Complete protection from hepatic neuroblastoma metastases induced by an mTH-based DNA vaccine with posttranscriptionally enhanced gene expression by WPRE and boosts with ch14.18–IL-2.
(A) Mice were immunized twice by oral gavage at 2-week intervals with 108 attenuated salmonella that contained either the empty vector, pcDNA3.1; pcDNA3.1 plus mTH; or pcDNA3.1 plus mTH-WPRE. All animals were injected intravenously with a lethal challenge of 5 × 105 NXS2 wild-type tumor cells 1 week after the second immunization and boosted 2 days thereafter with 10 μg ch14.18–IL-2 for 4 consecutive days. (B) Mice were killed 4 weeks after tumor cell challenge, and hepatic metastases were assessed by liver weight in milligrams and counting of individual metastatic foci. Ruler below images is marked in centimeters.
