| Objective To sequence and analyze the e6 and e7 sequence of human papillomavirus isolated in cervical cancer and precancerous lesion in China. And discuss HPV16 incidence in cervical disease. Methods Overlapping primers were designed according to the full-length genomes of E6 and E7 from the GenBank. PCR was used to amplify the E6E7 fragments. TA clone was used to select a purified clone in order to have better and valuable sequencing results. Then sequencing was performed and computer software was used to analyze the nucleic data, meanwhile, translate into amino acid sequence and phylogenetic trees were made by Sequencer, Bioedit, Mega et al. Results Twelve of 100 cervical samples contained HPV E6E7 DNA, but only 4(cervical carcinoma, n=4) had Asian type sequence and 8 (CIN, n=2; cervicitis, n=1; cervical carcinoma, n=5) had prototype sequence. The variant with two nucleotide change at E6 position 178 (T→G,D25E) and at E7 position 647 (A→G, N29S) was found in four cervical cancer samples with HPV16.One had a single nucleotide change at E6 position 335 (C→T,H78Y). Two variants from precancerosis were detected , one in a patient with cervicitis and the other in a patient with CIN. Both of them had nucleotide change at E7 position 647 (A→G, N29S).The variant with nucleotide change at E7 position 797 (T→C,L79S) was found in the patient with CIN, and the change at E7 position 832 (T→C,C91R) was found in CIN. 9 of 16 cancer ,2 of 16 CIN (12.5%) ,1 of 68 cervicitis (1.47%) contained HPV 16 E6E7 DNA. Conclusion: HPV16 is the chief cause of the cervical carcinoma .With the pace of the pathology, the proportion of HPV16 infection increases.And HPV16 is not likely the mainly resean of cervicitis.The HPV16 infectious ratio of squamous carcinoma is more than the ratio of adenocarcinoma.Analysis based on the E6E7 genome sequence of HPV 16 isolates suggest that naturally occurring sequence variants of E6 and E7 gene may have different oncogenic properties.
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