Enhanced neuroblastoma transduction for an improved antitumor vaccine.
BACKGROUND
A recent clinical trial of an antineuroblastoma vaccine used adenovirus serotype 5 (Ad5) vectors to transduce autologous tumor cells with the gene encoding IL-2. A method to improve transduction efficiency was sought to enable the use of lower viral titers, especially when in situ adenoviral-mediated tumor cell transduction is considered.


METHODS
A chimeric adenoviral delivery vector was utilized in which the fiber head from adenovirus serotype 3 was incorporated into the backbone of Ad5. Since the fiber head protein is responsible for viral attachment to target cells, a different spectrum and range of infectivity might result. Both the chimeric (Av9LacZ4) and Ad5 (Av1LacZ4) vectors were constructed to carry a beta-galactosidase transgene. The relative transduction efficiency of these two vectors was then evaluated in five tumor-derived short-term neuroblastoma cultures and four established neuroblastoma cell lines. Enzyme activity was assessed using three different methods: in situ staining, flow cytometric analysis, and a quantitative assay.


RESULTS
A significant improvement in transduction efficiency of the short-term neuroblastoma cultures with the new chimeric adenovector was demonstrated. A similar improvement in transduction efficiency was not observed in the established cell lines, suggesting that the cell surface receptor for the Ad 3 serotype had been lost in vitro. Increased transduction of tumor cells with N-myc amplification was also observed.


CONCLUSIONS
The newly constructed chimeric adenoviral vector transduces short-term neuroblastoma cultures more efficiently than the standard Ad5 vector. This vector will permit the use of lower viral titers and may be useful in other adenoviral-based gene-therapy protocols. Increased transgene expression in N-myc-amplified cells offers possible selectivity for in situ gene delivery.
D000260:Adenoviruses, Human; D019496:Cancer Vaccines; D005784:Gene Amplification; D016259:Genes, myc; D005822:Genetic Vectors; D006801:Humans; D007376:Interleukin-2 / Q000096:biosynthesis / Q000235:genetics*; D009447:Neuroblastoma / Q000276:immunology*; D016271:Proto-Oncogene Proteins c-myc / Q000096:biosynthesis / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D014162:Transfection / Q000379:methods; D014407:Tumor Cells, Cultured; D014614:Vaccines, Synthetic; D001616:beta-Galactosidase / Q000096:biosynthesis / Q000235:genetics