A novel mutant of human papillomavirus type 18 E6E7 fusion gene and its transforming activity.

BACKGROUND Persistent human papillomavirus (HPV) infection, especially with high-risk types such as HPV16 and HPV18, has been identified as the primary cause of cervical cancer. E6 and E7 are the major onco-proteins of high-risk HPVs, which are consistently expressed in HPV infected tissues but absent in normal tissues and represent ideal therapeutic targets for immunotherapy of cervical cancer. MATERIALS AND METHODS In this study, the optimized fusion gene HPV18 E6E7 (HPV18 ofE6E7) was constructed according to genetic codon usage for human genes. At the same time, for safety future clinical application, a mutant of HPV18 ofE6E7 fusion gene was generated by site-directed mutagenesis at L52G for the E6 protein and C98G for the E7 protein. RESULTS HPV18-E6E7 mutant (HPV18 ofmE6E7) constructed in this work not only lost the transformation capability for NIH 3T3 cells and tumorigenicity in BALB/c nude mice, but also maintained very good stability and antigenicity. CONCLUSION These results suggest that the mutant should undergo further study for application as a safe antigen- specific therapeutic vaccine for HPV18-associated tumors.