FIG. 6.

Efficiency of the vTR promoter sequences and the endogenous TR promoter sequences in homologous and heterologous systems and in vivo vTR expression. The promoter activity resulting from the transfection of the different viral, avian, murine, and human promoter constructs into avian MDV-infected (PA-5) and noninfected (LMH) cells (A and B), human (HeLa and SupT1), or murine (MEF) cell lines (C and D, respectively) was measured. The results are given as the ratio between the mean luciferase activity of the two promoter constructs considered (mentioned on the x axis or in the legend). (E) The levels of in vivo vTR expression were determined in PBLs collected from three chickens inoculated with the MDV-RB1B oncogenic strain and three chickens inoculated with the vaccine strains (HVT and MDV-Rispens) compared to three noninoculated control chickens. The results are presented as histograms, and the standard deviations are represented by bars.