Mapping of early SV40-specific functions by microinjection of different early viral DNA fragments

DNA sequences within the early simian virus 40 (SV40) genome region responsible for virus-specific tumor (T) and U antigenicity, stimulation of cell DNA synthesis, initiation of late SV40 gene expression and helper function for human adenovirus 2 were confined by experiments using microinjection of different early SV40 DNA fragments. All these early functions were detected in cells supplied with complete early viral information. Cells microinjected with DNA fragments containing about 80, 70 or 60% of thea early SV40 genome were still stained positively when challenged with antibody against T antigen, and the same cells were stimulated for cellular DNA synthesis when about 70% or more of the early viral information was available. DNA sequences at map position 0.67 are required for intracellular early viral transcription.