Safety of retrovirus gene therapy, Temin , 
Figure Legends 
Figure 1. Genome of a safe retrovirus vector and helper cell. The open boxes represent 
modified retrovirus long terminal repeats; the solid lines represent retrovirus 
sequences; the various filled boxes represent other sequences as labeled. R, 
repeat; an R and L, attachment sites; E, encapsidation sequence; PBS and PPT, 
primer sites for reverse transcription; gag, pol, and env are the coding genes of a 
retrovirus. The genomes in the helper cell are not drawn to scale with the vector. 
The inserted gene is oriented in the opposite orientation so a 3’ RNA processing 
sequence could be supplied without inhibiting virus production (see 
Temin, 1986b). 
Figure 2. Replication of a safe retrovirus vector. Shown from top to bottom are DNA of a 
safe retrovirus vector, RNA transcribed from this DNA, the DNA provirus formed 
by infection with this RNA, and RNA transcribed from this provirus. Symbols 
and abbreviations are as described in the legend of Figure 1. 
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Recombinant DNA Research, Volume 12 
