Baculoviruses and mammalian cell-based assays for drug screening.

Publisher Summary A few years ago, a new use for recombinant baculoviruses was revealed with the appearance of two publications demonstrating the delivery of recombinant gene expression cassettes containing reporter genes under control of mammalian cell-active promoters to mammalian cells primarily of liver origin. Subsequent work has shown that a number of cell types are susceptible to transduction. This system, referred to as “BacMam,” has found utility in a number of laboratories. This chapter focuses on the application of BacMam for configuring cell-based assays for automated screening of chemical libraries. Examples have been provided here from a wide range of target molecules demonstrating that the ease and versatility of BacMam-mediated gene delivery make it an excellent alternative to stable cell lines for the development of cell-based assays for drug screening. Inhibitors of histone deacetylase have been shown to enhance levels of gene expression in BacMam-transduced CHO cells, as have transcriptional transactivators that act on the CMV promoter. The report of an avian adenovirus gene product that acts as a histone deacetylase inhibitor and enhances gene expression in CHO cells suggests that modifications may be made to CHO cells to obtain new derivatives that act as efficient hosts for BacMam transduction. BacMam affords the ability to tailor an assay to better mimic a response seen in native tissues. The chapter shows that transduction of primary cells with BacMam viruses that direct the expression of a selectable marker and immortalization genes, such as large T antigen, may provide an efficient and gentle method to establish cell lines from primary tissues. Implementing BacMam-based assays on a large scale requires attention to the logistical considerations associated with handling of large numbers of biological agents discussed in this chapter. These considerations include: optimized virus production methods, reproducible virus titration, quality control assays, long-term storage/inventory systems, and distribution.