TABLE 3.

Relative expression of the luciferase gene delivered by U3 deletion and full-length LTR HIV-1 vectors

Target cells	Relative expressiona using the following internal promoter:
	CMVb		PGKc (dividing cells)
	Dividing cells	Gamma-irradiated cellsd
293T	2.39	2.10	2.2
HeLa	0.47	0.82	1.1e
F208	0.47	NDf	0.56
3T3	0.69	0.49	1.09e

^aLuciferase activity (mean from two assays) was plotted against p24, and a linear regression was calculated for each type of vector by using Criketgraph as for Fig. 2. Values are the ratios of the slopes. 

^bStocks of HR′CMVluciferase and HR′CMVluciferaseSIN-18 vectors were prepared in quadruplicate and used to transduce in parallel and in duplicate all four cell types. 

^cStocks of HR′PGKluciferase and HR′PGKluciferaseSIN-18 were prepared in triplicate and used to transduce in parallel and in duplicate all four cell types. 

^dEight thousand rads was delivered by a 3-min exposure to a ⁶⁰Co source. 

^eTransductions by U3 deletion and full-length LTR vectors were not significantly different (by Student’s t test). 

^fND, not determined.