Abstract
By hybridization under stringent conditions, one out of two anal carcinomas and one out of 36 laryngeal carcinomas were shown to harbor HPV 16 DNA in high copy number. Further analysis of both tumor DNAs indicated a rearrangement of the viral DNA in the tumor cells. HPV 16 DNA in the anal carcinoma could chiefly be found episomally in two different forms: (1) a minority as 7.9‐kb oligomeric episomes with no apparent modifications; (2) as 10.7‐kb rearranged oligomeric episomes with a duplication of the part of the viral genome encoding the open reading frames (ORF) E7, E1 and parts of E6 and E2. In the laryngeal carcinoma, integrated and episomal HPV 16 DNA molecules of 7.9 kb were present, together with rearranged molecules of approximately 18 kb with multiple duplications of the ORF E4 and parts of the ORFs E2, E5, L1 and L2. Possible consequences for transcription of the modified viral genomes are discussed.