiography was used to identify radioactive areas, and the individual areas were excised and the radiation was quantitated using a scintillation counter. The values presented were then normalized to the levels of virus as determined by p24 antigen ELISA. The total reaction time was for 60 minutes with samples being assayed at 1, 5, 15, 30 and 60 minutes. The order of the samples are HXB2-Met(i) (rectangles), HXB2-Met(e) (squares) and HXB2-WT (solid bars). Data is representative from three independent experiments.