Abstract
Two pairs of inverted repetitive (palindromic) sequences (IR 1a/b and IR 2a/b) were detected electron microscopically within the DNA of human papilloma virus 1 (HPV-1) after cleavage by
BamHI or
EcoRI endonucleases followed by denaturation and a short period of reassociation. The localization of these sequences within the genome was determined. After separation and isolation of the single HPV-1 DNA strands, IR 1a/b and IR 2a/b were identified by polyacrylamide-gel electrophoresis after prior digestion of the nonhomologous regions with S1 nuclease. The molecular weights of the palindromic sequences were determined to be 0.11 × 10
6 and 0.10 × 10
6.