FIGURE 5. Hepatic FPCV retention as function of hepatic HSV1-tk levels. Fifteen adult Swiss Webster mice were injected by tail vein with 0–2.0 x 10⁹ pfu of Ad-CMV-HSV1-tk virus and additional control virus to maintain total viral burden at 2.0 x 10⁹ pfu. Forty-eight (±1) hours later animals received tail vein injection of FPCV. Animals were killed 180 min later. Livers were removed and analyzed for ¹⁸F accumulation. Viral titer vs. FPCV %ID/g liver (left lobe) is shown. Excellent correlation is observed between FPCV %ID/g liver and amount of virus injected.