Transformation with specific fragments of adenovirus DNAs. I. Isolation of specific fragments with transforming activity of adenovirus 2 and 5 DNA

DNA of human adenoviruses 2 and 5 was cleaved by the restriction endonucleases Hsu I, Bam HI, Hpa I, and Sma I. The resulting fragments were separated and tested for their ability to transform primary baby rat kidney (BRK) cells, using the calcium technique. Fragments with transforming activity were obtained with endo's R·Eco RI (fragments A), Bam HI (fragments B of Ad2 and A of Ad5 DNA), and Hsu I (fragments G). The transforming fragments all represented the left terminal fragments of the respective restriction endonuclease cleavage products. The smallest fragment found to contain transforming activity was the Hsu I G fragment (molecular weight 1.7 · 10 6 for both Ad2 and Ad5 DNA). Transforming activity of both adeno DNAs was abolished by digestion with endo's R·Hpa I and Sma I. This indicated that these enzymes cleave into an area essential for transformation. A number of cell lines transformed by restriction endonuclease fragments were established and some of their properties were studied. All adeno DNA fragment-transformed lines were found to grow to only a very low level in 0.33% agarose medium (cloning efficiency Hsu I G-transformed cells, however, was atypical and differed from the usual pattern, in that the fluorencence was largely localized in the cytoplasm. Selection of Hsu I G-transformed cells in 0.33% agarose medium resulted in cell populations containing the typical adenovirus T antigen pattern.