| Human Papillomavirus (HPV) is human double-stranded DNA tumor virus. Human Papillomavirus Type 16 (HPV16), is high-risk HPV which infection in the genital tract with is very common. Epidemiological data and laboratory research demonstrate the relationship between HPV and occurrence and development of human malignant tumor sufficiently, especially high relationship between HPV16 and cervical cancer. HPV 16 and 18 cause up to ~90% of cervical cancers. In China, the occurrence of cervical cancer is highly associated with HPV 16. Therefore, a vaccine is necessary urgently needed to prevent or treat HPV 16 infection and HPV 16-associated diseases, so as to decrease the infection rate of HPV 16 and death rate of HPV 16-associated tumor patients.HPVs are difficult to propagate ex vivo culture or to infect species other than humans. So the strategy of HPV vaccine focuses on genetic engineering techniques. Molecular biological studies indicate that the capsid of HPV consists of L1 proteins and L2 proteins. The L1 proteins alone are sufficient enough to form virus-like particles (VLP), which play important roles in humoral immune and cellular immune response. So we choose VLP assembled from HPV 16 L1 proteins as candidate vaccine against HPV infection and HPV-associated disease.The primary amino acid sequences of L1 protein may affect the formation of thethree-dimension structure------VLP: some L1 variant proteins only formedcapsomeres, resulting in changes of their immunogenicity. So it is necessary to screen L1 gene used for vaccine production. The L1 proteins, which expressed in E.coli, are not able to form VLPs. Even if some little VLPs are formed by complicated operations such as denaturalization, naturalization, re-denaturalization, re-naturalization, the re-naturalization rate is poorly low (0.02-0.04%). It is obviously unsuitable for vaccine development and research; also it is difficult to...
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