Table 1.

Transducing activities of lentivirus vectors made with and without a functional tat gene in the packaging constructa

Transfer vectorTarget cellsMean transducing activity (TU/ng of p24) ± SEb
Withtat in packaging constructWithout tat in packaging construct
pHR′CMV-LacZ293T1,056 ± 54152 ± 26
pHR′CMV-LuciferaseHeLa3,000 ± 152152 ± 26
HeLa-tat3,777 ± 348486 ± 59
pHR′Luciferasec HeLa46 ± 10.3 ± 0.003
HeLa-tat3,296 ± 276174 ± 75
  • a Vectors were produced by transfection of the indicated transfer vector, a packaging construct either with (pCMVΔR8.91) or without (pCMVΔR8.93) a functional tatgene, and plasmid pMD.G into 293T cells. Serial dilutions of transfectant conditioned medium were incubated with the indicated cells, and the cultures were scored after 3 days. For calculating transduction activity, samples were selected from the linear portion of the vector dose-response curve.

  • b LacZ transduction was measured by 5-bromo-4-chloro-3-indolyl-β-d-galactopyranoside (X-Gal) staining and by expression of the number of blue cell colonies as a function of the amount of p24 antigen in the inoculum. eGFP transduction was measured by FACS analysis, multiplying the fraction of fluorescent cells by the number of infected cells, and expressing the result as a function of the amount of p24 antigen in the inoculum. Luciferase transduction was measured by luminescence in RLU above background of 50 μl of culture extract and dividing the number of RLU × 10−2 by the number of nanograms of p24 antigen in the inoculum. Means of duplicate (pHR2 PGK-eGFP) or triplicate (all other constructs) determinations are shown.

  • c Without internal promoter.