Objective To determine the function of human papillomavirus (HPV) E7 in DNA damage response of cervical intraepithelial neoplasia (CIN) Ⅲ cells. Methods Samples of CIN Ⅲ and child foreskin tissues were collected, with pathologically confirmed HPV positive and negative, respectively. Collagenase A was used for digesting tissues prior to primary culture. The HPV negative cells were infected with lentivirus E7 and pLV. Proteins (53BP1, NBS1, BRCA1 and RPA32) responsive to DNA double break damages were detected by indirect immunofluorescent staining after 0-8 h treatment with X-ray (2 or 5 Gy). Results After treatment with 2 or 5 Gy X-ray, 53BP1, NBS1, BRCA1 and RPA32 foci in HPV+ cells increased compared with HPV- cells (P5) were found in E7 infected cells than in pLV infected cells (P
