FIG. 1.

Instability of FX-sAd24 complexes results in reduced liver transduction by sAd24-derived vector. (A) The interactions of Ad5 and sAd24 virions with FX were analyzed using surface plasmon resonance. Viral particles bound to the biosensor chip (Ad5 at a coating level of 1,387 resonance units [ru] and sAd24 at 1,699 ru) were probed with soluble FX. Colored lines correspond to the signals obtained in duplicate runs at each tested concentration of FX (blue, 12.5 nM; red, 25 nM; brown, 50 nM; green, 100 nM; and black, 200 nM). As evidenced by the dissociation part of the sensorgrams, the FX-sAd24 complexes were much less stable than the FX-Ad5 complexes. (B) Whole-body images of female nude mice that were injected intravenously (tail vein) with an Ad5- or an sAd24-derived vector, each expressing a dual-modality TL reporter (HSV tk fused with Fluc). Mice injected with 2 × 10¹⁰ VP (upper panels) and 10¹¹ VP (lower panels) of either Ad5TL (left panels) or sAd24TL (right panels) are shown. The intensities of the light signals in the selected regions of interest (red squares) are shown as pseudocolor overlays. Here and in Fig. 8 and 9, the pseudocolor scale shows the signal intensity range. Notably, the relative infectivities of Ad5TL and sAd24TL, which had been determined by the spot assay in 293/Her2 cells in vitro, were 10 VP/infectious units and 53 VP/infectious units, respectively. p/s/cm²/sr, photons/s/cm2/steradian. (C) On the left on each panel, PET images (coronal slices) of Ad-injected animals enabled by ¹⁸F-labeled FEAU are shown. On the right, these PET images are superimposed on the CT images that provide anatomic landmarks. The white-dotted contours show the tracer uptake by the livers (L) and the spleens (S) of the animals. The signals in the bladders (B) are due to physiologic accumulation of the small-molecule tracer in the urine rather than vector-expressed HSV tk activity. The pseudocolor scale between the panels shows the PET signal intensity range, from 0 (black) to 6 times the mean muscle uptake value (white). (D) Activities of Fluc reporter in homogenates of tissue samples collected from mice injected with 2 × 10¹⁰ VP or 10¹¹ VP of either Ad5TL (black bars) or sAd24TL (white bars) is shown. Each bar represents an average signal intensity (shown in relative light units [rlu] per entire organ) measured in organ samples obtained from five animals. Error bars indicate the standard deviations calculated for duplicate data points.