Nucleotide and amino acid sequence variation in the L1 and E7 open reading frames of human papillomavirus type 6 and type 16.

Human papillomavirus (HPV) type 6 and type 16 DNA sequence variants were found by partially sequencing the L1 and E7 open reading frames, using templates generated with the polymerase chain reaction. Identical variants were found in patients from widely separated locations, such as the United States, the Philippines, and India. The same sequence variants of HPV 16 were found in women with invasive cervical carcinoma and in women with no evidence of disease. Variation in the predicted amino acid sequences of the HPV 16 L1 and E7 proteins was found. A single nucleotide change at position 6433 was found in about 50% of the HPV 16 DNAs, resulting in a change in predicted amino acid sequence from threonine to alanine at the equivalent position in the L1 protein. Predicted amino acid changes were found in the HPV 16 E7 proteins at amino acid positions 28, 29, and 47. Variation at these positions could affect known properties of the E7 protein, including binding to the retinoblastoma protein.