Cheung Ying-Kit, Cheng Samuel Chak-Sum, Sin Fion Wan-Yee, Xie Yong
Department of Biology, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China.
Vaccine. 2004 Dec 16;23(5):629-38. doi: 10.1016/j.vaccine.2004.07.010.
Human papillomavirus Type 16 (HPV16) infections can cause neoplasia, which is thought to be closely associated with the development of cervical cancers. In the study, we attempted to construct a DNA plasmid encoding a HPV16 capsid protein (L1) and a HPV16 oncoprotein (E7), which was capable of preventing HPV16 infection and eliminating HPV16-infected cells. A plasmid, L1E7hpSCA1, encoding the L1 and E7 genes with the codon usage optimized for mammalian cell expression, was constructed. Mutations were introduced into the E7 gene sequence for reducing its oncogenicity. C57BL/6 mice were intramuscularly immunized at tibialis anterior (TA) muscles with the newly constructed L1E7hpSCA1 plasmid. The immune responses induced by the L1E7hpSCA1 plasmid (with codon optimization) and a control L1E7pSCA1 plasmid (without codon optimization) were compared. It is shown that the L1E7hpSCA1 was able to induce much stronger immune responses than the L1E7pSCA1. Sera obtained from immunized animals were found to contain anti-HPV16 antibodies as detected by ELISA and hemagglutination inhibition (HAI) assays. Cytotoxicity and interferon-gamma assays showed that spleenocytes from immunized animals were able to recognize and lyze E7 expressing tumor TC-1 cells. Moreover, the growth of E7 expressing tumor mass was inhibited in vaccinated mice. In vivo tumor protection test indicated that tumor formation was prevented in the experimental animals (67%) after vaccination with L1E7hpSCA1, while for the control group injected with L1E7pSCA1 only and the animal group injected with pSCA1 only, tumor formation was observed in all experimental animals. Our results suggest that the L1E7h gene (with codon optimization) is more effective against HPV16 than the L1E7 gene (without codon optimization). The L1E7hpSCA1 plasmid was able to provide protection against E7 expressing tumor, and it might have the potential to be a vaccine candidate for HPV prevention.
16型人乳头瘤病毒（HPV16）感染可引发肿瘤形成，人们认为这与宫颈癌的发生密切相关。在本研究中，我们试图构建一种DNA质粒，该质粒编码HPV16衣壳蛋白（L1）和HPV16癌蛋白（E7），能够预防HPV16感染并清除HPV16感染的细胞。构建了一种质粒L1E7hpSCA1，其编码的L1和E7基因的密码子使用情况针对哺乳动物细胞表达进行了优化。对E7基因序列进行了突变，以降低其致癌性。将新构建的L1E7hpSCA1质粒经胫骨前（TA）肌肉对C57BL/6小鼠进行肌肉注射免疫。比较了L1E7hpSCA1质粒（密码子优化）和对照L1E7pSCA1质粒（未进行密码子优化）诱导的免疫反应。结果表明，L1E7hpSCA1能够诱导比L1E7pSCA1更强的免疫反应。通过ELISA和血凝抑制（HAI）试验检测发现，免疫动物血清中含有抗HPV16抗体。细胞毒性和干扰素-γ试验表明，免疫动物的脾细胞能够识别并裂解表达E7的肿瘤TC-1细胞。此外，接种疫苗的小鼠中表达E7的肿瘤块生长受到抑制。体内肿瘤保护试验表明，用L1E7hpSCA1接种疫苗后，实验动物（67%）的肿瘤形成得到预防，而仅注射L1E7pSCA1的对照组和仅注射pSCA1的动物组中，所有实验动物均观察到肿瘤形成。我们的结果表明，L1E7h基因（密码子优化）比L1E7基因（未进行密码子优化）对HPV16更有效。L1E7hpSCA1质粒能够提供针对表达E7肿瘤的保护，并且可能有潜力成为预防HPV的候选疫苗。
