MAPPING THE IN-VIVO DISTRIBUTION OF HERPES-SIMPLEX VIRIONS

We describe a method for labeling enveloped viral particles with a rad iotracer, indium-lll, allowing labeled viruses to be traced in viveo b y nuclear imaging. After initial optimization experiments, a labeling efficiency of 83% (incorporation yield) was achieved for herpes simple x virus (HSV), resulting in a specific activity of 30 mu Ci/10(9) PFU, The labeling procedure did not significantly reduce the infectivity o f the labeled virus and the virus did not release any significant amou nts of the radionuclide within 12 hr after labeling. Sequential imagin g of animals after intravenous administration of the labeled virus sho wed fast accumulation in the liver and redistribution from the blood p ool (immediately after injection) to liver and spleen (12-24 hr after injection). At 12 hr after injection 7% of the virus-associated In-111 had been eliminated from the body and the remaining organ distributio n of the virus was as follows: spleen 28.7 +/- 5.4% ID/g; liver, 26.0 +/- 5.1% ID/g; kidney, 9.8 +/- 3.1% ID/g; lung, 5.7 +/- 1.0% ID/g; and lower amounts in other organs, Our results indicate that the describe d method allows qualitative and quantitative assessment of viral biodi stribution in vivo by nuclear imaging.