Targeting of biotinylated compounds to its target tissue using a low-density lipoprotein receptor–avidin fusion protein

The very high binding affinity of avidin to biotin is one of the highest to occur in nature. We constructed a fusion protein composed of avidin and the endocytotic LDL receptor in order to target biotinylated molecules to cells of the desired tissues. In addition to the native avidin, charge-mutated and nonglycosylated avidins were utilized as part of the fusion proteins, in order to modify its properties. All of the fusion protein versions retained the biotin-binding capacity. Although the specificity was not increased, however, fusion proteins composed of natural avidin and nonglycosylated avidin bound most efficiently to the biotinylated ligands. Fluorescence microscopy and atomic force …

Magnetic resonance imaging of viral particle biodistribution in vivo

We describe here a technique for the visualization of viral vector delivery by magnetic resonance imaging (MRI) in vivo. By conjugating avidin-coated baculoviral vectors (Baavi) with biotinylated ultra-small superparamagnetic iron oxide particles (USPIO), we are able to produce vector-related MRI contrast in the choroid plexus cells of rat brain in vivo over a period of 14 days. Ten microlitres of 2.5 x 10(10) PFU/ml nuclear-targeted LacZ-encoding Baavi with bUSPIO coating was injected into rat brain ventricles and visualized by MRI at 4.7 T. As baculoviruses exhibit restricted cell-type specificity in the rat brain, altered MRI contrast was detected in the choroid plexus of the injected ve…

CMR 2005: 12.06: Ultra-small iron oxide nanoparticle (USPIO)-labeled baculoviruses as novel MRI agents for imaging viral vector biodistributionin vivo