Properties of Syrian hamster cells transformed by human papillomavirus type 16

Adult Syrian hamster kidney cells were transfected with a mixture of plasmids containing human papillomavirus type 16 (HPV16) E6/E7 open reading frames (ORFs), activated Ha-ras gene and neomycin resistance gene. From these cultures two lines were isolated which were oncogenic for newborn and 5-day-old but not for 3-week-old hamsters. Sublines oncogenic for 3-7-week-old hamsters were derived from tumours formed in animals inoculated within 5 days of birth. The cells contained HPV 16 DNA in an integrated form and HPV16 transcripts. The transcript patterns in low and high oncogenicity sublines were different. Very few tumour-bearing animals possessed antibodies reactive with E6- and E7-derived synthetic peptides. On the other hand a majority of these animals gave a positive reaction in the lymphoproliferation assay with either E6 and E7 peptides or extracts from the transformed cells.