Physical Mapping of Temperature-sensitive Mutations of Adenoviruses

Mutants of DNA tumor viruses provide useful materials for analyzing the organization of viral genes and their expression in both the lytic and the transforming cycle. Ideally one would like to arrange for a selection or assay system to obtain mutations in specific regions of the genome; in fact, in some cases it has been possible to take advantage of the biological or physical properties of a virus to isolate specific classes of mutants. Examples of such mutants include the transformed cell-dependent mutants of polyoma (Benjamin 1970), host-range mutants of the adenovirus 2 (Ad2)-simian virus 40 (SV40) hybrid Ad2+ND1 (Grodzicker et al. 1974), and mutants of SV40 whose genomes are not cleaved by restricting endonuclease HpaII (Mertz et al. this volume). In most cases, however, such specific selection systems do not exist, and it is here that the use of conditional lethal mutants, specifically temperature-sensitive (ts) mutants, have been of...