The inGluc-MLV-DERSE plasmid consists of a Gaussia Luciferase (Gluc) sequence oriented in a reverse direction with respect to flanking MLV non-coding sequences. Within the non-coding Gluc sequence is an intron that is oriented in a forward direction relative to the viral non-coding regions (and can be spliced by the host cell). The plasmid is maintained in 293mCAT1 cells. In the absence of RCR, only minus-strand, spliced Gluc sequences are present in the cell. An RCR that infects the DERSE cell can package the RNA containing the minus-strand Gluc sequence. In the next round of infection reverse transcription of the encapsidated RNA produces a double-stranded DNA containing an uninterrupted Gluc gene. This gene is an intact, coding Gluc sequence that is subsequently integrated into the DNA of, and expressed by, the newly infected cell. Expression of Gluc is under the control of the cytomegalovirus (CMV) promoter.