Gene characterization of E6 and E7 gene of human papillomavirus of 15 cervical cancer in Beijing

Abstract

Conducting the gene characterization of the E6 and E7 gene of human papillomavirus 16 (HPV16) isolated from 15 cases of cervical cancer at Beijing. Overlapping primers were designed according to the full-length genomes of E6 and E7 from the GenBank and PCR was used to amplify the E6 and E7 fragments. TA clone was used to select a purified clone in order to have better and valuable sequencing results. Nucleotide and amino acid sequence were analyzed by the Sequencer, Bioedit, Mega et al. 8 of 15 (8/15) cervical samples contained HPV E6 and E7 gene, and 4 had Asian type like and 4 had Europe prototype like. There were two nucleotide mutation at E6 position 178 (T-->G,D25E) and at E7 position 647 (A-->G, N29S) in 4 Asian type like viruses. There were one nucleotide mutation at E6 position 335 (C-->T, H78Y) in 1 of 4 Europe prototype like virus. In the cervical cancer samples, 8 of 15 contained the HPV16E 6 and E7 gene. HPV16 E6 and E7 can not be detected in denosquamous carcinoma and adenocarcinoma. HPV16 is the main etiology of the cervical carcinoma. The HPV16 infectious ratio of squamous carcinoma is more than the ratio of adenocarcinoma. 178th nucleotide in E6 gene is the very important site to distinguish the Asia and the Europe prototype strain like. 178 nucleotide in E6 and 647 nucleotide in E7 are the frequent mutation site in cervical carcinoma. Analysis based on the E6 and E7 gene sequence of HPV 16 isolates suggests that naturally occurring sequence variants of E6 and E7 gene may have identify the oncogenic properties.